Expression Of FBA Gene From Rice Cytoplasm In Anabaena Sp.PCC 7120 And Its Regulation Of Photosynthesis Carbon Assimilation

Photosynthesis is the most important chemic reaction in the world since it is theultimately energy source of any living organisms. Photosynthesis contains a series of complexprocesses, and carbon assimilation is the most important part of them. Over the last 20 years,there were some unexpected findings about Calvin cycle with practicing of antisensetransgenic plants. As a result, under a wide range of condition, decrease ofribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity had little impact on thecontrol of carbon fixation. Meanwhile, non-regulated enzymes witch catalyzing reversiblereactions such as fructose 1,6-bisphosphate aldolases (FBA) which catalyzing the cleavage offructose 1, 6-bisphosphate (FBP) exerted significant control over carbon flux.In order to get more information about the regulation of FBA in Calvin cycle at genelevel, FBA gene from rice cytoplasm was transferred into filamentous, heterocystourcyanobacterium Anabaena sp. PCC 7120. Cells were grown in BG-II medium of different pHand Supplemented with different concentrating of NaHCO₃. Growth parameters,photosynthesis activity and enzyme activity of FBA were measured and compared betweentransgenic and wild type cells. Main experiments results are as following,1) FBA gene from rice cytoplasm was inserted behind PpsbA, the efficient lightinductive promoter from chloroplast, and constructed into shuttle expression vector pDC-FBAtogether. FBA transgenic Anabaena sp. PCC 7120 was obtained by the method of triprentalmating for conjugative transfer.2) The enzyme activity of FBA in transgenic cells was 31.2% higher than that of wildtype cells.3) Photosynthesis activities of transgenic cells were increased, with 19.2% higher in netphotosynthesis activity and 20.6% higher in true photosynthesis activity than wild type cells.After 17 days'growing period in the medium supplemented with 10 mM NaHCO3, thephotosynthesis activity of FBA transgenic cells became more distinguished from that of widetype cells, with 29.4% higher in net photosynthesis activity and 31.5% higher in truephotosynthesis activity. After 25 days'growing period, the gap became narrower, with 16.9%higher in net photosynthesis activity and 17% higher in true photosynthesis activity.4) Transgenic cells showed comparative advantages over the wild type cells in mostexperiments, especially in the medium of higher initial pH.