2021/10/20 更新

写真a

オカザキ ケイイチ
岡崎 桂一
OKAZAKI Keiichi
所属
教育研究院 自然科学系 農学系列 教授
農学部 教授
職名
教授
外部リンク

学位

  • 農学博士 ( 1986年3月   東北大学 )

研究キーワード

  • Plant Breeding

  • 植物育種

研究分野

  • 環境・農学 / 遺伝育種科学

経歴(researchmap)

  • 新潟大学農学部   Faculty of Agriculture   教授

    2009年8月 - 現在

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  • 新潟大学農学部   Faculty of Agriculture   准教授

    2008年5月 - 2009年7月

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  • 新潟大学農学部   Faculty of Agriculture   助教授

    2000年7月 - 2008年4月

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  • 新潟大学農学部   Faculty of Agriculture   助手

    1994年10月 - 2000年6月

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  • 富山県農業技術センター野菜花き試験場

    1986年4月 - 1994年9月

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経歴

  • 新潟大学   農学部   教授

    2018年4月 - 現在

学歴

  • 東北大学   農学研究科   農学専攻博士課程(農学博士)

    1983年4月 - 1986年3月

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    国名: 日本国

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  • 東北大学

    - 1986年

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  • 東北大学   農学研究科   農学専攻修士課程

    1981年4月 - 1983年3月

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    国名: 日本国

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  • 新潟大学   農学部   農学科

    1977年4月 - 1981年3月

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    国名: 日本国

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所属学協会

 

論文

  • Gene Expression Analysis in Response to Vernalization in Chinese Cabbage (<i>Brassica rapa</i> L.) 査読

    Ayasha Akter, Junji Miyazaki, Daniel J. Shea, Namiko Nishida, Satoko Takada, Naomi Miyaji, Hasan Mehraj, Motoki Shimizu, Md. Asad-ud Doullah, Takeshi Takasaki-Yasuda, Keiichi Okazaki, Ryo Fujimoto

    The Horticulture Journal   89 ( 3 )   268 - 277   2020年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Society for Horticultural Science  

    DOI: 10.2503/hortj.utd-150

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  • Comparison of Cold Responses for Orthologs of Cabbage Vernalization-related Genes 査読

    Etsuko Itabashi, Daniel J. Shea, Nobuko Fukino, Ryo Fujimoto, Keiichi Okazaki, Tomohiro Kakizaki, Takayoshi Ohara

    The Horticulture Journal   88 ( 4 )   462 - 470   2019年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • The role of FRIGIDA and FLOWERING LOCUS C genes in flowering time of Brassica rapa leafy vegetables. 査読

    Takada S, Akter A, Itabashi E, Nishida N, Shea DJ, Miyaji N, Mehraj H, Osabe K, Shimizu M, Takasaki-Yasuda T, Kakizaki T, Okazaki K, Dennis ES, Fujimoto R

    Scientific Reports   9 ( 1 )   13843   2019年9月

  • Allele specific DNA marker for fusarium resistance gene FocBo1 in Brassica oleracea 査読

    Maho Sato, Motoki Shimizu, Daniel J. Shea, Mozammel Hoque, Takahiro Kawanabe, Naomi Miyaji, Ryo Fujimoto, Eigo Fukai, Keiichi Okazaki

    Breeding Science   69   308 - 315   2019年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Long noncoding RNAs in Brassica rapa L. following vernalization. 査読

    Shea DJ, Nishida N, Takada S, Itabashi E, Takahashi S, Akter A, Miyaji N, Osabe K, Mehraj H, Shimizu M, Seki M, Kakizaki T, Okazaki K, Dennis ES, Fujimoto R

    Scientific Reports   9 ( 1 )   9302   2019年6月

  • How Brassica oleracea FLOWERING LOCUS C 2 works in Brassica rapa genetic background 招待

    Namiko Nishida, Daniel J. Shea, Keiichi Okazaki, Ryo Fujimoto

    AusCanola 2018 Proceedings E-book   127 - 131   2018年9月

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    記述言語:英語  

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  • Genome re-sequencing, SNP analysis, and genetic mapping of the parental lines of a commercial F-1 hybrid cultivar of Chinese cabbage 査読

    Daniel J. Shea, Motoki Shimizu, Etsuko Itabashi, Naomi Miyaji, Junji Miyazaki, Kenji Osabe, Makoto Kaji, Keiichi Okazaki, Ryo Fujimoto

    BREEDING SCIENCE   68 ( 3 )   375 - 380   2018年6月

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    記述言語:英語   出版者・発行元:JAPANESE SOC BREEDING  

    The genome-wide characterization of single nucleotide polymorphism (SNP) between cultivars or between inbred lines contributes to the creation of genetic markers that are important for plant breeding. Functional markers derived from polymorphisms within genes that affect phenotypic variation are especially valuable in plant breeding. Here, we report on the genome re-sequencing and analysis of the two parental inbred lines of the commercial F-1 hybrid Chinese cabbage cultivar "W77". Through the genome-wide identification and classification of the SNPs and indels present in each parental line, we identified about 1,500 putative nonfunctional genes in each parent. We designed cleaved amplified polymorphic sequence (CAPS) markers using specific mutations found at Eco RI restriction sites in the parental lines and confirmed their Mendelian segregation by constructing a linkage map using 96 F-2 plants derived from the F-1 hybrid cultivar, "W77". Our results and data will be a useful genomic resource for future studies of gene function and metagenomic studies in Chinese cabbage.

    DOI: 10.1270/jsbbs.17124

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  • The production and characterization of a <i>BoFLC2</i> introgressed <i>Brassica rapa</i> by repeated backcrossing to an F<sub>1</sub>. 査読

    Shea DJ, Tomaru Y, Itabashi E, Nakamura Y, Miyazaki T, Kakizaki T, Naher TN, Shimizu M, Fujimoto R, Fukai E, Okazaki K

    Breeding science   68 ( 3 )   316 - 325   2018年6月

  • Breeding of lilies and tulips—interspecific hybridization and genetic background— 査読

    Agnieszka Marasek-Ciolakowska, Tomotaro Nishikawa, Daniel J. Shea, Keiichi Okazaki

    Breeding Science   68 ( 1 )   35 - 52   2018年

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    記述言語:英語   出版者・発行元:Japanese Society of Breeding  

    Lilies and tulips (Liliaceae family) are economically very important ornamental bulbous plants. Here, we summarize major breeding goals, the role of an integrated method of cut-style pollination and fertilization followed by embryo rescue and mitotic and meiotic polyploidization involved in new assortment development. Both crops have been subjected to extensive interspecific hybridization followed by selection. Additionally, spontaneous polyploidization has played a role in their evolution. In lilies, there is a tendency to replace diploids with polyploid cultivars, whereas in tulip a majority of the cultivars that exist today are still diploid except for triploid Darwin hybrid tulips. The introduction of molecular cytogenetic techniques such as genomic in situ hybridization (GISH) permitted the detailed studies of genome composition in lily and tulip interspecific hybrids and to follow the chromosome inheritance in interspecific crosses. In addition, this review presents the latest information on phylogenetic relationship in lily and tulip and recent developments in molecular mapping using different DNA molecular techniques.

    DOI: 10.1270/jsbbs.17097

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  • The role of FLOWERING LOCUS C in vernalization of Brassica: The importance of vernalization research in the face of climate change

    Daniel J. Shea, Etsuko Itabashi, Satoko Takada, Eigo Fukai, Tomohiro Kakizaki, Ryo Fujimoto, Keiichi Okazaki

    Crop and Pasture Science   69 ( 1 )   30 - 39   2018年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:CSIRO  

    As climatic changes occur over the coming decades, our scientific understanding of plant responses to environmental cues will become an increasingly important consideration in the breeding of agricultural crops. This review provides a summary of the literature regarding vernalization research in Brassicaceae, covering both the historical origins of vernalization research and current understanding of the molecular mechanisms behind the regulatory pathways involved in vernalization and subsequent inflorescence. We discuss the evolutionarily conserved biology between the model organism Arabidopsis thaliana and the Brassica genus of crop cultivars and contrast the differences between the genera to illustrate the importance of Brassica-specific research into vernalization.

    DOI: 10.1071/CP16468

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  • Comparison of transcriptome profiles by Fusarium oxysporum inoculation between Fusarium yellows resistant and susceptible lines in Brassica rapa L. 査読

    Naomi Miyaji, Motoki Shimizu, Junji Miyazaki, Kenji Osabe, Maho Sato, Yusuke Ebe, Satoko Takada, Makoto Kaji, Elizabeth S. Dennis, Ryo Fujimoto, Keiichi Okazaki

    PLANT CELL REPORTS   36 ( 12 )   1841 - 1854   2017年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Resistant and susceptible lines in Brassica rapa have different immune responses against Fusarium oxysporum inoculation.Fusarium yellows caused by Fusarium oxysporum f. sp. conglutinans (Foc) is an important disease of Brassicaceae; however, the mechanism of how host plants respond to Foc is still unknown. By comparing with and without Foc inoculation in both resistant and susceptible lines of Chinese cabbage (Brassica rapa var. pekinensis), we identified differentially expressed genes (DEGs) between the bulked inoculated (6, 12, 24, and 72 h after inoculation (HAI)) and non-inoculated samples. Most of the DEGs were up-regulated by Foc inoculation. Quantitative real-time RT-PCR showed that most up-regulated genes increased their expression levels from 24 HAI. An independent transcriptome analysis at 24 and 72 HAI was performed in resistant and susceptible lines. GO analysis using up-regulated genes at 24 HAI indicated that Foc inoculation activated systemic acquired resistance (SAR) in resistant lines and tryptophan biosynthetic process and responses to chitin and ethylene in susceptible lines. By contrast, GO analysis using up-regulated genes at 72 HAI showed the overrepresentation of some categories for the defense response in susceptible lines but not in the resistant lines. We also compared DEGs between B. rapa and Arabidopsis thaliana after F. oxysporum inoculation at the same time point, and identified genes related to defense response that were up-regulated in the resistant lines of Chinese cabbage and A. thaliana. Particular genes that changed expression levels overlapped between the two species, suggesting that they are candidates for genes involved in the resistance mechanisms against F. oxysporum.

    DOI: 10.1007/s00299-017-2198-9

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  • IntroMap: a signal analysis based method for the detection of genomic introgressions 査読

    Daniel J. Shea, Motoki Shimizu, Namiko Nishida, Eigo Fukai, Takashi Abe, Ryo Fujimoto, Keiichi Okazaki

    BMC GENETICS   18 ( 1 )   101   2017年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BIOMED CENTRAL LTD  

    Background: Breeding programs often rely on marker-assisted tests or variant calling of next generation sequence (NGS) data to identify regions of genomic introgression arising from the hybridization of two plant species. In this paper we present IntroMap, a bioinformatics pipeline for the screening of candidate plants through the application of signal processing techniques to NGS data, using alignment to a reference genome sequence (annotation is not required) that shares homology with the recurrent parental cultivar, and without the need for de novo assembly of the read data or variant calling.
    Results: We show the accurate identification of introgressed genomic regions using both in silico simulated genomes, and a hybridized cultivar data set using our pipeline. Additionally we show, through targeted marker-based assays, validation of the IntroMap predicted regions for the hybrid cultivar.
    Conclusions: This approach can be used to automate the screening of large populations, reducing the time and labor required, and can improve the accuracy of the detection of introgressed regions in comparison to a marker-based approach. In contrast to other approaches that generally rely upon a variant calling step, our method achieves accurate identification of introgressed regions without variant calling, relying solely upon alignment.

    DOI: 10.1186/s12863-017-0568-5

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  • QTL mapping for tuberous stem formation of kohlrabi (Brassica oleracea var. gongylodes L.)

    Mozammel Hoque, Daniel J. Shea, Mitsuru Asada, Md. Asad-ud-Doullah, Motoki Shimizu, Ryo Fujimoto, Eigo Fukai, Keiichi Okazaki

    MOLECULAR BREEDING   37 ( 9 )   2017年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The tuberous stem of kohlrabi is an important quantitative trait, which affects its yield and quality. Genetic control of this trait has not yet been unveiled. To identify the QTLs controlling stem swelling of kohlrabi, a BC 1 population of 92 plants was developed from a cross of broccoli DH line GCP04 and kohlrabi var. Seine. A wide range of variation in tuberous stem diameter was observed among the mapping populations. We constructed a genetic map of nine linkage groups (LGs) with different types of markers, spanning a total length of 913.5 cM with an average marker distance of 7.55 cM. Four significant QTLs for radial enlargement of kohlrabi stem, namely, REnBo1, REnBo2, REnBo3, and REnBo4 were detected on C02, C03, C05, and C09, respectively, and accounted for the phenotypic variation of 59% for the stem diameter and 55% for the qualitative grading of tuberous stem in classes. Then, we confirmed the stability of identified QTLs using BC1S1 populations derived from the BC1 plants having heterozygous alleles at the target QTL and homozygous kohlrabi alleles at the remaining QTLs. REnBo1 and REnBo2 using 128 plants of BC(1)68S(1) and 94 plants of BC(1)43S(1), respectively, and REnBo3 and REnBo4 using 152 plants of BC(1)57S(1) were detected at the same positions as the respective QTLs of the BC1 population. Confirmation of QTLs in two successive generations indicates that the QTLs are persistent. The QTLs obtained in this study could be useful in marker-assisted selection of kohlrabi breeding, and to understand the genetic mechanisms of stem swelling and storage organ development in kohlrabi and other Brassica species.

    DOI: 10.1007/s11032-017-0709-6

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  • Assessment of DNA markers for seed contamination testing and selection of disease resistance in cabbage

    Kazutaka Kawamura, Motoki Shimizu, Takahiro Kawanabe, Zujing Pu, Taro Kodama, Makoto Kaji, Kenji Osabe, Ryo Fujimoto, Keiichi Okazaki

    EUPHYTICA   213 ( 1 )   2017年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Cabbage (Brassica oleracea L. var. capitata) is an important vegetable worldwide. Most Japanese commercial cultivars of cabbage use an F-1 hybrid seed production system. The purity of F-1 hybrid seeds is important and the assessment of purity based on DNA markers can be highly accurate. In addition, selection of agronomically important traits such as disease resistance based on DNA markers is useful for breeding of cabbage. The aim of this study is to demonstrate the effectiveness of DNA marker-assisted selection in cabbage. In this study we distinguished the parental S haplotypes in 35 F-1 hybrid cultivars by combining several linked DNA markers. Thirty-one highly polymorphic simple sequence repeats (SSR) markers were screened from 175 reported SSR markers, which are useful for assessment of the purity of F-1 hybrid seeds. We examined the relationship between the DNA marker based genotype and the phenotype by an inoculation test of clubroot disease. A co-dominant PCR-RFLP marker was developed for selection of Fusarium yellows resistance and the genotypes using this marker were consistent with inoculation test in all tested samples.

