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

Reproductive isolation plays a significant role in the prevention of gene flow between different plant species. Isolation factors can vary, acting either pre- or postzygotically. Trillium camschatcense and T.tschonoskii are herbaceous perennials which frequently grow together in Hokkaido, Japan. Natural hybrid formation, T.×hagae, between these species is common, and occurs asymmetrically with T.camschatcense as the maternal parent and T.tschonoskii as the paternal. Here, we examined the efficiency of each reproductive isolation factor to clarify which factor was responsible for the frequency and asymmetry of the hybridization. We found that prezygotic barriers, self fertilization and conspecific pollen precedence, are major isolation factors in both parental species, and that T.tschonoskii as a maternal parent has more effective prezygotic barriers than T.camschatcense. In addition, hybrids with T.tschonoskii as the maternal parent were not observed to reach the flowering stage. We concluded that prezygotic isolation factors in the both species act as main barriers to prevent natural hybridization, and that asymmetry of the isolating barriers between these species would promote T.camschatcense as the maternal parent of the hybrids. © 2012 The Society for the Study of Species Biology.

DOI： 10.1111/j.1442-1984.2012.00378.x

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

The importance of interplant volatile signaling in plant-herbivore interactions has been a contentious issue for the past 30 years. We revisit willows as the system in which evidence for interplant signaling was originally found, but then questioned. We established three well-replicated experiments with two willow species (Salix exigua and Salix lemmonii) to address whether the receipt of an interplant signal from a neighboring willow reduces herbivore damage. Additionally we tested whether this signal is volatile in nature, and whether plants signal better to themselves than they do to other individuals. In all three experiments, we found evidence that cues from a damaged neighbor reduce subsequent herbivory experienced by willows. In one experiment, we showed that bagging of clipped tissue, which prevents the exchange of volatile signals, removed the effect of neighbor wounding. This was consistent with results from the other two experiments, in which clipping potted neighbors connected only through airborne volatile cues reduced damage of receivers. In one year, we found evidence that the perception of volatile signals from genetically identical clones was more effective at reducing foliar damage to a neighbor than signals from a genetically different individual. However, this trend was not significant in the following year. In three well-replicated experiments, we found strong evidence for the importance of interplant volatile cues in mediating herbivore interactions with willows.

DOI： 10.1007/s00442-013-2610-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

The ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviours; such ability is less well studied for plants. Many plants, including Artemisia tridentata, have been found to respond to volatile cues emitted by experimentally wounded neighbours to increase levels of resistance to herbivory. We report that this communication was more effective among A. tridentata plants that were more closely related based on microsatellite markers. Plants in the field that received cues from experimentally clipped close relatives experienced less leaf herbivory over the growing season than those that received cues from clipped neighbours that were more distantly related. These results indicate that plants can respond differently to cues from kin, making it less likely that emitters will aid strangers and making it more likely that receivers will respond to cues from relatives. More effective defence adds to a growing list of favourable consequences of kin recognition for plants.

