Nitrate-dependent shoot sodium accumulation and osmotic functions of sodium in Arabidopsis under saline conditions
Nitrate-dependent shoot sodium accumulation and osmotic functions of sodium in Arabidopsis under saline conditions
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DOI：
10.1111/tpj.13556
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发表时间：
2017-07-01
期刊：
影响因子：
7.2
通讯作者：
Rodriguez-Navarro, Alonso
中科院分区：
文献类型：
--
作者：
Alvarez-Aragon, Rocio;Rodriguez-Navarro, Alonso
提高农作物在盐碱地或盐水灌溉下的生产力，将是克服威胁世界人口的粮食和淡水危机的一项重要技术进步。然而，即使将糖生植物转化为在海水灌溉下繁衍生息的植物在生物学上是可行的，目前关于Na+效应的知识也不足以支持这一技术进步。有趣的是，关于 Na+ 吸收及其在植物中的功能的关键细节尚未明确。我们在此提出，在盐水条件下，两个串联的硝酸盐依赖性转运系统将Na+吸收并加载到木质部，构成了拟南芥芽中Na+积累的主要途径；该途径也可以与高浓度的氯化物一起发挥作用。在nrt1.1硝酸盐转运突变体中，植物Na+积累部分有缺陷，这表明NRT1.1部分介导或调节硝酸盐依赖性Na+转运。拟南芥植物暴露于-1.0 MPa (400 mOsm)渗透势24小时，在山梨醇或Na/MES中表现出高失水和枯萎，其中Na+无法积累。相比之下，在 NaCl 中，积累 Na+ 的植物损失少量水分，并且仅出现短暂的枯萎。我们讨论了在暴露于高 NaCl 浓度的拟南芥植物中，根部 Na+ 吸收和组织积累实现了渗透调节的主要功能，即使这些过程会导致长期毒性。 意义说明 获得耐 NaCl 作物是农业研究中的一个主要挑战。尽管进行了广泛的研究，但糖类植物对高氯化钠水平的重要反应尚未明确。特别是根部 Na+ 吸收和渗透压调节。我们发现，硝酸盐依赖性运输主导了芽中 Na+ 的积累，并且这种积累与渗透胁迫的缓解相关。我们讨论了目前的知识低估了盐水条件下糖生植物中 Na+ 的渗透功能。
Improving crop plants to be productive in saline soils or under irrigation with saline water would be an important technological advance in overcoming the food and freshwater crises that threaten the world population. However, even if the transformation of a glycophyte into a plant that thrives under seawater irrigation was biologically feasible, current knowledge about Na+ effects would be insufficient to support this technical advance. Intriguingly, crucial details about Na+ uptake and its function in the plant have not yet been well established. We here propose that under saline conditions two nitrate-dependent transport systems in series that take up and load Na+ into the xylem constitute the major pathway for the accumulation of Na+ in Arabidopsis shoots; this pathway can also function with chloride at high concentrations. In nrt1.1 nitrate transport mutants, plant Na+ accumulation was partially defective, which suggests that NRT1.1 either partially mediates or modulates the nitrate-dependent Na+ transport. Arabidopsis plants exposed to an osmotic potential of -1.0 MPa (400 mOsm) for 24h showed high water loss and wilting in sorbitol or Na/MES, where Na+ could not be accumulated. In contrast, in NaCl the plants that accumulated Na+ lost a low amount of water, and only suffered transitory wilting. We discuss that in Arabidopsis plants exposed to high NaCl concentrations, root Na+ uptake and tissue accumulation fulfil the primary function of osmotic adjustment, even if these processes lead to long-term toxicity.Significance Statement Obtaining NaCl tolerant crops is a major challenge in agricultural research. Although extensively investigated, important responses of glycophytes to high NaCl levels have not yet been well established; especially, root Na+ uptake and osmotic adjustments. We show that nitrate-dependent transport dominates Na+ accumulation in shoots and that this accumulation correlates with relief of the osmotic stress; we discuss that the current knowledge undervalues the osmotic function of Na+ in glycophytes under saline conditions.