The mechanisms of the toxic effects of Cd and Pb on plant cell growth are still poorly understood. In particular, little is known about their interactive effects, which usually occur in the environment. Moreover, the data that do exist in the literature are controversial. This study describes experiments that were performed with maize (Zea mays) coleoptile segments, which is a classical model system for studies of plant cell elongation growth. Cadmium and lead, which were added at 0.1 mM, reduced the endogenous and IAA-induced elongation growth of maize coleoptile cells. When both metals were added together or in sequence, their effect on IAA-induced growth was more toxic. The medium pH changes, which were measured simultaneously with growth, indicated that while Pb stopped IAA-induced proton extrusion, Cd only partially diminished it. Although Cd was generally more accumulated than Pb in the maize coleoptile segments, when IAA was added together with Pb, it significantly increased the accumulation of the metal. The short-term electrophysiological experiments showed that the addition of Cd caused the depolarisation of the membrane potential (E_m), whereas Pb caused membrane hyperpolarisation. In the long-term electrophysiological experiments, it was found that the Cd-induced E_m changes are complex. In conclusion, these results suggest that the effects of Cd and Pb as well as their combination on the elongation growth of maize coleoptile cells and the accumulation of the metals result, among others, from different ionic mechanisms by which each metal change the membrane potential of the cells.

镉和铅对植物细胞生长的毒性作用机理仍然知之甚少。特别是，人们对它们通常在环境中发生的交互作用知之甚少。此外，文献中确实存在的数据存在争议。这项研究描述了使用玉米（Zea mays）进行的实验胚芽鞘片段，这是用于研究植物细胞伸长生长的经典模型系统。以0.1 mM添加的镉和铅减少了玉米胚芽鞘细胞内源性和IAA诱导的伸长生长。当两种金属一起添加或按顺序添加时，它们对IAA诱导的生长的毒性更大。在生长过程中同时测量的中等pH值变化表明，尽管Pb停止了IAA诱导的质子挤出，但Cd仅部分消除了它。尽管在玉米胚芽鞘部分，镉的累积量通常高于铅，但是当IAA与铅一起添加时，它会大大增加金属的累积量。短期电生理实验表明，添加Cd会引起膜电位（E _m），而铅则引起膜超极化。在长期的电生理实验中，发现镉诱导的E _m变化是复杂的。总之，这些结果表明，Cd和Pb以及它们的组合对玉米胚芽鞘细胞伸长生长和金属积累的影响，除其他外，是由不同的离子机理导致的，每种金属通过这些离子机理改变了膜电位。细胞。