Mapping QTLs for Heat Tolerance and Correlation between Heat Tolerance and Photosynthetic Rate in Rice

A double haploid (DH) population derived from a cross between Azucena (japonica) and IR64 (indica), was used for detecting additive effect(A) of quantitative trait loci(QTL) and their additive×additive epistasis(AA) for rice heat tolerance under field and greenhouse experiments. Seed setting rate of 109 DH lines was scored as the parameter of heat tolerance. QTL analysis was conducted by using the constructed molecular linkage map and software QTLmapper 1.0. Six additive effect QTLs were detected on chromosome 1,3,4,8 and 11, respectively. Eight pairs of epistasis effects QTLs were detected on chromosome 1,2,3,4,5,7,8 and 11 with variance explained being 2.27%-8.13%. Photosynthetic rate and heat tolerance were measured at maximum tillering and heading stage, and results showed that photosynthetic rate at heading stage was significantly positive correlated with heat tolerance.