Integrated strategy to prevent mycotoxin risks (Inspyr)

Fusarium head blight (FHB) poses an increasing threat to wheat and barley crops in the UK. Under high disease pressure, current varieties are unable to restrict accumulation of deoxynivalenol (DON) mycotoxin to below EU thresholds. This project set out to facilitate incorporation of FHB resistance into UK varieties to reduce/eliminate the risk of trichothecene mycotoxins entering the food chain and enhance production efficiency. The project aimed to identify and characterise new sources of FHB resistance in wheat and barley and determine whether it is possible to break the association between the semi-dwarfing gene (Rht2) and susceptibility to FHB. The project also investigated the potential of an integrated approach combining host resistance with fungicides to further reduce the risk of mycotoxin accumulation on grain.

The presence of awns appears to increase FHB resistance. This finding is significant because almost all UK wheat varieties lack awns and this may, in part, account for the overall high level of susceptibility in UK wheat varieties.

Most UK varieties carry the semi dwarfing gene (Rht2). The presence of this gene has long been associated with susceptibility to FHB. The Inspyr project revealed that the effect is due, not to the Rht2 gene itself, but to a nearby gene. Using markers located near the susceptibility gene, it is now possible for breeders to select lines of the desired height for UK conditions but that lack the FHB susceptibility factor. This should provide a very rapid means to improve the overall FHB resistance of UK wheat varieties.

The Inspyr project demonstrated that an integrated approach of growing FHB resistant varieties and treating with appropriate fungicides at the time of flowering provides a means to reduce the risk of DON accumulation in grain exceeding EU thresholds. This offers an approach to maintain crop and consumer health, even under conditions of high disease pressure.

While in wheat, greater resistance to FHB is often associated with greater plant height this does not appear to be the case for barley. A potent FHB resistance was identified in the heritage barley variety Chevallier that functions independently of plant height.

The findings of the Inspyr project offer plant breeders and growers a number of ways in which to improve the overall FHB resistance of UK wheat and barley varieties and to reduce the risk of mycotoxin accumulation in grain in their crops, even when exposed to high disease pressure.

Further work will be required to find the optimum number and type of FHB resistances required to work alongside the available fungicides to eliminate the risk posed by FHB in most circumstances. Additional work will also be required to identify how the resistances interact with different fungicide chemistries to provide optimal control.