    DOI: 10.1007/s10681-016-1821-0

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  • Identification of the Fusarium yellows resistance genes; its application for marker-assisted selection in Brassica rapa

    Naomi Miyaji, Motoki Shimizu, Satoko Takada, Takeshi Takasaki-Yasuda, Makoto Kaji, Kenji Osabe, Elizabeth S. Dennis, Keiichi Okazaki, Ryo Fujimoto

    Brassica 2016 Abstract Book   185 - 190   2016年10月

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    記述言語:英語  

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  • Marker-assisted selection of low erucic acid quantity in short duration Brassica rapa

    Md. Masud Karim, Nazmoon Naher Tonu, Mohammad Shakhawat Hossain, Taketo Funaki, M. Bahadur Meah, Delwar M. Hossain, M. Asad ud-Doullah, Eigo Fukai, Keiichi Okazaki

    EUPHYTICA   208 ( 3 )   535 - 544   2016年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Low erucic acid (LEA) rapeseed, which has accumulated mutant fatty acid elongase genes at the BnFAE1.1 and BnFAE1.2 loci of the A- and C-genome, respectively, is an important oilseed crop. Short growing turnip rape (B. rapa) is also important as a catch crop in the continuous cropping of rice in Asia but there is no LEA B. rapa cultivar for cultivation in South Asia. In order to develop LEA turnip rape cultivars, high erucic acid turnip rape cultivars were interspecifically crossed as recurrent parents to a canola quality rapeseed. In the meantime, we monitored incorporation of the mutant bnfae1.1 (e1) gene into A-genome of turnip rape, using a dCAPS primer pair, which can amplify PCR fragment only for the mutant e1 gene from A-genome. The early backcross progenies showed poor seed set, but which was improved in advanced progenies. Finally, homozygous e1e1 genotypes were established in the selfed progenies of BC2-BC3, and their LEA content was confirmed by gas-chromatography analysis. Our results and promising lines will contribute to LEA-trait selection in turnip rape and rapeseed breeding.

    DOI: 10.1007/s10681-015-1596-8

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  • Genetic distance of inbred lines of Chinese cabbage and its relationship to heterosis

    Kazutaka Kawamura, Takahiro Kawanabe, Motoki Shimizu, Atsushi J. Nagano, Natsumi Saeki, Keiichi Okazaki, Makoto Kaji, Elizabeth S. Dennis, Kenji Osabe, Ryo Fujimoto

    Plant Gene   5   1 - 7   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier B.V.  

    Chinese cabbage (Brassica rapa L. var. pekinensis) is an important vegetable in Asia. Most Japanese commercial cultivars of Chinese cabbage use an F1 hybrid seed production system because of the high yielding cultivars produced. An efficient method for predicting hybrid performance in the parental generations is desired, and genetic distance between parental lines might be a good indicator of the level of hybrid vigor in a cross. Information concerning the genetic relationships among parental candidate inbred lines is useful for variety protection. The number of DNA markers available that can be used to assess the purity of inbred lines is limited in B. rapa. The aim of this study is to use DNA markers to assess the genetic distance between inbred lines to examine early developmental and yield heterosis so as to develop methods for selecting the best parental lines for the production of hybrids. We screened highly polymorphic SSR and CAPS markers to assess the genetic uniformity of inbred lines and characterize their genetic relationship. We examined the early size and yield heterosis in 32 F1 hybrids of Chinese cabbage. There was a moderate correlation in mid-parent heterosis between leaf size at 21 days after sowing and harvested biomass but not in best-parent heterosis. In contrast there was no correlation between genetic distance and mid-parent or best-parent heterosis, indicating that genetic distance does not predict the heterosis phenotype.

    DOI: 10.1016/j.plgene.2015.10.003

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  • Genetic characterization of inbred lines of Chinese cabbage by DNA markers; towards the application of DNA markers to breeding of F1 hybrid cultivars 査読

    Kazutaka Kawamura, Takahiro Kawanabe, Motoki Shimizu, Keiichi Okazaki, Makoto Kaji, Elizabeth S. Dennis, Kenji Osabe, Ryo Fujimoto

    Data in Brief   6   229 - 237   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier Inc.  

    Chinese cabbage (Brassica rapa L. var. pekinensis) is an important vegetable in Asia, and most Japanese commercial cultivars of Chinese cabbage use an F1 hybrid seed production system. Self-incompatibility is successfully used for the production of F1 hybrid seeds in B. rapa vegetables to avoid contamination by non-hybrid seeds, and the strength of self-incompatibility is important for harvesting a highly pure F1 seeds. Prediction of agronomically important traits such as disease resistance based on DNA markers is useful. In this dataset, we identified the S haplotypes by DNA markers and evaluated the strength of self-incompatibility in Chinese cabbage inbred lines. The data described the predicted disease resistance to Fusarium yellows or clubroot in 22 Chinese cabbage inbred lines using gene associated or gene linked DNA markers.

    DOI: 10.1016/j.dib.2015.11.058

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  • Changes in the Proteome of Xylem Sap in Brassica oleracea in Response to Fusarium oxysporum Stress 査読

    Zijing Pu, Yoko Ino, Yayoi Kimura, Asumi Tago, Motoki Shimizu, Satoshi Natsume, Yoshitaka Sano, Ryo Fujimoto, Kentaro Kaneko, Daniel J. Shea, Eigo Fukai, Shin-Ichi Fuji, Hisashi Hirano, Keiichi Okazaki

    FRONTIERS IN PLANT SCIENCE   7   31   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:FRONTIERS MEDIA SA  

    Fusarium oxysporum f.sp. conlutinans (Foc) is a serious root-invading and xylem-colonizing fungus that causes yellowing in Brassica oleracea. To comprehensively understand the interaction between F oxysporum and B. oleracea, composition of the xylem sap proteome of the non-infected and Foc-infected plants was investigated in both resistant and susceptible cultivars using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after in-solution digestion of xylem sap proteins. Whole genome sequencing of Foc was carried out and generated a predicted Foc protein database. The predicted Foc protein database was then combined with the public B. oleracea and B. rapa protein databases downloaded from Uniprot and used for protein identification. About 200 plant proteins were identified in the xylem sap of susceptible and resistant plants. Comparison between the non-infected and Foc-infected samples revealed that Foc infection causes changes to the protein composition in B. oleracea xylem sap where repressed proteins accounted for a greater proportion than those of induced in both the susceptible and resistant reactions. The analysis on the proteins with concentration change 2-fold indicated a large portion of up- and down-regulated proteins were those acting on carbohydrates. Proteins with leucine-rich repeats and legume lectin domains were mainly induced in both resistant and susceptible system, so was the case of thaumatins. Twenty-five Foc proteins were identified in the infected xylem sap and 10 of them were cysteine-containing secreted small proteins that are good candidates for virulence and/or avirulence effectors. The findings of differential response of protein contents in the xylem sap between the non-infected and Foc-infected samples as well as the Foc candidate effectors secreted in xylem provide valuable insights into B. oleracea-Foc interactions.

    DOI: 10.3389/fpls.2016.00031

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  • Molecular and cellular characteristics of hybrid vigour in a commercial hybrid of Chinese cabbage 査読

    Natsumi Saeki, Takahiro Kawanabe, Hua Ying, Motoki Shimizu, Mikiko Kojima, Hiroshi Abe, Keiichi Okazaki, Makoto Kaji, Jennifer M. Taylor, Hitoshi Sakakibara, W. James Peacock, Elizabeth S. Dennis, Ryo Fujimoto

    BMC PLANT BIOLOGY   16   45   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BIOMED CENTRAL LTD  

    Background: Heterosis or hybrid vigour is a phenomenon in which hybrid progeny exhibit superior performance compared to their parental inbred lines. Most commercial Chinese cabbage cultivars are F-1 hybrids and their level of hybrid vigour is of critical importance and is a key selection criterion in the breeding system.
    Results: We have characterized the heterotic phenotype of one F-1 hybrid cultivar of Chinese cabbage and its parental lines from early- to late-developmental stages of the plants. Hybrid cotyledons are larger than those of the parents at 4 days after sowing and biomass in the hybrid, determined by the fresh weight of leaves, is greater than that of the larger parent line by approximately 20 % at 14 days after sowing. The final yield of the hybrid harvested at 63 days after sowing is 25 % greater than the yield of the better parent. The larger leaves of the hybrid are a consequence of increased cell size and number of the photosynthetic palisade mesophyll cells and other leaf cells. The accumulation of plant hormones in the F-1 was within the range of the parental levels at both 2 and 10 days after sowing. Two days after sowing, the expression levels of chloroplast-targeted genes in the cotyledon cells were upregulated in the F-1 hybrid relative to their mid parent values. Shutdown of chlorophyll biosynthesis in the cotyledon by norflurazon prevented the increased leaf area in the F-1 hybrid.
    Conclusions: In the cotyledons of F-1 hybrids, chloroplast-targeted genes were upregulated at 2 days after sowing. The increased activity levels of this group of genes suggested that their differential transcription levels could be important for establishing early heterosis but the increased transcription levels were transient. Inhibition of the photosynthetic process in the cotyledon reduced heterosis in later seedling stages. These observations suggest early developmental events in the germinating seedling of the hybrid may be important for later developmental vigour and yield advantage.

    DOI: 10.1186/s12870-016-0734-3

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  • Development of primer sets that can verify the enrichment of histone modifications, and their application to examining vernalization-mediated chromatin changes in Brassica rapa L. 査読

    Takahiro Kawanabe, Kenji Osabe, Etsuko Itabashi, Keiichi Okazaki, Elizabeth S. Dennis, Ryo Fujimoto

    GENES & GENETIC SYSTEMS   91 ( 1 )   1 - 10   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:GENETICS SOC JAPAN  

    Epigenetic regulation is crucial for the development of plants and for adaptation to a changing environment. Recently, genome-wide profiles of histone modifications have been determined by a combination of chromatin immunoprecipitation (ChIP) and genomic tiling arrays (ChIP on chip) or ChIP and high-throughput sequencing (ChIP-seq) in species including Arabidopsis thaliana, rice and maize. Validation of ChIP analysis by PCR or qPCR using positive and negative regions of histone modification is necessary. In contrast, information about histone modifications is limited in Chinese cabbage, Brassica rapa. The aim of this study was to develop positive and negative control primer sets for H3K4me3 (trimethylation of the 4th lysine of H3), H3K9me2, H3K27me3 and H3K36me3 in B. rapa. The expression and histone modification of four FLC paralogs in B. rapa, before and after vernalization, were examined using the method developed here. After vernalization, expression of all four BrFLC genes was reduced, and accumulation of H3K27me3 was observed in three of them. As with A. thaliana, the vernalization response and stability of FLC repression correlated with the accumulation of H3K27me3. These results suggest that the epigenetic state during vernalization is important for high bolting resistance in B. rapa. The positive and negative control primer sets developed here revealed positive and negative histone modifications in B. rapa that can be used as a control for future studies.

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  • Map-based cloning of a candidate gene conferring Fusarium yellows resistance in Brassica oleracea

    Motoki Shimizu, Zi-jing Pu, Takahiro Kawanabe, Hiroyasu Kitashiba, Satoru Matsumoto, Yusuke Ebe, Monari Sano, Taketo Funaki, Eigo Fukai, Ryo Fujimoto, Keiichi Okazaki

    THEORETICAL AND APPLIED GENETICS   128 ( 1 )   119 - 130   2015年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We identified the candidate gene conferring yellow wilt resistance (YR) in B. oleracea . This work will facilitate YR breeding programs for B. oleracea and its closely related species.
    Yellow wilt disease is one of the most serious diseases of cabbage worldwide. Type A resistance to the disease is controlled by a single dominant gene that is used in cabbage breeding. Our previous QTL study identified the FocBo1 locus controlling type A resistance. In this study, the FocBo1 locus was fine-mapped by using 139 recombinant F-2 plants derived from resistant cabbage (AnjuP01) and susceptible broccoli (GCP04) DH lines. As a result, we successfully delimited the location of FocBo1 within 1.00 cM between markers, BoInd 2 and BoInd 11. Analysis of BAC and cosmid sequences corresponding to the FocBo1 locus identified an orthologous gene of Bra012688 that was recently identified as an candidate gene that confers yellows resistance in Chinese cabbage. The candidate gene-specific DNA markers and phenotypes in F-1 cabbage cultivars and their selfed F-2 populations showed a perfect correlation. Our identification of the candidate gene for FocBo1 will assist introduction of fusarium resistance into B. oleracea cultivars and contribute further understanding of interaction between Brassica plants and fusarium.

    DOI: 10.1007/s00122-014-2416-6

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  • Identification of candidate genes for fusarium yellows resistance in Chinese cabbage by differential expression analysis

    Motoki Shimizu, Ryo Fujimoto, Hua Ying, Zi-jing Pu, Yusuke Ebe, Takahiro Kawanabe, Natsumi Saeki, Jennifer M. Taylor, Makoto Kaji, Elizabeth S. Dennis, Keiichi Okazaki

    PLANT MOLECULAR BIOLOGY   85 ( 3 )   247 - 257   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Fusarium yellows caused by Fusarium oxysporum f. sp. conglutinans is an important disease of Brassica worldwide. To identify a resistance (R) gene against Fusarium yellows in Chinese cabbage (Brassica rapa var. pekinensis), we analyzed differential expression at the whole genome level between resistant and susceptible inbred lines using RNA sequencing. Four hundred and eighteen genes were significantly differentially expressed, and these were enriched for genes involved in response to stress or stimulus. Seven dominant DNA markers at putative R-genes were identified. Presence and absence of the sequence of the putative R-genes, Bra012688 and Bra012689, correlated with the resistance of six inbred lines and susceptibility of four inbred lines, respectively. In F-2 populations derived from crosses between resistant and susceptible inbred lines, presence of Bra012688 and Bra012689 cosegregated with resistance, suggesting that Bra012688 and Bra012689 are good candidates for fusarium yellows resistance in Chinese cabbage.

