DISSERTATION RESEARCH: Dissecting microbial mediation of plant-herbivore interactions in the wild

如果仔细观察，大多数植物都有被昆虫咀嚼、挖掘或以其他方式吃掉的痕迹。另一种形式的攻击者，真菌和细菌，也很常见，并且可能通过其对供人类食用的蔬菜的影响而熟悉;这些病原体产生黑点，枯萎的叶子或其他腐烂的迹象。由于每种类型的攻击者在自然界中都很常见，植物已经进化出了预防或最小化它们造成的损害的方法。但是，正如万事通不精通任何东西一样，植物也很难同时抵御所有类型的攻击者。也就是说，被细菌感染的植物通常更容易受到昆虫的影响，反之亦然。这些现象被称为权衡？有益于生物体的行为或反应之间的负面相互作用？它们的进化起源和生态后果仍不清楚。该项目探讨了本土植物是否受到防御昆虫和细菌的权衡的影响，以及个体植物的防御状态如何影响同一植物的整个种群对被攻击的反应。先前的研究结果表明，在一种原生植物-芹菜的野生种群中，细菌丰度与采叶蝇的攻击之间存在正相关。该项目将把细菌对芹菜及其食草动物的生态影响与植物化学和防御的变化联系起来，这些变化可能是观察到的影响的基础，以及细菌中可能指导特定植物防御的基因和基因产物。这种防御权衡的证据已经在许多作物物种中发现，并且在实验室条件下也观察到了，但是缺少本地植物及其野生细菌和昆虫攻击者的例子。通过在自然条件下使用野生物种，该项目将提供一个假设，即叶栖细菌作为一个无处不在的，但神秘的第三个球员在昆虫和植物之间的关系的测试。研究结果将有助于为全球农业系统中的害虫和病原体管理提供信息，并与粮食安全明显相关。 此外，研究人员将指导本科生收集和解释数据，并将在公立学校工作，与教师和高中生分享他们的结果。

If one looks closely, most plants bear some signs of having been chewed, mined, or otherwise eaten by insects. Another form of attacker, fungus and bacteria, is also common, and may be familiar through its effects on vegetables intended for human consumption; these pathogens create black spots, wilted leaves, or other signs of rot. Because each type of attacker is so common in nature, plants have evolved means of preventing or minimizing the damage they inflict. But just as the jack-of-all-trades is master of none, plants have difficulty defending themselves against all types of attacker simultaneously. That is, plants infected with bacteria are often more susceptible to insects, and vice versa. These phenomena are called trade-offs?negative interactions between behaviors or responses that otherwise benefit organisms?and their evolutionary origins and ecological consequences remain unclear. This project explores whether native plants are affected by a trade-off in defense against insects and bacteria, and how the defense status of individual plants affects how entire populations of the same plants respond to being attacked. Prior results show a positive association between bacterial abundance and attack by a leaf-mining fly across a wild population of a native plant, bittercress. This project will link the ecological impact of bacteria on bittercress and its herbivores to changes in plant chemistry and defenses that may underlie the observed effects, as well as genes and gene products in bacteria that may direct particular plant defenses. Evidence for this defense trade-off has been found for many species of crops and likewise has been observed in laboratory conditions, but examples for native plants and their wild bacterial and insect attackers are missing. By using wild species in natural conditions, this project will provide a test of the hypothesis that leaf-dwelling bacteria act as a ubiquitous but cryptic third player in the relations between insects and plants. Results will help inform management of pests and pathogens in agricultural systems worldwide, with clear relevance to food security. Also, the researchers will mentor undergraduate students in collection and interpretation of data, and will work in public schools to share their results with teachers and high school students.