School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, PR China; Zhuhai College of Jilin University, Zhuhai, Guangdong, 519041, PR China.
Shanghai Administrative & Directive Station for Afforestation, Shanghai, 200020, PR China.
Chemosphere. 2018 Dec;212:124-132. doi: 10.1016/j.chemosphere.2018.08.072. Epub 2018 Aug 17.
Phytoextraction efficiency of cadmium (Cd) contaminated soil mainly depended upon the mechanism of plants in absorption, translocation, distribution, and detoxification of Cd. A pot experiment was designed to investigate Cd distribution and accumulation among the different leaves of tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis) and its regulation by Nitrilotriacetic acid (NTA), a biodegradable chelating agent. The results showed that Cd concentrations in the senescent and dead leaves were 3.2 and 5.3 fold of that in the emerging leaves of tall fescue, and 19.3 and 25.1 fold of that in the emerging leaves of Kentucky bluegrass, respectively. The lower Cd concentrations were maintained in the emerging and mature leaves to avoid Cd toxicity. In the emerging and mature leaves, Cd was mainly accumulated in the vascular bundles and epidermis. No Cd dithizonate color was observed in the mesophyll tissues of Kentucky bluegrass and only minor Cd was observed in the mesophyll tissues of tall fescue. In the senescent leaves, Cd dithizonate complexes were located in the protoplasts and cell walls of all leaf tissues. NTA greatly promoted Cd translocation and distribution to the senescent and dead leaves of tall fescue, but no significant effect was observed in Kentucky bluegrass. Our results indicate that a young leaf protection mechanism might be involved in their Cd hypertolerance. The Cd preferential accumulation could lead a novel phytoextraction strategy by the continuously harvesting the senescent and dead leaves of tall fescue and Kentucky bluegrass.
植物提取受污染土壤中的镉（Cd）的效率主要取决于植物在吸收、转运、分配和解毒 Cd 方面的机制。本研究采用盆栽实验，研究了氮三乙酸（NTA）作为一种可生物降解的螯合剂，对高羊茅（Festuca arundinacea）和草地早熟禾（Poa pratensis）不同叶片中 Cd 的分布和积累及其调控机制。结果表明，高羊茅衰老和死亡叶片中的 Cd 浓度分别为新生叶片的 3.2 和 5.3 倍，草地早熟禾衰老和死亡叶片中的 Cd 浓度分别为新生叶片的 19.3 和 25.1 倍。新生和成熟叶片中维持较低的 Cd 浓度，以避免 Cd 毒性。在新生和成熟叶片中，Cd 主要积累在维管束和表皮中。在草地早熟禾的叶肉组织中未观察到二硫代氨基甲酸盐的颜色，而在高羊茅的叶肉组织中仅观察到少量 Cd。在衰老叶片中，Cd 二硫代氨基甲酸盐复合物位于所有叶片组织的原生质体和细胞壁中。NTA 极大地促进了 Cd 向高羊茅衰老和死亡叶片的转运和分布，但对草地早熟禾没有显著影响。研究结果表明，高羊茅可能存在一种年轻叶片保护机制来应对 Cd 毒害。Cd 的优先积累可以通过不断收获高羊茅和草地早熟禾的衰老和死亡叶片，提出一种新的植物提取策略。