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  • Production of high yield short duration Brassica napus by interspecific hybridization between B. oleracea and B. rapa

    Md. Masud Karim, Asfakun Siddika, Nazmoon Naher Tonu, Delwar M. Hossain, Md. Bahadur Meah, Takahiro Kawanabe, Ryo Fujimoto, Keiichi Okazaki

    BREEDING SCIENCE   63 ( 5 )   495 - 502   2014年1月

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    記述言語:英語   出版者・発行元:JAPANESE SOC BREEDING  

    Brassica napus is a leading oilseed crop throughout many parts of the world. It is well adapted to long day photoperiods, however, it does not adapt well to short day subtropical regions. Short duration B. nap us plants were resynthesized through ovary culture from interspecific crosses in which B. rapa cultivars were reciprocally crossed with B. oleracea. From five different combinations, 17 hybrid plants were obtained in both directions. By self-pollinating the F-1 hybrids or introgressing them with cultivated B. napus, resynthesized (RS) F-3 and semi-resynthesized (SRS) F-2 generations were produced, respectively. In field trial in Bangladesh, the RS B. napus plants demonstrated variation in days to first flowering ranging from 29 to 73 days; some of which were similar to cultivated short duration B. napus, but not cultivated short duration B. rapa. The RS and SRS B. napus lines produced 2-4.6 and 1.6-3.7 times higher yields, respectively, as compared to cultivated short duration B. napus. Our developed RS lines may be useful for rapeseed breeding not only for subtropical regions, but also for areas such as Canada and Europe where spring rapeseed production can suffer from late spring frosts. Yield and earliness in RS lines are discussed.

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  • Accumulation of quantitative trait loci conferring broad-spectrum clubroot resistance in Brassica oleracea

    Hiroya Tomita, Motoki Shimizu, Md Asad-ud Doullah, Ryo Fujimoto, Keiichi Okazaki

    MOLECULAR BREEDING   32 ( 4 )   889 - 900   2013年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Throughout the world, clubroot disease is one of the most damaging diseases affecting Brassica oleracea. To develop marker-assisted selection (MAS) that could assist the incorporation of durable clubroot resistance (CR) into cultivars, previous genetic analyses have identified several CR quantitative trait loci (CR-QTL). However, the independent and cumulative effects of each CR locus against various isolates have rarely been tested. Previously, we identified one major CR-QTL and four minor CR-QTL in the F2 plants from broccoli doubled haploid (DH) line x cabbage DH line of B. oleracea. In the present study, to clarify their effectiveness for controlling disease involving various isolates, inoculation testing was conducted in genotypes with various combinations of the CR genes, which were selected using the DNA markers closely associated with each CR-QTL. In exploring the overall disease incidence, it was apparent that a single involvement of the major CR gene located in the PbBo(Anju)1 locus, or accumulation of CR genes in the minor CR-QTL, is not enough to confer sufficient resistance. One major CR gene in the QTL PbBo(Anju)1 locus plus two to three minor CR genes conferred moderate resistance. The genotype in which all of the CR genes locating in the five QTL including PbBo(Anju)1 were accumulated showed the highest resistance, and it was broadly resistant against six isolates. Accumulation of several CR genes by MAS is necessary to conduct CR breeding in B. oleracea. Our developed DNA markers can be used efficiently to make selections of required loci for the acquisition of resistance, and use of these markers will be a powerful tool for CR breeding in B. oleracea.

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  • Comparison of Positions of QTLs Conferring Resistance to Xanthomonas campestris pv. campestris in Brassica oleracea 査読

    TONU NAZMOON NAHER, DOULLAH MD. ASAD-UD, SHIMIZU MOTOKI, KARIM MD. MASUD, KAWANABE TAKAHIRO, FUJIMOTO RYO, OKAZAKI KEIICHI

    American Journal of Plant Sciences   4 ( 8 )   11 - 20   2013年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Scientific Research  

    Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is possibly the most important disease of Brassica worldwide. To compare chromosomal positions of Xcc resistance loci in Brassica oleracea between the present and published studies and to develop marker assisted selection (MAS) to resistance against Xcc race 1, we constructed a B. oleracea map, including pW, pX an

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  • Genetic mapping of a fusarium wilt resistance gene in Brassica oleracea

    Zi-jing Pu, Motoki Shimizu, Yan-ju Zhang, Tomohiko Nagaoka, Takeshi Hayashi, Hidetaka Hori, Satoru Matsumoto, Ryo Fujimoto, Keiichi Okazaki

    MOLECULAR BREEDING   30 ( 2 )   809 - 818   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Fusarium wilt caused by Fusarium oxysporum f. sp. conglutinans is one of the most important diseases of Brassica crops, resulting in severe reductions in yield and quality. To characterize the inheritance pattern of fusarium resistance, a cross between a susceptible broccoli and a resistant cabbage was subjected to segregation analysis. Results indicated that resistance was controlled by a single dominant allele. This gene was named Foc-Bo1 and mapped to linkage group seven (O7) by both the segregation test and quantitative trait locus (QTL) analysis. The QTL on O7 was detected with a logarithm of odds score (LOD) of 19.5, which was above the threshold value with genome-wide 1% significance level (2.01). A minor QTL was also detected on O4 with a LOD score of 2.06. Inoculation tests indicated that stable expression of fusarium resistance at high temperatures required Foc-Bo1 homozygosity. The association between Foc-Bo1 and the closest simple sequence repeat marker (KBrS003O1N10) was analyzed in three F3 populations. Based on these studies, KBrS003O1N10 represents an effective marker-assisted selection (MAS) tool for breeding fusarium wilt resistance into Brassica oleracea crops. To our knowledge, this is the first paper to map the fusarium-resistance gene in Brassica species and to validate the effectiveness of MAS in improving fusarium resistance in these important plants.

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  • Multiple Mechanisms and Challenges for the Application of Allopolyploidy in Plants 査読

    Kenji Osabe, Takahiro Kawanabe, Taku Sasaki, Ryo Ishikawa, Keiichi Okazaki, Elizabeth S. Dennis, Tomohiko Kazama, Ryo Fujimoto

    International Journal of Molecular Sciences   13 ( 7 )   8696 - 8721   2012年7月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:MDPI AG  

    DOI: 10.3390/ijms13078696

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  • Application of nitrous oxide gas as a polyploidizing agent in tulip and lily breeding

    Keiichi Okazaki, Shotarou Nukui, Hideaki Ootuka

    Floriculture and Ornamental Biotechnology   6   39 - 43   2012年1月

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    Nitrous oxide has been successfully applied to zygotes as a polyploidizing agent in various crops. More recently nitrous oxide treatments have been applied at male gamete formation resulting in production of diploid gametes in tulips and lilies. Additionally this treatment can be used to overcome pollen sterility of interspecific hybrids via polyploidization of archesporial cells in developing anthers. This paper provides a review of some of the literature and results of our experiments using nitrous oxide for chromosome doubling of gametes and zygotes, as well as pollen mother cells to overcome pollen sterility of the interspecific hybrids. These methods have important implications for lily and tulip breeding. ?2012 Global Science Books.

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  • Phylogenetic Analysis of Wild and Garden Tulips Using Sequences of Chloroplast DNA

    R. Yanagisawa, T. Kuhara, T. Nishikawa, D. Sochacki, A. Marasek-Ciolakowska, K. Okazaki

    XXIV INTERNATIONAL EUCARPIA SYMPOSIUM SECTION ORNAMENTALS: ORNAMENTAL BREEDING WORLDWIDE   953   103 - 110   2012年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:INT SOC HORTICULTURAL SCIENCE  

    Coding regions of trnL and matK and intergenic spacer (IGS) region of trnT-L in chloroplast were sequenced to analyze phylogenetic relationship of the genus Tulipa, including 27 cultivars, and 32 species tulips, by using Amana edulis as an outgroup. 12 variable sites out of 421 base pairs (bps) in the trnL, 19 variable sites out of 834 bps in the matK, and 62 variable sites out of 733 bps in the trnT-L are detected, indicating that the trnL has evolved more slowly and less informative for the classification. Five types of the sequences were identified in the trnL, 14 types in the matK and 20 types in the trnT-L IGS. The obtained results were summarized as follows. Clusianae subsection can be distinguished from Leiostemones and Eriostemones sections. Although T. praestans and T. tubergeniana are included in Eichleres section in the traditional classification, the two species are not sister relationships with Eichleres section in molecular phylogeny. Eichleres subsection except for T. praestans and T. tubergeniana is monophyletic and closely related to the species of Tulipa section. The garden tulips were divided the three groups. Group A included T. tubergeniana, T. schrenkii and 'Duc van Tol' tulips including 'Keizerskroon', indicating that T. schrenkii is contributed to the production of 'Duc van Tol' tulips. Group C included 10 cultivars such as 'Faust' and 'Zulu' which were recorded in the 19th century, indicating that cultivars included in Group C originated from a very old common progenitor of the ancestral cultivar and species. B group included 13 cultivars of T. gesneriana, T. acuminata, T. marjoretti and T. praecox, supporting a hypothesis that T. acuminata and T. marjoretti contributed to develop garden tulips. Our present data, while very informative, could not identify what species contributes to the large variability of late flowering tulips such as 'Darwin' and 'Cottage'.

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  • Multiple mechanisms and challenges for the application of allopolyploidy in plants

    Kenji Osabe, Takahiro Kawanabe, Taku Sasaki, Ryo Ishikawa, Keiichi Okazaki, Elizabeth S. Dennis, Tomohiko Kazama, Ryo Fujimoto

    International Journal of Molecular Sciences   13 ( 7 )   8696 - 8721   2012年

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    記述言語:英語   出版者・発行元:MDPI AG  

    An allopolyploid is an individual having two or more complete sets of chromosomes derived from different species. Generation of allopolyploids might be rare because of the need to overcome limitations such as co-existing populations of parental lines, overcoming hybrid incompatibility, gametic non-reduction, and the requirement for chromosome doubling. However, allopolyploids are widely observed among plant species, so allopolyploids have succeeded in overcoming these limitations and may have a selective advantage. As techniques for making allopolyploids are developed, we can compare transcription, genome organization, and epigenetic modifications between synthesized allopolyploids and their direct parental lines or between several generations of allopolyploids. It has been suggested that divergence of transcription caused either genetically or epigenetically, which can contribute to plant phenotype, is important for the adaptation of allopolyploids. © 2012 by the authors
    licensee MDPI, Basel, Switzerland.

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  • N2O induces mitotic polyploidization in anther somatic cells and restores fertility in sterile interspecific hybrid lilies

    Shotarou Nukui, Satomi Kitamura, Tomoyo Hioki, Hideaki Ootsuka, Kazumitsu Miyoshi, Takao Satou, Yuka Takatori, Tomo Oomiya, Keiichi Okazaki

    BREEDING SCIENCE   61 ( 4 )   327 - 337   2011年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPANESE SOC BREEDING  

    Fertile plants undergoing male gametogenesis can be treated with nitrous oxide (N2O) gas to obtain 2n male gametes. N2O treatment is also expected to restore the fertility of interspecific hybrids through meiotic restitution or mitotic amphidiploidization. However, this technique has few applications to date, and it is unknown how N2O treatment restores fertility in sterile hybrids. To establish optimal N2O treatment conditions and determine its cytological mechanism of action, we treated various sized floral buds with N2O gas at different anther developmental stages from fertile and sterile hybrid lilies. N2O treatment using the optimal 1-4 mm floral buds induced mitotic polyploidization of male archesporial cells to produce 2n pollen in fertile hybrid lilies. In sterile hybrid lilies, N2O treatment doubled the chromosome number in male archesporial cells followed by homologous chromosome pairing and normal meiosis in pollen mother cells (PMC), resulting in restoration of pollen fertility. Backcrossing the resultant fertile pollen to Lilium x formolongi produced many triploid BC1 plants. Thus N2O treatment at the archesporial cell proliferating stage effectively overcame pollen sterility in hybrid lilies, resulting in fertile, 2n pollen grains that could produce progeny. The procedure presented here will promote interspecific or interploidy hybridization of lilies.

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  • Midgut juice of Plutella xylostella highly resistant to Bacillus thuringiensis Cry1Ac contains a three times larger amount of glucosinolate sulfatase which binds to Cry1Ac compared to that of susceptible strain

    Takanori Yamazaki, Toshiki Ishikawa, Ganesh N. Pandian, Keiichi Okazaki, Kohsuke Haginoya, Yuka Tachikawa, Toshiaki Mitsui, Kazuhisa Miyamoto, Chanan Angusthanasombat, Hidetaka Hori

    PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY   101 ( 2 )   125 - 131   2011年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    Midgut juice of Plutella xylostella strain PXR which is resistant to Cry1Ac was biochemically characterized relative to the susceptible PXS strain. The midgut juice of PXR (PXR-Juice) was shown to process Cry1Ac protoxin to 60 kDa active toxin with the same processing pattern as that of juice from PXS (PXS-Juice) in SOS-PAGE. PXS larvae which were given the Cry1Ac toxin pre-processed with PXR-Juice were killed with the same rate as that with Cry1Ac pre-activated by trypsin. PXR-Juice was found to contain three times larger amount of 66 kDa protein (P66) than PXS-Juice and the N-terminal amino acid sequence of P66 was matched to that of glucosinolate sulfatase in data base search. The protein band of P66 was coincided with the band of p-nitro phenyl sulfatase activity in zymogram. P66 purified to homogeneity in SOS-PAGE bound to Cry1Ac and soybean agglutinin, and K-D for Cry1Ac was estimated to be 718 nM with surface plasmon resonance analysis. Using purified sulfatase, K-m and V-max were estimated and involvement of the enzyme in the PXR resistance was discussed. (C) 2011 Elsevier Inc. All rights reserved.

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  • Ethylene production during clubroot development in turnip

    T.Ishikawa, K. Okazaki, K. Itoh, T. Mitsui, H. Hori

    新潟大学農学部研究報告   63 ( 2 )   83 - 87   2011年3月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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  • Isoform-Specific Localization of Brassica rapa Nitrilases in Root Infected with Plasmodiophora brassicae Revealed Using In Situ Hybridization Probes Improved with Locked Nucleic Acids

    Toshiki Ishikawa, Keiichi Okazaki, Tomohiko Nagaoka, Kimiko Itoh, Toshiaki Mitsui, Hidetaka Hori

    JOURNAL OF PLANT GROWTH REGULATION   29 ( 2 )   210 - 222   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We established an in situ hybridization (ISH) technique by modification of hybridization probes with locked nucleic acids (LNAs) and demonstrated isoform-specific localization of transcripts of Brassica rapa nitrilase (BrNIT-T) genes in clubroot tissue infected with Plasmodiophora brassicae. Chimeric oligo DNA probes containing LNAs demonstrated highly improved specificities and could discriminate between BrNIT-T1 and BrNIT-T2. These LNA-containing probes were applied to ISH. BrNIT-T1 was strongly expressed in cells containing expanding secondary plasmodia of P. brassicae, but not in cells containing resting spores. On the other hand, BrNIT-T2 transcripts were localized in noninfected cells rather than infected cells during the clubroot growth phase but coexisted with mature resting spores at a later phase of clubroot development. Immunostaining for indole-3-acetic acid (IAA) revealed IAA accumulation in cells containing growing plasmodia. IAA immunostaining in infected cells was reduced as the pathogen formed resting spores, but the signal was again enhanced in cells containing mature resting spores at a later phase of infection, suggesting that IAA is involved in both the early growth and the latest maturation phase of clubroot development. Expression of BrNIT-T1 and BrNIT-T2 in turnip roots was upregulated by exogenous treatment with cytokinin and jasmonic acid, respectively. Thus, these two phytohormones are possible triggers of abnormal IAA production in clubroot tissue via induction of the respective nitrilase. Given these results, we propose a model for isoform-specific roles of B. rapa nitrilases in auxin biosynthesis involved in phytohormone crosstalk during development of clubroot disease.

