Identification of a microsatellite marker associated with Pm3 resistance alleles to powdery mildew in wheat

The Pm3 resistance locus, located on chromosome 1A in wheat, confers race-specific resistance to the obligate biotrophic fungus Blumeria graminis (DC) E.O. Speer f. sp. tritici , the causal agent of powdery mildew. Several Pm3 alleles are still effective in controlling the disease in Europe. A genetic map was constructed to map the Pm3g allele in the recombinant inbred line progeny from the cross 'RE9001' (susceptible) x 'Courtot' (resistant). Two microsatellite markers were closely mapped to Pm3g . The PSP2999 marker, which cosegregates with this allele, was shown to detect the presence of the Pm3g resistance allele in other cultivars. A collection of 56 wheat cultivars or advanced lines carrying one Pm3 allele was used to assess the allele-specific amplification of the PSP2999 marker. The same amplification pattern was obtained for lines with Pm3a , Pm3b , Pm3e , Pm3f and Pm3g alleles. Twenty genotypes carrying Pm3d showed a specific amplification pattern. This marker allowed the detection of the Pm3d allele in highly resistant lines whose resistance gene combinations were unknown. It was concluded that PSP2999 is a useful marker to detect Pm3 alleles in parents and to manage them in breeding programmes.