Identification of RAPD markers linked to the gene PM1 for resistance to powdery mildew in wheat

Powdery mildew caused by Blumeria graminis DC. f sp. tritici Em. Marchal is an important disease of wheat (Triticum aestivum L. em Thell). We report here the identification of three random amplified polymorphic DNA (RAPD) markers closely linked to a gene for resistance to B. graminis in wheat. RAPD-PCR (polymerase chain reaction) analysis was conducted using bulked segregant analysis of closely related lines developed from a segregating F-5 family. The F-5 family was derived from a cross between the susceptible cultivar Clark and the resistant line Zhengzhou 871124. Genetic analysis indicated that resistance of Zhengzhou 871124 to powdery mildew is conferred by the gene Pm1, After performing RAPD-PCR analysis with 1300 arbitrary 10-mer primers and agarose-gel electrophoresis, two RAPD markers, UBC320(420) and UBC638(550), were identified to be co-segregating with the disease resistance, No recombinants were observed between either of the RAPD markers and the gene for resistance to powdery mildew after analysis of 244 F-2 plants, The third RAPD marker. OPF12(650), was identified with denaturing gradient-gel electrophoresis (DGGE), and was determined to be 5.4 +/- 1.9 cM from the resistance gene. UBC320(420) and UBC638(550) were present in wheat powdery mildew differential lines carrying the gene Pm1, suggesting linkage between these markers and the Pl?tl resistance gene. Co-segregation between Pm1 and the two markers UBC320(420) and UBC638(550) was confirmed in a segregating population derived from a cross with CI14114. the wheat differential line carrying Pm1. The method of deriving closely related lines from inbred families that are segregating for a trait of interest should find wide application in the identification of DNA markers linked to important plant genes. The RAPD marker UBC638(550) was converted to a sequence tagged site (STS), RAPD markers tightly linked to target genes may facilitate selection and enable gene pyramiding for powdery mildew resistance in wheat breeding programs.