Genetic Engineering and Transformation

Fusarium head blight (FHB) significantly reduces grain yield and quality. Identification of genes that govern FHB resistance/susceptibility will facilitate biotechnology-assisted development of superior wheat varieties with FHB resistance. Our study on global expression profiling using microarray and real-time PCR identified three genes that are significantly highly expressed (up-regulated) in the resistant cv. Ning 7840 in comparison with the susceptible cv. Clark. Since these genes were always expressed to a greater extent in the resistant cultivar than in the susceptible cultivar, these could be very important genes for FHB resistance. A cluster of genes with significantly higher expression levels (down-regulated) in the susceptible cultivar Clark relative to the Ning 7840 was also discovered. These genes may facilitate fungal growth in a spike. Further investigation of the functions of these genes may provide useful information for understanding the mechanisms of FHB resistance. To investigate the biological function of these candidate genes, RNAi-mediated gene silencing will be used to knock out their corresponding homologous mRNAs in wheat. Double stranded hairpin RNA molecules corresponding to up-regulated genes will be targeted to resistant cultivars while dsRNA from downregulated genes will be targeted to susceptible cultivars to create loss-of-function plants. RNAi constructs using pANDA vector are underway.