苯丙烯酸预处理对弱光下黄瓜叶片抗氧化特性的影响

Effects of Exogenous Cinnamic Acid on Reactive Oxygen Metabolism in Cucumber Leaves Under Low Light Stress

为了探明外源苯丙烯酸在弱光逆境胁迫下对黄瓜叶片抗氧化特性的影响,本实验以‘津春4号’黄瓜(Cucumis sativus L.)品种为材料,用50μmol苯丙烯酸处理2 d,然后分别置于正常光照(500μmol/(m·s)和弱光(80μmol/(m·s)下生长6 d。探究黄瓜在抗弱光胁迫中外源苯丙烯酸是否通过抗氧化酶在对膜脂过氧化起作用。结果表明,在第2天,苯丙烯酸预处理降低了MDA含量、O_2^(.-)生成速率以及H_2O_2含量,提高了抗坏血酸过氧化物酶(APX)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性。第8天,苯丙烯酸预处理降低了弱光胁迫下MDA含量、O_2^(.-)生成速率以及H_2O_2含量,提高了SOD、APX、过氧化氢酶(CAT)、GSH-Px活性。因此,外源苯丙烯酸预处理通过抗氧化酶的作用缓解了弱光下黄瓜叶片的膜脂过氧化损伤。

To investigate the effects of exogenous cinnamic acid on reactive oxyen metabolism in cucumber leaves under low light stess, cucumber seedlings( Cucumis sativus cv. Jinchun No. 4)were pretreated with 50 μ mol cinnamic acid for 2 d and then were cultivated at normal light intensity of 500 μmol/(m·s)and low light intensity of 80 μmol/(m·s)for 6 d. We investigated if cinnamic acid could protect cucumber plantlets under low light stress,and examined whether the protective effect related to antioxidant enzymes and lipid-peroxidation regulation or not. The results showed that at 2 d,exogenous cinnamic acid decreased levels of malonaldehyde(MDA),superoxide radical(O_2^(.-))and hydrogen peroxide(H_2O_2),elevated the activities of antioxidant enzymes superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and ascorbate peroxidase(APX)in cucumber leaves. At 8 d,the combination of cinnamic acid pretreatment and low light decreased the contents of MDA,H_2O_2 and O_2^(.-),enhanced the activities of SOD,catalase(CAT),APX and GSH-Px compared with non-pretreated plants. The exogenous cinnamic acid is able to moderate antioxidant enzyme activities and decrease lipid peroxidation in certain extent,it reduces stress intensity at low light.