| Rice (Oryza sativd) is one of the world's most important food crop, occupying an important position in the global food production and consumption. China is one of the country to grow rice, the rice planting area accounts for about19%of the total area of the world rice cultivation while the production is about21%, the datum fully demonstrated that china created a stunning performance in the production of rice under the less favorable land conditions relying on the progress of the agricultural science and technology. Consequently, research of the hybrid rice and of popularization play a crucial role in improving rice production in China.Three-line hybrid rice has made great contributions to China's grain production since it was popularized. However, it is longer and more difficult to foster a more productive combination with the development of hybrid rice. Consequently, it is inevitable to find new ways to improve the heterosis. Study of two-line hybrid rice effectively solve the problem that three-line hybrid rice are limited by sterile cytoplasm and the relationship of restorer lines and maintainer lines, then a number of super hybrid rice appear. Currently, the promotion of two-line hybrid combination has not been studied the effect of the cytoplasm and could not answer whether it is the best cytoplasmic-nuclear interaction combination, which is detrimental for the full development of two-line heterosis. In this paper, we set thermoperiod sensitive genie male sterile line-ZhunS as control, investigate the impact of cytoplasm from North American planting rice-Lemont and common wild rice-Chaling Wild rice to photosynthetic characteristics and photosynthetic genes'expression to promote the cognition of the cytoplasmic effect at the molecular level and provide some theoretical guidance for the selection of the best quality of the nuclear preparation and the most favorable female parent in theory. Main results are as follows:1. Comparison of biological yield among isonuclear alloplasmic male sterile linesWe set ZhunS as control, comparison of biological yield between Lemont//ZhunS and Chaling//ZhunS showed the daily dry weights of Chaling//ZhunS were higher than others', while ZhunS and Lemont//ZhunS showed no significant difference.2. Comparison of photosynthetic characteristics among the isonuclear alloplasmic male sterile linesWe set ZhunS as control, compare the content of photosynthetic pigments,net photosynthetic rate and Rubisco activity of functional leaves among ZhunS,Lemont//ZhunS and Chaling//ZhunS in tillering stage. We came to the result that the photosynthetic pigments of the three were almost the same, however, the net photosynthetic rate of the Chaling//ZhunS was16.3%higher than the ZhunS while Lemont//ZhunS was8.4%lower than the control and the Rubisco activity of Chaling//ZhunS was42.2%higher than ZhunS while the variety Lemont//ZhunS was68.7%of the control ZhunS.3. Differential expression of photosynthetic genes among the isonuclear alloplasmic male sterile linesWe set ZhunS as control, compare the four photosynthetic genes'(psbA, rbcL, rbcS and rca) expression difference between Lemont//ZhunS and Chaling//ZhunS on the level of mRNA. We achieved the result that the expression of the four genes in these three materials exist the differences as well, in the expression of cytoplasm genes psbA and rbcL, Lemont//ZhunS had no significant difference with control, but was significantly lower than that of Chaling//ZhunS; in the expression of nuclear gene rbcS and rca, Chaling//ZhunS had no significant difference with Lemont//ZhunS, but the two materials were significantly higher than that of control ZhunS.Results reached above fully showed that different sources of cytoplasm lead to different net photosynthetic rates and photosynthetic key enzyme activities, and then caused different biological yield, which may relate to expression of photosynthetic genes; the dual-purpose male sterile lines whose cytoplasm from Changling Wild Rice had advantages than the others, which will provide a reference for selecting female parents in two-line hybrid breeding. |
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