Responses of the key enzymes involved in proline metabolism in rice seedling under water stress

Using rice seedlings at two-leaf stage as tested materials,the free proline content and activities of enzymes involved in proline metabolism were studied under water stress induced by 15%PEG.The results showed that the proline content increased obviously under stress,reached the maximum after 24 h and then decreased.The activities of △1-pyrroline-5-carboxylate synthetase(P5CS) and ornithine-δ-aminotransferase(δ-OAT),the key enzymes of proline accumulation,increased significantly and then declined;while the activity of proline dehydrogenase(ProDH),a key enzyme of proline degradation,declined significantly and then increased.