An Integrated Study of Metarhizium-Plant Interactions

旨在养活日益增长的世界人口和气候变化引起的相关问题的可持续农业做法要求优化资源利用和减少粮食生产对环境的影响。帮助实现这些目标的一种方法是将有益的微生物整合到植物微生物群中。我们计划研究昆虫病原真菌绿僵菌在植物根部微生物群中的整合及其对农业重要植物健康的影响。 绿僵菌主要生活在根际(植物根部附近的土壤区域)，分布世界各地，很容易从土壤中恢复。绿僵菌(Metarhizium spp.)具有双重生态作用：它们既是昆虫病原体，又是根际定居者。将绿僵菌作为昆虫病原体和植物根部定殖者的生活方式联系起来，我们已经表明这种真菌与植物的关系是有益的。我们已经证明，受感染昆虫的真菌菌丝体迁移到植物根部，然后根部被定植。随后，昆虫产生的氮素被转移到植物体内。我们还表明，这是一种共生关系，昆虫的氮由真菌提供给植物，以换取植物的碳(即碳水化合物)。阐明这种真菌与植物的联系将产生植物与微生物相互作用的另一种想法。 拟议研究的总主题是通过在土壤中应用绿僵菌来改善植物健康。我们复杂的相互关联的研究计划将重点放在这种相互作用的三个组成部分上：(1)植物代谢组学，即植物产生的化合物，包括植物免疫激素；(2)绿僵菌及其各自的代谢物；(3)根微生物组。 我们将通过使用分析化学技术和基因测序来实现我们的目标。我们预计，使用这些分析技术收集的数据将使我的实验室能够阐明土壤中微生物之间的相互作用，包括绿僵菌，绿僵菌产生的代谢物，以及植物对这些微生物根部定植的反应。一个基本的问题是，为什么这种植物允许某些有益微生物(如绿僵菌)在根上定居，但对病原微生物却做出防御反应？绿僵菌会产生与植物沟通的化合物吗？植物对这些化合物有何反应？确定绿僵菌是如何作为植物共生体工作的，以及它们何时和为什么工作，将提供对微生物与植物相互作用的分子理解。绿僵菌与其他植物根部定植真菌有共同之处，我们希望我们的结果能有很多应用。我们的研究对植物保护、植物生产力、植物次生代谢产物的产生以及植物根际生态关联的一般知识具有重要意义。

Sustainable agricultural practices aimed at feeding a growing world population and the associated problems arising from climate change requires optimizing resource use and reducing the environmental impacts of food production. One way to assist in achieving these goals is to integrate beneficial microorganisms into plant microbiomes. We plan to study the integration of the insect pathogenic fungus Metarhizium into the plant root microbiome and its effects on the health of agriculturally important plants. Metarhizium, which resides primarily in the rhizosphere (region of the soil in the vicinity of plant roots), has a world-wide distribution and can be easily recovered from soils. Metarhizium spp. have a dual ecological role: they are both insect pathogens and rhizosphere colonizers. Connecting the lifestyles of Metarhizium both as insect pathogens and as plant root colonizeers, we have shown that the relationship of this fungus to plants is beneficial. We have shown that fungal mycelia from infected insects migrate to plant roots that are then colonized. Subsequently the insect-derived nitrogen is transferred to the plant. We have also shown that this is a symbiotic association where insect nitrogen is provided to the plant by the fungus in exchange for plant carbon (i.e., carbohydrates). Elucidating the association of this fungus with plants will generate alternate ideas of plant-microbe interactions. The overall theme of the proposed research is improvement of plant health by the application of Metarhizium to soils. Our complex interconnected research program will focus on three components of this interaction (1) plant metabolomics , that is, the compounds produced by the plant, including plant immune hormones, (2) Metarhizium strains and their respective metabolome, and (3) the root microbiome. We will accomplish our goals by using analytical chemical techniques and gene sequencing. We anticipate that data collected from using these analytic techniques will allow my lab to elucidate the interactions between microorganisms in the soil, including Metarhizium, the metabolites that Metarhizium produces and the responses by the plant to root colonization by these microorganisms. One basic question is why does the plant allow root colonization by certain beneficial microorganisms such as Metarhizium but responds defensively to pathogenic microorganisms? Does Metarhizium produce compounds that communicate to the plant and how does the plant respond to those compounds? Identifying how Metarhizium work as plant symbionts, and when and why they work, would provide a molecular understanding of the interactions of microbes with plants. Metarhizium have commonalities with other plant root colonizing fungi and we expect our results to have many applications. Our research has implications on plant protection, plant productivity, plant secondary metabolite production and general knowledge of ecological associations in the plant rhizosphere.