Abstract

ATP-binding cassette (ABC) transporters hydrolyze ATP to transport a wide range of substrates.Fusarium graminearumis a major causal agent of Fusarium head blight, which is a severe disease in wheat worldwide.FgABCC9(FG05_07325) encodes an ABC-C (ABC transporter family C) transporter inF. graminearum, which was highly expressed during the infection in wheat and was up-regulated by the plant defense hormone salicylic acid (SA) and the fungicide tebuconazole. The predicted tertiary structure of the FgABCC9 protein was consistent with the schematic of the ABC exporter. Deletion ofFgABCC9resulted in decreased mycelial growth, increased sensitivity to SA and tebuconazole, reduced accumulation of deoxynivalenol (DON), and less pathogenicity towards wheat. Re-introduction of a functionalFgABCC9gene into ΔFgABCC9recovered the phenotypes of the wild type strain. Transgenic expression ofFgABCC9inArabidopsis thalianaincreased the accumulation of SA in its leaves without activating SA signaling, which suggests thatFgABCC9functions as an SA exporter. Taken together,FgABCC9encodes an ABC exporter, which is critical for fungal exportation of SA, response to tebuconazole, mycelial growth, and pathogenicity towards wheat.

Keywords:ABC transporter;SA;Fusarium head blight;mycotoxin