为了研究重金属复合胁迫下温度变化对陆生植物的毒性效应的影响,实验采用水培的方法,设置对照和Cu-Cd复合胁迫(10 μmol·L1 Cu+10μmol·L-1Cd)2个处理,每个处理分别设置3个不同的培养温度(8/4℃、25/20℃和35/30℃),对小麦进行48 h的暴露实验,测定小麦幼苗的生长及其对重金属和矿质营养元素的吸收与亚细胞分布等指标.结果表明,温度处理和Cu-Cd复合胁迫对小麦幼苗的生长均没有产生明显影响,但是,随温度的升高,小麦幼苗对Cu和Cd的吸收均显著增加,同时Cu和Cd在小麦根部细胞壁组分的分配比例降低,而在可溶性组分的分配比例明显增加.温度处理和Cu-Cd复合胁迫均能明显影响小麦幼苗对矿质营养元素的吸收,二者对小麦幼苗矿质营养元素吸收存在交互作用,表现为对微量矿质营养元素(Fe、Mn和Zn)吸收的交互作用大于大量矿质营养元素(K、Ca和Mg),且对根部微量矿质营养元素含量影响的交互作用最为突出.另一方面,Cu-Cd复合胁迫和温度变化能够显著影响根部微量矿质营养元素Fe、Mn和Zn在亚细胞水平的分布,总体趋势为Cu-Cd复合胁迫下随着温度的升高,Fe、Mn和Zn在小麦根部细胞可溶性组分的分配比例增加,而在细胞壁组分的分配比例显著降低.实验结果表明,温度作为一个重要的环境因子,能够明显影响重金属对小麦的生态毒性效应.%To study the effect of temperature on the ecotoxic response of terrestrial plants under combined stress of copper and cadmium, wheat seedlings were exposed to the combined stress of copper and cadmium (10 mol·L-1Cu + 10 mol·L-1 Cd) under three different temperatures (8/4℃, 25/20 ℃ and 35/30℃)for 48 h using hydroponic methods. The indicators of wheat seedlings growth and the uptake and subcellular distribution of heavy metals and mineral elements were measured. The results indicated that the combined treatment of Cu and Cd at different temperatures did not inhibit the growth of wheat seedlings. However, temperature significantly influenced the uptake and subcelhilar distributions of Cu and Cd in wheat seedlings. It appeared that the contents of Cu and Cd in wheat seedlings increased with temperature elevation, and the distribution of Cu and Cd increased in soluble fraction but decreased in cell wall fraction in wheat seedling roots with temperature elevation. Both temperature treatment and combined stress of Cu and Cd could exert significant effect on the uptake of mineral elements by wheat seedlings. The uptake of micro-mineral elements (Fe, Mn and Zn) by wheat seedlings was more significantly affected by temperature than the uptake of macro-mineral elements (K, Ca and Zn). The interaction of temperature and combined stress of Cu and Cd was strong, especially on the uptake of micro-mineral elements by wheat seedling roots. Furthermore, the subcellular distributions of Fe, Mn and Zn in wheat seedling roots were significantly affected by the combined stress of Cu and Cd, as well as temperature. In general, with temperature elevation, the distributions of Fe, Mn and Zn in soluble fractions increased, while the distributions in cell wall significantly decreased. Thus, it is indicated that temperature as an important environmental factor can obviously influence the ecotoxic response of wheat seedlings under combined stress of heavy metals.
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