Lead is an important environmental pollutant, extremely toxic to plants and other living organisms. In the present study, possible ameliorating effects of salicylic acid (SA) were investigated at biochemical levels in maize exposed to lead stress. The elevation in hydrogen peroxide and malondialdehyde contents and the decline in protein thiol (PT) level were revealed under lead stress. The SA pretreatment prevented a lead-induced decrease in chlorophyll and PT contents, as well as an increase in lipid peroxidation and hydrogen peroxide levels. Lead stressed plants which are pretreated with salicylic acid accumulated more ascorbic acid, glutathione and stimulated more antioxidant enzymes activity than plants treated with lead alone. In addition, SA pretreatment of seed enhanced l-cysteine desulfhydrase activity and endogenous hydrogen sulfide content. The results indicate that SA regulates the response of plants to lead stress and suggest hydrogen sulfide as a downstream signal molecule which might be involved in SA-induced lead tolerance.

铅是一种重要的环境污染物，对植物和其他生物具有剧毒。在本研究中，在生化水平下研究了铅胁迫下玉米中水杨酸（SA）可能的改善作用。在铅胁迫下显示出过氧化氢和丙二醛含量的升高以及蛋白质硫醇（PT）水平的降低。SA预处理可防止铅诱导的叶绿素和PT含量降低，以及脂质过氧化和过氧化氢水平升高。用水杨酸预处理的含铅植物比单独用铅处理的植物积累更多的抗坏血酸，谷胱甘肽和刺激更多的抗氧化酶活性。此外，SA预处理种子增强的升-半胱氨酸脱硫酶活性和内源性硫化氢含量。结果表明，SA调节植物对铅胁迫的反应，并建议将硫化氢作为下游信号分子，可能参与SA诱导的铅耐受性。