24-表油菜素内酯对低温胁迫下葡萄幼苗抗氧化系统及渗透调节物质的影响

Effects of 24-Epibrassinolide on the Antioxidant System and Osmotic Adjustment Substance in Grape Seedlings (V.vinifera L.) Under Chilling Stress

【目的】探讨外源EBR(24-表油菜素内酯)对低温胁迫下葡萄幼苗抗氧化系统及渗透调节物质的影响。【方法】以欧亚种(Vitis vinifera L.)鲜食葡萄品种‘紫脆无核’营养袋扦插苗为试材,分别在4℃和0℃低温条件下,研究外源EBR对葡萄幼苗4种抗氧化酶活性(CAT、SOD、POD及APX)、超氧阴离子()和丙二醛(MDA)含量以及渗透调节物质游离脯氨酸、可溶性糖和可溶性蛋白含量的影响。【结果】在两种低温胁迫条件下,外源EBR处理均使葡萄叶片抗氧化酶CAT、POD、SOD及APX活性升高,且总体与对照之间差异显著;同时也使葡萄叶片抗氧化物质GSH及AsA含量升高,在4℃和0℃条件下,GSH平均含量较对照分别升高5.4%及7.8%,AsA含量分别升高8.8%及13.0%;EBR处理使叶片及MDA含量降低,平均较对照分别降低28.5%及17.3%,MDA含量分别降低6.8%及7.5%;EBR处理明显提高了葡萄幼苗叶片脯氨酸、可溶性糖及可溶性蛋白含量,平均含量较对照分别提高8.4%和59.1%、3.5%和5.2%及18.6%和25.0%。【结论】在低温胁迫下,外源EBR通过提高抗氧化酶活性、抗氧化物质含量及渗透调节物质含量,减少了活性氧(ROS)的积累及膜脂过氧化产物MDA的产生,增强了葡萄幼苗耐低温胁迫的能力。

[Objective] This study was conducted to determine the influence of the exogenous EBR （24-Epibrassinolide） on the antioxidant system and osmotic adjustment substance of the grape seedlings under chilling stress. [Method] With table grape cultivar ＇Zicuiwuhe＇ （Vitis vinifera L.） as experimental material and were grown in nutrition bags, 0.1 mg.L-1 EBR was sprayed on grape seedling leaves, the effects of the exogenous EBR on four antioxidant enzyme activities （CAT, SOD, POD and APX）, superoxide anion （O2, malondialdehyde （MDA） content, free proline, soluble sugar and the soluble protein content of grape seedling under low temperature of 4℃ and 0℃ were compared with water （control）. [ Result ] Under the condition of two low temperature stress, grape seedling leaves, treated with exogenous EBR, the activities of antioxidative enzymes such as ascorbate peroxidase （APX）, catalase （CAT）, peroxidase （POD） and superoxide dismutase （SOD） increased compared with the control, and had significant differences between the EBR treatment and control. The EBR treatment also greatly enhanced the contents of ascorbic acid （AsA）and glutathione （GSH） during chilling stress, compared to the control, the average content of GSH and AsA increased by 5.4% and 7.8%, 8.8% and 13.0% under 4℃ and 0℃ conditions, respectively. However the content of O2 and MDA decreased by 28.5% and 17.3%, 6.8% and 7.5%, respectively. The leaves of grape seedlings which were treated with EBR improved the contents of free proline, soluble sugar and soluble protein, as a result, the average content of them increased by 8.4% and 59.1%, 3.5% and 5.2%, 18.6% and 25.0% under 4℃ and 0℃, respectively. [ Conclusion] Exogenous EBR reduced the accumulation of reactive oxygen species （ROS） and the content of MDA, and could play positive roles in the alleviation of oxidative damage caused by ROS overproduction through enhancing antioxidant defense system, meanwhile enhanced the grape seedlings osmotic adjustment substance, resulting in improving the tolerance of grape seedlings to chilling stress.