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Microbial Species Interactions and Disease Suppression in the Phytobiome

Linda Kinkel: Department of Plant Pathology/University of Minnesota

<div>Phytobiomes represent complex networks of interacting plant and microbial species. Our work explores the roles of plant community diversity, plant host, soil nutrient status, and fungal and bacterial species interactions in determining the pathogen-suppressive potential and composition of soil and foliar microbiomes. Our results show that rhizosphere <em>Streptomyces</em> associated with the same plant host are significantly more pathogen-suppressive and less niche-differentiated when the host grew in monoculture vs. within a high-diversity plant community. These data suggest that plant community diversity plays a critical role in determining the likelihood of antagonistic arms race coevolution vs. niche differentiation among sympatric soil populations, with significant implications for plant disease suppression. The power of fungal-bacterial coevolutionary species interaction in mediating inhibitory phenotypes is similarly evident in the observation that <em>Fusarium </em>are significantly better at inhibiting sympatric than allopatric populations of <em>Streptomyces</em>, and that inhibition is positively correlated with niche overlap between sympatric <em>Fusarium</em> and <em>Streptomyces</em> isolate pairs. This work illustrates the complex networks of species interactions that contribute to determining the pathogen suppressive potential of indigenous soil microbes.</div>