The ABC transporter BcatrB affects the sensitivity of Botrytis cinerea to the phytoalexin resveratrol and the fungicide fenpiclonil

During pathogenesis, fungal pathogens are exposed to a variety of fungitoxi c compounds. This may be particularly relevant to Botrytis cinerea, a plant pathogen that has a broad host range and, consequently, is subjected to ex posure to many plant defense compounds. In practice, the pathogen is: contr olled with fungicides belonging to different: chemical groups. ATP-binding cassette (ABC) transporters might provide protection against plant defense compounds-and fungicides by ATP-driven efflux mechanisms. To test this hypo thesis, we cloned BcatrB, an ABC transporter-encoding gene from B. cinerea. This gene encodes a 1,439 amino acid protein with nucleotide binding fold: (NBF) and transmembrane (TM) domains in a [NBF-TM6](2) topology. The amino acid sequence has 31 to 67% identity with ABC transporters from various fun gi. The expression of BcatrB is up regulated by treatment of B. cinerea ger mlings with the grapevine phytoalexin resveratrol and the fungicide fenpicl onil. BcatrB replacement mutants are not affected in saprophytic growth on different media but are more sensitive to resveratrol and fenpiclonil than the parental isolate. Furthermore, virulence of Delta BcatrB mutants on gra pevine leaves was slightly reduced. These results indicate that BcatrB is a determinant in sensitivity of B. cinerea to plant defense compounds and fu ngicides.