水分胁迫条件下苹果幼苗叶绿体抗氧化代谢研究

以苹果属八棱海棠和平邑甜茶组培幼苗为试材，研究了不同浓度ＰＥＧ６０００溶液处理条件下幼苗叶绿Ｏ_２~－和Ｈ_２Ｏ_２代谢变化。结果表明，随着水分胁迫的加重，苹果属植物叶绿体光合放氧活性和ＰＳⅡ电子传递活性先上升而后下降；叶绿体Ｏ_２~－和Ｈ_２Ｏ_２产生速率持续上升；ＳＯＤ、ＣＡＴ、ＡｓＡ－ＰＯＤ、ＧＲ活性在轻度水分胁迫条件下显著上升，在重度水分胁迫条件下显著下降，脂质过氧化产物ＭＤＡ含量则呈相反的趋势；叶绿体ＡｓＡ和ＧＳＨ含量随水分胁迫而下降；叶绿体膜脂质组分随水分胁迫而出现饱和脂肪酸含量上升，不饱和脂肪酸含量下降，不饱和脂肪酸指数下降，类脂中饱和脂肪酸和不饱和脂肪酸的这种变化主要发生在ＭＧＤＧ、ＤＧＤＧ、ＳＬ和ＰＧ中。综合分析阐明了水分胁迫条件下苹果属植物叶绿体Ｏ_２~－和Ｈ_２Ｏ_２产生与清除的生理机理。种间各指标比较表明，水分胁迫条件下八棱海棠幼苗叶绿体比平邑甜茶具有较强的抗氧化能力。

Antioxidant Metabolism of the Chloroplast in Apple Seedling Under Water Stress

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.