Ecological and evolutionary constraints of plant tolerance to herbivory

一些植物可以耐受植食性和组织损伤而不降低适合度（或产量），但我们对耐受性性状的进化和生态学，甚至植物补偿能力的机制知之甚少。此外，我们仍然缺乏对植物防御草食动物抗性（避免被吃掉）和耐受性（忍受被吃掉）的两个组成部分是否在其与植物生长和繁殖的生态和进化关系方面存在差异的基本了解。尽管事实上植物种群内耐受性反应的表达和固定可能具有巨大的生态后果，例如通过降低生物防治剂对入侵杂草的有效性，或支持作物中更多样化的昆虫群落。事实上，理论表明，对植食性的耐受性可能在其对植食性昆虫及其天敌的种群动态的影响方面与植物抗性有着根本的不同，例如，通过避免植物-昆虫抗性进化中典型的进化军备竞赛。更好地了解植物耐受性性状及其影响不仅可以解决围绕植物防御变异和植物-昆虫相互作用特异性的一些突出的生态学和进化问题，而且还可以为植物改良和保护计划提供可操作的目标。 我提出的研究计划的长期目标是提供一个机制和遗传框架，以了解生态学和植物耐食草动物的进化。为了实现这一目标，我和我实验室的HQP将使用田间、温室和实验室实验：1）确定耐受性的生化和生理机制; 2）探索耐受性性状的遗传标记; 3）确定耐受性对关键生物相互作用的生态影响; 4）比较经历生态和进化分歧的植物种群的耐受性进化。特别是，跨越植物-昆虫相互作用梯度的种群（例如驯化作物及其野生亲属）之间的性状比较，将是理解植物性状与昆虫种群动态之间在生态和进化时间尺度上的关系的有力方法。 在植物育种和作物生产中，将植物对草食动物耐受性的遗传和生化机制结合起来具有变革的潜力。尽管昆虫负荷很高，但植物耐受性可能对植物产量产生很大影响，并可能减缓和破坏害虫抗性的进化，这突出了这项研究的紧迫性。事实上，由于植物的耐受性反应可能与多种胁迫反应有关，包括干旱，温度和除草剂的应用，因此本研究计划的产品将适用于害虫管理以外的其他植物改良。

Some plants can tolerate herbivory and tissue damage without reductions in fitness (or yield), yet we know very little about the evolution and ecology of tolerance traits, or even the mechanisms involved in plant compensatory ability. Moreover, we still lack a basic understanding of whether the two components of plant defense against herbivores resistance (avoiding being eaten) and tolerance (enduring being eaten) differ in their ecological and evolutionary relationships to plant growth and reproduction. This is despite the fact that the expression and fixation of tolerance responses within plant populations may have immense ecological consequences, e.g. through decreasing the effectiveness of biocontrol agents for invasive weeds, or supporting a more diverse insect community in crops. Indeed, theory suggests that tolerance of herbivory may fundamentally differ from plant resistance in its effects on the population dynamics of insect herbivores and their natural enemies, e.g by avoiding the evolutionary arms race typical in plant-insect resistance evolution. A greater understanding of plant tolerance traits and impact could not only resolve some of the outstanding ecological and evolutionary questions around variation in plant defense and specificity in plant-insect interactions, but also produce an actionable target for plant improvement and protection programs. My proposed research program's long-term objective is to provide a mechanistic and genetic framework to understand the ecology and evolution of plant tolerance of herbivory. To achieve this, HQP in my lab and I will use field, greenhouse, and laboratory experiments to: 1) Identify biochemical and physiological mechanisms of tolerance; 2) Explore genetic markers for tolerance traits; 3) Determine ecological impacts of tolerance on key biotic interactions; and 4) Compare the evolution of tolerance in plant populations that have experienced ecological and evolutionary divergence. In particular, the comparison of traits among populations that span a gradient of plant-insect interactions (e.g. domesticated crops and their wild relatives), will be a powerful approach to understand the relationships among plant traits and insect population dynamics across ecological and evolutionary time scales. There is transformative potential for incorporating the genetic and biochemical mechanisms of plant tolerance to herbivory in plant breeding and crop production. Plant tolerance could have a large impact on plant yields despite high insect loads, and could slow and disrupt the evolution of pest resistance, which underscores the urgency of this research. Indeed, as tolerance responses in plants are likely related to a multitude of stress responses, including to drought, temperature and herbicide application, the products of this research program will be applicable to other plant improvements beyond pest management.