Plant salt tolerance relies on a coordinated functioning of different tissues and organs. Salinity tissue tolerance is one of the key traits that confer plant adaptation to saline environment. This trait implies maintenance low cytosolic Na⁺/K⁺ ratio in metabolically active cellular compartments. In this study, we used Nitraria sibirica Pall., a perennial woody halophyte species, to understand the mechanistic basis of its salinity tissue tolerance. The results showed that the growth of seedlings was stimulated by 100–200 mM NaCl treatment. The ions distribution analysis showed that the leaves act as an Na⁺ sink, while the plant roots possess superior K⁺ retention. The excessive Na⁺ absorbed from the soil was mainly transported to the shoot and was eventuallysequestrated into mesophyll vacuoles in the leaves. As a result, N. sibirica could keep the optimal balance of K⁺/Na⁺ at a tissue- and cell-specific level under saline condition. To enable this, N. sibirica increased both vacuolar H⁺-ATPase and H⁺-PPase enzymes activities and up-regulated the expressions of NsVHA, NsVP1 and NsNHX1 genes. Vacuolar Na⁺ sequestration in the leaf mesophyll, mediated by NsVHA, NsVP1 and NsNHX1, reduced the Na⁺ concentration in cytosol and inhibited further K⁺ loss. Meanwhile, N. sibirica enhanced the Two Pore K⁺ expression at the transcriptional level to promote K⁺ efflux from vacuole into cytoplasm, assisting in maintaining cytosolic K⁺ homeostasis. It is concluded that the tissue tolerance traits such as vacuolar Na⁺ sequestration and intracellular K⁺ homeostasis are critical to confer adaptation of N. sibirica to soil salinity.

中文翻译：

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赋予多年生盐生物种 Nitraria sibirica Pall 耐盐性的组织耐受机制。

植物耐盐性依赖于不同组织和器官的协调功能。盐度组织耐受性是赋予植物适应盐度环境的关键特征之一。这种特性意味着在代谢活跃的细胞区室中维持低的胞质 Na ⁺ /K ⁺比率。在这项研究中，我们使用了多年生木本盐生植物Nitraria sibirica Pall. 来了解其组织耐盐性的机制基础。结果表明，100-200 mM NaCl 处理刺激了幼苗的生长。离子分布分析表明，叶子充当Na ⁺汇，而植物根部具有优异的K ⁺保留。过量的 Na ⁺从土壤中吸收的主要是运输到枝条，最终被隔离在叶子中的叶肉液泡中。因此，在盐水条件下，西伯利亚猪笼草可以在组织和细胞特异性水平上保持 K ⁺ /Na ⁺的最佳平衡。为了实现这一点，N. sibirica增加了液泡 H ⁺ -ATPase 和 H ⁺ -PPase 酶的活性，并上调了NsVHA、NsVP1和NsNHX1基因的表达。由NsVHA、NsVP1和NsNHX1介导的叶肉液泡 Na ⁺螯合，降低细胞质中的 Na ⁺浓度并进一步抑制 K ⁺损失。同时，N. sibirica在转录水平上增强了两个孔 K ^{+ 的}表达，以促进 K ⁺从液泡流出到细胞质中，协助维持细胞质 K ⁺稳态。得出的结论是，组织耐受性特征，例如液泡 Na ⁺螯合和细胞内 K ⁺稳态，对于赋予西伯利亚对土壤盐度的适应性至关重要。