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首页> 外文期刊>Journal of Experimental Botany >Root responses to cadmium in the rhizosphere: a review
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Root responses to cadmium in the rhizosphere: a review

机译：根际对镉的根响应：综述

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This article reviews the responses of plant roots to elevated rhizosphere cadmium (Cd) concentrations. Cadmium enters plants from the soil solution. It traverses the root through symplasmic or apoplasmic pathways before entering the xylem and being translocated to the shoot. Leaf Cd concentrations in excess of 5–10 μg g−1 dry matter are toxic to most plants, and plants have evolved mechanisms to limit Cd translocation to the shoot. Cadmium movement through the root symplasm is thought to be restricted by the production of phytochelatins and the sequestration of Cd-chelates in vacuoles. Apoplasmic movement of Cd to the xylem can be restricted by the development of the exodermis, endodermis, and other extracellular barriers. Increasing rhizosphere Cd concentrations increase Cd accumulation in the plant, especially in the root. The presence of Cd in the rhizosphere inhibits root elongation and influences root anatomy. Cadmium concentrations are greater in the root apoplasm than in the root symplasm, and tissue Cd concentrations decrease from peripheral to inner root tissues. This article reviews current knowledge of the proteins involved in the transport of Cd across root cell membranes and its detoxification through sequestration in root vacuoles. It describes the development of apoplastic barriers to Cd movement to the xylem and highlights recent experiments indicating that their maturation is accelerated by high Cd concentrations in their immediate locality. It concludes that accelerated maturation of the endodermis in response to local Cd availability is of functional significance in protecting the shoot from excessive Cd loads.
机译：本文回顾了植物根系对根际镉（Cd）浓度升高的响应。镉从土壤溶液进入植物。它在进入木质部并转移到枝条之前，通过同质或非质质途径穿越根部。超过5–10μgg −1 干物质的叶片中Cd浓度对大多数植物有毒，并且植物已经进化出限制Cd易位的新机制。镉通过根部同质体的运动被认为受植物螯合螯合物的产生和液泡中螯合镉螯合的限制。 Cd向木质部的无质运动可受外皮，内胚层和其他细胞外屏障的发展限制。根际Cd浓度的增加会增加Cd在植物中的积累，尤其是在根部。根际中Cd的存在会抑制根的伸长并影响根的解剖结构。根部无性质中的镉浓度比根部同质性高，并且组织Cd浓度从周围到内部根组织都降低。本文回顾了有关Cd跨根细胞膜运输及其通过隔离在根液泡中解毒的蛋白质的当前知识。它描述了Cd向木质部移动的质外性障碍的发展，并着重强调了最近的实验，表明它们的成熟被其附近局部高浓度的Cd所加速。结论是，响应于局部Cd的可用性，内胚层的加速成熟在保护芽免受过量Cd负荷的作用中具有重要的功能。

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