The Fine Mapping Of Rice Thermo-sensitive Genic Male Sterile Gene Of Zhu1S And Rice Thermo-sensitive White Striped Leaf Mutant Gene Of Zhong1W (Oryza Sativa)

ZhulS is a thermo-sensitive genic male sterile line of rice with low critical temperature of fertility alteration and excellent combining ability, which has been widely exploited as a female parent in Chinese two-line hybrid rice breeding. In this study, the cytological observations of pollen sterility, the classical genetic of male sterility trait were analysised and the thermo-sensitive genie male sterile gene of ZhulS was fine mapped, respectively. The rice thermo-sensitive white striped leaf mutant Zhong1W was mutated from cv. Nipponbare by EMS. Zhong1W showed white striped leaves at the seedling stage and tillering stage when the temperature was below28℃, then the white striped phenotype restored gradually to green until mature along with the temperature rising. In this study, the agronomic traits, chlorophyll content during different development stages, chloroplast ultrastructure within different leaf color parts, the classical genetic analysis and molecular mapping of Zhong1W leaf color mutant gene have been investigated. The all major study results are as follows:1The cytological observations of ZhulS pollen sterility indicated that the pollen abortion was dated from early microspore and which continued to pollen maturation, it can not provide the nutrients for microspore development because of the tapetum cell delayed disintegration which lead to pollen abortion. The anther wall cells ultrastructure observations during Zhu1S pollen abortion stage further confirmed the results of cytological observations, that due to the not timely disintegration of tapetum cells then the microspores can not get enough nutrients during the development stage which lead to pollen abortion.2Genetic analysis showed that Zhu1S thermo-sensitive genic male sterility was controlled by a single recessive nuclear gene. There was partly allelic sterile gene between Zhu1S and AnnongS-1and FulongS. However, there was no allelic sterile gene between Zhu1S and C815S and Peiai64S.3The thermo-sensitive genic male sterile gene of Zhu1S, which was named tms9temporarily, was finally mapped on the short arm of the chromosome2between the Indel markers Indel101and Indel91with the physic distance of30.2Kb.4There are seven candidate genes in the30.2Kb positioning interval according to the bioinformatics analysis. Finally, according to the results of candidate genes expression under the fertile and sterile conditions of Zhul S and the candidate genes sequencing, the sixth candidate gene (LOC_Os02g12290) was at last considered as the possible target gene of thermo-sensitive genic male sterile gene for Zhu1S, and futher genetically modified function complementary verification tests are underway.5At maturity, the plant height of the thermo-sensitive white striped leaf mutant Zhong1W was significantly shorter than that of the wild type. While the other agronomic characters between Zhong1W and its wild type showed no significant difference.6During the fourth leaf stage, tillering stage and booting stage, the Chlorophyll a content, Chlorophyll b content and the total Chlorophyll content of Zhong1W were all lower than that of its wild type, while during the heading stage, the Chlorophyll a content, Chlorophyll b content and the total Chlorophyll content between Zhong1W and its wild type have no significant difference.7The number of chloroplast in the white part of Zhong1W leaves was much less than that of its wild type, the thylakoids were vague and degraded, and the grana lamellar became more loosely-packed, discontinued and significantly reduced in number. In addition, the number of osmium corpuscle in the chloroplasts of Zhong1W was much more than that of its wild type, while the starch granule of which was significantly reduced. Within the green part of Zhong1W, the leaf color showed light green, and the number of chloroplast in the mesophyll cell was increased, and there were also some chloroplasts with well-developed grana lamellar structure similar to that of the wild-type in the mesophyll cells.8Genetic analysis showed that the rice thermo-sensitive white striped leaf mutant trait of ZhonglW was controlled by a single recessive gene. ZhonglW thermo-sensitive white striped leaf gene was finally mapped on the telomere region of chromosome9and positioned between SSR markers RM23742and RM23759, which are separated by approximately486.5kb. There are five BAC clones in the mapping interval. Zhong1W thermo-sensitive white striped leaf gene was temporarily named wsll.