Quantitative Trait Loci Associated with Heat Tolerance in Rice (Oryza sativa L.)

A total of 310 BC2F2 lines derived from the cross of OM5930/N22 were evaluated for heat stress at flowering. Genetic map was set up with 264 polymorphic SSRs to detect linkage to the target traits. The map covers 2,741.63 cM with an average interval of 10.55 cM between two marker loci. Markers associated with heat tolerance were located mostly on chromosomes 3, 4, 6, 8, 10 and 11. The proportion of phenotypic variation explained by each QTL ranged from 17.1% for RM160 to 36.2% for RM3586. Four QTLs were detected for filled grains per panicle on chromosome 4 at the interval of RM468 - RM7076 and RM241 - RM26212, explaining 13.1 and 31.0% of the total phenotypic variation, respectively. Two QTLs controling unfilled grain percentage was also detected at loci RM554 and RM3686 on chromosome 3 explaining 25.0 and 11.2% of the total phenotypic variance. One QTL was detected for 1,000-grain weight located at the locus RM103 on chromosome 6, explaining 30.6% of the total phenotypic variance. Also, a QTL at the locus RM5749 on chromosome 4 was identified which explained 10.8% of the total phenotypic variance of grain yield. A single QTL at the interval of RM3586- RM160 on chromosome 3 was detected in conformity with the QTL findings for heat tolerance in previous studies.