Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resource Science, Zhejiang University, Hangzhou, 310058, China.
Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou, 310058, China.
Environ Pollut. 2021 Jun 1;278:116837. doi: 10.1016/j.envpol.2021.116837. Epub 2021 Mar 2.
Sedum alfredii is a Cd/Zn hyperaccumulator native to China, which was collected from a mined area where Mn content in soil was extremely high, together with Zn and Cd content. We investigated the tolerance and accumulation ability of Mn and its possible association with Cd hyperaccumulation in this plant species by using MP-AES, SR-μ-XRF, and RT-PCR. The results showed that the hyperaccumulating ecotype (HE) S. alfredii exhibited high tolerance to Mn and accumulating around 10,000 and 12,000 mg kg Mn in roots and shoots, respectively, without exhibiting toxicity under 5000 mg kg Mn treatment for 4 weeks. Exposure to Cd significantly reduced plant uptake of Mn. In contrast, exogenous Mn application significantly improved root uptake and root-to-shoot translocation of Cd, resulting in the increased Cd accumulation in the shoots of HE S. alfredii. SR-μ-XRF analysis demonstrated that high Mn (20 μM) exposure resulted in higher intensities of Cd localized in both stem vascular bundles and cortex, as well as leaf mesophyll cells, than in those treated with low Mn levels (0.2 μM or 2.0 μM). RT-PCR analysis of several genes possibly involved in Mn/Cd transportation showed that expression of SaNramp3 in roots was significantly reduced under high Mn exposure. These results suggested a significant interaction between Cd and Mn in the HE S. alfredii plants, possibly through their competition for transporters and theoretically provided a strategy to improve the efficiency of Cd extraction from polluted soils by this plant species, after using appropriate nutrient management of Mn.
Sedum alfredii 是一种原产于中国的 Cd/Zn 超积累植物，它是从一个矿区采集的，那里的土壤中 Mn 含量极高，同时还有 Zn 和 Cd 含量。我们通过使用 MP-AES、SR-μ-XRF 和 RT-PCR 研究了该植物物种对 Mn 的耐受性和积累能力，以及 Mn 与 Cd 超积累之间的可能联系。结果表明，超积累生态型（HE）Sedum alfredii 对 Mn 具有高耐受性，在 5000mg/kg Mn 处理 4 周后，根和地上部分分别积累约 10000 和 12000mg/kg Mn，而没有表现出毒性。Cd 的暴露显著降低了植物对 Mn 的吸收。相比之下，外源 Mn 的应用显著提高了 Cd 的根吸收和根到地上部分的转运，导致 HE Sedum alfredii 地上部分 Cd 积累增加。SR-μ-XRF 分析表明，高 Mn（20μM）暴露导致 Cd 在茎维管束和皮层以及叶肉细胞中的定位强度高于低 Mn 水平（0.2μM 或 2.0μM）。对几种可能参与 Mn/Cd 转运的基因的 RT-PCR 分析表明，SaNramp3 在根部的表达在高 Mn 暴露下显著降低。这些结果表明，在 HE Sedum alfredii 植物中，Cd 和 Mn 之间存在显著的相互作用，可能是通过它们对转运蛋白的竞争，从理论上为提高该植物物种从污染土壤中提取 Cd 的效率提供了一种策略，即在适当的 Mn 营养管理后。
