桑树景天庚酮糖-1,7-二磷酸酶基因的遗传转化及生物学功能分析

Genetic Transformation and Biological Function Analysis of the Sedoheptulose-1,7-bisphosphatase Gene from Mulberry

景天庚酮糖-1,7-二磷酸酶(SBPase)在植物光合作用卡尔文循环过程中控制着碳的流入和再生,在碳固定的基本途径中起着重要作用。利用已克隆到的桑树景天庚酮糖-1,7-二磷酸酶基因(MSBPase)cDNA全长序列,构建其植物表达载体转化拟南芥,检测结果表明转基因植株中MSBPase在转录水平和蛋白质水平上成功表达。对转基因拟南芥植株的表型观察发现,转基因植株与野生型植株相比叶色较绿,叶片数较多,株型较大,生长旺盛,且营养生长期明显缩短,呈现早花现象;对转基因拟南芥植株的生理生化特性分析发现,转基因株系叶片中SBPase的活性和净光合速率显著增强,叶片中的淀粉和可溶性糖含量及植株干质量增加。因此,MSBPase具有提高植株光合固定CO2的效率和光合能力,促进植株生长的作用,可以作为桑树基因工程育种的候选基因。研究结果也为进一步研究MSBPase的代谢调控机制奠定了基础。

edoheptulose-1,7-bisphosphatase（SBPase） controls inflow and regeneration of carbon in Calvin cycle of plant photosynthesis,playing an important role in basic pathways of carbon fixation.The cloned full-length cDNA of mulberry sedoheptulose-1,7-bisphosphatase gene（MSBPase） was used to construct plant expression vector and subsequently transformed into Arabidopsis thaliana.Successful expression of MSBPase in the transgenic plants was detected at both transcriptional and protein levels.Phenotype analysis to the transgenic Arabidopsis thaliana plants indicated that,compared to the wild type plants,the transgenic plants had greener leaves,more leaves per plant and bigger plant size.Besides,the transgenic plants grew more vigorously,had shorter vegetative growth period and appeared early blosso-ming.Analyses to physiological and biochemical characteristics of the transgenic Arabidopsis thaliana plants revealed that the SBPase activity and net photosynthetic rate in leaves of the transgenic plants were enhanced significantly,starch and soluble sugar content in leaves and dry mass of the transgenic plants were all higher than those of wild type plant.Therefore,expression of MSBPase gene can increase the rate of CO 2 fixation and photosynthesis of plants.It can promote plant growth,beinga candidate gene for mulberry genetic engineering.These findings also provide a good basis for further studies on metabolic regulatory mechanism of MSBPase.