Studies On Fertility And Ub_L40 Genes Expression For F₁ Hybrid Of Different Critical Male Sterile Temperature Of Thermo-sensitive Genic Male Sterile Rice

Rice is a staple food for most of the population in the world, whose yield growth will be attributed primarily to the utilization of its hybird vigor. There exist two main systems in China:the traditional three-line system and the novel two-line system. However, every PTGMS line must bear a lower critical steirlity temperature point(CSTP),which is regarded as the lowermost temperature for PTGMS lines to keep the absolute male sterility status under long-day photoperiod. Therefore, the lowermost temperature for PTGMS lines has become an important issue for two-line hybrid breeding. Annong S-1 is the first Indica TGMS in china,but it is easily affected by the temperature because of its high critical temperature. Zhu1 S has promoted the rapid development of two-line hybrid rice due to its lower critical temperature. There have been some reports about the change rules of the lowermost temperature for PTGMS lines, whereas, the relationship between the regulation of the TGMS line’s molecular mechanisms and its different critical temperature remains to be further studied.To guide breeding TGMS Line with lower critical sterility temperature, and to provide a clear reference for the inheritance of TGMS line, the research will treat the pollen fertility of the filial generationwhich originates from different thermo-sensitive genic male sterile. The levels of UbL40 m RNA in meiophase under various temperature will be studied, too. The main results are as follows:1.All TGMS lines in rice were treated by low temperature water of23.5℃ for 6 days within their thermo-sensitive stages of fertility altemation. The results showed that: The F1 hybrid were sterile which originates from Zhu1 S who has the lowest critical steirlity temperature point(CSTP) and 35 S who has lower CSTP, Zhu1 S and the TGMS lines who have higher CSTP(including Zhun S, Anxiang S), Zhu1 S and Annong S-1 who has higher CSTP,respectively.The F1 hybrid has a little fertile with stainable pollen rate of 1% which originates from parent materials with lower critical temperature(including H628 S and 35S) and Zhun1 S who has higher CSTP. The F1 hybrid fertile with stainable pollen rate of 10% which originates from parent materials with lower critical steirlity temperature point and the highest critical steirlity temperature point. The F1 hybrid fertile with stainable pollen rate of 5%to 15% which originates from parent materials with higher critical steirlity temperature point and higher critical steirlity temperature point,the F1 hybrid fertile with stainable pollen rate of 15% which originates from parent materials with the highest critical steirlity temperature point and higher critical steirlity temperature point.2.There is no significant difference in fertility betweenF1.generations.of.Annong S-1/Zhu1 S.and.Zhu1S/Annong S-1,H628S/Anno ng S-1 and Annong S-1/Zhu1 S,which indicts that cytoplasm plays no or relatively small effects on the fertility difference of the two parents.Nueleargene(s) would be the decisive factor of the CSTP difference.3. The results show that the expression levels of UbL401, Ub L402 and Ub L404 in the young spike of the F1 hybrid with high rate of stainable pollen were lower than that with low rate of stainable pollen, which indicts that pollen fertility was positively related to the expression level of UbL40 in the young spike. The paper also reveals that the expression levels of UbL401 and UbL404 in the young spike of the F1 hybrid were higher than UbL402 at high temperature.