Differential transcriptome analyses of three wheat genotypes in their response to Fusarium Head Blight and trichothecenes

Fusarium Head Blight (FHB) is a disease of wheat and other cereal crops, where Fusarium graminearum and related species infects the wheat inflorescence during and post-anthesis. The fungus produces trichothecene toxins that accumulate in the grain of infected head, and are required for disease spread. Microarrays were used to observe differential gene expression in the uninoculated spikelets of FHB-challenged wheat spikes in three wheat genotypes. A summary of our findings will be published in Plant Pathology. Three wheat genotypes were used: (1) 'Superb', an FHB-susceptible Canadian wheat cultivar; (2) GS-1-EM0040 (CIMMYT11x'Superb'*2), a double haploid line with good resistance to initial infection (Type 1 resistance), and moderate resistance to disease spread (Type 2 resistance); and (3) GS-1-EM0168 (CM82036x'Superb'*2), a double haploid line with moderate Type 1 resistance, and good Type 2 resistance. Five inocula were used: (A) water, (B) FgTri5+ (GZ3639, a trichothecene-producing F. graminearum strain); (C) FgTri5- (GZT40, a trichothecene-non-producing mutant of the F. graminearum strain GZ3639); (D) FgTri5 supplemented with deoxynivalenol (DON), which is the main trichothecene produced by FgTri5+; and (E) DON. The inocula were injected into two spikelets near the center of the spike during early stages of anthesis, and spikelets above and below the inoculation point were collected at 3, 8, and 24 h after inoculation. A zero-hour un-inoculated control was also collected from each line. Total RNA was extracted from collected spikelets, and microarray analysis was perfomed using the Affymetrix Wheat GeneChip.