Genetic Basis Research On High Temperature Resistance In Anthesis Of Special Heat Tolerance Rice N22

Along with global warming, high temperature stress has been becoming a vital menace when extreme high temperature climate appears frequently. Breeding new rice cultivars with stable seed-set ratio when high temperature climate occurs in rice anthesis is a crucial approach to mitigate the impact of high temperature climate that influences the growth and development, the yields, and the quality of rice severely. It is one of the most concerned traits currently that the yields will be badly impacted because of seed-set ratio declining fearfully after heat stress in anthesis. The materials and theory support can be provided in high temperature ecological adaptability breeding by selecting of specific high temperature tolerance rice resources and genetic basis research of its high temperature tolerance ability.In this study, the primary mapping of rice heat tolerance concerned QTL of rice in anthesis has been achieved by bulked segregation analysis (BSA) with 349 SSR molecular markers, when the heat tolerance ability of parents and more than 300 individuals F₂ population, structured by Gui99 (female parent) and N22 (male parent), were evaluated with comparative seed-set ratio after high temperature treatment in got-up light-temperature chamber. The male parent was selected from N22 materials that were gathered in different ages by IRRI germplasm gene library after evaluation of heat tolerance ability with seed-set ratio and analysis of genetic differences by SSR molecular marker. The basic results of the research are summarized as follows:1. The high temperature tolerance ability of N22 germplasm resources that were gathered in different ages and domestic constantly employed materials were identified. The variance analysis of the materials' seed-set ratio after 33℃average temperature treatment in plant growth chamber showed that the high temperature tolerance ability of N22-2006, Shuhui527, N22-1996, Mianhui725 and Gui99 fall in turn. The growth ability, development period, and heat tolerance ability of different N22 materials diversities were detected. The N22-1984 was absent from high temperature treatment because of feeble growth and delayed anthesis of more than 10 days. The seed-set ratio of N22-1996 was lower than N22-2006 whereas it is not remarkable.2. The DNA polymorphism of 76 SSR molecular markers was manifested among N22-1984, N22-1996 and N22-2006 with 349 markers, namely 21.8% diversity rate. The check of polymorphism maintenance after materials' propagation revealed that the diversities between N22-1984 and the other two materials were invariable, while it had been vanished between N22-1996 and N22-2006. The germplasm diversity of N22-1984 was reckoned primarily, while the difference between N22-1996 and N22-2006 was ascribed to resumable aberrance by self-cross.3. The treatment results of parents (Gui99 and N22) and F₂ population with 32℃average temperature in plant growth chamber displayed that the difference of average comparatively seed-set ratio between Gui99 and N22 was extreme remarkable with the value of 0.6831% and 14.0121%, and the comparatively seed-set ratio of F₂ population, located among 0.00%～70.19% and 4.89% of average value, and represented consecutive distribution that was leaned to female parent Gui99 with skewness 3.23 and kurtosis 14.89.4. 41 SSR molecular markers, which took its source at 166 markers within 349 markers that were detected diversities between Gui99 and N22, namely 47.6% diversity rate, had been digged out stable polymorphism between resistable and affected pool. 25 SSR molecular markers of 41 markers were separated into 6 linkage groups by mapping software Mapmaker/EXP (version 3.0b) analyzing linkage among markers and structuring genetic linkage map, while the other 16 markers had been failed to link.5. The 6 heat tolerance concerned QTLs of rice in anthesis that distributed in 1, 2, 3, 6 and 10 chromosomes separately, and whose variance explained value were varied between 6.6%～63.3%, had been mapped with interval mapping software Mapmaker/QTL (version 1.1b).