Current knowledge on resistance to Fusarium head blight in tetraploid wheat

Fusarium head blight (FHB) is a serious threat worldwide due to its dramatic consequences and effects on small grain cereal production such as yield and quality losses and most importantly mycotoxin contamination. Durum wheat ( Triticum durum Desf.) is particularly susceptible to FHB. Enhancing resistance has proven difficult due to the narrow genetic variation for this trait in the durum wheat gene pool. Broadening the genetic basis by incorporating resistance alleles from wild and cultivated relatives is a promising approach for durum resistance breeding. This review summarizes the current information on sources available for FHB resistance improvement in durum wheat which include wild and cultivated tetraploid wheat, hexaploid wheat and alien species. The genetic basis of FHB resistance of a few tetraploid sources in the T. durum background has been dissected by QTL mapping. So far, thirteen QTL with small to moderate effects have repeatedly been detected on 11 chromosomes with alleles improving FHB resistance deriving from relatives and durum wheat itself. Notably, the QTL found in tetraploid wheat populations largely overlap with the QTL identified in hexaploid wheat suggesting a common genetic basis of FHB resistance. FHB resistance breeding by allele introgression into durum wheat is feasible, and QTL pyramiding appears a practicable strategy for durum resistance breeding.