Cytological Studies Of Hybrid Female Gamete Sterility And Gene Mapping Of S7,in Rice (Oryza Sativa L.)

Rice has strong heterosis of inter-subspecies, breeder seek to use of heterosis for increasing rice yield. However, the hybrid F1always sterility, which is a major barrier for widely use of the heterosis. In the1980s, wide compatibility gene(WCGs) S5-n was discovered, this made a new opportunity for using heterosis. With the deepening of research, researcher found S5-n couldn’t overcome all of hybrid sterility, and a series of new hybrid sterility locus have been found. So, in order to make full use of heterosis, more and more hybrid sterility genes should be deepen research in the future.One of the parents of this research Ingra is the summer cultivation in India subcontinent Bengal area, Cpslo17is Java carrying S5-n, IR36is a representative test in Indica, but it is compatible in S7locus.After Tianhua’s research of our lab, we performed fine mapping and cytological studies of S7gene. Main results are like this:1. Cytological studies of rice hybrid sterility gene S7In this study, in order to found real reasons of Ingra/Cpslo17hybrid sterility, we investigated every factor which impact spikelet fertility. Observation result showed, fertility of pollen、dehiscence of anther、pollen adhered on the stigmas、pollen germinate on the stigmas、pollen tube elongation on the stigmas are same as parent Ingra. Those results indicate that male gamete couldn’t affect spikelet fertility. Using laser scanning confocal microscope observed mature embryo saces, we found half of embryo sac with polar nucleus’s position abnormal, while another half of embryo sac are normal. After observed unfertilized embryo sac7day after flowing, we found almost all of them are embryo sac with polar nucleus’s position abnormal. We investigated genotype of hybrid seeds in backcross population which crossed by mother hybrid plant and father Ingra, results shown all of fertilized embryo sac are with S7-ai, while embryo sac with S7-cp couldn’t fertilized. Those resultes suggest that F1hybrid spikelet sterility of Ingra/Cpslol7is caused by embryo sac with abnomal position of polar nucleus.2. Fine mapping of rice hybrid sterility gene S7In this study, Ingra/IR36//Cpslol7BC1F2and Ingra/Cpslo17F2:3populations was used to check and fine mapping S7gene. The check result shows S7was located between marker TI21and TI26, the span was755kb, and the span of Tianhua’s location was contained in it. We designed much more new primers in755kb of S7’s location, to scan all of recombinant plants in mapping populations, associated with the spikelet fertility, we finally located the S7gene between markers GS22-d and TI53-In, the span was300kb. Gene prediction analysis indicate that in this region there are72open reading frames, of which there are15for encoding hypothetical protions,12for encoding unknown proteins, and45for encoding function proteins. The study established a good foundation for further molecular biological study of S7gene.