Mapping and validation of a new QTL for adult-plant resistance to powdery mildew in Chinese elite bread wheat line Zhou8425B

Key message Four QTLs for adult-plant resistance to powdery mildew were mapped in the Zhou8425B/Chinese Spring population, and a new QTL on chromosome 3B was validated in 103 wheat cultivars derived from Zhou8425B. Zhou8425B is an elite wheat ( Triticum aestivum L.) line widely used as a parent in Chinese wheat breeding programs. Identification of genes for adult-plant resistance (APR) to powdery mildew in Zhou8425B is of high importance for continued controlling the disease. In the current study, the high-density Illumina iSelect 90K single-nucleotide polymorphism (SNP) array was used to map quantitative trait loci (QTL) for APR to powdery mildew in 244 recombinant inbred lines derived from the cross Zhou8425B/Chinese Spring. Inclusive composite interval mapping identified QTL on chromosomes 1B, 3B, 4B, and 7D, designated as QPm.caas - 1BL . 1 , QPm.caas - 3BS , QPm.caas - 4BL . 2, and QPm.caas - 7DS , respectively. Resistance alleles at the QPm.caas - 1BL.1 , QPm.caas - 3BS, and QPm.caas - 4BL . 2 loci were contributed by Zhou8425B, whereas that at QPm.caas - 7DS was from Chinese Spring. QPm.caas - 3BS , likely to be a new APR gene for powdery mildew resistance, was detected in all four environments. One SNP marker closely linked to QPm.caas - 3BS was transferred into a semi-thermal asymmetric reverse PCR (STARP) marker and tested on 103 commercial wheat cultivars derived from Zhou8425B. Cultivars with the resistance allele at the QPm.caas - 3BS locus had averaged maximum disease severity reduced by 5.3%. This STARP marker can be used for marker-assisted selection in improvement of the level of powdery mildew resistance in wheat breeding.