Dissertation Research: Effects of legume-rhizobia symbiosis on plant-insect interactions

豆科植物与固氮根瘤菌共同进化的共生关系以其提高土壤肥力的能力为特征。虽然豆科植物-根瘤菌相互作用的许多方面已经被很好地表征，但对这种相互作用对其他生物，特别是食草动物的影响知之甚少。豆科植物接种根瘤菌后所引起的生理变化可能改变植物的防御能力和寄主的营养品质。此外，这种影响的性质和强度可能因根瘤菌菌株而异，因此可能对宿主植物产生不同程度的抗性。本项目的目的是：1)表征根瘤菌对不同饲料生态位食草动物生产性能的影响；2)确定接种如何改变植物对草食的反应；3)区分根瘤菌菌株对植物抗草食动物的特异性作用。试验将在大豆植株上进行，从根瘤菌、硝酸盐肥料或两者的组合中吸收氮。本研究将为草食动物在豆科植物-根瘤菌共生进化中的作用提供新的认识。探索根瘤菌保护寄主植物免受食草动物侵害的机制可能有助于开发新的和更有效的作物接种剂，从而有助于可持续农业实践。

The coevolved mutualism between legumes and nitrogen fixing rhizobia bacteria is distinguished by its capacity to increase soil fertility. While many aspects of the legume-rhizobia interaction have been well-characterized, little is known about the effects of this mutualism on other organisms, particularly herbivores. Physiological changes induced in legume plants upon inoculation with rhizobia may alter plant defenses and nutritional quality of the host. Moreover, the nature and intensity of such effects may vary across rhizobial strains, which may thus confer different levels of resistance to host plants. The objectives of this project are to: 1) characterize the effects of rhizobia on the performance of herbivores from different feeding niches; 2) determine how plant responses to herbivory are altered by inoculation; and 3) distinguish rhizobia strain-specific effects on plant resistance to herbivores. Experiments will be performed on soybean plants receiving nitrogen from rhizobia, nitrate fertilizers, or a combination of the two. This study will provide new insights into the role of herbivores in the evolution of the legume-rhizobia mutualism. Exploring mechanisms by which rhizobia may protect host plants from herbivores may facilitate the development of novel and more efficient inoculants for crop plants and thus contribute to sustainable agricultural practices.