The FgCYP51B Y123H mutation confers reduced sensitivity to prochloraz and is important for conidiation and ascospore development in Fusarium graminearum.

Abstract

Fusarium graminearum is one of the most important causal agent of Fusarium Head Blight disease and now were controlled mainly by chemicals such as DMI fungicides. FgCYP51B is one of the DMI targets in F. graminearum and Tyrosine123 is an important amino acid in Fusarium graminearum CYP51B, located in one of the predicted substrate binding pockets based on the binding mode between demethylation inhibitors (DMIs) and CYP51B. Previous study suggests that resistance to DMI fungicides is primarily attributed to point mutations in the CYP51 gene and that the Y123H mutation in F. verticillioides CYP51 confers prochloraz resistance in the laboratory. To investigate the function of FgCYP51B Y123 residue in the growth and development, pathogenicity, and DMI-resistance, the FgCYP51B Y123H mutant was generated and analyzed. Results revealed that Y123H mutation led to reduced conidial sporulation and affected ascospore development and moreover, the mutation conferred reduced sensitivity to prochloraz. The qPCR and molecular docking were performed to investigate the resistance mechanism. Results indicated that Y123H mutation changed the target gene expression and decreased the binding affinity of FgCYP51 to prochloraz. These results will attract more attention to the potential DMI-resistant mutation of F. graminearum and further deepen our understanding of the DMI resistance mechanism.