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  • Identification of QTLs that control clubroot resistance in Brassica oleracea and comparative analysis of clubroot resistance genes between B. rapa and B. oleracea

    T. Nagaoka, M. A. U. Doullah, S. Matsumoto, S. Kawasaki, T. Ishikawa, H. Hori, K. Okazaki

    THEORETICAL AND APPLIED GENETICS   120 ( 7 )   1335 - 1346   2010年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    To perform comparative studies of CR (clubroot resistance) loci in Brassica oleracea and Brassica rapa and to develop marker-assisted selection in B. oleracea, we constructed a B. oleracea map, including specific markers linked to CR genes of B. rapa. We also analyzed CR-QTLs using the mean phenotypes of F(3) progenies from the cross of a resistant double-haploid line (Anju) with a susceptible double-haploid line (GC). In the nine linkage groups obtained (O1-O9), the major QTL, pb-Bo(Anju)1, was derived from Anju with a maximum LOD score (13.7) in O2. The QTL (LOD 5.1) located in O5, pb-Bo(GC)1, was derived from the susceptible GC. Other QTLs with smaller effects were found in O2, O3, and O7. Based on common markers, it was possible to compare our finding CR-QTLs with the B. oleracea CR loci reported by previous authors; pb-Bo(GC)1 may be identical to the CR-QTL reported previously or a different member contained in the same CR gene cluster. In total, the markers linked to seven B. rapa CR genes were mapped on the B. oleracea map. Based on the mapping position and markers of the CR genes, informative comparative studies of CR loci between B. oleracea and B. rapa were performed. Our map discloses specific primer sequences linked to CR genes and includes public SSR markers that will promote pyramiding CR genes in intra- and inter-specific crosses in Brassica crops. Five genes involved in glucosinolates biosynthesis were also mapped, and GSL-BoELONG and GSL-BoPro were found to be linked to the pb-Bo(Anju)1 and Bo(GC)1 loci, respectively. The linkage drag associated with the CR-QTLs is briefly discussed.

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  • Synthesis of high quality probe using locked nucleic acid (LNA) and exploitation for ISH

    T. Ishikawa, K. Okazaki, K. Itoh, T. Mitsui, H. Hori

    Bulletin of the Faculty of Agriculture, Niigata University   63 ( 1 )   35 - 39   2010年3月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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  • Induction of 2n gametes and 4n embryo in Lilium (Lilium × formolongi hort.) by nitrous oxide gas treatment

    T. Sato, K. Miyoshi, K. Okazaki

    Acta Horticulturae   855   243 - 247   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    The effect of nitrous oxide gas (N2O) treatment on the induction of 2n male gametes and 4n embryo in Lilium × formolongi hort. was examined. Lilium × formolongi hort. is an artificial hybrid between Lilium longiflorum Thunb. and Lilium formosanum Wall. In general the members in the genus Lilium are propagated vegetatively. However, Lilium × formolongi hort. is exceptionally propagated by seeds and blooms 6-8 months after sowing. Seeds of Lilium × formolongi hort. cultivars &#039;Raizan&#039; was sown in a plastic tray with 200 holes on 5 February 2008 and seedlings bearing 2-3 leaves were transplanted in 10.5 cm (in diameter) pots on 5 May, grown under ambient conditions in a green house. When the first flower bud of each plant were reached 15-30 mm in length, these buds were sampled consecutively and observed by the aceto-carmine squash method to determine the meiotic stage of pollen mother cells. The buds ranging from 19-23 mm in length contained pollen grains at prophase I to tetrad. Immediately after the staging of pollen grains, plants with the buds in the same length were treated with N2O gas for 48h at 6 atm at room temperature. The diameter of mature pollen grains in metaphase, obtained from the plants with buds of 22 mm in length at the time of exposure to N2O gas, ranged from 76 to 169 μm, although those from untreated ones ranged from 62 to 95 μm. For the induction of 4n embryo, plants were treated with N2O gas for 72h at 6 atm 13 days after the pollination. Plants with pollinated ovaries grew visually normal after the treatment with N2O gas and these capsules were harvested 75-85 days after pollination. We obtained many plantlets from these capsules. Of 49 randomly selected seedlings, 22 were revealed to be tetraploid by flow cytometry. We could demonstrate that N2O gas treatment was useful for the manipulation of both male gamete as well as zygotic embryo for breeding Lilium × formolongi on polyploid level.

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  • EVALUATION OF RESISTANCE IN Brassica rapa TO DARK POD SPOT (Alternaria brassicicola) USING THE IN VITRO DETACHED POD ASSAY

    M. A. U. Doullah, M. B. Meah, G. M. Mohsin, A. Hassan, T. Ikeda, H. Hori, K. Okazaki

    SABRAO JOURNAL OF BREEDING AND GENETICS   41 ( 2 )   101 - 113   2009年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:EMILUZ PRINTING INDUSTRIES INC  

    Alternaria brassicicola is a common virulent seed-borne fungal pathogen globally found in Brassica crops. Various factors for inoculation of detached pods were studied using several Brassica rapa genotypes to identify resistance in the pod setting stage of B. rapa cultivars. Optimal conditions for pod inoculation were (1) inoculum concentration of 5 x 10(3) conidia/ml, (2) incubation temperature of 20-25 degrees C, and (3) a 48-h waiting period post inoculation using 25-day-old pods. A pod screening test using 43 cultivars of B. rapa effectively distinguished various levels of resistance between cultivars. As a result, we identified cultivars viz &apos;Yajima kabu&apos;, &apos;Saishin&apos; and &apos;Shimofusa kabu&apos; as resistant. The resistant B. rapa cultivars are useful not only for B. rapa breeding, but also for breeding programs for other Brassica species, such as B. napus, which is derived from B. rapa and B. oleracea and has little genetic variation due to the limited size of the descendent population.

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  • Mechanism of action of nitrous oxide gas applied as a polyploidizing agent during meiosis in lilies

    Satomi Kitamura, Masako Akutsu, Keiichi Okazaki

    SEXUAL PLANT REPRODUCTION   22 ( 1 )   9 - 14   2009年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Nitrous oxide gas (N(2)O) can be used to produce polyploid plants, but the mechanism of action is unknown. The actin and microtubule cytoskeleton was observed in N(2)O-treated microsporocytes of Lilium spp &apos;Asiatic hybrid lilies&apos; using fluorescence microscopy after staining with DAPI, FITC-conjugated tubulin antibody, and phalloidin-conjugated Alexa Fluor 546. Additionally, microsporocytes of L. longiflorum were observed with acetocarmine staining following N(2)O treatment. A typical metaphase I microtubule distribution was observed in control microsporocytes. After treatment with N(2)O for 24 h, microtubules were effectively depolymerized; this prevented chromosomes from moving to the poles, resulting in chromosome retention in the center of N(2)O-treated cells. Cell plate formation took place without delay, however, yielding one daughter cell with a diploid genome and another daughter without chromosomes. In addition, N(2)O treatment often induced micronuclei due to aberrant chromosome separation during cytokinesis. Actin filaments in microsporocytes are insensitive to N(2)O. These findings indicate that N(2)O mediates polyploidization by inhibiting microtubule polymerization, but not actin filament formation, during microsporocyte meiosis.

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  • Diploid endosperm formation in Tulipa spp. and identification of a 1:1 maternal-to-paternal genome ratio in endosperms of T-gesneriana L.

    Hitoshi Mizuochi, Hironori Matsuzaki, Takehiko Moue, Keiichi Okazaki

    SEXUAL PLANT REPRODUCTION   22 ( 1 )   27 - 36   2009年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Most Liliaceae plants have the tetrasporic Fritillaria-type embryo sac and normally form diploid embryos and pentaploid endosperms derived from a 4:1 maternal-to-paternal genome ratio (4m:1p) after double fertilization. Here we characterize embryo sac and endosperm formation in Tulipa spp. of Liliaceae. Chromosome analysis using seeds derived from 2x x 2x crosses of Tulipa gesneriana (2n = 2x = 24) identified diploid chromosome number in the endosperm. Similarly, flow cytometric analysis confirmed diploid endosperm formation in T. gesneriana, T. fosteriana (2n = 2x = 24) and T. greigii (2n = 2x = 24). To further study the possible mechanism of diploid endosperm formation, we made interploidy crosses of triploid (2n = 3x = 36) x diploid in which aneuploid seeds with various chromosome numbers (2n = 25-36) were produced. Again, flow cytometric analysis confirmed the same ploidy level in both embryos and endosperms at all aneuploidy levels, suggesting that only a single haploid polar nucleus contributes to endosperm formation at fertilization. Histological observation further confirmed the physical separation of two polar nuclei by a large vacuole in the Fritillaria-type embryo sac of T. gesneriana that appeared to prevent the fusion of the two polar nuclei that originated at the micropylar and chalazal ends before fertilization. Taken together, these results indicate that diploid endosperms (1m:1p) are normally formed in Tulipa spp. by fusion of the micropylar polar nucleus (n) and a spermatid (n) but not by normal triple fusion. We also show that tulip endosperm partially overcomes the triploid block mechanism that occurs in interploidy crosses. Based on these observations, the possible role of triple nuclear fusion in double fertilization is discussed.

    DOI: 10.1007/s00497-008-0088-6

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  • Analysis of introgression of the Tulipa fosteriana genome into Tulipa gesneriana using GISH and FISH

    Agnieszka Marasek, Keiichi Okazaki

    EUPHYTICA   160 ( 2 )   217 - 230   2008年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Southern hybridization and genomic in situ hybridization (GISH) have demonstrated that 'Purissima' (2n = 2x = 24) is an interspecific hybrid comprised of one genome of Tulipa (T.) gesneriana and one genome of T. fosteriana. Backcrossing T. gesneriana with 'Purissima' was partially successful. Simultaneous GISH and fluorescence in situ hybridization (FISH) distinguished chromosomes from both parent genomes, as well as recombinant chromosomes, in interspecific hybrids and their progeny. Chromosome recombination was observed in all cultivars except 'Purissima' and 'Kouki' (2n = 3x = 36). 'Kouki' (2n = 3x = 36) had two genomes of the T. gesneriana and a single genome of the T. fosteriana. The number of nonrecombinant T. fosteriana chromosomes in 'Judith Leyster' (2n = 4x = 48) and 'Purissima' progeny varied from two in 'Hatsuzakura' to six in 'Kikomachi' and 'Momotaro'. The number and type of recombinant chromosomes also differed among cultivars. The total number of translocations ranged from one in 'Kikomachi' to six in 'Hatsuzakura'. Each was a combination of a single T. fosteriana fragment and a single T. gesneriana fragment, indicating that they resulted from a single crossover event. Sequential GISH and FISH analysis with rDNA probes yielded chromosome-specific markers that were used to identify most of the chromosomes in 'Purissima' progeny. This is the first report of introgression of T. fosteriana chromatin into the T. gesneriana genome.

    DOI: 10.1007/s10681-007-9539-7

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  • Molecular cloning of Brassica rapa nitrilases and their expression during clubroot development

    Toshiki Ishikawa, Keiichi Okazaki, Haruka Kuroda, Kimiko Itoh, Toshiaki Mitsui, Hidetaka Hori

    MOLECULAR PLANT PATHOLOGY   8 ( 5 )   623 - 637   2007年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL PUBLISHING, INC  

    Three isoforms of nitrilase were cloned from turnip, Brassica rapa L., and their expression during clubroot development caused by Plasmodiophora brassicae was investigated. The isoforms were designated BrNIT-T1, BrNIT-T2 and BrNIT-T4 based on homology to known nitrilases. BrNIT-T1 and BrNIT-T2 have 80% homology to three nitrilases from Arabidopsis thaliana (AtNIT1, AtNIT2 and AtNIT3). BrNIT-T4 showed 90% homology to AtNIT4. To confirm their enzyme activity, the recombinant proteins were expressed in Escherichia coli. The recombinant BrNIT-T1 and BrNIT-T2 but not BrNIT-T4 converted indole-3-acetonitrile to indole-3-acetic acid, an endogenous plant auxin, although kinetic analysis showed that indole-3-acetonitrile is a poor substrate compared with various aliphatic and aromatic nitriles. By contrast, the recombinant BrNIT-T4 specifically converted beta-cyano-L-alanine to aspartic acid and asparagine and these findings agree with the idea that it is involved in the cyanide detoxification pathway. Real-time PCR analysis clearly showed that these isoforms were differentially expressed during clubroot development. BrNIT-T1 transcripts were very low in non-infected roots but were enhanced up to 100-fold in infected roots exhibiting club growth. By contrast, BrNIT-T2 transcripts remained at a very low level during clubroot formation. All these results clearly indicate the specific involvement of BrNIT-T1 in clubroot formation. The BrNIT-T4 transcripts were substantially reduced in the clubroot-growing phase, but thereafter they increased rapidly to a level found in non-infected roots as the clubroot growth reached a plateau. These findings suggest the specific involvement of BrNIT-T4 in clubroot maturation. In fully developed clubs, the BrNIT-T1 and BrNIT-T2 transcripts also increased. Free indole-3-acetic acid (IAA) content increased in the early and the latest phase of infected roots compared with noninfected roots, but decreased substantially at the middle phase. Thus, free IAA may play a role in the initiation and maturation of clubroot. Total IAA content was significantly higher in infected roots than in non-infected roots throughout clubroot development and IAA conjugation/conjugate hydrolysis system as well as BrNIT-Ts appear to be involved in clubroot development.

    DOI: 10.1111/J.1364-3703.2007.00414.X

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  • Evaluation of roles of amidase which converts indole-3-acetamide to indole-3-acetic acid, in formation of clubroot in turnip.

