Mapping of QTL for resistance to powdery mildew and resistance gene analogues in perennial ryegrass

The objective of this study was to map resistance gene analogues (RGA) and quantitative trait loci (QTL) for powdery mildew resistance in perennial ryegrass ( Lolium perenne  L.). The mapping population consisted of 184 F₂ genotypes produced from a cross between one genotype of a synthetic perennial ryegrass variety Veyo and one genotype from the perennial ryegrass ecotype Falster. The greenhouse infection was measured as number of sporulating colonies on a 10-cm leaf area with the maximum possible number of colonies to be counted set to 50. The range of infection scores in the population was 0–50 and the heritability was 71.7%. In total, two QTL for powdery mildew resistance were identified, and mapped to linkage groups (LG) LG3 and LG7. Individually, these QTL explained between 7.5% and 22.1% of the total phenotypic variation. Six RGA and three laccases were mapped to LG2, LG3, LG4, LG5 and LG7, however, no close linkage between RGA and QTL was observed.