镉铅复合胁迫下根表铁锰氧化胶膜厚度对美洲商陆富集镉的影响

为了探讨根表铁锰氧化胶膜厚度及共存离子铅(Pb)对美洲商陆富集镉(Cd)影响,采用水培的方法,诱导培育了胶膜厚度具有极显著差异的美洲商陆(低膜美洲商陆、中膜美洲商陆和高膜美洲商陆),分别进行低Cd低Pb、低Cd高Pb、高Cd低Pb、高Cd高Pb等4种不同金属组合的胁迫处理,观察美洲商陆生长状况、测定植株对Cd的富集量、抗胁迫生理活性物质的表达量.结果表明:中膜和高膜美洲商陆侧根发达,新生根较多,高Cd胁迫对根系发育有较强的抑制作用.高Cd条件下,植株对Cd的富集量为高膜美洲商陆中膜美洲商陆低膜美洲商陆,高膜美洲商陆Cd总富集量可达89765.69 mg·kg-1(以干重计).低Cd条件下,植株对Cd的富集量为低膜美洲商陆高膜美洲商陆中膜美洲商陆.高Pb处理,可提高低膜和高膜美洲商陆Cd富集量,但显著降低中膜美洲商陆Cd富集量.根系分泌的可溶性还原糖含量、叶及根部合成的可溶性蛋白含量与根表铁锰氧化胶膜的厚度成正相关.中膜和高膜美洲商陆叶片及根部可溶性蛋白含量还受到不同金属组合胁迫的影响.镉铅复合胁迫使美洲商陆叶片及根部可溶性蛋白含量极显著高于对照组.

Effects of iron-manganese plaque thickness on Cd accumulation in Phytolacca americana under Cd-Pb combined stress

In this study, the effect of iron-manganese plaque amounts on Cd accumulation in Phytolacca americana under Pb-Cd combined stress was investigated with various physio-biochemical parameters (growth conditions, Cd accumulation and the expression levels of stress resistant physiological activator). Results indicated that P. americana with middle plaque and thick plaque had developed lateral roots and more new roots. High Cd concentration significantly inhibited the root elongation. Cd accumulation in P. americana at high Cd concentration was in the order:thick plaque>middle plaque>thin plaque. The accumulation of Cd in P. americana with thick plaque could reach 89765.69 mg·kg^-1. With low Cd concentration, Cd accumulation decreased in the order:thin plaque> thick plaque> middle plaque. High Pb concentration could improve Cd concentration in P. americana with thin plaque and thick plaque, but significantly decreased Cd accumulation in P. americana with middle plaque. Soluble sugar from roots and soluble protein from both roots and leaves were positively correlated with iron-manganese plaque amounts. Soluble protein from both roots and leaves of P. americana with middle plaque and thick plaque also had positive correlation with the combined stress of different metals. Furthermore, under Pb-Cd combined stress, the soluble protein contents in roots and leaves of P. americana were higher than those in the control group.