玉米ppc基因过表达对转基因水稻光合速率的影响

通过转基因技术将外源ppc基因导入水稻以期增加产量是国内外的重要研究领域。然而，关于ppc基因过表达能否提高转基因水稻的光合速率至今尚无定论。本研究将玉米ppc基因导入水稻中花8号，获得大量转基因水稻植株。经PCR筛选、PEPC活性测定、Southern和Western杂交分析，表明玉米ppc基因已经整合到受体水稻基因组中，并得到了正确和高效的表达。测定了温室内种植的T₁代6个PEPC活性不同的转基因水稻植株的光合速率，只有活性最高的株系的光合速率显著增加，增加的幅度为27.3%。在旱作栽培条件下测定了T₃代33个转基因株系的光合速率，结果表明在高温、高光强下，绝大多数转基因水稻的光合速率增加，最大提高了68.8%。比较6个转基因株系的T₁和T₃代看到，逆境胁迫条件下转基因水稻光合速率明显提高。以上结果表明水稻中导入ppc基因可以提高其光合速率，特别是逆境条件下的光合速率。

Effect of Overexpression of Maize ppc Gene on Photosynthesis in Transgenic Rice Plants

Overexpression of ppc gene in transgenic rice to improve photosynthesis and yield have brought extensive interest in the world.Many attempts have been made to transfer maize ppc gene to rice plants using genetic engineering techniques.But there was still a controversy on whether overexpression of PEPC could increase photosynthetic rates(Pn) in transgenic rice plants.We thought the different results were caused by the difference on materials,ppc gene inserting site and the measuremental circumstance.In order to validate our ideas,we repeated to introduce maize ppc gene into rice plants by Agrobacterium-mediated transformation and many transgenic rice plants were obtained.PCR,Southern,Western analyse and PEPC activity detection indicated that the maize ppc gene was integrated into rice genome and expressed correctly and efficiently.The Pn was 27.3% higher in one transgenic line with the highest PEPC activity than in untransformed plants.The increase is at least in part due to the enhanced stomatal conductivity and higher internal CO2 concentration.Nearly all the ppc transgenic rice lines showed higher Pn(up to 68.8%) than untransformed plants grown in dry field and full sunlight.Compared with that in appropriated conditions,the six transgenic lines showed higher Pn in stress condition.These results indicated that photosynthesis can be improved by introduction of PEPC into rice,especially in stress conditions.