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为给土壤重金属复合污染条件下冬小麦生长发育安全性和稳定性的正确评价提供科学依据，采用聚丙烯酰胺凝胶电泳(PAGE)方法研究了低于国家“土壤环境质量标准(GB 15618-1995)”规定的Ⅱ类土壤环境基准值(350.0 mg·kg^-1干土，pH>7.5)时的Pb²⁺对Cd²⁺污染下冬小麦幼苗过氧化物酶(POD)同工酶表达的影响。结果表明，在冬小麦幼苗3周龄时，土壤Cd²⁺污染对其POD同工酶的表达表现出抑制效应，其中10.0 mg·kg^-1干土的Cd²⁺抑制作用最强；除50.0和80.0 mg·kg^-1干土的Pb²⁺可分别减缓5.0和10.0 mg·kg^-1干土的Cd²⁺对POD表达的抑制作用外，其他浓度的Pb²⁺表现出与Cd²⁺协同抑制POD表达的现象。在冬小麦幼苗7周龄时，土壤Cd²⁺浓度超过10.0 mg·kg^-1干土后对POD同工酶表达表现为抑制效应，且表达量随着Cd²⁺浓度的升高而表现出依次降低的趋势；除120.0和180.0 mg·kg^-1干土的Pb²⁺可减缓Cd²⁺对POD同工酶表达的抑制效应外，其他低浓度的Pb²⁺与Cd²⁺均表现出协同抑制POD表达的现象。说明土壤Pb²⁺浓度低于国家“土壤环境质量标准”规定的Ⅱ类土壤环境基准值350 mg·kg^-1干土(pH>7.5)时，主要表现为加重Cd²⁺污染对冬小麦幼苗POD同工酶表达的抑制效应。

英文摘要:

The effects of the low dose of Pb²⁺ (< 350.0 mg·kg^-1dry soil) on the response of POD isozymes in winter wheat seedlings to Cd²⁺ stress were analyzed by Polyacrylanid Gel Electrophoresis (PAGE). The results indicated that the expression of POD isozymes was inhibited by Cd²⁺ and the expression content was the lowest under the stress of 10.0 mg·kg^-1dry soil at the third week after winter wheat seedlings emerged, moreover, low doses of Pb²⁺ aggravated the inhibition of Cd²⁺ on the expression of POD isozymes except for 50.0 and 80.0 mg·kg^-1 dry soil. The expression content of POD isozymes decreased with the increase of the Cd²⁺concentration at the seventh week after winter wheat seedlings emerged, and low doses of Pb²⁺ aggravated the inhibition of Cd²⁺ on the expression of POD isozymes except for 120.0 and 180.0 mg·kg^-1 dry soil.

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