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

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.