外源脯氨酸对高温胁迫下黄瓜幼苗叶片AsA-GSH循环和光合荧光特性的影响

Effects of Exogenous Proline on the Ascorbat-glutahione Cycle and Photosynthetic Fluorescence Characteristics in Leaves of Cucumber Seedlings under High Temperature Stress

以抗热性较弱的黄瓜品种‘新泰密刺’为试材,在人工气候箱内采用营养液栽培法,研究了外源脯氨酸(Pro)预处理对高温胁迫下黄瓜幼苗叶片抗坏血酸-谷胱甘肽循环和光合荧光特性的影响。结果显示:(1)与清水处理相比,高温胁迫4 h和8 h时,Pro预处理黄瓜幼苗叶片单脱氢抗坏血酸还原酶(MDAR)活性、GSH(还原型谷胱甘肽)/GSSG(氧化型谷胱甘肽)比值及GSH含量显著升高;(2)在高温胁迫8 h时,Pro预处理幼苗的净光合速率(Pn)、气孔导度(Gs)及PSⅡ的最大光化学效率(Fv/Fm)、光化学淬灭系数(qP)均显著升高,而蒸腾速率(Tr)和非光化学淬灭系数(NPQ)降低。研究表明,外源Pro预处理可显著提高高温胁迫下黄瓜幼苗叶片抗坏血酸-谷胱甘肽循环清除H2O2能力和叶片光合能力,有效缓解高温胁迫对黄瓜叶片抗氧化系统和光合系统的伤害,从而增强植株的耐热性。

The experiment was carried out by cucumber cultivar ＇Xintai Mici＇ with weak heat resistance in climate chambers and hydroponics to investigate the negative effects of high temperature on AsA-GSH cycle and photosynthetic fluorescence characteristics of seedling leaves and the positive effects of exogenous proline pretreatment.The results showed that：（1）compared with the water treatment,under high temperature stress（treat 4 h,8 h）.The activities of MDAR,the ratio of GSH/GSSG,and the content of GSH in leaves of cucumber seedlings were significantly increased in proline pretreatment.（2）Under high temperature stress（treat 8 h）,proline pretreatment significantly increased Pn,Gs,Fv/Fm and qP in leaves of cucumber seedlings,but Tr and NPQ decreased.The results indicated that exogenous praline pretreatment significantly enhanced scavenging activity on H2O2 of AsA-GSH cycle and photosynthetic capacity in leaves of cucumber seedlings,and efficiently alleviated the injury of cucumber seedlings to antioxidant system and photosynthetic system under high temperature stress.Therefore,exogenous proline could enhance heat resistance of cucumber seedlings to high temperature stress.