Dissertation Research: The biotic environment and the context-dependent nature of plant-microbial symbiosis

植物体内常常藏有各种各样的微生物。植物与这些微生物共生体之间的相互作用影响着陆地植物群落的多样性、结构和功能。在许多这样的相互作用中，微生物为宿主植物提供养分，以换取植物的碳。丛枝菌根真菌和根瘤菌是豆科植物中两种常见的营养植物共生体。这些共生体中的每一个有利于或对抗它们的植物伙伴的方式各不相同，部分取决于土壤养分水平。此外，植物可以将资源分配给多个合作伙伴，允许同时存在交互作用，以影响交互作用的成本和收益。该项目评估了生物(即共生共生体)和非生物(即土壤养分水平)因素对植物-微生物相互作用后果的相对重要性。大多数关于植物-微生物相互作用的研究集中在单一宿主和单一共生体上。然而，在自然界中，植物同时与许多共生体相互作用。这个项目从实验上检验了自然植物-微生物相互作用这一特征的重要性。本工程的成果适用于生态修复的多个目标。由于豆科植物具有固定氮素的能力，它们是植物群落的重要成员，而且往往是恢复管理中的优先物种。许多恢复项目始于后农业领域。虽然自然地区的土壤往往是养分有限的，但受干扰的环境往往受到高水平的人类养分沉积的影响。因此，该项目通过揭示非自然营养水平和土壤群落豆类-根瘤菌相互作用的后果来帮助恢复工作的成功。我们将把这个项目的工作纳入当地一家儿童科学博物馆的一个特别项目中，该项目旨在阐明地下生物过程和生物体。

Plants often harbor a wide variety of microbial organisms within their bodies. Interactions between plants and these microbial symbionts influence the diversity, structure, and function of terrestrial plant communities. In many such interactions the microbe provides host plants with nutrients in exchange for carbon from the plant. Arbuscular mycorrhizal fungi, a soil fungus that specializes in the acquisition of phosphorus, and rhizobia, a nitrogen-fixing soil bacterium are two common nutritional plant symbionts of legume plants. The manner in which each of these symbionts benefits or antagonizes their plant partner varies and is partially determined by soil nutrient levels. Moreover, plants can allocate resources to multiple partners, allowing for the presence of simultaneous interactions to influence the costs and benefits of the interaction. This project evaluates the relative importance of biotic (i.e. co-occurring symbionts) and abiotic (i.e. soil nutrient levels) factors on the consequences of plant-microbial interactions.The majority of investigations on plant-microbial interactions have focused a single host and a single symbiont. Yet in nature plants simultaneously interact with many symbionts. This project experimentally examines the importance of this feature of natural plant-microbe interactions. Results of this project are applicable to many goals of ecological restoration. Because of their ability to fix nitrogen, legumes are important members of plant communities, and are often priority species in restoration management. Many restoration projects begin in post-agricultural fields. While the soils of natural areas are often nutrient limited, disturbed environments are often subjected to high levels of anthropological nutrient deposition. Thus this project aids the success of restoration efforts by shedding light onto the consequences of both unnatural nutrient levels and the soil community the legume-rhizobia interactions. We will incorporate work from this project into a special program at a local children's science museum that elucidates below-ground biological process and organisms.