Genomic regions associated with resistance to Fusarium wilt in castor identified through linkage and association mapping approaches

Fusarium wilt, caused by Fusarium oxysporum f. sp. ricini, is the most destructive disease in castor. Host plant resistance is the best strategy for the management of wilt. Identification of molecular markers linked to wilt resistance will enhance the efficiency and effectiveness of breeding for wilt resistance. In the present study, genomic regions linked to wilt resistance were mapped using a bi-parental population of 185 F-6-RILs and a genetically diverse panel of 300 germplasm accessions. Quantitative trait loci (QTL) analysis performed using a linkage map consisting of 1090 SNP markers identified a major QTL on chromosome 7 with an LOD score of 18.7, which explained 44% of the phenotypic variance. The association mapping performed using genotypic data from 3465 SNP loci revealed 69 significant associations (p < 1 x 10(-4)) for wilt resistance. The phenotypic variance explained by the individual SNPs ranged from 0.063 to 0.210. The QTL detected in the bi-parental mapping population was not identified in the association analysis. Thus, the results of this study indicate the possibility of vast gene diversity for Fusarium wilt resistance in castor.