Response of Ascorbic Acid Metabolism in Apple Rootstocks Leaves under Drought Stress

To investigate relationship between the ascorbate content and to anti-drought of apple rootstockes,we studied the changes of ascorbate and glutathione and key enzymes activities of AsA biosynthesis and recycling were studyed in Malus sieversii(drought-resistant variety) and M.hupehensis(drought-sensitive variety) seedlings under drought stress.The results showed that ascorbate contents and activities of related metabolism enzymes did not have significant differences between M.sieversii and M.hupehensis seedlings in well-water condition.Under drought stress,the change trends of AsA,total AsA,GSH and total GSH contents were consistent in both of seedlings,but the increased extent of them in M.sieversii were more than that in M.hupehensis.The leaves of M.sieversii showed higher activities of GalLDH,DHAR and GR,and ratio of AsA/DHA and GSH/GSSG than that of M.hupehensis under drought stress.It was suggested that M.sieversii with higher anti-drought stress abilities is due to have capability of maintaining higher abilities of AsA biosynthesis and recycling than that of M.hupehensis under drought stress.