Abstract
Glycine betaine (GB) is an important osmoprotectant that enables plants to resist abiotic stresses such as salinity, low-temperature and drought. GB can be synthesized in many organisms, including animals, plants and bacteria. In higher plants, GB is synthesized through two-step oxidations of choline.However, rice, an important food crop, cannot synthesize GB. Recently, an enzyme , encoded by TpGSDMT gene finding in a diatom Talassiosira pseudonana, which can catalyze the three successive methylation steps of glycine to form GB. And this biosynthetic pathway for GB synthesis is also the simplest in living organisms. Here, TpGSDMT gene was isolated from Talassiosira pseudonana and cloned into overexpression vector pBWA(V)HS that contains CaMV 35S promoter, and then the constructed vector was introduced into rice(Oryza sativa L. ssp. Japonica).The GB content in transgenic rice that overexpression TpGSDMT was significantly increased , and the tolerance to salt and low-temperature was markedly enhanced in thses transformants.These results indicate the TpGSDMT gene can be used for genetic improvement of crop plants resistance to abiotic stress.