Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Construction Of A Linkage Map Based On SSR Markers And Genetic Analysis Of Resistance To Powdery Mildew In Melon

Nobuko Fukino , Takayoshi Ohara , Miyuki Kunihisa , Satoru Matsumoto

  NIVTS, 360 Kusawa, Ano, Mie, Japan

Powdery mildew caused by Sphaerotheca fuliginea results in severe economic losses in melon (Cucumis melo L.). The melon breeding line PMAR No.5 (supposed to be AR5) shows strong resistance to powdery mildew and has been used for breeding. A genetic map of melon was constructed on a recombinant inbred line population derived from a cross between PMAR No.5 and the susceptible cultivar Harukei No.3, based on 148 SSR, six CAPS, 30 RAPD markers, the cotton aphid resistance gene, the MNSV resistance gene, and the flesh-color gene. The map identified 20 linkage groups spanning 1,050 cM of the genome. Segregation analysis of responses to powdery mildew race 1 in recombinant inbred lines (RILs) identified two dominant and independent genes governing the resistance in PMAR No.5. As a result of a quantitative trait locus (QTL) analysis, two QTLs were detected on independent linkage groups. One major QTL explained 57.5% of phenotypic variation while the other locus explained 20.6%. Segregation analysis of 180 F2 plants derived from a different cross revealed that the resistance gene is flanked by two SSR markers. The map distance between these markers was estimated to be 6 cM.