砷超富集植物蜈蚣草中高效的砷酸盐还原由新型砷酸盐还原酶PvHAC1和PvHAC2介导。

Efficient arsenate reduction in As-hyperaccumulator Pteris vittata are mediated by novel arsenate reductases PvHAC1 and PvHAC2.

作者信息

Li Xinyuan, Sun Dan, Feng Huayuan, Chen Junxiu, Chen Yanshan, Li Hongbo, Cao Yue, Ma Lena Q

机构信息

State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.

School of the Environment, Nanjing Normal University, Nanjing, Jiangsu 210023, China.

出版信息

J Hazard Mater. 2020 Nov 15;399:122895. doi: 10.1016/j.jhazmat.2020.122895. Epub 2020 May 15.

DOI:10.1016/j.jhazmat.2020.122895

Abstract

Arsenic-hyperaccumulator Pteris vittata is efficient in As absorption, reduction, and translocation. But the molecular mechanisms and locations of arsenate (AsV) reduction in P. vittata are still unclear. Here, we identified two new arsenate reductase genes from P. vittata, PvHAC1 and PvHAC2. Two PvHAC genes encoded a rhodanase-like protein, which were localized in the cytoplasm and nucleus. Both recombinant Escherichia coli strains and transgenic Arabidopsis thaliana lines showed arsenate reductase ability after expressing PvHAC genes. Further, expressing PvHAC2 enhanced As tolerance and reduced As accumulation in A. thaliana shoots under AsV exposure. Based on expression pattern analysis, PvHAC1 and PvHAC2 were predominantly expressed in the rhizomes and fronds of P. vittata. Different from those of HAC homologous genes in non-hyperaccumulators, little PvHAC was expressed in the roots. Besides, PvHAC1 expression was strongly upregulated under AsV exposure but not AsIII. The data suggest that arsenate reductase PvHAC1 in the rhizomes coupled with arsenate reductase PvHAC2 in the fronds of P. vittata played a critical role in As-hyperaccumulation by P. vittata, which helps to further improve its utility in phytoremediation of As-contaminated soils.

摘要

砷超富集植物蜈蚣草在砷的吸收、还原和转运方面效率很高。但蜈蚣草中砷酸盐（AsV）还原的分子机制和位置仍不清楚。在此，我们从蜈蚣草中鉴定出两个新的砷酸盐还原酶基因，PvHAC1和PvHAC2。两个PvHAC基因编码一种类硫氰酸酶蛋白，定位于细胞质和细胞核中。表达PvHAC基因后，重组大肠杆菌菌株和转基因拟南芥株系均表现出砷酸盐还原酶活性。此外，在AsV暴露下，表达PvHAC2可增强拟南芥的耐砷性并减少其地上部的砷积累。基于表达模式分析，PvHAC1和PvHAC2主要在蜈蚣草的根茎和叶片中表达。与非超富集植物中HAC同源基因不同的是，PvHAC在根中的表达量很少。此外，PvHAC1的表达在AsV暴露下强烈上调，但在AsIII暴露下没有上调。这些数据表明，蜈蚣草根茎中的砷酸盐还原酶PvHAC1与叶片中的砷酸盐还原酶PvHAC2在蜈蚣草的砷超积累中起关键作用，这有助于进一步提高其在砷污染土壤植物修复中的应用价值。