    T. Ishikawa, H Kuroda, K. Okazaki, K. Itoh, T.Mitsui, H. Hori

    新潟大学農学部研究報告   60 ( 1 )   53 - 60   2007年6月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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  • Production of 2n pollen of Asiatic hybrid lilies by nitrous oxide treatment

    Masako Akutsu, Satomi Kitamura, Ryo Toda, Ichiro Miyajima, Keiichi Okazaki

    EUPHYTICA   155 ( 1-2 )   143 - 152   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Tetraploid varieties of lilies have superior agronomic traits such as large flowers and resistance to physiological disorders. In the present study, we attempted to induce 2n pollen of Asiatic hybrid lilies by arresting the meiotic process with nitrous oxide (N2O) gas. To determine which meiotic stage is optimal for induction of 2n pollen, plants with attached buds at different meiotic stages were treated with N2O for 24 h in a pressure-tolerant cylinder. A few 2n pollen grains were induced using plants with anthers in prophase I, whereas mixed pollen grains of differing size were produced using plants undergoing meiotic metaphase predominantly in anthers. Although normal lily pollen grains are elliptical, nitrous oxide exposure induced giant pollen grains that appeared spherical. Flow cytometry analysis showed that the giant pollen grains were diploid. When mixed pollen that included normal and giant pollen was crossed to tetraploid cultivars, the resulting seedlings were tetraploid and aneuploid, indicating that the giant pollen grains were diploids that could generate tetraploid seedlings through fusion to diploid eggs supplied from a tetraploid female parent. Thus, treatment with N2O is useful for the production of 2n lily pollen and may provide a new approach for tetraploid lily breeding.

    DOI: 10.1007/s10681-006-9317-y

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  • Molecular cloning of Tulipa fosteriana rDNA and subsequent FISH analysis yields cytogenetic organization of 5S rDNA and 45S rDNA in T-gesneriana and T-fosteriana

    Hitoshi Mizuochi, Agnieszka Marasek, Keiichi Okazaki

    EUPHYTICA   155 ( 1-2 )   235 - 248   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    In this study, Tulipa fosteriana was found to contain 45S rDNA repeat units of 9.7 and 9.5 kb, in which at least 7 types of 45S rDNAs were identified by restriction site analysis. For 5S rDNA, repeat units ranging from 364 bp to 396 bp were identified. The diploid cultivars (2n = 2x = 24) 'Christmas Dream' and 'Queen of Night,' representing the horticultural group T. gesneriana, and 'Red Emperor', belonging to T. fosteriana, were compared cytogenetically using cloned 5S and 45S rDNAs. Fluorescence in situ hybridization (FISH) analysis identified many rDNA sites located on each chromosome in the diploid genomes. For example, we identified 71 sites of 5S rDNA and 10 sites of 45S rDNA in 'Red Emperor'. Additionally, FISH analyses enabled construction of karyotypes for these cultivars. Karyotype comparison of T. gesneriana cultivars showed conservation of repetitive rDNA unit positioning. A clear difference in chromosome size and signal pattern was observed between T. gesneriana and T. fosteriana cultivars. Here we demonstrate the unique nature of the highly repeated 5S rDNA units in these Tulipa species and the usefulness of FISH karyotyping with cloned 5S and 45S rDNAs to clearly distinguish between chromosomes from T. gesneriana and T. fosteriana.

    DOI: 10.1007/s10681-006-9325-y

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  • Mapping and characterization of FLC homologs and QTL analysis of flowering time in Brassica oleracea

    K. Okazaki, K. Sakamoto, R. Kikuchi, A. Saito, E. Togashi, Y. Kuginuki, S. Matsumoto, M. Hirai

    THEORETICAL AND APPLIED GENETICS   114 ( 4 )   595 - 608   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The FLC gene product is an inhibitor of flowering in Arabidopsis. FLC homologs in Brassica species are thought to control vernalization. We cloned four FLC homologs (BoFLCs) from Brassica oleracea. Three of these, BoFLC1, BoFLC3 and BoFLC5, have been previously characterized. The fourth novel sequence displayed 98% sequence homology to the previously identified gene BoFLC4, but also showed 91% homology to BrFLC2 from Brassica rapa. Phylogenetic analysis showed that this clone belongs to the FLC2 clade. Therefore, we designated this gene BoFLC2. Based on the segregation of RFLP, SRAP, CAPS, SSR and AFLP loci, a detailed linkage map of B. oleracea was constructed in the F-2 progeny obtained from a cross of B. oleracea cv. Green Comet (broccoli; non-vernalization type) and B. oleracea cv. Reiho (cabbage; vernalization type), which covered 540 cM, 9 major linkage groups. Six quantitative trait loci (QTL) controlling flowering time were detected. BoFLC1, BoFLC3 and BoFLC5 were not linked to the QTLs controlling flowering time. However, the largest QTL effect was located in the region where BoFLC2 was mapped. Genotyping of F-2 plants at the BoFLC2 locus showed that most of the early flowering plants were homozygotes of BoFLC-GC, whereas most of the late- and non-flowering plants were homozygotes of BoFLC-Rei. The BoFLC2 homologs present in plants of the non-vernalization type were non-functional, due to a frameshift in exon 4. Moreover, duplications and deletions of BoFLC2 were detected in broccoli and a rapid cycling line, respectively. These results suggest that BoFLC2 contributes to the control of flowering time in B. oleracea.

    DOI: 10.1007/s00122-006-0460-6

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  • GISH analysis of hybrids produced by interspecific hybridization between Tulipa gesneriana and T. fosteriana

    A. Marasek, K. Okazaki

    PROCEEDINGS OF THE 22ND INTERNATIONAL EUCARPIA SYMPOSIUM SECTION ORNAMENTALS: BREEDING FOR BEAUTY, PT II   743   133 - +   2007年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:INT SOC HORTICULTURAL SCIENCE  

    Genomic in situ hybridization (GISH) was used to understand the process of interspecific tulip hybrid diploid (2n = 2x = 24), triploid (2n = 3x = 36) and tetraploid (2n = 4x = 48) cultivar formation. Simultaneous hybridization of differentially labelled genomic probes enabled chromosomes derived from T. gesneriana and T. fosteriana to be distinguished in all cultivars tested. Diploid cultivar 'Shirayukihime' contained one set of chromosomes from T. gesneriana and one set from T. fosteriana. In triploid cultivars 'Come Back', 'Diplomate', 'Pink Impression' and 'Oxford', 24 chromosomes were derived from T. gesneriana and 12 chromosomes originated from T. fosteriana. The genome of tetraploid cultivar 'Ollioules' comprised 36 chromosomes from T. gesneriana and 12 chromosomes from T.fosteriana. In all tulip hybrids, GISH signals were localized predominately in telomeric/subtelomeric and intercalary regions of T. gesneriana chromosomes, whereas T. fosteriana chromosomes were painted more evenly along the chromosome length. In triploid and tetraploid cultivars, cross-hybridization to putative rRNA gene sites was observed at telomeric and intercalary locations of some chromosomes, although additional experiments are needed to identify what kind of repetitive DNA families are arranged as nested elements interspersed in the tulip genome.

    DOI: 10.17660/ActaHortic.2007.743.18

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  • The origin of Darwin hybrid tulips analyzed by flow cytometry, karyotype analyses and genomic in situ hybridization

    Agnieszka Marasek, Hitoshi Mizuochi, Keiichi Okazaki

    EUPHYTICA   151 ( 3 )   279 - 290   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Chromosome morphology was studied in diploid cultivars of Tulipa fosteriana and T. gesneriana (2n = 2x = 24) and triploid Darwin hybrids (2n = 3x = 36) developed from interspecific crosses of T. gesneriana and T. fosteriana. Chromosomes were arranged in the karyotype according to decreasing total length. Based on our karyotypic analysis, we propose that median chromosomes may serve as markers for diploid genotypes. Discriminant analysis with respect to total chromosome length and short arm length showed a significant difference between the size of the larger median chromosomes of T. gesneriana and T. fosteriana Comparison of median chromosome length in Darwin hybrid tulips showed that two larger chromosomes and one smaller chromosome were derived from T. gesneriana and T. fosteriana, respectively. This finding was clearly and unambiguously confirmed by simultaneous hybridization of differentially labeled genomic probes of T. fosteriana and T. gesneriana to metaphase chromosomes of the triploid cultivar 'Yellow Dover', thereby enabling us to distinguish between the 24 chromosomes derived from T. gesneriana and 12 chromosomes derived from T. fosteriana. Thus, genomic in situ hybridization and median chromosome analyses can be useful to identify the genome constitution of triploid Darwin hybrid tulips. In addition, their hybridity was readily verified by flow cytometry using vegetative tissue of Darwin hybrid tulips. Our results clarify the process of Tulipa cultivar formation and will be useful for interspecific hybridization breeding.

    DOI: 10.1007/s10681-006-9147-y

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  • Development of an effective screening method for partial resistance to Alternaria brassicicola (dark leaf spot) in Brassica rapa

    M. A. U. Doullah, M. B. Meah, K. Okazaki

    EUROPEAN JOURNAL OF PLANT PATHOLOGY   116 ( 1 )   33 - 43   2006年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    In order to develop a method to measure resistance to Alternaria brassicicola (cause of dark leaf spot disease) in Brassica rapa, the effects of inoculum concentration, leaf stage, leaf age and incubation temperature of inoculation on infection were studied under controlled conditions using several B. rapa genotypes. Three inoculation methods (cotyledon, detached leaf and seedling inoculation) were evaluated for this purpose. The detached leaf inoculation test was the most suitable for screening B. rapa genotypes because clear symptoms were observed on the leaves in less than 24 h, and there was a significant positive correlation between the results from the detached leaf inoculation test and the seedling inoculation test, an established method considered to yield reliable results. In addition, it was very easy to screen plants for resistance on a large scale and to maintain standard physical conditions using detached leaves. For successful infection, inoculum concentration should be adjusted to 5 x 10(4) conidia ml(-1), and incubation temperature should be between 20 degrees C and 25 degrees C. The 3rd/4th true leaves from 30 day-old plants were optimal for inoculation. In a screening test using 52 cultivars of B. rapa, the detached leaf test effectively discriminated between various levels of partial resistance among cultivars. As a result, we identified two cultivars, viz Saori and Edononatsu, as highly resistant and five cultivars, viz Tokinashi Taisai, Yajima Kabu, Purara, Norin-F-1-Bekana and Tateiwa Kabu, as having borderline resistance.

    DOI: 10.1007/s10658-006-9035-2

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  • Comparison of the genome structure of the self-incompatibility (S) locus in interspecific pairs of S haplotypes

    Ryo Fujimoto, Keiichi Okazaki, Eigo Fukai, Makoto Kusaba, Takeshi Nishio

    GENETICS   173 ( 2 )   1157 - 1167   2006年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:GENETICS  

    The determinants of recognition specificity of self-incompatibility in Brassica are SRK in the stigma and SP11/SCR in the pollen, both of which are encoded in the S locus. The nucleotide sequence analyses of many SRK and SP11/SCR alleles have identified several interspecific pairs of S haplotypes having highly similar sequences between B. oleracea and B. rapa. These interspecific pairs of S haplotypes are considered to be derived from common ancestors and to have maintained the same recognition specificity after speciation. In this study, the genome structures of three interspecific pairs of S haplotypes were compared by sequencing SRK, SP11/SCR and their flanking regions. Regions between SRK and SP11/SCR in B. oleracea were demonstrated to be much longer than those of B. rapa and several retrotransposon-like sequences were identified in the S locus in B. oleracea. Among the seven retrotransposon-like sequences, six sequences were found to belong to the ty3 gypsy group. The gag sequences of the retrotransposon-like sequences were phylogenetically different from each other. In Southern blot analysis using retrotransposon-like sequences as probes, the B. oleracea genome showed more signals than the B. rapa genome did. These findings suggest a role for the S locus and genome evolution in self-incompatible plant species.

    DOI: 10.1534/genetics.104.037267

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  • Plasmodiophora brassicae-induced cell death and medium alkalization in clubroot-resistant cultured roots of Brassica rapa

    H Takahashi, T Ishikawa, M Kaido, K Takita, T Hayakawa, K Okazaki, K Itoh, T Mitsui, H Hori

    JOURNAL OF PHYTOPATHOLOGY   154 ( 3 )   156 - 162   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BLACKWELL PUBLISHING  

    Plasmodiophora brassicae causes clubroot in the turnip, Brassica rapa L. We used organ cultures of adventitious roots from B. rapa seedlings to investigate the initial response of resistant and susceptible cultivars to P. brassicae infection. Primary plasmodia of P. brassicae were observed in root hairs of both susceptible and resistant cultured roots. On the other hand, secondary plasmodia were able to proliferate only in the susceptible root culture but not in the resistant one. Root cultures from the susceptible cultivar all developed clubroot 4 weeks after treatment with 10(4), 10(5) or 10(6) spores/ml, but roots from the resistant cultivar did not develop clubroot under the same conditions. Cell death, as measured by Evans blue and TTC dye methods, was observed in cultured roots from the resistant cultivar but did not occur in roots from the susceptible cultivar after exposure to P. brassicae spores. Cell death was inhibited almost completely by EGTA and verapamil but not by the calmodulin antagonist W7. These results suggest the involvement of Ca2+ in P. brassicae-induced cell death. Alkalization of the root culture medium of the resistant cultivar was observed 2 days after treatment with P. brassicae spores but was not observed in root culture medium from the susceptible strain. We conclude that our root culture system must be a useful tool for further studies of the molecular mechanism of clubroot resistance.

    DOI: 10.1111/j.1439-0434.2006.01076.x

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  • Comparison of diploid and chimeric forms (4×/2×) of Asiatic hybrid lilies (Lilium spp.) under natural and early forcing culture

    K. Okazaki, Y. Hane, Y. Hane

    New Zealand Journal of Crop and Horticultural Science   33 ( 3 )   261 - 267   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A variant of the Asiatic hybrid lilies (Lilium spp.), ‘Kiyotsubeni’, selected by a grower, was similar to the original form but displayed slight morphological differences. We determined that this variant form was a tetraploid/diploid periclinal chimera based on stomatal guard cells, pollen size, and chromosome number. Morphological and physiological changes associated with polyploidisation were identified by comparing diploid and chimeric forms (4×/2×) of ‘Kiyotsubeni’ under natural conditions and early forcing culture. Under early forcing culture, the chimeric form flowered earlier and displayed a shorter stem and broader leaves than the diploid form. The chimeric form also had a softer stem. Diploid ‘Kiyotsubeni’ was more susceptible to leaf scorch than the chimeric form. These results demonstrate that differences in ploidy influence agronomic traits and that the periclinal chimera (4×/ 2×) is effective for generating resistance against leaf scorch. ? 2005 Taylor &amp; Francis Group, LLC.

