Li Bo, Qiu Jiaen, Jayakannan Maheswari, Xu Bo, Li Yuan, Mayo Gwenda M, Tester Mark, Gilliham Matthew, Roy Stuart J
Australian Centre for Plant Functional GenomicsAdelaide, SA, Australia; School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia; Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and TechnologyThuwal, Saudi Arabia.
School of Agriculture, Food and Wine, Waite Research Institute, University of AdelaideAdelaide, SA, Australia; ARC Centre of Excellence in Plant Energy BiologyAdelaide, SA, Australia.
Front Plant Sci. 2017 Jan 5;7:2013. doi: 10.3389/fpls.2016.02013. eCollection 2016.
The accumulation of high concentrations of chloride (Cl) in leaves can adversely affect plant growth. When comparing different varieties of the same Cl sensitive plant species those that exclude relatively more Cl from their shoots tend to perform better under saline conditions; however, the molecular mechanisms involved in maintaining low shoot Cl remain largely undefined. Recently, it was shown that the NRT1/PTR Family 2.4 protein (NPF2.4) loads Cl into the root xylem, which affects the accumulation of Cl in Arabidopsis shoots. Here we characterize NPF2.5, which is the closest homolog to NPF2.4 sharing 83.2% identity at the amino acid level. is predominantly expressed in root cortical cells and its transcription is induced by salt. Functional characterisation of NPF2.5 via its heterologous expression in yeast () and oocytes indicated that NPF2.5 is likely to encode a Cl permeable transporter. Arabidopsis T-DNA knockout mutant plants exhibited a significantly lower Cl efflux from roots, and a greater Cl accumulation in shoots compared to salt-treated Col-0 wild-type plants. At the same time, [Formula: see text] content in the shoot remained unaffected. Accumulation of Cl in the shoot increased following (1) amiRNA-induced knockdown of transcript abundance in the root, and (2) constitutive over-expression of . We suggest that both these findings are consistent with a role for NPF2.5 in modulating Cl transport. Based on these results, we propose that NPF2.5 functions as a pathway for Cl efflux from the root, contributing to exclusion of Cl from the shoot of Arabidopsis.
叶片中高浓度氯离子（Cl）的积累会对植物生长产生不利影响。在比较同一对Cl敏感植物物种的不同品种时，那些从地上部排除相对较多Cl的品种在盐胁迫条件下往往表现更好；然而，维持地上部低Cl含量所涉及的分子机制仍 largely undefined。最近的研究表明，NRT1/PTR家族2.4蛋白（NPF2.4）将Cl加载到根木质部中，这会影响拟南芥地上部Cl的积累。在这里，我们对NPF2.5进行了表征，它是与NPF2.4最接近的同源物，在氨基酸水平上具有83.2%的同一性。NPF2.5主要在根皮层细胞中表达，其转录受盐诱导。通过在酵母（）和卵母细胞中的异源表达对NPF2.5进行功能表征表明，NPF2.5可能编码一种Cl通透转运体。与盐处理的Col-0野生型植物相比，拟南芥T-DNA敲除突变体植株根部的Cl外流显著降低，地上部的Cl积累更多。与此同时，地上部的[公式：见文本]含量不受影响。在（1）amiRNA诱导根中[转录本丰度降低和（2）[的组成型过表达后，地上部Cl的积累增加。我们认为这两个发现都与NPF2.5在调节Cl转运中的作用一致。基于这些结果，我们提出NPF2.5作为Cl从根中流出的途径，有助于拟南芥地上部排除Cl。
