Abstract：
Cadmium (Cd) pollution of soil occurs worldwide. Phytoremediation is an effective approach for cleaning up Cd polluted soil. Fast growing Populus species with high Cd uptake capacities are desirable for phytoremediation. Thus, it is important to elucidate the molecular functions of genes involved in Cd uptake by poplars. In this study, PcPLAC8-10, a homolog of Human placenta-specific gene 8 (PLAC8) implicated in Cd transport was functionally characterized in Populus × canescens. PcPLAC8-10 was transcriptionally induced in Cd-treated roots and it encoded a plasma membrane-localized transporter. PcPLAC8-10 exhibited Cd uptake activity when expressed in yeast cells. No difference in growth was observed between wild type (WT) and PcPLAC8-10-overexpressing poplars. PcPLAC8-10-overexpressing poplars exhibited increases in net Cd2+ influxes by 192% and Cd accumulation by 57% in the roots. However, similar reductions in biomass were found in WT and transgenic poplars when exposed to Cd. The complete motif of CCXXXXCPC in PcPLAC8-10 was essential for its Cd transport activity. These results suggest that PcPLAC8-10 is a plasma membrane-localized transporter responsible for Cd uptake in the roots and the complete CCXXXXCPC motif of PcPLAC8-10 plays a key role in its Cd transport activity in poplars.
摘要：
土壤镉（Cd）污染在世界范围内普遍存在。植物修复是清除Cd污染土壤的有效途径。具有高Cd吸收能力的快速生长的杨树物种对于植物修复是理想的。因此，阐明杨树吸收Cd基因的分子功能非常重要。在这项研究中,PcPLAC8-10是与Cd转运有关的人类胎盘特异性基因8（PLAC8）的同源物，在杨树×canescens中具有功能特征。PcPLAC8-10在Cd处理的根中被转录诱导，并且编码质膜定位的转运蛋白。PcPLAC8-10在酵母细胞中表达时表现出Cd摄取活性。在野生型（WT）和过表达PcPLAC8-10的杨树之间没有观察到生长差异。过表达PcPLAC8-10的杨树在根部的净Cd2流入量增加了192％，Cd积累量增加了57％。然而,当暴露于Cd时，在WT和转基因杨树中发现了类似的生物量减少。PcPLAC8-10中CCXXXXCPC的完整基序对于其Cd运输活性至关重要。这些结果表明，PcPLAC8-10是质膜定位的转运蛋白，负责根中Cd的吸收，PcPLAC8-10的完整CCXXXXCPC基序在杨树中的Cd转运活性中起关键作用。