    DOI: 10.1080/01140671.2005.9514358

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  • New aspects of tulip breeding: Embryo culture and polyploid

    K Okazaki

    Proceedings of the Ninth International Symposium on Flower Bulbs, Vols 1 and 2   673 ( 673 )   127 - 140   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE  

    In order to improve bulb productivity and ornamental characteristics in tulips, it is necessary to increase genetic variation by using breeding techniques such as overcoming of interspecific barrier, embryo rescue of abortive embryos and induction of polyploids. To identify interspecific barrier between species, crossing experiments have been studied about fifty years ago and recently embryo rescue technique just has been attempted in Holland. In polyploid breeding, colchicine treatment is a common technique to produce polyploids, whereas nitrous oxide has been applied to zygotes as a polyploidizing agent in various crops. This paper reviews some of the literature and our results regarding to embryo rescue technique and also reports on the usefulness of 2n pollen induced with nitrous gas in tulip breeding.

    DOI: 10.17660/ActaHortic.2005.673.14

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  • Induction of 2n pollen in tulips by arresting the meiotic process with nitrous oxide gas

    K Okazaki, K Kurimoto, Miyajima, I, A Enami, H Mizuochi, Y Matsumoto, H Ohya

    EUPHYTICA   143 ( 1-2 )   101 - 114   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Triploid tulips have agronomically desirable traits such as vigorous growth and large flower size, but only a portion of all cultivated tulips is triploid. To apply 2n pollen to polyploid breeding of tulips, the polyploidizing agent, nitrous oxide gas (N2O), was applied to bulbs. In tulips, meiosis in anthers occurs inside the bulbs from mid- to late-October. When meiosis in anthers (excised from bulbs) reached metaphase I, we treated other bulbs of the same clones with N2O for 24-48 h. Most of the treated plants produced pollen grains with a wide-ranging or bimodal size distribution, indicating a mixture of n, 2n and aneuploid pollen grains. The use of pollen containing a relatively high proportion of giant pollen grains tended to yield larger numbers of triploids in the progeny. The number of giant pollen grains could be increased when N2O-treated pollen grains were suspended in 10% sucrose and then sieved through a nylon mesh. Very few polyploids were observed in some cross combinations, even those involving pollen with a relatively high proportion of giant grains. Even so, this low polyploid yield most likely is due to a triploid block, because the capsules obtained in the crosses of the diploidxN(2)O-treated plants contained some abnormal seeds, which were mostly triploid. Embryo culture was useful in rescuing abnormal embryos. The present study reveals that 2n pollen can be produced at high frequency using N2O during tulip breeding.

    DOI: 10.1007/s10681-005-2910-7

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  • Phylogenetic relationships among Lilium auratum Lindley, L. auratum var. platyphyllum Baker and L. rubellum Baker based on three spacer regions in chloroplast DNA.(共著)

    Tomotaro Nishikawa, Keiichi Okazaki, Tsukasa Nagamine

    Breeding Sci.   52 ( 3 )   207 - 213   2002年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We postulate the phylogenetic relationships of section Archelirion (genus Lilium) based on the nucleotide sequence variations of three spacer regions in chloroplast DNA, trnT-trnL, trnL-trnF and atpB-rbcL. The sequences aligned provided a matrix of 1,627 bp, and were analyzed phylogenetically by the maximum parsimony method. Section Archelirion was divided into two major clades, one consisting of L. auratum var. auratum and L. rubellum, and the other consisting of the rest of taxa in Archelirion. The cytoplasm of the former clade was regarded as the rubellum type (eastern type), and that of the latter clade as the japonicum type (western type). Each taxon was monophyletic, but two varieties of L. auratum were belonged to a different clade. The phylogeny of L. auratum var. auratum is different from that of L. auratum var. platyphyllum, and it has a sister-relationship with L. rubellum. These results provide a more convincing phylogenetic relationship within section Archelirion.

    DOI: 10.1270/jsbbs.52.207

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  • Phylogenetic analysis of section Sinomartagon in genus Lilium using sequences of the internal transcribed spacer region in nuclear ribosomal DNA

    Tomotaro Nishikawa, Keiichi Okazaki, Katsuro Arakawa, Tsukasa Nagamine

    Breeding Science   51 ( 1 )   39 - 46   2001年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We postulates the phylogenetic relationships of section Sinomartagon using 64 Lilium taxa and two related taxa based on nucleotide sequence variations in the internal transcribed spacer regions of nuclear ribosomal DNA. Excluding the 5.8S unit, a total of 479 bp were analyzed by three methods, i.e. maximum likelihood, maximum parsimony and neighbor-joining. Sinomartagon was polyphyletic and divided into five groups: (1) L. henryi, (2) L. henricii, L. macklinae, L. oxypetalum and L. nanum, (3) L. nepalense, (4) L. duchartrei, L. lankongense, L. amoenum, L. wardii and L. taliense, and (5) 10 other taxa of subsections 5a and 5b. This classification did not correspond to the subsections defined by Comber (1949), and all the groups should be recognized as distinct taxa. The second group which included mainly Nomocharis-like Lilium, should be treated as a different taxon such as section Lophophorum. Since the last group with section Dauricum and L. bulbiferum included L. davidii, the type of Sinomartagon, they could be considered to correspond to the true section Sinomartagon. The results provide a more convincing phylogenetic position for Sinomartagon.

    DOI: 10.1270/jsbbs.51.39

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  • Characterization of Brassica S-haplotypes lacking S-locus glycoprotein

    T Suzuki, M Kusaba, M Matsushita, K Okazaki, T Nishio

    FEBS LETTERS   482 ( 1-2 )   102 - 108   2000年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Self-incompatibility (SI) in Brassica is regulated by a single multi-allelic locus, S, which contains highly polymorphic stigma-expressed genes, SLG and SRK. While SRK is shown to be the determinant of female SI specificity, SLG is thought to assist the function of SRK. Here we report that the SLG genes of self-incompatible S(18) and S(60) homozygotes of Brassica oleracea hare an in-frame stop codon and a 23 bp deletion resulting in a frame-shift, respectively. The finding that these SLC genes do not encode functional SLG proteins suggests that SLG is not essential for SI. The possible role of SLG in SI was discussed. (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0014-5793(00)02048-2

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  • Interspecific hybrids between Lilium nobilissimum and L-regale produced via ovules-with-placental-tissue culture

    Y Obata, Y Niimi, M Nakano, K Okazaki, Miyajima, I

    SCIENTIA HORTICULTURAE   84 ( 1-2 )   191 - 204   2000年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Reciprocal pollination was made between Lilium nobilissimum and L. regale. Pollen tubes reached the base of style within 144 h after pollination, but no mature seeds were obtained in either cross combination. Explants, or ovules-with-placental-tissue excised from each carpel 30 and 40 days after pollination (DAP), were cultured on a medium composed of major salts of B-5 macronutrient (Gamborg, O.L., Miller, R.A., Ojima, K., 1968. Exp. Cell Res. 50, 151-158), micronutrient, Fe-EDTA and vitamins of MS (Murashige, T., Skoog, F., 1962. Physiol. Plant. 15, 473-497), 5% sucrose and 0.2% gellan gum. In L. regale x Lilium nobilissimum, 3% of ovules excised at 30 DAP and 9% of those excised at 40 DAP developed into seedlings. In Lilium nobilissimum x L. regale, only 3.6% of ovules excised 40 DAP developed into seedlings, and none of the ovules excised 30 DAP produced any seedlings. Bulbs of L;. regale and hybrids transplanted to soil showed some resistance to bulb-rot, leaf-top scorch, browning spots and/or streaking on leaves, but those of Lilium nobilissimum were sensitive to these diseases. Flowering individuals were nearly intermediate between parents in their morphological characteristics. All flowering individuals (2n = 24 chromosomes) were identified as hybrids based on karyotype, isozyme and random amplified polymorphic DNA analyses. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-4238(99)00115-6

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  • Sequence and structural diversity of the S locus genes from different lines with the same self-recognition specificities in Brassica oleracea

    M Kusaba, M Matsushita, K Okazaki, Y Satta, T Nishio

    GENETICS   154 ( 1 )   413 - 420   2000年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:GENETICS  

    Self-incompatibility (SI) is a mechanism for preventing self-fertilization in flowering plants. In Brassica, it is controlled by a single multi-allelic locus, S, and it is believed that two highly polymorphic genes in the S locus, SLG and SRK: play central roles in self-recognition in stigmas. SRK is a putative receptor protein kinase, whose extracellular domain exhibits high similarity to SLG. We analyzed two pairs of lines showing cross-incompatibility (S-2 and S2-b; S-13 and S13-b). In S-2 and S2-b, SRKs were more highly conserved than SLGs. This was also the case with S-13 and S13-b. This suggests that the SRKs of different lines must be conserved for the lines to have the same self-recognition specificity. In particular, SLG(2-b) showed only 88.5% identity to SLG(2), which is comparable to that between the SLGs of different S haplotypes, while SRK2-b showed 97.3% identity to SRK? in the S domain. These findings suggest that the SLGs in these S haplotypes are not important for self-recognition in SI.

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  • Ploidy of progenies in crosses between diploid, triploid and tetraploid in tulip.

    K Okazaki, M Nishimura

    PROCEEDINGS OF THE XXV INTERNATIONAL HORTICULTURAL CONGRESS, PT 12   522 ( 522 )   127 - 133   2000年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE  

    Interploidy crosses between diploid (2x=24), triploid (3x=36) and tetraploid (2x=48) tulip varieties (T. gesneriana, T. fosteriana, and their hybrids) were conducted. Diploids and aneuploids were obtained from 2x X 3x and 3x X 2x crosses (T. gesneriana X T. gesneriana). In the 2x X 3x crosses 92.6% were diploids and 7.4% were aneuploids, while in the 3x X 2x crosses 60.0% were diploids and 40.0% were aneuploids, and the ratio of progenies with lower chromosome number (24 - 30) was significantly higher than that of theoretical expectations in the both crosses. In crosses involving Darwin Hybrids (interspecific varieties between T. gesneriana and T. fosteriana), two crosses among 62 cross combinations produced progenies and the resulting seedlings had chromosome number ranging from 24 to 36. These seedlings would be useful in the introgression of genes from T. fosteriana into T. gesneriana.

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  • A molecular phylogeny of Lilium in the internal transcribed spacer region of nuclear ribosomal DNA

    T Nishikawa, K Okazaki, T Uchino, K Arakawa, T Nagamine

    JOURNAL OF MOLECULAR EVOLUTION   49 ( 2 )   238 - 249   1999年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER VERLAG  

    Phylogenetic relationships among 55 species of Lilium, Cardiacrinum giganteum, and Nomocharis saluenensis were inferred from nucleotide sequence variations in the internal transcribed spacer (ITS) regions of 18S-25S nuclear ribosomal DNA. The phylogeny derived from ITS sequences estimated using maximum-likelihood methods indicated that: (1) most of the species construct their own clade according to the classification based on morphological features at the section level; (2) section Daurolirion is not independent of Sinomartagon, and it is appropriate to integrate two sections as Sinomartagon; (3) it is appropriate that L. henryi and L. bulbiferum are classified into subsection 6a and Sinomartagon-Daurolirion, respectively; (4) subsection 6b is much closer to Sinomartagon than subsection 6a and Archelirion, and it arose directly from Sinomartagon; and (5) Lilium is much closer to Nomocharis than Cardiocrinum Phylogenetic estimation using sequences of the ITS region is suitable at: the levels of genus, section, and most of subsection.

    DOI: 10.1007/PL00006546

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  • Characterization of S tester lines in Brassica oleracea: Polymorphism of restriction fragment length of SLG homologues and isoelectric points of S-locus glycoproteins

    K. Okazaki, M. Kusaba, D. J. Ockendon, T. Nishio

    Theoretical and Applied Genetics   98 ( 8 )   1329 - 1334   1999年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Forty three S tester lines of Brassica oleracea were characterized using DNA and protein gel-blotting analyses. DNA gel-blot analysis of HindIII-digested genomic DNA with class-I and class-II SLG probes revealed that 40 lines could be classified as class-I S haplotypes while three lines could be classified as class-II S haplotypes. The band patterns in the S tester lines were highly polymorphic. Although the S tester lines typically showed two bands corresponding to SLG and SRK in the analysis with the class-I SLG probe, only one band was observed in the S24 homozygote. This band was identified as SRK, suggesting that this haplotype has no class-I SLG band. In the analysis using the class-II SLG probe, one plant yielded a different band pattern from the known class-II haplotypes, S2, S5 and S15. Unexpectedly, this plant was reciprocally cross-incompatible with the S2 haplotype. Therefore, it was designated as S(2-b). We found an S13 haplotype having a restriction fragment length polymorphism different from that of the S13 homozygotes of the S tester line. These findings indicate that S homozygous lines with the same S specificity do not necessarily show the same band pattern in the DNA gel-blot analysis. Soluble stigma proteins of 32 S homozygotes were separated by isoelectric focusing and detected using anti-S22SLG antiserum. S haplotype-specific bands were detected in 27 S homozygotes but not in five S homozygotes, including the S24 homozygote. This is consistent with the observation that the S24 haplotype had no SLG band.

    DOI: 10.1007/s001220051199

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  • 農業技術体系花卉編、遠縁雑種の利用

    養賢堂、東京   93 - 101   1997年

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  • ブラシカ属におけるカンランおよびハクサイの雑種後代の育種学研究(共著)

    北陸作物学会報   31   42 - 44   1996年

  • Lilium species native to Japan, and breeding and production of Lilium in Japan

    K Okazaki

    INTERNATIONAL SYMPOSIUM ON THE GENUS LILIUM   414 ( 414 )   81 - 92   1996年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE  

    Lilies are widely distributed in all prefectures of Japan. From the analysis of karyotypes (Noda 1987) and the numerical study (Asano 1986), Lilium species native to Japan are Japan, including L. longiflorum and L. speciosum which are also distributed in Taiwan and China. Sixty-seven million bulbs are produced on about 430 hectares in Japan. Kagoshima Prefecture is the major producer of L. longiflorum. Asiatic Hybrids are mainly produced in Niigata and Hokkaido Prefecture. L. speciosum is produced In Toyama. One hundred and fifty-seven million cut-flowers are produced on about 550 hectares. Such as L. longiflorum, which is located mainly in Kagoshima, Koochi and Fukuoka. L. x formolongi are grown on 11 ha in Hyogo and on 40 ha in Nagano. Oriental Hybrids and Asiatic Hybrids are produced in almost all of the prefectures. In Niigata and Hokkaido, many varieties of Asiatic Hybrid have been developed by private breeders and research stations. Mr. Nishimura, in Nagano, started crossing L. formosanum with L. longiflorum around 1928 and then developed L. x formolongi which has the characteristic of flowering within a year from seeds and has broad leaves like L. longiflorum. As L. x formolongi are propagated by seeds, there is no problems of virus infection during forcing for cut flower production. Techniques overcoming the barriers between species, cut-style pollination, embryo-culture, etc., have been developed in Japan. Recently some newer hybrids have appeared by crossing L. longiflorum and L. x formolonqi with the other species using embryo culture.

