FgSKN 7 and FgATF 1 have overlapping functions in ascosporogenesis, pathogenesis and stress responses in F usarium graminearum

Abstract

Summary Fusarium head blight caused by F usarium graminearum is one of the most destructive diseases of wheat and barley. Deoxynivalenol ( DON ) produced by the pathogen is an important mycotoxins and virulence factor. Because oxidative burst is a common defense response and reactive oxygen species ( ROS ) induces DON production, in this study, we characterized functional relationships of three stress‐related transcription factor genes FgAP 1 , FgATF 1 and FgSKN 7. Although all of them played a role in tolerance to oxidative stress, deletion of FgAP 1 or FgATF 1 had no significant effect on DON production. In contrast, F gskn7 mutants were reduced in DON production and defective in H 2 O 2 ‐induced TRI gene expression. The F gap1 mutant had no detectable phenotype other than increased sensitivity to H 2 O 2 and F gap1 F gatf1 and F gap1 F gskn7 mutants lacked additional or more severe phenotypes than the single mutants. The F gatf1 , but not F gskn7 , mutant was significantly reduced in virulence and delayed in ascospore release. The F gskn7 F gatf1 double mutant had more severe defects in growth, conidiation and virulence than the F gatf1 or F gskn7 mutant. Instead of producing four‐celled ascospores, it formed eight small, single‐celled ascospores in each ascus. Therefore, FgSKN 7 and FgATF 1 must have overlapping functions in intracellular ROS signalling for growth, development and pathogenesis in F . graminearum .

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