Study On Physiological And Biochemical Effect Of The Cyanobacteria Pepc Gene Transformation Of Tobacco

In recent years, more and more attention has been paid to the introduction of C4 photosynthetic gene into C3 plants to raise their photosynthetic capacity by recombinant DNA technology. And the most important enzyme was the PEPC(phosphoenolpyruvate carboxylase). So, the PEPC from thermophilic cyanobacterium was tried to express in tobacco to improve the photosynthetic capacity. Three light inducible plant expression vectors were constructed using the Gateway technology, including pH-Prbcs-KsPEPC, pH-Prbcs-SvPEPC and pH-T-Prbcs-KsPEPC(SvPEPC is wild type, KsPEPC is mutant). Then the plant expression vectors were transformed into wild type tobacco (WT) and ZMPCK transgenic tobacco (P7) via Agrobacterium-mediated method.4 types of transgenic tobacco were obtained, which containing two types of transgenic single genes tobaccos (TKsPEPC-WT (PEPC product localled in chloroplast) and KsPEPC-WT (PEPC product localled in cytoplasm)) and two types of transgenic double genes tobaccos (TKsPEPC-P7 (PEPC product localled in chloroplast) and KsPEPC-P7 (PEPC product localled in cytoplasm)). First of all, the analysis of genomic level, transcription level and translation level were taken with transgenic tobaccos. Then, the enzyme activity, plant height, carbohydrates content of the transgenic tobaccos were detected. Analysis results were summary as follows: The PEPC gene had been inserted into the tobacco's genome, and the gene's transcription level was very high; The PEPC enzyme activity in transgenic plants was higher than the non-transgenic plants. Enzyme activity of transgenic tobaccos which product localled in chloroplast was slightly higher than transgenic tobacco which product localled in cytoplasm. The PEPC+ZmPCK transgenic double genes tobacco's enzyme activity were higher than ZmPCK transgenic single genes tobacco, but had no obvious difference from the PEPC transgenic single genes tobacco;(3)The glucose content and sucrose content in all 8 types of transgenic tobacco were lower than the wild type tobacco. However, the starch content had no changes.These results demonstrated that overexpression of the PEPC gene from thermophilic cyanobacterium might enhance the PEPC enzyme activity in tobacco and also had effects on the carbohydrates content of the transgenic tobaccos. It would provide experimental foundation for introducing C4 photosynthetic characteristics into C3 Plants to improve the photosynthetic capacity of C3 plants.