Locating two novel genes for resistance to powdery mildew from Avena byzantina in the oat genome

Powdery mildew of oats is a major threat to intensive oat farming under humid climate, and the use of resistant cultivars is the most environmentally friendly way of achieving safe yields. In this study, the genetic mapping of unexplored resistance genes from Avena byzantina accessions AVE2406 and AVE2925, designated Pm9 and Pm10, is described. Both accessions were crossed with susceptible cultivars, and monogenic segregation was established based on detached leaf segment tests. The two recombinant inbred line (RIL) populations RIL29 (with AVE2925) and RIL24 (with AVE2406) were phenotyped for powdery mildew resistance and genotyped with DArTseq. The genetic map of RIL24 had 2,516 markers in 30 linkage groups with a length of 2,641.5 cM; for RIL29, 921 markers were allocated to 30 linkage groups totalling to 1,378.2 cM. A major resistance QTL in RIL24 harbouring Pm9 was mapped to Mrg21 of the consensus map using BLASTn analysis. For RIL29, a QTL was found on Mrg03. The results support that at least Pm9 is different from the powdery mildew resistance genes mapped so far.