Identification of molecular markers for resistance to Stagonospora nodurum blotch in wheat

Stagonospora nodorum blotch (SNB) is a fungal disease of wheat causing leaf and glume blotch. The disease occurs in many wheat growing regions worldwide and is considered to be among the major diseases of wheat in humid temperate climates, resulting in significant losses in grain quality and yield. The development of resistant cultivars is the most efficient and environmentally sustainable means of controlling SNB. However, incorporation of resistance to SNB into wheat using conventional methods is difficult because resistance appears to be inherited as a quantitative character in the majority of cultivars. Furthermore, agronomic traits such as plant height, earliness, and winter growth habit also influence the development of the disease. The complexity of resistance mechanisms has made it difficult to assess resistance in new wheat cultivars. The use of quantitative resistance in breeding programs would be greatly facilitated by marker-assisted selection. Therefore, the aim of this proposal is to identify and localize the genes involved in the resistance to leaf and glume blotch of wheat and to quantify the magnitude of their effects. Mapping populations of recombinant F1-derived doubled haploid (DH) lines from two crosses between two partially resistant (Frontana and CM 82036) and one susceptible wheat cultivar (Remus) will be evaluated for leaf and glume blotch resistance at the adult stage in the greenhouse and in the field. The availability of data on leaf and glume blotch resistance together with information of molecular markers will allow to determine quantitative trait loci (QTLs). Number and effect of QTLs involved in both resistance traits will be estimated. The ultimate goal of the QTL analysis is to develop tools that are useful for marker assisted selection for SNB resistance in practical breeding programs.