    DOI: 10.17660/ActaHortic.1996.414.8

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  • 富山県大百科事典

    1996年

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  • ユリ・チューリップ、週刊朝日百科・植物の世界

    朝日新聞社   15   1996年

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  • Callus induction and regeneration of some species of ┣DBLilium(/)-┫DB. (共著)

    Acta Horticulturae   392   97 - 106   1995年

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  • Interspecific hybrids between Lilium 'Oriental' hybrid and L. 'Asiatic' hybrid produced by embryo culture with revised media. 査読

    Keiichi Okazaki, Yoshito Asano, Katsuji Oosawa

    Ikushugaku zasshi   44 ( 1 )   59 - 64   1994年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Society of Breeding  

    DOI: 10.1270/jsbbs1951.44.59

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  • 花柱切断受粉法と胚培養法を用いた交雑によるアジアティックハイブリッドへのヒメユリ形質の導入(共著)

    園芸学会雑誌   63   825 - 833   1994年

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  • 品種および品種改良-ユリ-、花専科・育種と栽培

    誠文堂新光社.東京   13 - 36   1993年

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  • チューリップの自家不和合性に対する促成栽培、柱頭切断及び高温処理の影響(共著)

    岡崎 桂一, 村上 欣治

    園学雑   61 ( 2 )   405 - 411   1992年

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  • 胚培養によるテッポウユリ、シンテッポウユリとオトメユリ、ササユリの間種雑(共著)

    岡崎 桂一, 馬田 雄史, 浦島 修, 川田 穣一, 国重 正昭, 村上 欣治

    園学雑   60 ( 4 )   997 - 1002   1992年

  • Some Newer hybrid lilies obtained through embryo culture.

    Proceedings of symposium on integration of in vitro techniques in ornamental plant breeding.   1990年

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  • Structures of N-glycosidic saccharide chains in S-glyco-proteins, products of G-genes associated with self-incompatibility in Brassica campestris.

    Seiji TAKAYAMA, Akira ISOGAI, Chise TSUKAMOTO, Hideyuki SHIOZAWA, Yukari UEDA, Kokichi HINATA, Keiichi OKAZAKI, Koshi KOSEKI, Akinori SUZUKI

    Agriculture and Biological Chemistry   53 ( 3 )   713 - 722   1989年

  • EXISTENCE OF A COMMON GLYCOPROTEIN HOMOLOGOUS TO S-GLYCOPROTEINS IN 2 SELF-INCOMPATIBLE HOMOZYGOTES OF BRASSICA-CAMPESTRIS 査読

    A ISOGAI, S TAKAYAMA, H SHIOZAWA, C TSUKAMOTO, T KANBARA, K HINATA, K OKAZAKI, A SUZUKI

    PLANT AND CELL PHYSIOLOGY   29 ( 8 )   1331 - 1336   1988年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPANESE SOC PLANT PHYSIOLOGISTS  

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  • S-LOCUS-SPECIFIC GLYCOPROTEINS ASSOCIATED WITH SELF-INCOMPATIBILITY IN BRASSICA-CAMPESTRIS

    A ISOGAI, S TAKAYAMA, C TSUKAMOTO, Y UEDA, H SHIOZAWA, K HINATA, K OKAZAKI, A SUZUKI

    PLANT AND CELL PHYSIOLOGY   28 ( 7 )   1279 - 1291   1987年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPANESE SOC PLANT PHYSIOLOGISTS  

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  • Sequences of S-glycoproteins, products of the Brassica campestris self-incompatibility locus 査読

    Seiji Takayama, Akira Isogai, Chise Tsukamoto, Yukari Ueda, Kokichi Hinata, Keiichi Okazaki, Akinori Suzuki

    Nature   326 ( 6108 )   102 - 105   1987年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    DOI: 10.1038/326102a0

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  • REPRESSING THE EXPRESSION OF SELF-INCOMPATIBILITY IN CRUCIFERS BY SHORT-TERM HIGH-TEMPERATURE TREATMENT

    K OKAZAKI, K HINATA

    THEORETICAL AND APPLIED GENETICS   73 ( 4 )   496 - 500   1987年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER VERLAG  

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  • STRUCTURE OF CARBOHYDRATE CHAINS OF S-GLYCOPROTEINS IN BRASSICA-CAMPESTRIS ASSOCIATED WITH SELF-INCOMPATIBILITY

    S TAKAYAMA, A ISOGAI, C TSUKAMOTO, Y UEDA, K HINATA, K OKAZAKI, K KOSEKI, A SUZUKI

    AGRICULTURAL AND BIOLOGICAL CHEMISTRY   50 ( 6 )   1673 - 1676   1986年6月

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    記述言語:英語   出版者・発行元:JAPAN SOC BIOSCI BIOTECHN AGROCHEM  

    DOI: 10.1271/bbb1961.50.1673

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  • ISOLATION AND SOME CHARACTERIZATION OF S-LOCUS-SPECIFIC GLYCOPROTEINS ASSOCIATED WITH SELF-INCOMPATIBILITY IN BRASSICA-CAMPESTRIS

    S TAKAYAMA, A ISOGAI, C TSUKAMOTO, Y UEDA, K HINATA, K OKAZAKI, A SUZUKI

    AGRICULTURAL AND BIOLOGICAL CHEMISTRY   50 ( 5 )   1365 - 1367   1986年5月

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    記述言語:英語   出版者・発行元:JAPAN SOC BIOSCI BIOTECHN AGROCHEM  

    DOI: 10.1271/bbb1961.50.1365

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  • Role of stigma in the expresssion of selfincompatibility in curcifers in view of genetic analysis. In Biotechnology and Ecology of Pollen, Mulcahy, Mulcahy and Ottaviano(ed)(共著)

    1986年

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  • アブラナ科植物における自家不和合性・自家和合性の生理遺伝的研究(博士学位論文)

    東北大学   1986年

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  • ANALYSIS OF S-ALLELES AND S-GLYCOPROTEINS IN F1-HYBRID VARIETIES OF JAPANESE RADISH (RAPHANUS-SATIVUS L) 査読

    K OKAZAKI, K HINATA

    JAPANESE JOURNAL OF BREEDING   34 ( 2 )   237 - 245   1984年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPANESE SOC BREEDING  

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  • 我国ダイコン品種のS遺伝子とS糖タンパク質の分析(共著)

    育種学雑誌   34   237 - 245   1984年

  • Gene analysis of self-incompatibility in Brassica campestris var. Yellow Sarson(a case of recessive epistatic modifier). (共著)

    Proceeding of the Sixth international Rapeseed Conference, Paris   1   354 - 359   1983年

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▶ 全件表示

書籍等出版物

  • ユリをつくりこなす : 開花調節と高品質栽培の実際

    今西, 英雄( 範囲: p9-34)

    農山漁村文化協会  2006年12月  ( ISBN:4540052454

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    総ページ数:256p   記述言語:日本語

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  • 植物育種学辞典

    日本育種学会( 範囲: 7項目)

    培風館  2005年9月  ( ISBN:4563077887

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    総ページ数:vii, 785p   記述言語:日本語

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  • ユリの胚培養と育種、花のバイオ技術

    誠文堂新光社.東京  1992年 

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MISC

  • Brassica rapaにおける近交系統の純度検定に最適なDNAマーカーのスクリーニング

    川村 和隆, 佐伯 なつみ, 江部 裕介, 阿部 寛史, 清水 元樹, 長部 謙二, 岡崎 桂一, 川辺 隆大, 藤本 龍, 川村 和隆, 佐伯 なつみ, 江部 裕介, 阿部 寛史, 清水 元樹, 長部 謙二, 岡崎 桂一, 川辺 隆大, 藤本 龍

    新潟大学農学部研究報告   66 ( 2 )   111 - 124   2014年3月

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    記述言語:英語   出版者・発行元:新潟大学農学部  

    親候補となる近交系統の作成は、植物の一代雑種(F1)品種の育成過程の最初の段階である。一般的に遺伝的に均一な近交系統の育成には5、6世代以上の自殖が必要であると考えられている。DNAマーカーを利用した近交系の純度検定は信頼性が高いが、Brassica rapa L. では、純度検定に有効なDNAマーカーの報告は少ない。本研究では、F1品種の両親系統間の多型を見分けることができるDNAマーカーを見出すために、321のSSRプライマー対を試した。F2集団では、両親系統のゲノムが分離することから、両親系統の塩基配列の多型を追跡することが可能となる。材料にはハクサイの市販F1品種であるW77のF2個体を用いた。59のDNAマーカーでF2集団の個体間で多型が見られたことから、これらのDNAマーカーは純度検定に有効的であると考えられた。

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  • Brassica oleraceaにおける近交系統の純度検定に最適なDNAマーカーのスクリーニング

    富田 寛也, 清水 元樹, 久米 千織, 川辺 隆大, 長部 謙二, 岡崎 桂一, 藤本 龍

    新潟大学農学部研究報告 = Bulletin of the Faculty of Agriculture, Niigata University   65 ( 2 )   137 - 147   2013年3月

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    出版者・発行元:新潟大学農学部  

    近交系統の作成は、植物のF1品種の育成過程の最初の段階である。遺伝的に均一な近交系統の育成には5、6世代以上の自殖が必要であると考えられている。DNAマーカーを利用した近交系の純度検定は信頼性が高いが、B. oleraceaでは、純度検定に有効なDNAマーカーの報告は少ない。本研究では、F1品種の両親系統間の多型を見分けることができるDNA マーカーを見出すために、175のSSRプライマー対を試した。F2集団では、両親系統のゲノムが分離することから、両親系統の塩基配列の多型を追跡することが可能となる。そこで、材料にはキャベツの市販F1品種であるYR錦秋協力152のF2個体を用いた。12のDNAマーカーでF2集団の個体間で多型が見られたことから、これらのマーカーは純度検定に有効的であると考えられた。

    CiNii Article

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  • モモアカアブラムシに殺虫活性を示すBacillus thuringiensis サイトトキシン、Cyt2Aa

    小山尚生, 佐野義孝, 田中未希, 萩野谷功輔, Boonhiang, Promodonkoy, Chanan Angsuthanasambat, 三ツ井敏明, 高屋朋彰, 谷口正之, 岡崎桂一, 堀 秀隆

    新潟大学農学部研究報告   63 ( 2 )   77 - 81   2011年3月

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    記述言語:日本語   掲載種別:記事・総説・解説・論説等(大学・研究所紀要)   出版者・発行元:新潟大学農学部  

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  • Effective simple incision or partial snare resection for symptomatic duodenal cystic lesions, duplication cysts, and choledochoceles

    M. Matsushita, K. Uchida, A. Nishio, K. Okazaki

    Endoscopy   41 ( 10 )   918   2009年

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    記述言語:英語   掲載種別:速報,短報,研究ノート等(学術雑誌)  

    DOI: 10.1055/s-0029-1215142

    Scopus

    PubMed

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講演・口頭発表等

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Works(作品等)

  • 21世紀グリーンフロンティア研究-高付加価値花きの開発

    2000年
    -
    2002年

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共同研究・競争的資金等の研究

  • 新規に開発した異種染色体置換部分解析ツールを用いたブラシカ作物の春化機構の解析

    研究課題/領域番号:18H02173  2018年4月 - 2021年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    岡崎 桂一, 深井 英吾, 柿崎 智博, 藤本 龍, 板橋 悦子

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    配分額:17420000円 ( 直接経費:13400000円 、 間接経費:4020000円 )

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  • 超劣性形質である植物栄養器官肥大(シンク化)機構の遺伝解析

    研究課題/領域番号:17K19262  2017年6月 - 2020年3月

    日本学術振興会  科学研究費助成事業 挑戦的研究(萌芽)  挑戦的研究(萌芽)

    岡崎 桂一

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    配分額:6500000円 ( 直接経費:5000000円 、 間接経費:1500000円 )

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  • ブラシカ作物の種子春化・緑体春化機構の解明と緑体春化型ハクサイの育成

    研究課題/領域番号:15H04433  2015年4月 - 2018年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    岡崎 桂一, 深井 英吾, 柿崎 智博, 藤本 龍, 板橋 悦子

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    配分額:16770000円 ( 直接経費:12900000円 、 間接経費:3870000円 )

    セイヨウナタネの49系統の春化特性を調査し,イスズナタネ(春化要求性,低い)×合成ナプス(春化要求性,強)のF2集団育成した。また,ハクサイの第2染色体の上端にキャベツ由来の開花抑制遺伝子BoFLC2領域を導入した系統(以降,育成ハクサイ系統という)を育成したほか,キャベツ,ハクサイにおける, BrFLC1/2/3の発現量の多様性が春化要求量の多様性と関連性がある可能性を示した。また,RNA-seq解析では,BoFLC2座において低温処理によってlncRNAの発現が誘導されることを示した。育成ハクサイ系統は元品種のハクサイ品種比べ高い晩抽性を示し,育種母本として利用できることが示された。

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  • ブラシカのエピゲノム解析及び、植物形質に関わる後天的な転写制御の解明に向けて

    研究課題/領域番号:24780002  2012年4月 - 2014年3月

    日本学術振興会  科学研究費助成事業 若手研究(B)  若手研究(B)

    藤本 龍, 川辺 隆大, 加治 誠, 岡崎 桂一

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    配分額:4550000円 ( 直接経費:3500000円 、 間接経費:1050000円 )

    本研究では、日本及びアジア地域で主要な野菜であるハクサイ (Brassica rapa)を用いて、ゲノム全体のエピジェネティックな修飾状態を明らかにすることを目的として研究を行った。ゲノム全体のDNAのメチル化状態とヒストンの化学修飾状態について調べた。また、春化処理後や、病原菌感染時にみられるゲノムワイドなエピジェネティックな修飾状態を明らかにすることを目的に研究を行った。春化処理後には、鍵遺伝子であるFLCにH3K27me3の修飾が蓄積し、FLCの転写レベルが下がることを明らかにした。

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  • ブラシカ オレラセアの根こぶ病抵抗性遺伝子のポジショナルクローニングと機能解析

    研究課題/領域番号:23580003  2011年 - 2013年

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    岡崎 桂一

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    配分額:5460000円 ( 直接経費:4200000円 、 間接経費:1260000円 )

    キャベツの根こぶ病抵抗性遺伝子の単離を目的とする。これを達成するため,抵抗性と罹病性親の間で多型が検出できる30マーカーを抵抗性遺伝子領域にマップできた。これらのマーカーを用い,抵抗性と罹病性親後代のF2分離集団から抵抗性遺伝子領域内に組み換えを起こしている個体を選抜しグラフイカルジェノタイプを作成し,抵抗性遺伝子が座乗する領域をある程度絞り込んだほか,抵抗性と罹病性親の次世代シーケンサー解析から抵抗性遺伝子が座乗する領域のシークエンスを決定した。今後,本研究で単離したPbBoAnju1領域に対応するBACおよびコスミドから,候補遺伝子を含むサブクローンを育成し相補性検定を実施する予定である。

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  • ブラシカオレラセアの根こぶ病抵抗性の遺伝子解析と抵抗性選抜DNAマーカーの開発

    研究課題/領域番号:11F01083  2011年 - 2013年

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    岡崎 桂一, DOULLAH M.-U.

