Fan Wei, Liu Changying, Cao Boning, Qin Meiling, Long Dingpei, Xiang Zhonghuai, Zhao Aichun
State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
Front Plant Sci. 2018 Jun 29;9:879. doi: 10.3389/fpls.2018.00879. eCollection 2018.
The zinc-regulated transporters, iron-regulated transporter-like proteins (ZIPs), the natural resistance and macrophage proteins (NRAMP), the heavy metal ATPases (HMAs) and the metal tolerance or transporter proteins (MTPs) families are involved in cadmium (Cd) uptake, translocation and sequestration in plants. Mulberry ( L.), one of the most ecologically and economically important (as a food plant for silkworm production) genera of perennial trees, exhibits excellent potential for remediating Cd-contaminated soils. However, there is no detailed information about the genes involved in Cd transport in mulberry. In this study, we identified 31 genes based on a genome-wide analysis of the genome database. According to bioinformatics analysis, the four transporter gene families in were distributed in each group of the phylogenetic tree, and the gene exon/intron structure and protein motif structure were similar among members of the same group. Subcellular localization software predicted that these transporters were mainly distributed in the plasma membrane and the vacuolar membrane, with members of the same group exhibiting similar subcellular locations. Most of the gene promoters contained abiotic stress-related -elements. The expression patterns of these genes in different organs were determined, and the patterns identified, allowing the categorization of these genes into four groups. Under low or high-Cd concentrations (30 μM or 100 μM, respectively), the transcriptional regulation of the 31 genes in root, stem and leaf tissues of seedlings differed with regard to tissue and time of peak expression. Heterologous expression of , and in increased the sensitivity of yeast to Cd, suggested that these transporters had Cd transport activity. Subcellular localization experiment showed that the four transporters were localized to the plasma membrane of yeast and tobacco. These results provide the basis for further understanding of the Cd tolerance mechanism in , which can be exploited in Cd phytoremediation.
锌调节转运蛋白、铁调节转运蛋白样蛋白（ZIPs）、天然抗性相关巨噬细胞蛋白（NRAMP）、重金属ATP酶（HMAs）以及金属耐受性或转运蛋白（MTPs）家族参与植物对镉（Cd）的吸收、转运和螯合。桑树（桑属）是多年生树木中生态和经济价值最为重要的属之一（作为蚕生产的食物来源），在修复镉污染土壤方面具有巨大潜力。然而，关于桑树中参与镉转运的基因尚无详细信息。在本研究中，我们基于对桑树基因组数据库的全基因组分析鉴定出31个基因。通过生物信息学分析，桑树中的四个转运蛋白基因家族分布在系统发育树的各个组中，同一组的成员间基因外显子/内含子结构和蛋白质基序结构相似。亚细胞定位软件预测这些转运蛋白主要分布在质膜和液泡膜上，同一组的成员具有相似的亚细胞定位。大多数基因启动子含有非生物胁迫相关元件。我们测定了这些基因在不同器官中的表达模式，并据此将这些基因分为四组。在低镉或高镉浓度（分别为30 μM或100 μM）下，桑树幼苗根、茎和叶组织中31个基因的转录调控在组织和表达峰值时间方面存在差异。桑树的三个基因在酵母中的异源表达增加了酵母对镉的敏感性，表明这些转运蛋白具有镉转运活性。亚细胞定位实验表明这四个转运蛋白定位于酵母和烟草的质膜。这些结果为进一步了解桑树的耐镉机制提供了基础，可用于镉的植物修复。
