Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 210037, China.
Faculty of Science and Department of Forest Resources Management, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Genes (Basel). 2022 Jul 23;13(8):1313. doi: 10.3390/genes13081313.
Potassium ion (K+) channels and transporters are key components of plant K+ absorption and transportation and play an important role in plant growth and development. This study revealed that K+ channels and transporters are involved in the salt tolerance molecular mechanism and metabolites of the halophyte representative plant Tamarix ramosissima (T. ramosissima) in response to NaCl stress, providing a theoretical basis for the mitigation of salt stress using halophytes. Through transcriptome sequencing and metabolite detection analysis of 0 h, 48 h and 168 h by applying exogenous K+ to the roots of T. ramosissima under NaCl stress, 15 high-quality Clean Data bases were obtained, Q20 reached more than 97%, Q30 reached more than 92%, and GC content reached 44.5%, which is in line with further bioinformatics analysis. Based on the Liquid chromatography−mass spectrometry (LC-MS) analysis, the roots of T. ramosissima were exposed to exogenous potassium for 48 h and 168 h under NaCl stress, and 1510 and 1124 metabolites were identified in positive and negative ion mode, respectively. Through orthogonal projections to latent structures discriminant analysis (OPLS-DA) model analysis, its metabolomic data have excellent predictability and stability. The results of this study showed that there were 37 differentially expressed genes (DEGs) annotated as Class 2 K+ channels (Shaker-like K+ channel and TPK channel) and Class 3 K+ transporters (HAK/KUP/KT, HKT and CPAs transporter families). Among them, 29 DEGs were annotated to the gene ontology (GO) database, and the most genes were involved in the GO Biological Process. In addition, the expression levels of Unigene0014342 in the HAK/KUP/KT transporter and Unigene0088276 and Unigene0103067 in the CPAs transporter both first decreased and then increased when treated with 200 mM NaCl for 48 h and 168 h. However, when treated with 200 mM NaCl + 10 mM KCl for 48 h and 168 h, a continuous upward trend was shown. Notably, the expression level of Unigene0016813 in CPAS transporter continued to increase when treated with 200 mM NaCl and 200 mM NaCl + 10 mM KCl for 48 h and 168 h. 3 DEGs, Unigene0088276, Unigene0016813 and Unigene0103067, were dominated by the positive regulation of their related metabolites, and this correlation was significant. The results showed that these DEGs increased the absorption of K+ and the ratio of K+/Na+ under NaCl stress at 48 h and 168 h after adding exogenous potassium and enhanced the salt tolerance of T. ramosissima. Notably, the expression level of Unigene0103067 in the CPAs transporter was consistently upregulated when 200 mM NaCl + 10 mM KCl was treated for 48 h and 168 h. The positive regulatory metabolites were always dominant, which better helped T. ramosissima resist salt stress. Unigene0103067 plays an important role in enhancing the salt tolerance of T. ramosissima and reducing the toxicity of NaCl in roots. Additionally, phylogenetic tree analysis showed that Unigene0103067 and Reaumuria trigyna had the closest genetic distance in the evolutionary relationship. Finally, 9 DEGs were randomly selected for quantitative real-time PCR (qRT-PCR) verification. Their expression trends were completely consistent with the transcriptome sequencing analysis results, proving that this study’s data are accurate and reliable. This study provides resources for revealing the molecular mechanism of NaCl stress tolerance in T. ramosissima and lays a theoretical foundation for cultivating new salt-tolerant varieties.
钾离子（K+）通道和转运蛋白是植物 K+吸收和运输的关键组成部分，在植物生长和发育中发挥着重要作用。本研究揭示了 K+通道和转运蛋白参与了盐生植物代表植物柽柳（Tamarix ramosissima）对 NaCl 胁迫的耐盐分子机制和代谢物，为利用盐生植物缓解盐胁迫提供了理论依据。通过对 NaCl 胁迫下柽柳根部施加外源 K+后 0 h、48 h 和 168 h 的转录组测序和代谢物检测分析，获得了 15 个高质量的 Clean Data 库，Q20 均超过 97%，Q30 均超过 92%，GC 含量达到 44.5%，符合进一步生物信息学分析的要求。基于液相色谱-质谱联用（LC-MS）分析，在 NaCl 胁迫下，柽柳根部施加外源钾 48 h 和 168 h，分别在正、负离子模式下鉴定出 1510 种和 1124 种代谢物。通过正交投影到潜在结构判别分析（OPLS-DA）模型分析，其代谢组学数据具有良好的预测性和稳定性。研究结果表明，有 37 个差异表达基因（DEGs）被注释为类 2 K+通道（Shaker-like K+通道和 TPK 通道）和类 3 K+转运蛋白（HAK/KUP/KT、HKT 和 CPAs 转运家族）。其中，29 个 DEGs 被注释到基因本体（GO）数据库，大多数基因参与 GO 生物过程。此外，在 HAK/KUP/KT 转运蛋白中 Unigene0014342 和 CPAs 转运蛋白中 Unigene0088276 和 Unigene0103067 的表达水平在 200 mM NaCl 处理 48 h 和 168 h 时先降低后升高，而在 200 mM NaCl+10 mM KCl 处理 48 h 和 168 h 时则呈持续上升趋势。值得注意的是，CPAs 转运蛋白中 Unigene0016813 的表达水平在 200 mM NaCl 和 200 mM NaCl+10 mM KCl 处理 48 h 和 168 h 时持续增加。3 个 DEGs，Unigene0088276、Unigene0016813 和 Unigene0103067，主要由其相关代谢物的正调控主导，且这种相关性显著。结果表明，这些 DEGs 在施加外源钾后 48 h 和 168 h 时增加了 K+的吸收和 K+/Na+的比值，增强了柽柳的耐盐性。值得注意的是，CPAs 转运蛋白中 Unigene0103067 的表达水平在 200 mM NaCl+10 mM KCl 处理 48 h 和 168 h 时始终呈上调趋势。正调控代谢物始终占主导地位，这更好地帮助柽柳抵抗盐胁迫。Unigene0103067 在增强柽柳耐盐性和降低根中 NaCl 毒性方面发挥着重要作用。此外，系统进化树分析表明，在进化关系中，Unigene0103067 与柽柳的亲缘关系最近。最后，随机选择 9 个 DEGs 进行定量实时 PCR（qRT-PCR）验证。它们的表达趋势与转录组测序分析结果完全一致，证明了本研究数据的准确性和可靠性。本研究为揭示柽柳耐 NaCl 胁迫的分子机制提供了资源，为培育新的耐盐品种奠定了理论基础。
