AFLP Markers Linked to Fom-2, a Gene Conferring Resistance to Fusarium Wilt of Melon (Cucumis melo L.)
Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29634
Claude E. Thomas
USDA, ARS, U.S. Vegetable Laboratory, 2875 Savannah Highway, Charleston, SC 29414
Ralph A. Dean
Department of Plant Pathology & Physiology, Clemson University, Clemson, SC 29634
Additional index words. Cucumis melo, AFLP, marker-assisted selection, gene tagging, fusarium wilt
Abstract. Fusarium wilt caused by Fusarium oxysporum f.sp. melonis is one of the most devastating diseases in melon production worldwide. Efficient control measures for this soilborne pathogen other than using resistant varieties are not available. Tagging resistance genes with molecular markers facilitates the cloning of the gene and marker-assisted selection in breeding programs. We screened resistant and susceptible bulks constructed from F2 progenies using AFLP techniques with 240 Pst I/Mse I and 200 EcoR I/Mse I primer combinations. Fifteen markers potentially linked to Fom-2 (responsible for resistance to races 0 and 1 of the fungus) were identified with EcoR I/Mse I primer pairs and mapped relative to the gene. Pst I/Mse I primer pairs did not identify any markers related to Fom-2. A RAPD marker was found to cosegregate with the gene and two AFLP markers were found to flank Fom-2 based on the current mapping population. A survey of diverse melon genotypes showed that those markers can be used to predict phenotypes in terms of resistance to the pathogen. The markers are being converted to codominant PCR markers for easier use in a selection program.