Abstract
Glycinebetaine (betaine) is a compatible solute that allows plants to tolerate various kinds of environmental stress, such as cold, freezing and high salt. To examine a direct relationship between the synthesis of betaine and the stress tolerance in plants, we transformed plants, such as Arabidopsis thaliana, Oriza sativa (rice) and Lycopersicon esculentum (tomato), are unable to synthesize betaine, with the codA gene for choline oxidase from a soil bacterium that catalyzes the synthesis of betaine from choline. We observed that resultant transgenic plants obtained the ability to synthesize betaine at a concentration no higher than 1 mM and to tolerate various kinds of stress. These findings indicate that betaine effectively enhances the ability of crossprotection against environmental stress but is ineffective in osmotic regulation.
