The ABC transporter BcatrB from Botrytis cinerea is a determinant of the activity of the phenylpyrrole fungicide fludioxonil

This study demonstrates that the ATP-binding cassette (ABC) transporter Bca trB from Botrytis cinerea influences the activity of phenylpyrrole fungicid es against the pathogen. This conclusion is based on toxicity assays and no rthern analysis experiments which show that BcatrB replacement mutants, whi ch do not express the BcatrB gene, show an increased sensitivity to the phe nylpyrrole fungicides fludioxonil and fenpiclonil. Mutants overexpressing B catrB exhibit a decreased sensitivity to these fungicides. In addition, acc umulation of fludioxonil by BcatrB replacement mutants was higher than by w ild-type isolates. For mutants overexpressing BcatrB the reverse was observ ed. Additional ABC and major facilitator superfamily (MFS) transporter gene s were identified in an expressed sequence tag (EST) database, suggesting t hat B cinerea has gene families of ABC and MFS transporters. Corresponding fragments of ten ABC (BcatrC-BcatrN) and three MFS transporter genes (Bcmfs 1-4) were cloned and characterised. Fludioxonil affected the transcript lev el of some members of these gene families in germlings during a short treat ment with the fungicide at sub-lethal concentrations. Hence, other ABC and MFS transporters may affect the activity of phenylpyrrole fungicides as wel l. Other fungicides such as the anilinopyrimidine fungicide cyprodinil, the azole fungicide tebuconazole, the dicarboximide fungicide iprodione and th e strobilurin fungicide trifloxystrobin also induced transcription of some of the ABC and MFS transporter genes identified. Therefore, we propose that various ABC and MFS transporters function in protection of the fungus agai nst fungicides and are involved in multi-drug resistance development. (C) 2 001 Society of Chemical Industry.