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    配分額:1400000円 ( 直接経費:1400000円 )

    本研究では, キャベツ(B. oleracea)に同定されている5つの根こぶ病抵抗性QTLから, 抵抗性遺伝子をクローンニングするとともに, 最も効果の大きいQTL, pbBo (Anju1)近傍に分子マーカーを位置づけ, マーカー利用選抜技術を確立することが目的である。
    PbBo (Anju) 1領域とシンテニーのあるシロイヌナズナの第5染色体に着目しての開発したESTマーカーについて, SCAR化を行った。また, 同領域がより近縁種であるB. rapaの第2染色体とも相同性を示すことを利用して, 分子マーカーを設計した。その結果, 設計した42ESTマーカーのうち, 22マーカーをPbBoAnju1領域, 13cM内にマップできた。抵抗性親×罹病性親由来のF2分離集団において, 今回作成したPbBoAnju1近傍マーカーを用いたDNA検査の結果と病原菌の接種検定の結果が一致し, DNAマーカー選抜が確実に機能することを確認することができた。
    PbBo (Anju) 1が存在すると推定される領域とシンテニーを示すシロイヌナズナやB. rapaゲノムの対応領域が明らかになった。この結果と, 次世代シーケンサーを用いた抵抗性親と罹病性親の全ゲノムシーケンス解析から決定したPbBo (Anju) 1が座乗するゲノム領域のシークエンス結果を合わせて, 現在, PbBo (Anju) 1座の候補遺伝子の同定を行っている。現時点で, NBS-LRRモチーフなど病害抵抗性遺伝子の特徴を持つも複数の遺伝をターゲット領域内に見いだしており, これらを根こぶ病抵抗性遺伝子(PbBoAnju1)の候補遺伝子として挙げている。

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  • ユリ科花き園芸作物のゲノム同定とゲノム倍加技術の開発

    研究課題/領域番号:19580024  2007年 - 2009年

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    岡崎 桂一

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    配分額:4030000円 ( 直接経費:3100000円 、 間接経費:930000円 )

    倍数性および種間交雑育種法は園芸作物の育種として極めて重要である。そこで,本研究では,染色体倍加の新技術として,笑気ガス処理による花粉の染色体を倍加する方法や種間雑種の不稔性を回復する技術を開発した。また,ゲノムや染色体の同定を行うため,rDNAを用いたFISH解析やGISH解析により,雑種のゲノム構成を明らかにする技術を開発した。これらの技術は,ユリおよびチューリップの染色体同定に有効であるとともに,不稔性種間交雑種の稔性を回復させ交配母本とし利用できることを示した画期的な育種法を提示するものである。

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  • 染色体分析及びDNA多型に基づくチューリップの系統分類と雑種起源の解明

    研究課題/領域番号:05F05186  2005年 - 2006年

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    岡崎 桂一, MARASEK Agnieszka

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    配分額:2400000円 ( 直接経費:2400000円 )

    1)これまでは,T.fosterianaに属するとされていた栽培種'Purissima'が,T.gesnerianaとT.fosterianaの雑種であることが明らかになった.その倍数性は2倍性であり種子稔性があるため,たくさんの雑種個体が育成されているが,その後代の染色体をGISHで調査したところ,T.gesnerianaとT.fosterianaの染色体間で多数の組み換えが起こっていることが明らかになった.
    2)次に,T.gesnerianaとT.fosterianaの雑種後代でそれぞれの種の染色体がどのように組み合わされているか調べるため,FISHによる染色体識別を試みた.まず,チューリップの5SrDNAをPCRを用いてクローンニングしたところ,T.fosterianaの典型的な5SrDNAは390bpのリピートユニットを持ち,遺伝子領域は120bpであったが,ユニット内に変異を持つリピートユニットが少なくとも2種類存在することがわかった.さらに,T.fosteriana 45SrDNAのリピートユニットが9.4Kbpであることがわかった。T.gesneriana 45SrDNAは,T.fosterianaのものと異なり,それぞれを容易に識別できるEcoR Iサイトをスペーサー内に持っていた.クローンニングしたrDNAをプローブとしてFISHを行ったところ5srDNAは各染色体に散在し,T.gesnerianaでは約50個,T.fosterianaでは約70個存在した.一方,45SrDNAは両種とも約10個が数本の染色体に分散して同定された.これらのrDNAの染色体上での位置は,T.gesnerianaとT.fosteriana間で異なるほか,T.gesnerianaの品種間でも異なることが明らかになった.

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  • アラビドプシスのゲノム情報を利用したBrassicaの連鎖地図作成と遺伝分析

    研究課題/領域番号:13660005  2001年 - 2003年

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    岡崎 桂一, 坂本 浩司

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    配分額:1000000円 ( 直接経費:1000000円 )

    本実験では、一年生ブロッコリー品種'グリ-ンコメット'×二年生キャベツ品種'麗峰'のF2集団を用い連鎖地図を作成し、マッピング及びクローニングしたFLC、COと開花期QTLとの関連を調査した。
    1.Brassica oleraceaでは、既報の3つのFLC遺伝子ホモログ(BoFLC1,3,5)が報告されているが、今回新しいFLC遺伝子ホモログを同定できBoFLC2とした。
    2.157マーカーが座上し、15本の連鎖群を形成した(全長は1196.3cM)。マーカー数が少ない連鎖群を除くと主要な連鎖群は9本となった。これはB.olerecea(2n=18)から考えられる連鎖群数9本と等しい。この連鎖群には既報のシーケンスを元に43個の構造遺伝子がマッピングされた。
    3.開花関連遺伝子は第1連鎖群にFLC5、CO、第2連鎖群にFLC1、FLC2、第6連鎖群にFLC3がマッピングされた。インターバルマッピング法により閾値LOD3.0以上の開花期関連QTLは第2連鎖群に3ヶ所、第3連鎖群に1ヶ所、第5連鎖群に2ヶ所検出することができ、それぞれのQTLをFT1〜6とした。FT3はFLC2のほぼ異上にLODピークが検出されたことからFLC2は本実験のF2集団における開花変異に影響を及ぼしていると推測された。
    4.本研究の結果、各研究者間でマップ情報の共有化が計れる構造遺伝子が乗ったB.oleraceaの連鎖地図を作成できた。またバーナリゼーション関連遺伝子FLCの新しいホモログ(BoFLC2)を同定するとともに、既報のFLCホモログを含め、全部で4個のFLCホモログを連鎖地図上へマップすることができた。これによって、開花期決定に効果的に働くFLCホモログと効果の小さいFLCホモログがあることがわかった。本実験のマップ情報及びFLCの遺伝子マーカーはB.oleracea育種のマーカーアシストセレクションに極めて有効であると思われた。

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  • 組織,器官およびプロトプラスト培養によるユリの増殖と育種に関する研究

    研究課題/領域番号:09460017  1997年 - 2000年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    新美 芳二, 岡崎 桂一, 中野 優

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    配分額:11800000円 ( 直接経費:11800000円 )

    4年間の本プロジェクトの研究成果の概要は以下の通りである。
    I 子球の増殖と生長:(1)りん片培養の好適培養条件(光の有無、培養温度)はユリの種類によって異なった;(2)葯培養で再生した子球は2倍体ではあったが、カルスから再生した子球と同様にウイルスフリー子球であった;(3)液体培地は固形培地と比べ子球の生長を促進するが、その培地中の250mMショ糖は培養開始12週間後までに完全になくなり、このときの培地の更新は子球生長を促進する。
    II 育種:(1)葯・小胞子培養、(1)0.25mMまたは0.5mMコルヒチン、48または72時間処理が葯由来半数性カルスの倍加に有効であった;(2)ピクロラムを添加した培地は、他のオーキシンを含む培地と比べ、'コネチカットキング'の半数性カルスを長期(60週間)にわたり維持するのに適していた;(3)単離小胞子はカルス誘導を形成したが、カルスは小植物体を再生しなかった。(2)胚珠培養、(1)交雑35-40日以前に摘出したリーガルユリとタモトユリとの交雑胚珠は植物体を形成しなかったが、40日後に摘出した胚珠は雑種植物を作った;(2)B5培地で培養した受精直後の胚珠では、まず胚珠培養で胚を発達させ、培養後半に胚培養を行うことにより植物体が発達した。(3)倍数性育種、(1)アジアティックハイブリッドの2倍体と4倍体植物の生育特性は、後者は前者と比べ開花時期は遅くなり、草丈や葉数が減少した;(2)葯培養から得た倍加半数体植物の生育は2倍体植物と比較して劣った;(3)笑気ガスの第1分裂中期の花粉母細胞処理は倍数性育種に有効な非還元配偶子の獲得に有効であった;(3)培養中のりん片の0.5mMコルヒチン処理は、4倍体植物体の再生に有効であった。(4)プロトプラスト培養と形質転換、(1)数種のユリの懸濁培養細胞からのプロトプラストはコロニーを形成した;(2)75カ月液体培地で培養した懸濁培養細胞は固定培地で器官を再生し、再生は不定芽または不定胚を経由する場合があった;(3)形質転換組織の選抜薬剤としてハイグロマイシンまたはビオラフォスがよいこと、アグロバクテリウムを接種されたカルスはgusA遺伝子の一過性発現を示した。

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  • 野生ユリの遺伝的分化と保全に関する研究

    研究課題/領域番号:09876009  1997年 - 1999年

    日本学術振興会  科学研究費助成事業 萌芽的研究  萌芽的研究

    岡崎 桂一, 長峰 司

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    配分額:2300000円 ( 直接経費:2300000円 )

    1.これまで、従来の形態による分類では不明確であった種の類縁関係をDNAシークエンス(rDNA)を用いて明らかにしてきた。今年度は、ユリ属の中でも、特に分類上混乱をきたしていたSinomartagon節を分析した。Sinomartagon節は多系統であり、6分岐群に分かれた。そのうちのひとつの分岐群は本節の基準種L.davidiiを含んでおり、真Sinomartagon節とみなすことができたが、その他の分岐群はSinomartagon節とは明らかに系統が異なっていた。
    2.rDNAを用いた系統解析では、ユリの類縁関係を明らかにすることができたが、一部の分岐については信頼性が低くかった。そこで、葉緑体のmatK領域を調査することにより、それらを明らかにすることにした。 matKより作成した系統樹では、Sinomartagon節と6b亜節の関係及びArchelirion節と6a亜節の関係はrDNAと同様であったが、Liriotypus節とL.amoenumは位置が前後した。またrDNAでは、L.henryiは6a亜節と姉妹関係にはあったが距離は大きかった。しかし、matKでは両者が明らかに近縁であることが示された。また、5c亜節に分類されるL.amoenumは、6a亜節やArchelirion節に姉妹関係であった。
    3.球根のin vitro保存を行い生存率や形態の変化を調査した。in vitro保存条件下2年間、小球の形態や生育が安定しており、本保存法は遺伝資源の保存に有効である。
    4.我が国に自生するヤマユリの自生地を国内5カ所(岩手、福島、新潟、長野、山梨)を調査した。

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  • Brassica oleraceaのクラスIIs複合遺伝子座の構造解析

    研究課題/領域番号:09262206  1997年

    日本学術振興会  科学研究費助成事業 重点領域研究  重点領域研究

    岡崎 桂一, 西尾 剛

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    配分額:3000000円 ( 直接経費:3000000円 )

    クラスIIS複合遺伝子座の構造を明らかにするためBrassicaの系統から既知のクラスIIに属するS2、S5、S15とは異なる新奇のゲノミックサザンパターンを示した個体を見出した。この個体はSLGのシークエンや交配実験からパターンは既存のS2テスターラインと異なるもののS2と同定された。さらに、ブロッコリの市販品種に多数見出されるので、今後このタイプのS2をS2ブロッコリタイプと呼ぶこととした。
    S2に見られるSLA遺伝子がS2テスターラインに検出されたが、S2ブロッコリタイプには見られなかった。すなわち、S2テスターラインとS2ブロッコリタイプは同じS2であっても、後者はS複合遺伝子座が変異しているものと思われた。
    S15ではゲノムDNAから3つのSホモログを単離した。HindIII断片6.2kbのホモログはSRKカイネースドメインのシークエンスを含んでいた。S15-8.0kbはSLG2に対してはDNAで99.0%と非常に高い相同性を示し、3非翻訳領域もSLG2に対してDNAで99.0%と高い相同性を示した。シークエンスの結果からS15の一部はS2由来の可能性が考えられた。S15のS遺伝子座を更に解析するために67個のS15コスミドクローンを解析した結果、2つのSホモログがひとつのクローン内に捕らえられたコスミドクローンがあったのでS15のS-locus上に複数個のS-likeな遺伝子がduplicateして乗っていると考えられる。
    SLAの有無、S15遺伝子上へのS2領域の組み換え、S15遺伝子座でのSホモログの重複などから複雑なクラスII S複合遺伝子座の構造の一端が明らかになった。

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  • Study on genetics and breeding of lily, tulip and crucifers

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    資金種別:競争的資金

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  • Genetics and breeding of lily and tulip. Self-incompatibility

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    資金種別:競争的資金

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