QTL controlling partial resistance to Stagonospora nodorum leaf blotch in winter wheat cultivar Alba

Stagonospora nodorum blotch (SNB) is an important foliar and glume disease in cereals. Inheritance of SNB resistance in wheat appears quantitative. The development of partially resistant cultivars seems to be the only effective way to combat the pathogen. Partial resistance components like length of incubation period (INC), disease severity (DIS) and length of latent period (LAT) were evaluated on a population of doubled-haploids derived from a cross between the partially resistant cultivar Alba and the susceptible cultivar Begra. Experiments were conducted in controlled environments and the fifth leaf was examined. Molecular analyses were based on bulked segregant analyses (BSA) and screening with 240 microsatellites DNA markers. The QTL analysis revealed QTL on chromosome 6AL (designated as QSnl.ihar-6A) and putative QTL on chromosome 6D. The QSnl.ihar-6A accounted for 36% of the phenotypic variance for DIS and 14% for INC. The putative QTL accounted for 10% of the variability in INC and 8% of DIS components of SNB resistance.