Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

In vascular plants, roots anchor themselves into the soil and take up water and nutrients to provide them to the shoots. Therefore, continuous growth and development of the roots are important for plant life. To achieve this, photosynthesizing leaves must be able to supply sufficient photoassimilates to the roots. However, the mechanisms by which plants maintain carbon levels in roots remain elusive. Here, we focused on the Arabidopsis (Arabidopsis thaliana) CLAVATA3/ESR-related 2 (CLE2) peptide, which was detected in Arabidopsis xylem exudate, and its homologs. CLE2 and CLE3 genes responded to carbon-deficient conditions. Loss- and gain-of-function mutant analyses showed that CLE genes positively affected root sucrose level. Mutations in the CLE genes resulted in a high shoot/root ratio under sucrose-free conditions. Grafting experiments demonstrated the systemic effect of CLE peptide genes. These findings provide insights into the molecular basis for the relationship between roots and leaves in maintenance of the root sucrose levels and growth.

DOI： 10.1093/plphys/kiac227

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

The xylem is the main pathway for the transport of water and molecules from roots to shoots. To date, it has been reported that secreted oligopeptides mediate root-to-shoot signaling, and some long-distance mobile oligopeptides have been detected in xylem exudates. However, the conservation of a number of oligopeptides and the overall features of peptide fragments contained in xylem exudates are poorly understood. Here, we conducted a comprehensive analysis of small proteins and peptides in tomato (Solanum lycopersicum) xylem exudates and characterized the identified peptide fragments. We found that putative secreted proteins were enriched in xylem exudates compared with all proteins in the tomato protein database. We identified seven oligopeptides that showed common features of bioactive oligopeptides, including homologs of CLV3/ESR-related (CLE), C-TERMINALLY ENCODED PEPTIDE (CEP), and CASPARIAN STRIP INTEGRITY FACTOR (CIF) peptides. Furthermore, five of the identified oligopeptides were homologs of the soybean xylem exudate-associated oligopeptides that we previously reported. Our results suggest that oligopeptides in xylem exudates are conserved across plant species and provide insights into not only root-to-shoot signaling but also the maintenance of the xylem conduit.

DOI： 10.3390/life12040592

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

Oryza longistaminata, a wild rice, vegetatively reproduces and forms a networked clonal colony consisting of ramets connected by rhizomes. Although water, nutrients, and other molecules can be transferred between ramets via the rhizomes, inter-ramet communication in response to spatially heterogeneous nitrogen availability is not well understood. We studied the response of ramet pairs to heterogeneous nitrogen availability using a split hydroponic system that allowed each ramet root to be exposed to different conditions. Ammonium uptake was compensatively enhanced in the sufficient-side root when roots of the ramet pairs were exposed to ammonium-sufficient and ammonium-deficient conditions. Comparative transcriptome analysis revealed that a gene regulatory network for effective ammonium assimilation and amino acid biosynthesis was activated in the sufficient-side roots. Allocation of absorbed nitrogen from the nitrogen-sufficient to the nitrogen-deficient ramets was rather limited. Nitrogen was preferentially used for newly growing axillary buds on the sufficient-side ramets. Biosynthesis of trans-zeatin (tZ), a cytokinin, was upregulated in response to the nitrogen supply, but tZ appeared not to target the compensatory regulation. Our results also implied that the O. longistaminata putative ortholog of rice (Oryza sativa) C-terminally encoded peptide1 plays a role as a nitrogen-deficient signal in inter-ramet communication, providing compensatory upregulation of nitrogen assimilatory genes. These results provide insights into the molecular basis for efficient growth strategies of asexually proliferating plants growing in areas where the distribution of ammonium ions is spatially heterogeneous.

