An Integrated Study of Metarhizium-Plant Interactions

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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.*****