Identification of QTL Associated with Resistance to Fusarium Wilt In Common Bean.

Fusarium wilt (FW) is a serious disease of common bean (Phaseolus vulgaris L.) that causes leaf chlorosis, plugging of the vascular tissue and decrease in crop yield. FW is caused by the fungus Fusarium oxysporum Schlectend. Fr. E. f. sp. phaseoli. Genetic resistance is the preferred approach to limit damage caused by this pathogen because other cultural methods are ineffective. Genes that confer resistance are known, however molecular markers and genetic maps have not been developed to allow marker assisted selection (MAS). Previous research used SSR, AFLP and RAPD primers to screen 139 recombinant inbred lines (RIL) of the population Lef-2RB X Sierra that had been evaluated for race 4 and race 5 FW resistance. The objectives of this study were to identify quantitative trait loci (QTL) associated with resistance to FW race 4 in the cultivar ‘Sierra’ and to increase the size of the Lef-2RB X Sierra linkage map. So far 11 markers, 5 SSR and 6 RAPDs, have been genotyped. We found two RAPD markers linked with race 5 resistance from Lef-2RB, both close to a QTL identified in previous research in our lab. These two markers explained 37.0% and 12.4% of the phenotypic variation, respectively. Additional markers will be run on the RIL and the results will be used for further QTL analysis and expansion of the linkage map.. This information will be helpful to bean breeders to incorporate resistance to FW through MAS.