Molecular Regulation Of Synthesis And Partitioning Of Photosynthetical Product In Rice

Ferredoxin-NADP+ reductase (FNR) is one of the important enzymes involving in many biochemical and physiological metabolism processes, such as electron transfer, carbon dioxide fixation, nitrogen assimilation and antioxidation. Overexpression of FNR gene was believed to facilitate acquisition and assimilation of carbon and nitrogen, leading to the high-yielding transgenic plants.In higher plants, the cytosolic fructose-1,6-bisphosphatase (cyFBPase) catalyzed the breakdown of fructose-1,6-bisphosphatate into fructose-6-phosphate and phosphate, which is the limiting step in the biosynthesis of sucrose. Continuous removal of PPi from the cytosol resulting from ectopic mesophyll-specific expression PPase gene will favor the biosynthesis of sucrose and photosynthesis of chloroplast. OsR-FNR gene was isolated from rice cv. Orzysa, and binary vector harboring OsR-FNR was constructed. With the method of Agrobacterium-mediated transformation, transgenic lines overexpressing OsR-FNR and its iso-gene L-FNR provided with IPK lab in Germany were obtained. Photosynthesis parameters of L-FNR transgenic plants were determined. In addition, T4 generation of FBP-PPase and rbcS-PPase transgenic plants were analyzed on several agricultural traits and photosynthetic performance. The results obtained follow as: 1) OsR-FNR gene was evidently induced with salt treatment in roots; 2) OsR-FNR gene and FNR promoter were isolated from rice cv. Orzysa, and binary vectors of them were constructed; 3) With the method of Agrobacterium-mediated transformation, OsR-FNR and L-FNR transgenic lines were obtained. L-FNR transgenic lines have higher photosynthetic efficiency than that of control; 4) Determination of CO2 fixation showed that transgenic plants worked better in photosynthesis no matter in high or low light density than wild type plants did. Metabolism and partitioning of photosynthetically fixed carbon were enhanced by mesophyll-specific expression of PPase gene...