New Stably Expressed Loci Responsible for Panicle Angle Trait in Japonica Rice in Four Environments

Panicle angle (PA) of 254 recombinant inbred lines derived from a cross between two japonica varieties Xiushui 79 and C Bao was investigated under four environments, and a genetic linkage map including 111 SSR markers was constructed. Genetic analysis was conducted by mixed major gene plus polygene inheritance models, and quantitative trait loci (QTLs) identification by the QTLNetwork 2.0 and the composite interval mapping approach of WinQTLCart 2.5 software. Results showed that the PA trait was controlled by two major genes plus polygenes, mainly by major genes. Eight QTLs for PA were detected by the QTLNetwork 2.0 software, and each locus explained 0.01% to 39.89% of the phenotypic variation. Twelve QTLs for PA were detected by the WinQTLCart 2.5 software, with each locus explaining 2.83% to 30.60% of the phenotypic variation. Two major QTLs (qPA9.2 and qPA9.5) distributed between RM3700 and RM3600 and between RM5652 and RM410, respectively, and a moderate QTL (qPA9.7) distributed between RM257 and OSR28, were both detected by the two methods in all of the four environments. The negative effect alleles of the three QTLs were from Xiushui 79. In addition, eight pairs of epistatic QTLs with minor effects were also detected. QTL × environment interactions were not significant for additive QTLs and epistatic QTL pairs.