DOI： 10.1098/rspb.2012.3062

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

1. There are now approximately 10 examples of plants that use volatile cues emitted by damaged neighbours to adjust their defences against herbivores. For two of these examples, preliminary evidence suggested that plants may experience net benefits from such eavesdropping, although eavesdropping was uncommon in one case and estimates of plant fitness were ambiguous in the other case. 2.In the current study, we examined the long-term consequences of exposure to cues emitted by experimentally clipped sagebrush neighbours. In this sagebrush system we have repeatedly found that sagebrush plants that have experimentally clipped neighbours experience less herbivore damage over the season than plants with unclipped control neighbours under field conditions. We followed a cohort of young sagebrush plants from emergence in 1999 for 12years. Neighbours of half of these plants were artificially clipped every spring from 2004-08 and survival and flowering was measured in each autumn from 1999-2011. 3.Survival of marked branches of young plants was not consistently affected by whether its neighbour was clipped. Plants near clipped neighbours produced more branches during this period than those near unclipped neighbours. There were no measurable treatment effects on plant survival over the 12years. Branches near clipped neighbours produced more inflorescences than branches near unclipped neighbours. 4.Seedlings were more likely to survive to the end of their first dry season in two different years near clipped neighbours compared to unclipped neighbours. 5.Synthesis. The results suggest different effects of clipped neighbours that depend on plant age. Responding to the cues of experimental clipping may provide a slight net benefit, considering these results and other published studies, even though these cues provided little predictive value about actual risk of herbivory. Responding to reliable cues may be even more beneficial and may favour plants that eavesdrop on neighbours. The results suggest different effects of clipped neighbours that depend on plant age. Responding to the cues of experimental clipping may provide a slight net benefit, considering these results and other published studies, even though these cues provided little predictive value about actual risk of herbivory. Responding to reliable cues may be even more beneficial and may favour plants that eavesdrop on neighbours. © 2012 The Authors. Journal of Ecology © 2012 British Ecological Society.

DOI： 10.1111/j.1365-2745.2012.01974.x

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

Volatile communication allows plants to coordinate systemic induced resistance against herbivores. The mechanisms responsible and nature of the cues remain poorly understood. It is unknown how plants distinguish between reliable cues and misinformation. Previous experiments in which clipped sagebrush branches were bagged suggested that cues are emitted or remain active for up to 3 days. We conducted experiments using plastic bags to block emission of cues at various times following experimental clipping. We also collected headspace volatiles from clipped and unclipped branches for 1 h, transferred those volatiles to assay branches, and incubated the assays for either 1 or 6 h. We found that assay branches that received volatile cues for less than 1 h following clipping of neighbors failed to induce resistance. Assay branches that received volatile cues for more than 1 h experienced reduced herbivory throughout the season. Branches incubated for 6 h with volatiles that had been collected during the first hour following clipping showed induced resistance. These results indicate that sagebrush must receive cues for an extended time (> 1 h) before responding; they suggest that the duration of cue reception is an important and overlooked process in communication allowing plants to avoid unreliable, ephemeral cues.

DOI： 10.1007/s11829-011-9180-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

To increase systemic resistance to herbivory, some clonal plants transmit internal cues among clonal ramets to prevent widespread damage to genets. Sagebrush (Artemisia tridentata) (Asteraceae) is known to use volatile cues to induce resistance within and between plants (so-called volatile communication). In the present study, we observed the extent and frequency of clonal growth in a natural sagebrush population in western North America to understand the influence of clonal growth on volatile communication. We used genetic analysis involving microsatellite markers and excavation of the root systems. In addition, we characterized the volatile profiles from the headspace of sagebrush ramets. Excavation of the root system of sagebrush plants revealed that sagebrush propagates clonally below ground and that daughter ramets grow near the mother stem. Volatiles were variable among genetically different ramets, although clonal ramets (genetically identical ramets) released similar volatiles, suggesting a genetic basis for volatile similarity. Sagebrush has been shown to be most responsive to volatiles released from artificially produced clones and suffers less herbivore damage as a result. Therefore, these results, taken into consideration together, imply that volatile communication may occur among genetically identical ramets under natural conditions, and that volatile similarity between the releaser and receiver may be recognized by the receiver and increase resistance against herbivory.

DOI： 10.1111/j.1442-1984.2011.00333.x

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Language：English   Publishing type：Thesis (other)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Plants progress through a series of distinct stages during development and plant developmental phases link with changing seasons through a year. Recent work indicated that many plants activate systemic-induced resistance after herbivore attack, although the role of both plant ontogeny and seasonal variation in resistance against herbivores has not been a focus of this work. We previously reported that sagebrush become more resistant to its herbivores when neighboring sagebrush plants were experimentally clipped. In this study we asked how the age of sagebrush affected systemic-induced resistance and whether there was seasonal variation in systemic resistance. Young plants showed strong evidence of systemic-induced resistance only if airflow was permitted among branches. Moreover, volatile communication between individuals was stronger in young plants. We also found that plants with neighbors clipped in May accumulated less damage throughout the season relative to plants with neighbors that were clipped later in the summer.

