School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, PR China.
School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, PR China.
Chemosphere. 2021 Aug;276:130186. doi: 10.1016/j.chemosphere.2021.130186. Epub 2021 Mar 9.
Phytoexcretion is a novel strategy to remediate cadmium (Cd) pollution by leaf excretion in tall fescue (Festuca arundinacea), which involves the processes of Cd leaf excretion, root-to-leaf translocation, and root uptake. A hydroponic experiment was designed to investigate a series of 11 zinc (Zn) concentrations on Cd leaf excretion in tall fescue under 75 μM Cd stress. The results showed that the promotions of Zn on Cd leaf excretion, root-to-leaf translocation, and leaf accumulation were concentration-dependent in tall fescue. Zn treatments at 90 and 135 μM resulted in the highest Cd leaf excretion with 118.1 and 123.6 mg/kg of Cd excretion amount and 27.0 and 26.6% of excretion ratio, which were 2.6 and 2.7 fold of the control (15 μM of Zn), respectively. Cd leaf excretion was decreased when Zn treatments reached 180 μM, which could be toxic to plants as indicated by the decline of plant biomass. Zn also promoted leaf Cd accumulation and Cd translocation from roots to leaves and reached the highest at 90 and 180 μM respectively. Root Cd accumulation decreased with the increase of Zn concentrations, but the total plant Cd uptake did not decrease significantly until Zn concentration reached 90 μM. Our results indicate that 90 μM of Zn treatment can be served as the threshold to promote Cd leaf excretion and improve the efficiency of Cd phytoexcretion in tall fescue.
植物排泄是一种通过叶片排泄将镉（Cd）污染修复的新策略，它涉及 Cd 叶片排泄、根到叶的转运和根吸收的过程。本研究设计了一个水培实验，以研究在 75 μM Cd 胁迫下，一系列 11 种锌（Zn）浓度对高羊茅（Festuca arundinacea）叶片排泄 Cd 的影响。结果表明，Zn 对 Cd 叶片排泄、根到叶的转运和叶片积累的促进作用在高羊茅中均表现出浓度依赖性。90 和 135 μM 的 Zn 处理导致 Cd 叶片排泄量最高，分别为 118.1 和 123.6 mg/kg 的 Cd 排泄量和 27.0 和 26.6%的排泄比，分别为对照（15 μM 的 Zn）的 2.6 和 2.7 倍。当 Zn 处理达到 180 μM 时，Cd 叶片排泄减少，这可能对植物有毒，因为植物生物量下降。Zn 还促进了 Cd 在叶片中的积累和从根部向叶片的转运，在 90 和 180 μM 时达到最高。随着 Zn 浓度的增加，根 Cd 积累减少，但总植物 Cd 吸收在 Zn 浓度达到 90 μM 之前没有显著下降。我们的结果表明，90 μM 的 Zn 处理可以作为促进 Cd 叶片排泄和提高高羊茅 Cd 植物排泄效率的阈值。
