摘要： 为研究外源NO对铝胁迫下西瓜根系的缓解作用，以西瓜品种早佳84-24为试验材料，在高浓度的铝胁迫（1 200 μmol/L）下外施硝普钠（NO供体），研究不同浓度（50，100，200，500 μmol/L）的NO对铝胁迫下西瓜根系生理及矿物质含量的影响。结果发现，高浓度铝离子胁迫下西瓜根系电解质渗透率及丙二醛含量增加，为维持渗透平衡根系中脯氨酸与可溶性糖含量显著增加，超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）的酶活性均显著降低。铝胁迫抑制了根系钙、镁、铁、磷元素的吸收，促进了钾、锌、铝元素的吸收，铜元素含量没有发生显著变化。在添加外源NO后，西瓜根系电解质渗透率及丙二醛含量下降，质膜过氧化程度降低，根系中可溶性糖的含量显著降低，脯氨酸的含量显著上升。SOD、POD、CAT酶活性均随着NO浓度的升高呈现出先增加后下降的趋势。NO不仅通过增加硝酸还原酶活性促进了氮元素的吸收积累，还促进了西瓜根系对钙、镁、铁、铜、磷元素的吸收，并抑制了根系对锌、铝、钾元素的含量积累。添加NO内源抑制剂L-NAME后NO对西瓜铝胁迫的缓解作用消失甚至起到抑制作用，说明外源施加SNP能够减轻铝胁迫下西瓜根系氧化损伤，并通过影响根系对营养元素的吸收来缓解铝毒作用。

关键词: 西瓜, 铝胁迫, NO, 抗氧化酶, 矿物质

Abstract: To study the alleviating effect of exogenous Nitric oxide(NO) on the root system of watermelon under aluminum stress,watermelon variety Zaojia 84-24 was used as the experimental material,and the effects of different concentrations(50,100,200,500 μmol/L) of NO on the physiological and mineral content of watermelon root under aluminum stress were studied by applying nitroprune(NO donor) under high concentration of aluminum stress(1 200 μmol/L). The results showed that the root electrolyte leakage and the content of malondialdehyde increased under high Al ion stress,and the activities of superoxide dismutase(SOD),peroxidase(POD) and catalase(CAT) were significantly decreased in order to maintain the osmotic equilibrium by significantly increasing the content of proline and soluble sugar in the root. Aluminum stress inhibited the absorption of Ca,Mg,Fe and P,promoted the absorption of K,Zn and Al,but the content of Cu had not changed significantly. After the addition of exogenous NO,the root electrolyte leakage and the content of malondialdehyde decreased,the degree of plasma membrane peroxidation decreased,the content of soluble sugar in the root decreased significantly,and the content of proline increased significantly. The activities of SOD,POD and CAT increased first and then decreased with the increase of NO concentration. NO not only promoted the absorption and accumulation of nitrogen by increasing the activity of nitrate reductase,but also promoted the absorption of Ca,Mg,Fe,Cu and P by watermelon roots,and inhibited the accumulation of Zn,Al and K contents by roots. The addition of L-NAME,an endogenous inhibitor of NO,eliminated the alleviating effect of NO on aluminum stress in watermelon and even inhibited it. These results indicated that exogenous SNP could alleviate oxidative damage of watermelon roots under Al stress,and alleviate the effects of Al toxicity by affecting the absorption of nutrient elements by roots.

Key words: Watermelon, Stress of aluminium, Nitric oxide, Antioxidant enzyme, Minerals

中图分类号: 

• S651.01