DOI： 10.1080/17429145.2010.545959

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

There are now approximately 10 documented examples of volatile plant communication that affect resistance to herbivores. For several of these cases, plants have been found to experience fitness benefits by responding to information (cues) released by experimentally damaged neighbors. However, it remains puzzling why plants might emit these cues following herbivore attack. One possibility is that release of cues is not adaptive for the emitter but rather cues leak out as a consequence of damage. Hypothetical benefits of emitting cues include: repelling herbivores; attracting predators of herbivores; suppressing germination of competitors; communicating with other branches of the same plant; and communicating with genetic relatives. Progress will be made in this field if we can find a system that is more tractable, allowing the nature of the cue to be identified and manipulated or allowing us to examine genetic constraints and influences on communication.

DOI： 10.1080/17429145.2010.536589

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

Previous studies reported that sagebrush plants near experimentally clipped neighbors experienced less herbivory than did plants near unclipped neighbors. Blocking air flow with plastic bags made this effect undetectable. However, some scientists remained skeptical about the possibility of volatile communication between plants since the existence and identity of a cue that operates in nature have never been demonstrated. We conducted an air transfer experiment that collected air from the headspace of an experimentally clipped donor plant and delivered it to the headspace of an unclipped assay plant. We found that assay plants treated with air from clipped donors were less likely to be damaged by naturally occurring herbivores in a field experiment. This simple air transfer experiment fulfills the most critical of Koch's postulates and provides more definitive evidence for volatile communication between plants. It also provides an inexpensive experimental protocol that can be used to screen plants for interplant communication in the field.

DOI： 10.1086/655222

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

Plants show many responses to herbivore damage caused by insects. We investigated the effect of the specialist leaf herbivore Luehdorfia puziloi on the performance of a deciduous forest understory perennial herb Asarum heterotropoides. We conducted artificial defoliation experiments with different levels of damage (0, 50 or 100% clipping) in the early growing period (flowering time: early May) and in the late growing period (when natural herbivory by L. puziloi larvae occurs: early June) in a natural population. Effects of the defoliation treatments on reproduction (seed-set ratio) of A. heterotropoides in the treated year and on survival and development of the plant in the subsequent year were investigated. Severe defoliation conducted in the early period resulted in less current-year seed production and increased regression to a dormant or non-reproductive stage in the following year, which would reduce the probability of future flowering. In contrast, defoliation conducted in the late period had no effect on the reproduction, survival and development of A. heterotropoides. Similarly, we found no obvious correlation between the damaged leaf area during the later period and seed set. Our results show that the specialist herbivore L. puziloi did not influence the performance of A. heterotropoides by damaging the plant later in the season when it was tolerant of damage.

DOI： 10.1111/j.1442-1984.2009.00263.x

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

DOI： 10.1111/j.1755-0998.2009.02796.x

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

Airborne communication can affect systemic induced resistance to herbivory on neighboring branches and individual plants. Sagebrush is the best known example of this phenomenon although the mechanisms of this communication system remain unidentified. We do not know the timing of emission or the chemical nature of the active cue. We investigated the timing of this phenomenon by using plastic bags to prevent propagation of volatile compounds and experimentally manipulated the timing of removal of these bags. We found that blocking the volatiles prevented systemic induced resistance. Experimentally allowing clipped branches to release cues for up to 3 days after clipping caused a reduction in damage in neighboring branches on the clipped plants. This indicates that active cues are released from the time we clipped for the next 3 days or that cues released immediately remained active over this time period. As we continue to evaluate potential chemicals as active cues in plant communication, this prolonged effectiveness may provide an important screen against which to evaluate any putative signals.

DOI： 10.1007/s11829-009-9060-0

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Language：Japanese   Publishing type：Research paper (other academic)  

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