Genetic Mapping Of The Reverse Thermo-sensitive Genic Male Sterility (rTGMS) Line Tb7S Derived From The Hybridization Between Cultivar (Oryza Sativa L.) And Wide Rice (Oryza Rufipogon Griff.)

Rice (Oryza Sativa L.) is one of the most important crops for more than half of human bejings all over the world. The discovery and successful utilization of a wild abortive type of cytoplasmic male sterile (CMS) line led to a highly efficient way for solving the food problems. Compared with the three-line system, the two-line system based on P/TGMS has many advantages:two-line hybrid rice technology no need for a maintainer line allows the choice of a wider range of parental combinations and avoids the negative effects of sterility including cytoplasm. So two-line breeding technology can be adopted more extensively in exploiting heterosis. Thermo-sensitive male sterile rice is classified into two categories:TGMS and reverse TGMS (rTGMS), rTGMS lines are sensitive to low temperature for the expression of male sterility, whereas, at a higher temperature they become male fertile, which is just the reverse of the TGMS system, because of the different fertility conversion’s rules, rTGMS can be used in a wider rice planting range.Our former study showed that Tb7S is an rTGMS line derived from the hybridization between wild rice and cultivated rice, its fertility is stable and uniform, so it is a perfect material for sterile gene mapping due to its male-sterile character which is controlled by two recessive genes. To make the mapping population, Tb7S was hybridized with a wide-compatible cultivar Zhong1159. The polymorphism of two parents using 589 SSR primers covering rice’s 12 chromosomes was analysed, then the polymorphic markers were used to detect the F2 individual plant, the two sterile genes were located on 10,9 chromosomes, and were named as rtmsl and rtms2 respectively, rtmsl was mapped between two indel markers, Indel-1(17.8.cM) and Indel-3(16.8 cM), the crossed physical distance is 724kbp; rtms2 was located beween RM24538(24.37cM) and RM24570(55.65cM) on 9 chromosome with the physical distance of 434kbp. So a good foundation was laid for fine mapping and cloning the Tb7S’sterile genes.