Association mapping and resistant alleles analysis for sheath blight resistance in rice

Abstract

To identify and map sheath blight (ShB) resistance loci in rice, we carried out association analysis of 456 rice accessions using 144 genome-wide markers based on GLM (Q), MLM (Q+K), and MLM (PCA+K) models of TASSEL software. The phenotyping were assayed at the seedling stage with a micro-chamber screening method. The results showed that thirteen markers were significantly associated with ShB resistance detected by using at least two models, which explained from 1.84% to 8.42% of the phenotypic variance. In addition, ten of the identified resistant loci were either quite near or within the interval of previously identified QTLs. RM1036, RM5371, and RM7585 were novel resistant loci that had not been previously reported. The resistant allele 150 of RM7585 showed the largest negative effect to ShB rating, allele 129 of RM5371 existed in 259 (56.8%) of 456 rice accessions, and 82 of RM1036 existed in 26 (5.7%) rice accessions. The number of putative resistant alleles presented in rice was highly and significantly correlated with the decrease of ShB rating. The resistant alleles identified in this study are readily available and can be exploited for marker-assisted selection.