DOI： 10.1093/plphys/kiac025

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Other Link： https://academic.oup.com/plphys/article-pdf/188/4/2364/43109834/kiac025.pdf

Language：English   Publishing type：Research paper (scientific journal)  

Pollen-free varieties are advantageous in promoting cut-flower production. In this study, we identified a candidate mutation which is responsible for pollen sterility in a strain of Lilium × formolongi, which was originally identified as a naturally occurred male-sterile plant in a seedling population. The pollen sterility occurred due to the degradation of pollen mother cells (PMCs) before meiotic cell division. Genetic analysis suggested that the male-sterile phenotype is attributed to one recessive locus. Transcriptome comparison between anthers of sterile and fertile plants in a segregated population identified a transcript that was expressed only in pollen-fertile plants, which is homologous to TDF1 (DEFECTIVE in TAPETAL DEVELOPMENT and FUNCTION1) in Arabidopsis, a gene encoding a transcription factor AtMYB35 that is known as a key regulator of pollen development. Since tdf1 mutant shows male sterility, we assumed that the absence transcript of the TDF1-like gene, named as LflTDF1, is the reason for pollen sterility observed in the mutant. A 30 kbp-long nanopore sequence read containing LflTDF1 was obtained from a pollen-fertile accession. PCR analyses using primers designed from the sequence suggested that at least a 30kbp-long region containing LflTDF1 was deleted or replaced by unknown sequence in the pollen-sterile mutant. Since the cross between L. × formolongi and Easter lily (L. longiflorum) is compatible, we successfully introgressed the male-sterile allele, designated as lfltdf1, to Easter lily. To our knowledge, this is the first report of molecular identification of a pollen-sterile candidate gene in lily. The identification and marker development of LflTDF1 gene will assist pollen-free lily breeding of Easter lilies and other lilies.

DOI： 10.3389/fpls.2022.914671

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

<jats:title>Abstract</jats:title>
<jats:p>Legumes utilize a shoot-mediated signaling system to maintain a mutualistic relationship with nitrogen-fixing bacteria in root nodules. In <jats:italic>Lotus japonicus</jats:italic>, shoot-to-root transfer of microRNA miR2111 that targets <jats:italic>TOO MUCH LOVE</jats:italic>, a nodulation suppressor in roots, has been proposed to explain the mechanism underlying nodulation control from shoots. However, the role of shoot-accumulating miR2111s for the systemic regulation of nodulation was not clearly shown. Here, we find <jats:italic>L. japonicus</jats:italic> has seven miR2111 loci, including those mapped through RNA-seq. <jats:italic>MIR2111-5</jats:italic> expression in leaves is the highest among miR2111 loci and repressed after rhizobial infection depending on a shoot-acting HYPERNODULATION ABERRANT ROOT FORMATION1 (HAR1) receptor. <jats:italic>MIR2111-5</jats:italic> knockout mutants show significantly decreased nodule numbers and miR2111 levels. Furthermore, grafting experiments using transformants demonstrate scions with altered miR2111 levels influence nodule numbers in rootstocks in a dose-dependent manner. Therefore, miR2111 accumulation in leaves through <jats:italic>MIR2111-5</jats:italic> expression is required for HAR1-dependent systemic optimization of nodule number.</jats:p>

DOI： 10.1038/s41467-020-19037-9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scientific Societies  

<jats:p> Legumes survive in nitrogen-limited soil by forming a symbiosis with rhizobial bacteria. During root nodule symbiosis, legumes strictly control the development of their symbiotic organs, the nodules, in a process known as autoregulation of nodulation (AON). The study of hypernodulation mutants has elucidated the molecular basis of AON. Some hypernodulation mutants show an increase in rhizobial infection in addition to developmental alteration. However, the relationship between the AON and the regulation of rhizobial infection has not been clarified. We previously isolated daphne, a nodule inception (nin) allelic mutant, in Lotus japonicus. This mutant displayed dramatically increased rhizobial infection, suggesting the existence of NIN-mediated negative regulation of rhizobial infection. Here, we investigated whether the previously isolated components of AON, especially CLAVATA3/ESR (CLE)-RELATED-ROOT SIGNAL1 (CLE-RS1), CLE-RS2, and their putative receptor HYPERNODULATION AND ABERRANT ROOT FORMATION1 (HAR1), were able to suppress increased infection in the daphne mutant. The constitutive expression of LjCLE-RS1/2 strongly reduced the infection in the daphne mutant in a HAR1-dependent manner. Moreover, reciprocal grafting analysis showed that strong reduction of infection in daphne rootstock constitutively expressing LjCLE-RS1 was canceled by a scion of the har1 or klavier mutant, the genes responsible for encoding putative LjCLE-RS1 receptors. These data indicate that rhizobial infection is also systemically regulated by CLE-HAR1 signaling, a component of AON. In addition, the constitutive expression of NIN in daphne har1 double-mutant roots only partially reduced the rhizobial infection. Our findings indicate that the previously identified NIN-mediated negative regulation of infection involves unknown local signaling, as well as CLE-HAR1 long-distance signaling. </jats:p>

