Characteristic Of Thermo-Sensitive Male Sterile In Chinese Cabbage And Its Breeding

The inheritance of thermo-sensitive traits and the cytomorphology of anthers during the fertility restoration in male sterile Chinese cabbage TsCMS7311 were studied in this research,which provided the theoretical foundation for heterosis utilization and breeding of thermo-sensitive male sterile line and also provided the basis for cytological reason of the fertility restoration after low temperature treatment.Inheritances of thermo-sensitive traits of 04C4-2,04C4-3,04C4-5 and 04C4-7 which were the random self-crossed plants of themo-sensitive male-sterile Chinese cabbage line TsCMS7311 were studied by naturally low temperature treatment outdoor and artificially controlled temperature treatment.The results showed that the progenies of the self-crossed single plants all took place fertility restoration from sterility to fertility after low temperature treatment, which occurred in 12~15 days after artificially controlled low temperature treatment and at flowering after field naturally low temperature treatment. The results also showed that the proportion of fertile plants to sterile plants both in naturally and artificially controlled temperature treatments were all fitted to 15:1 , which indicated that the thermo-sensitive trait was controlled by two pairs of dominant nuclear genes in male-sterile Chinese cabbage TsCMS7311. The themo-sensitive genes were denoted as Tm1 and Tm2,so the genotype of TsCMS7311 was denoted as S(rfrfTm1tm1Tm2tm2).Cytomorphology of anthers was investigated during the fertility restoration of TsCMS7311.The results were as follow:Firstly, there were no significant differences between normal TsCMS7311 and fertility restorer TsCMS7311 before the stage of archesporical cell. Secondly,under normal temperature, lots of anthers of normal TsCMS7311 stoped developing in the stage of archesporical cell,and 1~2 comers of a few anthers differentiated and produced archesporical cells,sporogenous cells and microspore mother cells which disintegrated during the first meiotic division. Thirdly, after low temperature treatment, the sterile fertility of anthers occured changeover and the anthers grew normally. From archesporical cells, sporogenous cells and microspore mother cells, the tetrads formed. Subsequently, microspores were freed from the tetrads of fertile anthers and were formed mature pollen grains. The tapetums of the fertile anthers disintegrated and disappeared finally. At last,flower buds less than 1mm that the anther growed before the stage of archesporical cell were the most sensitive to low temperature,which determined whether pollen sacs were produced. This observation firstly showed the cytological reason of the fertility restoration in thermo-sensitive male sterile Chinese cabbage after low temperature treatment.According to genetic characteristics of thermo-sensitive male sterile Chinese cabbage, a breeding strategy for the fully thermo-sensitive male-sterile line and thermo-insensitive male-sterile line was suggested. By self-crossing of thermo-sensitive male-sterile plant and crossing thermo-sensitive male-sterile plant with their corresponding maintainer,the fully thermo-sensitive male-sterile line S (rfrfTm1Tm1Tm2Tm2) and thermo-insensitive male-sterile line S(rfrftm1tm1tm2tm2) were bred. Out of nine plants harvesting a large amount of seeds,five plants because of having not fertility segragetion in low temperature treatment,were selected as fully thermo-sensitive male-sterile line,which have at least one homozygous sensitive gene site,and may breed homozygous themo-sensitive male-sterile line furtherly.