Data from: The genetics of phenotypic plasticity in plant defense: trichome production in Mimulus guttatus

Insect herbivory is a major driving force of plant evolution. Phenotypic plasticity and developmental variation provide a means for plants to cope with variable herbivory. We characterized the genetics of developmental variation and phenotypic plasticity in trichome density, a putative defensive trait of Mimulus guttatus (yellow monkeyflower). Our results are evaluated in relation to the optimal defense theory, which provides testable predictions for plastic and developmental patterns in defense traits. We found that both developmental stage and simulated insect damage affected trichome production, but in different ways. Plants were more likely to produce at least some trichomes on later leaves than on earlier leaves, regardless of damage. Damage did not affect the average probability of producing trichomes, but it did increase the density of hairs on trichome‐positive plants. We mapped trichome quantitative trait loci (QTL) by selectively genotyping a large panel of recombinant inbred lines derived from two highly divergent populations. Several highly pleiotropic QTL influenced multiple aspects of the trichome phenotype (constitutive, developmental, and/or plastic responses). Only one of the QTL influenced trichome induction following damage. In a result that is consistent with a central prediction of optimal defense theory, the high allele at this location was from the ancestral population with low constitutive trichome production.昆虫植食作用是推动植物演化的核心驱动力之一。表型可塑性与发育变异为植物应对多变的植食压力提供了适应性策略。本研究以黄色猴面花（Mimulus guttatus）的推定防御性状——毛状体密度（trichome density）为研究对象，解析了其发育变异与表型可塑性的遗传基础。本研究结果结合最优防御理论（optimal defense theory）进行解读，该理论可为防御性状的可塑性与发育模式提供可验证的理论预测。研究发现，植物发育阶段与模拟昆虫损伤均会影响毛状体的产生，但二者的作用模式存在差异。无论是否遭受损伤，植物后期长出的叶片相较于早期叶片，更易形成毛状体。昆虫损伤并未显著影响毛状体产生的平均概率，但可提升已形成毛状体植株的毛状体密度。本研究通过对源自两个高度分化种群的大型重组自交系（recombinant inbred lines, RIL）群体进行选择性基因分型，定位了毛状体相关的数量性状位点（quantitative trait loci, QTL）。多个具有高度多效性的QTL可同时调控毛状体表型的多个维度，包括组成型表达、发育模式以及可塑性响应。仅有一个QTL可调控损伤诱导的毛状体形成。该位点的高效应等位基因源自毛状体组成型表达水平较低的祖先种群，这一结果与最优防御理论的核心预测相符。