Studies on the heavy-metal tolerance and interactions between several metal-binding ligands in plants exposed to complex pollution conditions.

在目前的研究中，我们研究了植物在复杂条件下的重金属耐受性及其与金属结合配体相互作用的可能机制。我们发现(1)在番茄细胞中，植物螯合素(PC)的形成和积累参与了耐重金属特性的表达。在解毒机制上，Cd能强烈促进所需的PC-Cd络合物的形成，而其他元素如铜、As、B等则抑制其形成。(2)Cd和As的转运与文献中发现的PC、GSH等硫醇肽有关。然而，它们的转运会受到有机酸和一些无机物质(如硼酸盐)的显著影响。在不同金属和阴离子混合的条件下，它们从根到地上部的运输速率有很大的不同(例如，Cd和Zn的运输速度比Cd或As快得多，但其运输方式与某些有机配体有关)。在这里，硼酸盐促进Cd的运输，但抑制As向地上部的运输。(3)其他主要的一价和/或二价金属离子揭示了植物体内其他独特的与配体一起运输和再分配的机制，这些都为未来的研究提供了新的前景。

In the present studies, we examined the possible mechanisms for the heavy-metal tolerance and interactions with metal-binding ligands in plants exposed to complex conditions. We found(1) In tomato cells, phytochelatin (PC) formation and accumulation are involved in the expression of the heavy-metal tolerance characteristics. For the detoxification mechanism, required formation of the PC-complex can be strongly facilitated with Cd but inhibited by other elements such as Cu,As and B, which are not incorporated in the former PC-Cd complex.(2) Transports of Cd and As have been associated with the thiol peptides such as PCs and GSH in literatures. However, their transports can be significantly affected by organic acids and some inorganic such as borate. Under conditions where different metals and anions are mixed in medium, their transport rates from roots to shoots are very different (e.g. Cd and Zn are much faster than Cu or As, but in a manner which is correlated with some organic ligands).Here, borate facilitates the Cd transport but inhibits As transport to shoot.(3) Other major mono- and/or divalent metal ions reveal other unique mechanisms for transport and redistribution with ligands in plants, which taken together present new prospects in futurestudy.