Identification of genes associated with the 2DL QTL locus for fusarium head blight resistance.

The 2DL QTL from Wuhan 1 is a moderate resistance locus for Fusarium head blight (FHB), which has potential to improve the FHB resistance of bread wheat, and confer effective and durable resistance to novel wheat breeding lines. To identify genes associated with the 2DL QTL resistance locus, differentially expressed genes were identified by comparing a line carrying the 2DL QTL with a null sister line. Fourteen differentially expressed genes that were located on the 2DL chromosome arm, based on sequence information from the wheat genome, were characterized further by RT-qPCR; five of them were identified as having a similar differential expression pattern in 3 pairs of +/- 2DL lines. Another gene, called UN25696 and identified in previous expression work using microarray, was also confirmed to have a differential expression pattern in the 3 pairs of lines. Expression of the six candidate genes was then characterized in 78 lines of the double haploid mapping population derived from the cross Wuhan 1 x NuyBai, the population where the 2DL QTL was first identified. The expression QTL for genes UN25696, Traes_2DL_179570792 and Traes_2DL_89A313AC3 overlapped with the mapping interval for the 2DL QTL; however that of UN25696 was centered very close to the peak of the 2DL QTL, Our results suggest that UN25696, and possibly all three genes, contribute to the FHB resistance associated with the 2DL QTL.