Introducing The Maize PEPC Gene To Indica Restorer Lines And The Breeding Of High Photosynthetic Efficiency Rice

Rice(Oryza saliva L)is one of the important food crops. But the analysis of photosynthesis efficiency to high yield rice varieties showed that its photosynthesis efficiency was 1-1.5%, while its potential photosynthesis efficiency was 3-5%. In this research, restorer lines Shuhui881, Shuhui527 and Shuhui955, as gene acceptors were crossed with the transgenic rice Kitaake containing the PEPC gene from maize. In this study, photosynthetic characteristics and agronomic traits of Shuhui 881 were systematically analyzed, the main results as below:? The seeds of BC1F1 were screened on the medium with 40mg/L Hygrimycin for the first selection of the plants obtaining foreign PEPC gene.? The PCR analysis of F1, BC1F1, BC2F1 hybrids and parents indicated that the PEPC gene of maize had been integrated and could be inherited in the progenies.? In the plants obtaining maize PEPC gene, the activity of PEPCase was increased evidently compared to the check plants, it was increased as much as 8-20 folds. It could be seen that PEPC gene from maize was not only inherited, but also expressed in the progenies plants.? The light-saturated photosynthetic rates of BC2F1 plants were nearly 100% higher than that of Shuhui881 under natural conditions; The physiological indexes of the BC2F1 plants were markedly superior to that of Shuui881, increased 75% in quantum efficiency and 40% in the carboxylation efficiency, decreased 30 umo昺~-2晄~-1 in CO2 compensation. It demonstrated that the photosynthetic characteristics had been improved after the introducing of maize PEPC gene.? In the test of the tolerance to photoinhibition, plants containing the PEPC gene from maize exhibited a slighter photoinhibition than the check plants; After test, the leaves of color of the check plants turned yellow, while the leaves of plants containing the PEPCgene from maize still kept green; The chlorophyll content in the check plants was greatly decreased.The analysis of hybrids and Shuhui881 showed that the introducing of PEPC gene had some effects on the agronomic traits .The areas of BC2F1 plants were decreased remarkably, while the 1000-grain weight increased 17%, at the same time, the tiller and the panicle forming rate increased. The analysis of grain shape identified that grain length and grain width were not changed, but grain thickness was increased, so the increase of 1000-grain weight was the results of the improvements of photosynthetic characteristics. So, the improvements of the 1000-grain weight, the tiller, the panicle forming rate and the yield per hill maybe were the result of the introducing of PEPC gene from maize.In order to identify whether and how did the PEPC gene play a great role on the increase of photosynthetic efficiency, it was very necessary to study the backgrounds of hybrids, the correlation between the activity of PEPCase and photosynthetic characteristics, effects on the other rice materials introducing PEPC gene, such as restorer lines, sterile lines, and the photosynthetic characteristics under different conditions.