[Molecular identification and marker-assisted selection of Pm21 gene conferring resistance to powdery mildew in...

RAPD marker (OPH17(1400)) and SCAR markers (SCAR1400 and SCAR1265) as well as fluorescence in situ hybridization (FISH) technique were used to detect wheat powdery mildew resistance gene Pm21 derived from Haynaldia villosa (6AL/6VS) in different genetic background of wheat breeding program. Among a total of 372 RAPD amplification reactions, 28 reactions (7.53%) yield no amplification products, and the amplification products of 21 reactions (5.64%) were difficult to interpret the presence or absence of the OPH17(1400), indicating that RAPD marker OPH17(1400) is less reproducible and reliable, so that its usage in breeding program is limited. However, SCAR markers, SCAR1400 and SCAR1265, were amplified in all 488 PCR reactions, suggesting that SCAR markers are highly reproducible and reliable, and can be used in breeding program. The specific SCAR1265 made it possible to screen a large number of genotypes reliably and rapidly in practical breeding programs for the presence/absence detection between the resistant and susceptible plants. After backcrossed with common wheat lines for several times, no recombination between the 6VS chromosome of Haynaldia villosa and any of the wheat chromosomes was detected by using FISH.