Transgenic Tobacco Plants harboring the Trehalose Phosphate Synthase TPS gene of Escherichia coli increased Tolerance to Drought Stress

Trehalose consists of two glucose units linked together via an alpha-1,1-glycosidic linkage (1,1-alpha-D-glucopyranosyl-alpha-D-glucopyranoside) and a storage disaccharide carbohydrate that protects against a variety of drought stresses in microorganisms and plants grown in a drought environment. Trehalose is synthesized via sequential reactions by trehalose phosphate synthase (TPS), trehalose-6-phosphate phosphatase (TPP) and the hydrolytic enzyme alpha-trehalase (TRE). The trehalose-6-phosphate is synthesized from glucose-6-phosphate (G-6-P) and uridine-5'-diphosphoglucose (U-DPG) in a TPS-catalyzed reaction. Here, we constructed transgenic tobacco plants harboring the otsA gene of E. coli encoding for TPS via Agrobacterium tumefaciens-mediated transformation. T-0-otsA transformant tobacco plants were treated by withholding irrigation for 5 days. After drought treatment, the wild-type plants wilted and eventually died; however, the transgenic tobacco plants evidenced 25% to 60% tolerance against drought stress, depending on their transgenic lines. This variable drought tolerance may possibly have been dependent on the gene expressivity of individual lines of transgenic tobacco plants. In conclusion, E. coli otsA gene for trehalose synthesis transformed tobacco plants evidenced reduced wilting symptoms.