Quantitative trait loci analysis of adult plant resistance to Parastagonospora nodorum blotch in winter wheat cv. Liwilla ( Triticum aestivum L.)

Parastagonospora nodorum leaf and glume blotch (syn. Septoria nodorum blotch, SNB) is a severe disease in many wheat-growing areas worldwide. In a previous study, a mapping population, Liwilla × Begra, was used to detect several resistance quantitative trait loci (QTL) at the seedling stage. In this study the same mapping population was analysed at the adult plant stage under field and polytunnel conditions. After artificial inoculation the disease severity on leaves and glumes was scored as the areas under the disease progress curves for field tests and as the percentage of the leaf and glume area covered by necrosis for the polytunnel test. Three QTL associated with Septoria nodorum glume blotch resistance and two QTL associated with Septoria nodorum leaf blotch resistance were detected on chromosomes 1B, 3A, 4A and 7D. Each of the detected QTL explained only a small proportion of the total phenotypic variation, ranging from 9.1 to 20.0%. None of these QTL co-located with necrotrophic effector sensitivity loci or aligned with previously identified resistance loci at the seedling stage for the Liwilla × Begra population. SNB resistance QTL detected in our study did not overlap with QTL associated with morphological and developmental traits. Therefore they could be involved in the defence reaction and can be considered in wheat improvement for SNB resistance.