Dissertation Research: Mechanisms Underlying Complex Interactions Between Plants, Herbivores, and Arbuscular Mycorrhizal Fungi

在自然界和农业中，关于昆虫食草动物对植物影响的研究主要集中在食草动物和植物之间发生的直接相互作用上。然而，我们知道土壤生物，如有益菌根真菌（促进植物吸收营养）可以改变植物生长和植物间相互作用的结果。因此，我们预计这些土壤生物也可以改变植物-草食相互作用的结果。该研究测试了两种预测食草动物、植物和菌根真菌之间相互作用结果的新假设。营养假说认为，植物与菌根真菌的联系所增加的营养将直接转化为草食动物生长的增加，而防御修正假说认为，菌根真菌改变了植物防御的产生，使得以菌根植物为食的食草动物的生长比以非菌根植物为食的食草动物的生长减少。将进行两个实验来研究与菌根真菌有关的植物的食草性。这些实验将检验三种植物防御反应；测量草食动物对菌根存在的反应；并测量菌根对草食的反应，从而确定哪种假设与该系统所表现出的反应最一致。菌根-植物-草食相互作用的知识将为理解草食动物在农业中的影响作为菌根真菌在土壤群落中的功能提供预测工具。通过这些实验，PI将继续指导少数民族和女性本科生。这些学生将协助实施这些实验，同时开发和开展他们自己的项目；他们将提高他们的分析能力，拓宽他们进入各种科学领域的学术准备。

Studies of insect herbivore impacts on plants in nature and agriculture have primarily focused on the direct interactions that occur between an herbivore and a plant. However, we know that soil organisms such as beneficial mycorrhizal fungi (which promote nutrient absorption by plants) can alter plant growth and the outcome of plant-plant interactions. Therefore, we expect that these soil organisms can also change the outcome of a plant-herbivore interaction. The research tests two novel hypotheses for predicting the outcomes of interactions between herbivores, plants and mycorrhizal fungi. The Nutrition Hypothesis suggests that increased nutrition from a plant's association with mycorrhizal fungi will directly translate into increased herbivore growth, and the Modification of Defense Hypothesis suggests that mycorrhizal fungi alter the production of plant defenses such that herbivores feeding on mycorrhizal plants experience a decrease in growth compared to herbivores feeding on non-mycorrhizal plants. Two experiments will be conducted to examine herbivory on plants associated with mycorrhizal fungi. These experiments will examine three plant defense responses; measure herbivore responses to the presence of mycorrhizae; and measure mycorrhizal responses to herbivory, thereby determining which hypothesis is most consistent with the responses exhibited by this system. Knowledge of mycorrhizal-plant-herbivore interactions will provide a predictive tool for understanding the impact of herbivores in agriculture as a function of mycorrhizal fungi in the soil community. Through work on these experiments, the PI will continue mentoring minority and female undergraduates. These students will assist with the implementation of these experiments while developing and conducting their own projects; they will improve their analytical skills, and broadened their academic preparation to enter a variety of scientific fields.