Identification and characterization of a NADPH oxidase target in Fusarium graminearum

Abstract

Fusarium graminearum is a fungal plant pathogen that causes Fusarium Head Blight (FHB) on important food and feed cereal crops including wheat, maize and barley.Earlier studies identified distinct roles for NADPH oxidase (NOX) genes in F. graminearum. NOX enzymes generate reactive oxygen species (ROS) including hydrogen peroxide (H 2 O 2 ), which are important in signal transduction. To elucidate the mechanism of NOX dependent signaling in pathogenicity, a proteomics approach was used to examine redox changes in the ΔnoxA/B mutant and compared to wildtype F. graminearum strain. Candidate substrates of NOX enzymes were characterized by genetic analysis. Deletion and overexpression of one of the candidate genes, FGSG_10089 with modified cysteine residues confirmed that it is likely a genuine substrate of the NOX enzyme complex. Bioinformatics and expression analysis indicate that this protein may function as a virulence factor. Deletion of FGSG_10089 as well as modification of the cysteine residue C 325 resulted in reduced virulence on wheat. In addition, there was a decrease in production of 15-acetyl deoxynivalenol in culture.iii Acknowledgements I would like to thank my supervisor Dr. Gopal Subramaniam for his guidance and patience in helping me develop my research and writing skills. His enthusiasm for scientific progress and innovation is infectious and inspiring. Furthermore, I am grateful to my co-supervisor Owen Rowland and committee members Dr. Willmore and Dr.Vierula for their insights and assistance.