脯氨酸对高温胁迫下黄瓜幼苗活性氧代谢和渗调物质含量的影响

Effects of Proline on Reactive Oxygen Metabolism and Content of Osmotic Adjustment Substances of Cucumber under High Temperature Stress

以抗热性较弱的黄瓜品种新泰密刺为材料,研究了外源脯氨酸(Proline,Pro)对高温胁迫下黄瓜幼苗叶片活性氧代谢和渗透调节物质含量的影响。结果表明,高温胁迫下,黄瓜幼苗叶片的超氧阴离子(O2-.)产生速率、丙二醛(MDA)含量和电解质渗透率(EL)显著升高,细胞膜受到了明显的过氧化伤害;Pro预处理通过提高超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,增强了对活性氧(ROS)的清除能力,有效地缓解了由高温胁迫诱导的膜脂过氧化伤害;同时,Pro预处理提高了游离Pro、可溶性糖和可溶性蛋白的含量,增强了植株的渗透调节能力,从而维持了植株体内的水分平衡。结果说明,外源Pro通过提高高温胁迫下黄瓜幼苗叶片抗氧化酶活性和渗透调节物质含量,来降低体内ROS水平,提高植株的渗透调节能力,从而缓解高温胁迫对黄瓜叶片的膜脂过氧化伤害。

The effects of exogenous proline on reactive oxygen metabolism and content of osmotic adjustment substances in leaves of cucumber cultivar Xintaimici（with weak heat resistance） were investigated under high temperature stress.The results showed that superoxide anion free radical（O2-·） production rate,malondialialdehyde（MDA） content and leakage of electrolyte（EL） in leaves of cucumber seedlings were significantly increased by high temperature stress,and the membrane lipids were subjected to the peroxidation injury,proline pretreatment enhanced eliminative ability to active oxygen（ROS） and effectively alleviated membrane lipid peroxidative injury caused by high temperature stress by promotion of activities of superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT）.Meanwhile,proline pretreatment improved contents of free proline,soluble sugars and soluble proteins,and increased osmotic adjustment ability,as a result of maintenance to water balance in plants.These results suggested that exogenous proline could alleviate membrane lipid peroxidation caused by high temperature stress,suppress ROS levels and improve osmotic adjustment ability in leaves of cucumber seedlings by promotion of antioxidant enzymes activities and content of osmotic adjustment substances under high temperature stress.