24-表油菜素内酯预处理对干旱胁迫下葡萄幼苗抗氧化系统和渗透调节物质的影响

以酿酒葡萄‘雷司令’(Riesling)一年生营养袋扦插苗为材料,采用人工气候室水培试验,考察在聚乙二醇6000(PEG)模拟干旱条件下,不同浓度(0.05、0.10和0.20mg/L)24-表油菜素内酯(EBR)预处理对‘雷司令’幼苗活性氧、抗氧化物质、渗透调节物质含量和抗氧化酶活性的影响,以揭示EBR预处理对干旱胁迫下葡萄幼苗的抗旱机理。结果显示:(1)与正常生长(对照)相比,干旱胁迫显著提高葡萄幼苗叶片中超氧阴离子自由基(■)、过氧化氢(H_2O_2)和丙二醛(MDA)含量;与干旱胁迫处理(PEG)相比,不同浓度EBR预处理均可降低叶片中■、H_2O_2和MDA的含量。(2)与对照相比,PEG处理显著降低葡萄幼苗叶片的抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量;与PEG处理相比,各浓度EBR预处理均可显著提高葡萄叶片AsA与GSH的含量,且以0.10mg/LEBR处理效果最好。(3)随着干旱胁迫时间的延长,葡萄幼苗叶片中的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)与抗坏血酸过氧化物酶(APX)活性均呈先上升后下降的变化趋势,而在正常生长条件下酶活性基本保持不变;EBR预处理的葡萄叶片SOD、CAT、POD和APX活性均始终高于同期PEG处理。(4)PEG处理条件下,渗透调节物质脯氨酸和可溶性蛋白的含量整体高于对照;与PEG处理相比,不同浓度EBR预处理在干旱胁迫中后期均能显著提高葡萄叶片中脯氨酸和可溶性蛋白含量。研究表明,在干旱胁迫下,外源EBR预处理能够提高葡萄叶片抗氧化系统酶活性和渗透调节物质含量,有效降低干旱胁迫诱导的活性氧过度积累及膜脂过氧化程度,提高葡萄幼苗的抗旱能力,且以0.10mg/L EBR处理效果最佳。

Effect of 24 Epibrassinolide Pretreatments on the Antioxidant System and Osmotic Adjustment Substance in Vitis vinifera Seedlings under Drought Stress

In this study, Riesling annual nutrition bag cuttings were used as experimental material. We conducted artificial climate chamber hydroponic experiments to investigate the effect of various concentrations EBR (0.05, 0.10 and 0.20 mg/L) pretreatments on active oxygen, antioxidants, antioxidant enzymes activities and osmotic adjustment substance contents in grape (Vitis vinifera L.) seedlings with PEG simulating drought stress, revealing the mechanism of drought resistance of EBR on grape seedlings under drought stress. The results showed that: (1) compared with the growth control in normal, simulating drought stress significantly increased the contents of anion radical (O₂^-·), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) in the leaves of grape seedlings. Compared with the PEG treatment alone, different concentrations of EBR pretreatment could reduce the contents of O₂^-·, H₂O₂ and MDA in leaves. (2) Compared with the growth control in normal, the contents of ascorbic acid (AsA) and reduced glutathione (GSH) were significantly reduced in PEG treated seedlings. Compared with PEG treatment, EBR pretreatment significantly increased AsA and GSH contents in grape leaves, and 0.10 mg/L EBR treatment was the best. (3) Superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities in grape seedling leaves showed a trend of rising first and then decreasing in PEG treatment alone and it remained basically unchanged under normal growth conditions. Moreover, the activities of SOD, CAT, POD and APX in EBR pretreatment were always higher than those in PEG treatment. (4) The contents of proline and soluble protein in PEG treatment alone was higher than that growth control in normal. Different concentrations of EBR pretreatment could significantly increase the contents of proline and soluble protein in grape leaves during middle and late stages of drought stress. It was showed that under drought stress, EBR pretreatments could effectively reduce the excessive accumulation of reactive oxygen species (ROS) and the increase of membrane lipid peroxide level induced by drought stress through improving antioxidant defense system activities and osmotic adjustment substance contents in the leaves of grape seedlings, resulting in improving the drought resistance of wine grape seedlings. Among these, 0.10 mg/L EBR pretreatment got the most remarkable effect.