The Arabidopsis neutral amino acid transporter UmamiT20 confers Botrytis cinerea susceptibility

Plant pathogens rely on host-derived nutrients for proliferation, yet the mechanisms by which hosts supply these nutrients remain incompletely understood. Here, we show that infection of Arabidopsis thaliana by the necrotrophic fungus Botrytis cinerea leads to increased accumulation of amino acid transporter UmamiT20 in leaf veins surrounding the lesions. Functional assays demonstrate that UmamiT20 mediates amino acid transport of a wide range of neutral amino acids. Consistent with a role during infection, umamiT20 knock-out mutants displayed significantly reduced susceptibility to B. cinerea. Our findings extend the concept of transporter-mediated susceptibility beyond the SWEET sugar transporters in bacterial blight of rice, cassava and cotton, to a necrotrophic fungus and implicate nutrients other than sucrose, i.e., amino acids, in nutrition or nutrient signaling related to immunity. We hypothesize that stacking of mutations in different types of susceptibility-related nutrient carriers to interfere with access to several nutrients may enable engineering robust pathogen resistance in a wide range of plant-pathogen systems.