2014-甜瓜耐盐.docVIP

外源脯氨酸对盐胁迫下甜瓜幼苗根系 抗坏血酸-谷胱甘肽循环的影响 摘 要：以耐盐性不同的两个甜瓜品种为材料，采用营养液栽培，研究外源脯氨酸对盐胁迫下甜瓜幼苗根系抗坏血酸-谷胱甘肽循环的影响。结果表明：（1）盐胁迫条件下，抗坏血酸（ASA）、谷胱甘肽（GSH）含量降低，氧化型谷胱甘肽（GSSG）含量升高，且‘雪美’变化幅度大于‘玉皇’。（2）盐胁迫下，外源施用脯氨酸提高了两个甜瓜品种幼苗根系中ASA和GSH含量，降低了GSSG含量，同时也提高了两个甜瓜品种幼苗的GSH/GSSG比值，且对‘雪美’的作用效果大于‘玉皇’。（3）盐胁迫下，处理3d时，两个甜瓜品种的抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)活性均下降，‘雪美’甜瓜下降的幅度较大，随着胁迫时间的延长，5d时耐盐性较强的‘玉皇’甜瓜酶活性有所上升，而耐盐性较弱的‘雪美’甜瓜幼苗酶活性则进一步降低。（4）盐胁迫下，外源施用脯氨酸提高了APX、DHAR和GR酶的活性，对‘雪美’ 作用效果好于‘玉皇’。表明外源脯氨酸可以通过提高非酶促抗氧化物质ASA、GSH含量和抗氧化酶活性，改善抗坏血酸-谷胱甘肽循环清除活性氧能力， 缓解了盐胁迫对甜瓜植株的伤害。 关键词：脯氨酸；甜瓜；盐胁迫；抗坏血酸-谷胱甘肽循环 Effects of Exogenous Proline on the Ascorbat-glutahione Cycle in Roots of Melon Seedlings under NaCl stress Abstract: Effects of exogenous proline on the Ascorbat-glutahione Cycle in roots of two melon cultivars(Cucumis melo L. cv. Yuhuang and cv. Xuemei), differing in salt stress resistance, were investigated under salt stress in a nutrient solution culture system.The results showed that: (1) Salt stress decreased the content of ASA and GSH, increased GSSG, and the variation range of Xuemei was larger than Yuhuang. (2) exogenous proline increased the contents of ASA and GSH in two cultivars melon roots under salt stress, and also decreased the content of GSSG, increased the ratio of GSH/GSSG, and the range of Xuemei was larger than Yuhuang. (3) 3 days of salt treatment decreased APX, DHAR and GR activities of both melon cultivars, the effect was more markedly Xuemei than Yuhuang, with the extension of stress time, 3 days of salt treatment increased enzymes activities of Yuhuang, however, salt stress further reduce enzymes activities of Xuemei. (4) exogenous proline increased the activities of APX, DHAR and GR, ASA and GSH in two cultivars melon roots under salt stress, the effect was more markedly Xuemei than Yuhuang. Therefore, it showed that the exogenous proline can clear the ROS caused by salt stress by increasing the activities of antioxidant enzymed and non-enzymatic antioxidants content such as ASA and GSH that