Shiwen Wang1*, Lina Yin1,2, Xiping Deng1, Kiyoshi Tanaka2
1State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,
Institute of Soil and Water Conservation, Northwest A&F University,
2Faculty of Agriculture, Tottori University

The galactoglycerolipids, monogalactosyldiacylglycerol and digalactosyldiacylglycerol (MGDG and DGDG, respectively) are the predominant membrane lipids in green plant tissues, and they constitute ~75% of chloroplast lipids (Dörmann and Benning, 2002). In plants, MDGD biosynthesis is catalyzed by MGD synthase whichtransferring D-Gal from UDP-Gal to sn-1,2-diacylglycerol, and DGDG is synthesized by galactosylation of MGDG. Thus, MDG synthase is the key enzyme for the biosynthesis of galactolipids and, hence, construction of the plastid membranes. In the natural condition, plant growth is suffering various environmental stresses, and membranes in the plant cell become the major targets of these stresses. Regulation of membrane lipids property and composition are extremely important for plant to deal with such environmental stresses and made a considerable contribution for survival and adaptation. In order to investigate the function of MGD synthase in enhancing plant survival and adaptation ability under stresses, we have cloned a MGD synthase gene from rice (OsMGD), over expressed it in tobacco, and investigated the responses of OsMGD-overexpressing plants under salt, aluminum toxicity and phosphorus deficiency. Our result showed that the activity of MGDG synthase in transgenic tobacco was 2 to 4.5-fold than that of wild type, which indicated the OsMGD is a functional MGDG synthase gene in rice. Under these stresses, the transgenic tobacco grew better than wild type tobacco, exhibited higher chlorophyll content, fresh weight and the ratio of root to shoot than that of wild type. Our results show that OsMGD play an important role in coping various stresses for plants, which also provide us a possible approach to enhance plant multiple stresses tolerance.