Data from: The genetic architecture of constitutive and induced trichome density in two new RIL populations of Arabidopsis thaliana: phenotypic plasticity, epistasis, and bidirectional leaf damage response

Background: Herbivory imposes an important selective pressure on plants. In Arabidopsis thaliana leaf trichomes provide a key defense against insect herbivory; however, trichome production incurs a fitness cost in the absence of herbivory. Previous work on A. thaliana has shown an increase in trichome density in response to leaf damage, suggesting a mechanism by which the cost associated with constitutively high trichome density might be mitigated; however, the genetic basis of trichome density induction has not been studied. Results: Here, we describe the mapping of quantitative trait loci (QTL) for constitutive and damage induced trichome density in two new recombinant inbred line populations of A. thaliana; mapping for constitutive and induced trichome density also allowed for the investigation of damage response (plasticity) QTL. Both novel and previously identified QTL for constitutive trichome density and the first QTL for induced trichome density and response are identified. Interestingly, two of the four parental accessions and multiple RILs in each population exhibited lower trichome density following leaf damage, a response not previously described in A. thaliana. Importantly, a single QTL was mapped for the response phenotype and allelic variation at this locus appears to determine response trajectory in RILs. The data also show that epistatic interactions are a significant component of the genetic architecture of trichome density. Conclusions: Together, our results provide further insights into the genetic architecture of constitutive trichome density and new insights into induced trichome density in A. thaliana specifically and to our understanding of the genetic underpinnings of natural variation generally.

研究背景：植食作用对植物施加了重要的选择压。在拟南芥（Arabidopsis thaliana）中，叶片表皮毛（trichome）是抵御昆虫植食的关键防御结构；但在无植食压力的条件下，表皮毛的生成会产生适合度代价。既往针对拟南芥的研究表明，叶片受损后其表皮毛密度会升高，这提示存在一种可缓解组成型高表皮毛密度所带来的代价的机制，但目前尚未明确表皮毛密度诱导现象的遗传基础。
研究结果：本研究针对两个全新的拟南芥重组自交系（recombinant inbred line, RIL）群体，对组成型及损伤诱导型表皮毛密度的数量性状位点（QTL）进行了定位；通过对组成型与诱导型表皮毛密度的定位分析，还可同步探究损伤响应（可塑性）QTL。本研究不仅鉴定到了与组成型表皮毛密度相关的全新及既往已报道的QTL，还首次鉴定到了与诱导型表皮毛密度及损伤响应相关的QTL。值得关注的是，四个亲本种质中的两个，以及各群体中的多个重组自交系，在叶片受损后表皮毛密度反而降低，这一响应类型在拟南芥中此前尚未见报道。尤为关键的是，本研究定位到了一个与响应表型相关的QTL，该位点的等位基因变异似乎决定了重组自交系的响应轨迹。此外，数据显示上位性互作是表皮毛密度遗传架构的重要组成部分。
研究结论：综上，本研究结果不仅进一步阐明了拟南芥组成型表皮毛密度的遗传架构，还针对拟南芥的诱导型表皮毛密度提供了全新的认知，同时也为我们理解自然界变异的遗传基础提供了普适性的参考。