Detection of heat related QTL in rice at flowering stage using selected introgressed lines

To identify quantitative trait loci (QTL) underling heat tolerance in rice, four sets of BC₂F₅, Introgressed lines (ILs) were derived using four indica donors, (Jiangxisimiao, IR65600-27-1-2-2, Hanhui10 and Bala) with Minghui86 (MH86) restorer as the recurrent parent (RP). The heat stress index, HSI = (filled grain rate at normal condition – filled grain rate at heat stress condition)/ filled grain rate at normal condition, was employed to evaluate the heat tolerance of rice with other yield related traits exposing to heat stress during whole flowering period at two season in Hunan in the summer 2011 and 2012. There was no significant yield improvement of four populations under normal conditions in 2011 and 2012 except population MH86/Bala. Ranking was done according to the average HSI and grain yield (GY) for two years under stress condition. The best population was MH86/IR65600- 27-1-2-2 (K) which shows the lowest HSI (0.43) and the highest GY (10 g/plant). The second one was the population MH86/Hanhui10 (L) (9.65 g/plant, HSI 0.44), Population MH86/Bala (M) (9 g/plant, HSI 0.57) and population MH86/Jianxisimiao (J) (6.95 g/plant, HSI 0.62) were third and fourth, respectively according to the ranking results. A total of 13 QTLs were detected for HSI, including three for population J, six for K and two for L and two for population M. QTL associated with SSR marker RM180 was detected from 3 populations except population L. RM473, RM474, RM202 and RM237 were found at least from two populations suggesting that these are important in selection of heat tolerance QTLs in indica background.