【摘要】 研究不同低温胁迫下 (3℃ ,-2℃和 -1 0℃下分别处理 0 .5、3、6、9、1 2 h)扁桃离体叶片中 MDA含量、CAT活性和类胡罗卜素含量以及反映组织受伤害程度的膜透性变化和叶绿素降解间的关系 ,以探明膜脂过氧化在扁桃叶片低温伤害中的作用。 3℃处理初期 ,CAT活性、类胡罗卜素含量显著增加 ,叶片无明显伤害症状 (水渍、黄化等 ) ;-2℃和 -1 0℃下随处理时间的延长 ,叶片膜透性增大、叶绿素含量下降、MDA积累增多 ;同时 CAT活性、类胡罗卜素含量显著下降。MDA含量的增加与组织受伤害程度 (膜透性增加及叶绿素降解 )及抗氧化系统 (CAT和类胡罗卜素 )水平下降之间具有极显著的相关性。以 7个扁桃品种的田间越冬伤害指数及冬季所测枝条的 LT50 代表植株的冬季抗寒性 ,以 -5℃下处理4h和 8h后所测叶片 MDA相对含量代表叶片的抗寒性 ,发现 2者呈显著的相关性 ,表明 MDA可以作为鉴定扁桃品种抗寒性的指标。更多还原

【Abstract】 Effects of low temperature stress on lipid peroxidation, membrane and chlorophyll stability, and catalase (CAT) activity and carotenoid content were evaluated under laboratory freezing tests (3℃, -2℃ and -10℃ for 0.5, 3, 6, 9, and 12h, respectively), for possible use as cold hardiness selection criteria, in detached leaves of two almond cultivars (‘NePlus’ and ‘Nonpareil’, differing in cold tolerance). The application of moderate chilling treatment (3℃ within 9h) to almond leaves had significantly elevated levels of CAT activity (‘Nonpareil’ +17%~94%, ‘NePlus’ +38%~107%) and carotenoid content (‘Nonpareil’ +6%~31%, ‘NePlus’+10%~32%). Severe freezing treatments (-2℃ and -10℃) caused considerable injury in almond leaves as indicated by reduction in chlorophyll content (‘Nonpareil’ -26%, -44% and ‘NePlus’ -42%, -67%, respectively) and increasing in electrolyte leakage (‘Nonpareil’ +76%, +275% and ‘NePlus’ +196%,+379%, respectively ) , and enhanced oxidative stress as indicated by increasing in malondiadehyde (MDA) content ( ‘Nonpareil’+43%,+81% and ‘NePlus’ +70%, +110%, respectively), and decreasing in levels of antioxidants (CAT activity and carotinoid content). The decrease in antioxidant system and the increase in oxidative damage are closely correlated. These results provide some evidence for the view that low\|temperature responses in plants is due, at least in part, to oxidative stress, as a source of injury and as a signal to increase antioxidant defenses. We also found that the cold resistance of plant (measured by winter injury index of field plants and LT 50 of current year shoots in winter) correlated to that of leaves (measured by MDA content in leaves under laboratory freezing test, -5℃ for 4h and 8h) in 7 almond cultivars.更多还原