Analysis of Quantitative Trait Loci for Resistance to Rice False Smut

Abstract

A recombinant inbred line (RILs) population with 157 lines derived from an inter-subspecies cross of Daguandao/IR28 by the single seed descent method was used to detect quantitative trait loci (QTLs) conferring resistance to rice false smut (caused by Ustilaginoidea virens (Cooke) Takahashi) in 2007 and 2009. The disease rate index of the two parents and 157 RILs caused by rice false smut were scored and the QTLs for rice false smut resistance were detected accordingly by QTL Cartographer software. Seven QTLs controlling false smut resistance were detected on chromosomes 1, 2, 4, 8, 10, 11, and 12, respectively, with the phenotypic variance of 9.8-22.5%. There were five and four QTLs detected in 2007 and 2009, respectively, and only two QTLs were found in both two years, the phenotypic variation was explained by individual QTL ranged from 18.0% to 19.3% for these two QTLs, and the additive effects of these two QTLs contributed to the 8.0-16.3% decrease of disease index and therefore the disease resistance increased. The direction of the additive effects at six loci qFsr1, qFsr2, qFsr8, qFsr10, qFsr11, and qFsr12 coincided with that predicted by phenotypes of the parents, and the IR28 alleles at these loci had positive effect against rice false smut while the negative effects were found in Daguandao alleles at qFsr4. Both qFsr11 and qFsr12 should be useful in rice breeding for resistance to rice false smut in marker-assisted selection (MAS) program.