Abstract The Nitrate Transporter1/Peptide Transporter family member NPF7.3/NRT1.5 is responsible for long-distance transport of NO3− and involved in affecting salt and drought tolerance in plants. However, current studies have only focused on AtNRT1.5 from the stress-sensitive glycophyte Arabidopsis. In this study, the function of the NRT1.5 homolog ZxNRT1.5 from the typical xerophyte Zygophyllum xanthoxylum in ion transport and plants’ salt and drought tolerance was analyzed. The results indicated that ZxNRT1.5 was mainly expressed in the root stele, and its expression level was significantly induced by salt treatments and osmotic stress. Overexpression of ZxNRT1.5 in Arabidopsis showed that ZxNRT1.5 mediated root-to-shoot NO3− transport and contributed to enhancing NO3− uptake. Overexpression of ZxNRT1.5 increased Na+ accumulation by decreasing the expression of AtHKT1;1 in roots, and promoted root-to-shoot transport of K+ probably by changing polarization of cell membrane under salt stress. Meanwhile, ZxNRT1.5-overexpressing lines exhibited stronger tolerance to mannitol-induced osmotic stress, resulted from an increased accumulation of NO3− and the accumulation of a small quantity of Na+ that was beneficial for plant growth. These findings suggest that ZxNRT1.5 is not only essential for long-distance transport and accumulation of NO3−, but also involved in regulating Na+ and K+ transport, thereby modulating salt and drought tolerance.

中文翻译：

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来自旱生植物 Zygophyllum xanthoxylum 的 ZxNPF7.3/NRT1.5 通过调节 NO3-、Na+ 和 K+ 转运来调节耐盐性和耐旱性

摘要 硝酸盐转运蛋白 1/肽转运蛋白家族成员 NPF7.3/NRT1.5 负责 NO3− 的长距离转运，并影响植物的耐盐性和耐旱性。然而，目前的研究仅集中于来自胁迫敏感糖植物拟南芥的 AtNRT1.5。本研究分析了典型旱生植物 Zygophyllum xanthoxylum 的 NRT1.5 同源物 ZxNRT1.5 在离子转运和植物耐盐耐旱方面的作用。结果表明ZxNRT1.5主要在根柱中表达，其表达水平受盐处理和渗透胁迫显着诱导。ZxNRT1.5 在拟南芥中的过表达表明 ZxNRT1.5 介导了根到茎的 NO3− 转运并有助于增强 NO3− 吸收。ZxNRT1 的过度表达。5 通过降低根中 AtHKT1;1 的表达增加 Na+ 的积累，并可能通过改变盐胁迫下细胞膜的极化来促进 K+ 的根向地上部转运。同时，过表达ZxNRT1.5的株系对甘露醇诱导的渗透胁迫表现出更强的耐受性，这是由于NO3-的积累增加和少量有利于植物生长的Na+的积累所致。这些发现表明，ZxNRT1.5 不仅对 NO3− 的长距离运输和积累至关重要，而且还参与调节 Na+ 和 K+ 的运输，从而调节耐盐性和耐旱性。5-过表达株系对甘露醇诱导的渗透胁迫表现出更强的耐受性，这是由于NO3-的积累增加和少量有利于植物生长的Na+的积累。这些发现表明，ZxNRT1.5 不仅对 NO3− 的长距离运输和积累至关重要，而且还参与调节 Na+ 和 K+ 的运输，从而调节耐盐性和耐旱性。5-过表达株系对甘露醇诱导的渗透胁迫表现出更强的耐受性，这是由于NO3-的积累增加和少量有利于植物生长的Na+的积累。这些发现表明，ZxNRT1.5 不仅对 NO3− 的长距离运输和积累至关重要，而且还参与调节 Na+ 和 K+ 的运输，从而调节耐盐性和耐旱性。