| In order to explore the physiological and molecular mechanism of high temperature tolerance in indica/javanica recombinant inbreed line, the studies including effect of temperature on seed set, dynamic changes of plant hormones, genes differential expression and quantitative trait loci mapping were conducted by using of population of recombinant inbreed line, named as RIL47, under the treatment of high and natural temperature at flowering stage. The detailed results are as follows:1. The effect of high temperature on seed set of recombinant inbreed line population RIL47 at flowering stage has been studied. The results indicated that the seed set of population RIL47 was normal in the natural environment, but decreased significantly under the high temperature. Five heat tolerant lines (07C1619,07C1590, 07C1521,07C1706 and 07C1608) and three heat sensitive lines (07C1751,07CI710 and 07C1719) were selected from the 107 lines of population RIL47 by heat injured index.2. The endogenous plant hormone and free proline content (Pro) in panicle of line 07C1521 and 07C1751 at flowering stage were studied under different temperature. The results indicated that the contents of ZR, ABA and Pro in panicle were reduced gradually along with development of panicle under the natural temperature, but the contents of IAA in panicle fluctuated as low-high-low pattern. The contents of ZA and Pro in panicle of both lines increased at early stage and then decreased late but the ABA content increased all the time under high temperature. However the effect of high temperature on content of IAA in panicle was small after high temperature trarment. In addition, the contents of ZR, ABA and Pro in high temperature tolerant line 07C1521 were much lower than those in high temperature sensitive line 07C1571 under natural temperature, and the changes of Pro content in line 07C1521 were much more than those in line 07C1571 under high temperature.3. mRNA differential display technique has been used for exploring gene differential expression of 07C1590 treated with different temperature. Seven differentially expressed DN A fragments were obtained, five of them were specially expressed under high temperature, and the rest were specially expressed under natural temperature. Results of homological analysis indicated that:e9-H, g6-H, g7-H, i9-H and k4-N were highly homologous with the sequences in databases of mRNA and EST, but highly homologous sequences were not founded in database of proteins and the function of them could not be defined now. The highly homologous sequence of f9-H was not found in database of mRNA, and a highly homologous sequence was founded in database of EST but the function was not explained. The protein sequence of k7-N was highly homologous with that of NADH dehydrogenase subunit K.4. The whole genome molecular linkage map of SSR markers was constructed by use of 111 lines of recombinant inbred line population RIL47 as a mapping population. The molecular map comprises 61 SSR loci which covered a total distance of 2025.0 cM and the average distance between two loci was 33.20 cM. Among these SSR markers,43 markers (71.0%) exhibited distorted segregation (p<0.05), in which 30 of them leaned to 43S, the rest deviated to 770. Several SSR loci relate to seed set have been found by single marker analysis, but their dependability need to be validated.
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