P-317 - Did barley-associated fungi evolve core effectors with antimicrobial activity to target host-associated keystone microbes?

The plant microbiota is important for plant growth and fitness, and protects the plant from disease. For successful infection, pathogenic microbes need to overcome plant immunity as well as microbial antagonists that reside in the plant-associated microbiota. Thus, in addition to effectors that target host physiology, pathogenic fungi secrete effectors with selective antimicrobial activities to manipulate host microbiota. Based on a newly developed tool to predict antimicrobial effectors, we show that antimicrobial effectors occur across the fungal kingdom and across lifestyles. As fungi which colonize the same host plant encounter similar microbiota, we hypothesize that these fungi evolved shared antimicrobial effectors to target host-associated keystone microbes to facilitate tissue colonization. To address this hypothesis, we study a wide variety of fungi with different lifestyles that associate with barley (Hordeum vulgare). We identified several effector families with predicted antimicrobial activity which are enriched in these barley-associated fungi. We presently functionally validate these effectors and analyse their contribution to barley colonization. Additionally, we will study microbiota changes upon fungal infection. Altogether, we aim to enhance our understanding of the role of antimicrobial effectors in niche establishment.