Poster: Molecular & Cellular Plant-Microbe Interactions: Proteomics/Metabolomics/Genomics
783-P
Functional characterization of candidate effector proteins identified from the wheat scab fungus Fusarium graminearum
S. Lu (1), M. Edwards (1), S. Lu (1) (1) USDA-ARS Cereal Crops Research Unit, U.S.A.
Fungal pathogens often produce certain small secreted cysteine-rich proteins (SSCPs) during pathogenesis that may function in triggering resistance or susceptibility in specific host plants. We have recently identified a total of 190 SSCPs encoded in the genome of the wheat scab fungus Fusarium graminearum and found at least 23 SSCPs to be true extracellular proteins that are expressed in planta. To facilitate functional characterization, we compared the expression patterns between compatible and incompatible interactions by transcriptional analysis. A majority of SSCPs examined were found to be expressed in identical or similar patterns when the fungus attacked susceptible wheat cultivars such as Grandin and Wheaton. However, the expression patterns of at least 13 SSCPs were altered when the same pathogen infected the resistant cultivar Sumai 3: the expression of 11 SSCPs appeared to be suppressed or “down-regulated” at certain stages of infection while two others were apparently “up-regulated” at 4-8 days post inoculation. Gene knock-out experiments are underway with the priority given to these differentially expressed SSCPs. The resultant deletion mutants will be subjected to pathogenicity assays on both susceptible and resistant wheat cultivars to determine the roles of these candidate effector proteins in F. graminearum-wheat interactions. This study may provide new molecular insights into Fusarium head scab, a devastating disease of wheat crops worldwide.