Department of Public Health, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan.
Sci Rep. 2019 Mar 13;9(1):4347. doi: 10.1038/s41598-019-40671-x.
For mercury phytoextraction, we previously demonstrated in Arabidopsis thaliana that a constitutive and ubiquitous promoter-driven expression of a bacterial mercury transporter MerC fused with SYP121, a plant SNARE for plasma membrane protein trafficking increases plant mercury accumulation. To advance regulation of ectopic expression of the bacterial transporter in the plant system, the present study examined whether merC-SYP121 expression driven by a root epidermis specific promoter (pEpi) is sufficient to enhance mercury accumulation in plant tissues. We generated five independent transgenic Arabidopsis plant lines (hereafter pEpi lines) expressing a transgene encoding MerC-SYP121 N-terminally tagged with a fluorescent protein mTRQ2 under the control of pEpi, a root epidermal promoter. Confocal microscopy analysis of the pEpi lines showed that mTRQ2-MerC-SYP121 was preferentially expressed in lateral root cap in the root meristematic zone and epidermal cells in the elongation zone of the roots. Mercury accumulation in shoots of the pEpi lines exposed to inorganic mercury was overall higher than the wild-type and comparable to the over-expressing line. The results suggest that cell-type specific expression of the bacterial transporter MerC in plant roots sufficiently enhances mercury accumulation in shoots, which could be a useful phenotype for improving efficiency of mercury phytoremediation.
对于汞的植物提取，我们之前在拟南芥中证明，通过组成型和普遍的启动子驱动表达与 SYP121 融合的细菌汞转运蛋白 MerC，一种用于质膜蛋白运输的植物 SNARE，可以增加植物的汞积累。为了在植物系统中进一步调节细菌转运体的异位表达，本研究检查了由根表皮特异性启动子（pEpi）驱动的 merC-SYP121 表达是否足以增强植物组织中的汞积累。我们生成了五个独立的转基因拟南芥植物系（以下简称 pEpi 系），在 pEpi 的控制下表达了一种编码 MerC-SYP121 的转基因，该基因的 N 端标记有荧光蛋白 mTRQ2，pEpi 是一种根表皮启动子。对 pEpi 系的共焦显微镜分析表明，mTRQ2-MerC-SYP121 优先在根分生区的侧根帽和根伸长区的表皮细胞中表达。暴露于无机汞的 pEpi 系的地上部分汞积累总体上高于野生型，与过表达系相当。结果表明，细菌转运体 MerC 在植物根系中的细胞特异性表达足以增强地上部分的汞积累，这可能是提高汞植物修复效率的有用表型。
