Abstract

The tolerance of plants to Cd is a scientific and interesting issue for phytoremediation. In the current study, we attempt to reveal the physiological mechanism of the tolerance of Eichhornia crassipes to cadmium (Cd) by using hydroponic experiments. The results showed that the Cd absorption of E. crassipes was dose-dependent and the absorbed Cd was mainly maintained in the root. The fresh weight was greatly affected by Cd in the early stage of aquatic cultivation. The negative effect of Cd on E. crassipes is dose-dependent, but E. crassipes might adapt to moderate Cd pollution over time. The Cd stimulated the opening of the stomata, and the cell tightness ratio of E. crassipes increased with rising Cd concentrations. The administration of moderate levels of Cd stimulated the release of soluble protein, free proline, malondialdehyde, and soluble polysaccharide. Cd administration also stimulated the activity of superoxide dismutase, peroxidase (POD), catalase, and ascorbic acid peroxidase of E. crassipes, except for POD activity at the highest Cd concentration. This indicates that the physiological mechanism of the tolerance of E. crassipes to Cd depends on osmotic regulation, reduction of lipid peroxidation, improvement of antioxidant properties, increasing palisade tissue while decreasing sponge tissue, and increasing stomatal conductance.

摘要

植物对 Cd 的耐受性是植物修复的一个科学和有趣的问题。在目前的研究中，我们试图通过水培实验揭示凤眼莲对镉（Cd）耐受的生理机制。结果表明，凤尾莲对Cd的吸收呈剂量依赖性，吸收的Cd主要维持在根部。水产养殖初期鲜重受镉影响较大。Cd 对E. crassipes的负面影响是剂量依赖性的，但E. crassipes可能会随着时间的推移适应适度的 Cd 污染。Cd刺激气孔张开，E. crassipes的细胞紧密度比随着 Cd 浓度的增加而增加。适量 Cd 的给药刺激了可溶性蛋白质、游离脯氨酸、丙二醛和可溶性多糖的释放。除了在最高 Cd 浓度下的 POD 活性外，施用 Cd 还刺激了E. crassipes的超氧化物歧化酶、过氧化物酶 (POD)、过氧化氢酶和抗坏血酸过氧化物酶的活性。这表明凤梨对Cd耐受的生理机制取决于渗透调节、脂质过氧化的减少、抗氧化性能的改善、增加栅栏组织同时减少海绵组织和增加气孔导度。