Antioxidant Metabolism of the Chloroplast in Apple Seedling Under Water Stress
Yao Yuncong, Zhang Dapeng, Wang Younian, and Gao Xiahong (Beijing agricultural College, Changping, Beijing 102206; College of Plant Science and Technology, China Agricultural University)
30-day-old tissue cultured seedlings of Malus micromalus Makino and M. huehenisis (Pamp)Rehd. were used for studying the metabolism of O_2 and H_2O_2 in chloroplast and analyzing the difference of antioxidant preceeding under the treatments of 0-30% PEG6000 solutions for 48 hours. The results indicated that along with the increasing of water stress the photosynthetic O_2 evolution and the electron bansported rate of PS Ⅱ in the chloroplast were high at first and then down; but the when the treated concentration of PEG6000 was below 15%, but decreased at PEG6000 concentration between 15%-30%. O_2~- and H_2O_2 content increased consistently. The activities of SOD, CAT, AsAPOD and GR were significantly ascented under slight to moderate water stress conditions. The changes of MDA content in the chloroplast appeared to be an opposite trend to the SOD, CTA,AsApod and GR activities; and that with the increasing of the PEG6000 concerntration the saturated fatty acid content increased, the unsaturated fatty acid decreased obviously, such mainly occurred in MGDG, DGDG, SL and PG. All the results showed that the antioxidant capability of the choroplast of the seedlings of M. micromalus was better than that of M. hupehensis.