Dr. Shea Miller and Dr. Thérèse Ouellet, AAFC

Fusarium Head Blight (FHB) caused by F. graminearum is a devastating disease of wheat, affecting production, utilization, food safety and competitiveness in Canada. Although fungicide treatments and improved agronomic practices can help to reduce the FHB problem in low to moderate infection years, they are insufficient to prevent epidemics.

The only long-term sustainable solution is to develop resistant wheat cultivars. Although progress has been made in the production of varieties with some tolerance/resistance to FHB, higher resistance levels, and increased diversity in the sources of resistance used are required to produce wheat with durable resistance and that will sustain epidemic levels of FHB.

Progress has been made in the development of germplasm containing genetic material from wild grass species related to wheat, but little is known about the cellular and molecular basis of the acquired resistance. Our initial studies on two of those introgressed lines using the entire wheat spike indicated that the resistance mechanism is operating in the rachis of the infected floret, as there is little penetration of the fungus beyond the node of the inoculated floret in the resistant germplasm. Furthermore, changes in gene expression were noted at the molecular level that identified a group of genes whose expression profiles correlated with the resistance phenotype.

Current research will extend these studies by focussing on the chemical and molecular changes occurring in the wheat rachis. The knowledge acquired will be essential in establishing breeding priorities to combine the most promising traits with the few sources of resistance currently used in breeding programs, with the expectation that diversity and level of resistance will both be increased. Furthermore, the knowledge acquired will be applicable to breeding programs in all classes of wheat.

This project is supported through ORD.