Ascorbic Acid Accumulation and Related Enzyme Activities in Leaves of Non-heading Chinese Cabbage

Ascorbic acid (AsA) contents,together with the activities of L-galactono-1,4-lactone dehydrogenase (GalLDH),ascorbic acid oxidase (AAO),ascorbate peroxidase (APX),monodehydroascorbate reductase (MDAR) and dehydroascorbate reductase (DHAR) were measured with non-heading Chinese cabbage varieties,Changzhouwutacai,Aijiaohuang and Erqing during plant development.The result showed that the content of AsA accumulated continually but first increased in the initial stage of plant development and then decreased,and the AsA content of Changzhouwutacai was higher than that of Aijiaohuang and Erqing.The changes in GalLDH activity coincided with AsA accumulation rate during plant development.GalLDH activity in Changzhouwutacai was higher than that in other varieties.GalLDH activity was significantly positive correlated with AsA accumulation in three varieties.However,the changes in activities of AAO and APX were in the opposite trend with AsA content.Further more,AAO activity in Changzhouwutacai was significantly lower than that in the other two varieties.APX activity had no significant difference among the varieties.MDAR and DHAR activity was determined mainly in the latter period of the growth.The results indicated that AsA content is regulated mainly by GalLDH activity in non-heading Chinese cabbage,AsA metabolizing enzymes-AAO,has also played an important role in the accumulation of AsA.The role of MDAR and DHAR for AsA accumulation is main in the latter period of the growth.