DOI： 10.1094/mpmi-08-19-0223-r

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/jxb/ery364

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science ({PLoS})  

Nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi (AMF) form symbioses with plant roots and these are established by precise regulation of symbiont accommodation within host plant cells. In model legumes such as Lotus japonicus and Medicago truncatula, rhizobia enter into roots through an intracellular invasion system that depends on the formation of a root-hair infection thread (IT). While IT-mediated intracellular rhizobia invasion is thought to be the most evolutionarily derived invasion system, some studies have indicated that a basal intercellular invasion system can replace it when some nodulation-related factors are genetically modified. In addition, intracellular rhizobia accommodation is suggested to have a similar mechanism as AMF accommodation. Nevertheless, our understanding of the underlying genetic mechanisms is incomplete. Here we identify a L. japonicus nodulation-deficient mutant, with a mutation in the LACK OF SYMBIONT ACCOMMODATION (LAN) gene, in which root-hair IT formation is strongly reduced, but intercellular rhizobial invasion eventually results in functional nodule formation. LjLAN encodes a protein that is homologous to Arabidopsis MEDIATOR 2/29/32

DOI： 10.1371/journal.pgen.1007865

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.pbi.2018.04.006

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Authorship：Lead author   Language：English  

DOI： 10.1016/j.pbi.2016.07.009

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/tpj.13015

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/15592324.2014.1000138

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3389/fpls.2015.00161

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/ncomms3191

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Authorship：Lead author   Language：English  

DOI： 10.21769/BioProtoc.795

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pcp/pct022

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pcp/pcr071

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/j.1365-313X.2010.04474.x

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Host legumes control root nodule numbers by sensing external and internal cues. A major external cue is soil nitrate, whereas a feedback regulatory system in which earlier formed nodules suppress further nodulation through shoot-root communication is an important internal cue. The latter is known as autoregulation of nodulation (AUT), and is believed to consist of two long-distance signals: a root-derived signal that is generated in infected roots and transmitted to the shoot; and a shoot-derived signal that systemically inhibits nodulation. In Lotus japonicus, the leucine-rich repeat receptor-like kinase, HYPERNODULATION ABERRANT ROOT FORMATION 1 (HAR1), mediates AUT and nitrate inhibition of nodulation, and is hypothesized to recognize the root-derived signal. Here we identify L. japonicus CLE-Root Signal 1 (LjCLE-RS1) and LjCLE-RS2 as strong candidates for the root-derived signal. A hairy root transformation study shows that overexpressing LjCLE-RS1 and -RS2 inhibits nodulation systemically and, furthermore, that the systemic suppression depends on HAR1. Moreover, LjCLE-RS2 expression is strongly up-regulated in roots by nitrate addition. Based on these findings, we propose a simple model for AUT and nitrate inhibition of nodulation mediated by LjCLE-RS1, -RS2 peptides and the HAR1 receptor-like kinase.

DOI： 10.1093/pcp/pcn194

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pcp/pci138

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Language：English  

CiNii Article

CiNii Books

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Language：English   Publishing type：Research paper, summary (international conference)  

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Event date： 2019.3

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2017.3

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2016.11 - 2016.12

Language：English   Presentation type：Poster presentation  

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Event date： 2016.3

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2015.10

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2015.9

Language：English   Presentation type：Oral presentation (general)  

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