Abstract
We examined the role of putative rice (Oryza sativa L.) monogalactosyldiacylglycerol synthase (UDPgalactose: 1,2-diacylglycerol 3-b-D-galactosyl transferase; EC 2.4.1.46, MGDG synthase) gene OsMGD under salt and drought stresses by overexpressing in tobacco. OsMGD transgenic plants showed better growth and vigor under salt stress in vitro and maintained higher photosynthesis and PSII photon yield under salt and drought stresses than wild type. Transgenic plants had significantly higher contents of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and lipid-P than wild type. Upon salt stress, MGDG and DGDG maintained significantly higher levels than wild type. Overall fatty acid composition of MGDG and DGDG in wild type and OsMGD transgenic plants was basically unchanged during 72 h of salt stress, except for slight decreases in levels of α-linolenate of both galactolipids only in wild type plants. This indicated that OsMGD overexpressed plants maintained greater stability of galactolipid composition, membrane structure and functions to cope with salt tolerance.
