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Oral: Role of Phytobiomes in Plant Disease Control


Phyllosphere fungal endophyte effects on plant disease are context-dependent
P. BUSBY (1), G. Crutsinger (2), M. Barbour (2), G. Newcombe (3) (1) Oregon State University, U.S.A.; (2) UBC, Canada; (3) U Idaho, U.S.A.

Manipulative experiments demonstrate that individual fungal leaf endophytes can contribute to plant defense against pathogens. However, whether disease protection depends on species interactions within the leaf microbiome is not well known, particularly for complex microbiomes that exist in nature. We tested whether competition between a leaf rust pathogen and an endophytic mite affects fungal leaf endophyte antagonism of leaf rust disease in Populus. We manipulated competitive interactions between the rust pathogen and the mite by using a suite of Populus genotypes that differ in genetic resistance to the two organisms. We inoculated Populus leaves with fungal leaf endophytes and then evaluated rust disease severity. Endophytes reduced disease severity only in the absence of mite-rust competition, illustrating the importance of competition for plant microbiome function.