Plant ZIP genes represent an important transporter family and may be involved in cadmium (Cd) accumulation and Cd resistance. In order to explore the function of SmZIP isolated from Salix matsudana, the roles of SmZIP in Cd tolerance, uptake, translocation, and distribution were determined in the present investigation. The transgenic SmZIP tobacco was found to respond to external Cd stress differently from WT tobacco by exhibiting a higher growth rate and more vigorous phenotype. The overexpression of SmZIP in tobacco resulted in the reduction of Cd stress-induced phytotoxic effects. Compared to WT tobacco, the Cd content of the root, stem, and leaf in the transgenic tobacco increased, and the zinc, iron, copper, and manganese contents also increased. The assimilation factor, translocation factor and bioconcentration factor of Cd were improved. The scanning electron microscopy and energy dispersive X-ray analysis results of the root maturation zone exposed to Cd for 24 h showed that Cd was transferred through the root epidermis, cortex, and vascular cylinder and migrated to the aboveground parts via the vascular cylinder, resulting in the transgenic tobacco accumulating more Cd than the WT plants. Based on the transverse section of the leaf main vein and leaf blade, Cd was transported through the vascular tissues to the leaves and accumulated more greatly in the leaf epidermis, but less in the leaf mesophyll cells, following the overexpression of SmZIP to reduce the photosynthetic toxicity. The overexpression of SmZIP resulted in the redistribution of Cd at the subcellular level, a decrease in the percentage of Cd in the cell wall, and an increase of the Cd in the soluble fraction in both the roots and leaves. It also changed the percentage composition of different Cd chemical forms by elevating the proportion of Cd extracted using 2% HAc and 0.6 mol/L HCl, but lowering that of the Cd extracted using 1 mol/L NaCl in both the leaves and roots under 10 and 100 μmol/L Cd stress for 28 d. The results implied that SmZIP played important roles in advancing Cd uptake, accumulation, and translocation, as well as in enhancing Cd resistance by altering the Cd subcellular distribution and chemical forms in the transgenic tobacco. The study will be useful for future phytoremediation applications to clean up Cd-contaminated soil.

植物 ZIP 基因代表一个重要的转运蛋白家族，可能参与镉 (Cd) 积累和镉抗性。为了探索从松柳中分离出的SmZIP的功能，本研究确定了SmZIP在Cd耐受、吸收、易位和分布中的作用。研究发现，转基因SmZIP烟草对外部镉胁迫的反应与野生型烟草不同，表现出更高的生长速率和更有活力的表型。烟草中SmZIP的过度表达导致镉胁迫诱导的植物毒性作用减少。与WT烟草相比，转基因烟草根、茎、叶的Cd含量增加，锌、铁、铜、锰含量也增加。提高了Cd的同化因子、转运因子和生物富集因子。 Cd暴露24 h根成熟区的扫描电镜和能量色散X射线分析结果表明，Cd通过根表皮、皮层和维管柱迁移，并通过维管柱迁移到地上部分，导致转基因烟草比野生型烟草积累了更多的镉。从叶片主脉和叶片横切面来看，随着SmZIP过表达导致光合作用降低，Cd通过维管组织转运至叶片，在叶片表皮积累较多，而在叶片叶肉细胞积累较少。毒性。 SmZIP的过表达导致Cd在亚细胞水平上的重新分配，细胞壁中Cd的百分比降低，以及根和叶中可溶性部分中Cd的增加。改变了不同Cd化学形态的百分组成，使叶和根中2%HAc和0.6mol/L HCl提取的Cd比例提高，而1mol/L NaCl提取的Cd比例降低到10以下。 100 μmol/L Cd 胁迫 28 d。结果表明， SmZIP在促进 Cd 吸收、积累和易位以及通过改变转基因烟草中 Cd 亚细胞分布和化学形式来增强 Cd 抗性方面发挥着重要作用。该研究将有助于未来的植物修复应用，以清理镉污染的土壤。