Salinity stress is one of the most devastating abiotic stresses limiting plant growth and productivity. As a moderately salt-tolerant crop, shrub willow (Salix spp.) is widely distributed over the world and can provide multiple bioenergy product and environmental benefits. To delve into the salt tolerance mechanism and screen out salt-tolerant genes, two shrub willow cultivars (a salt-sensitive genotype JW9-6 and a salt-tolerant genotype JW2372) at three time points (0, 2, and 12 h) after NaCl treatments were used for RNA sequencing. A comparative analysis between genotypes and time points showed 1,706 differentially expressed genes (DEGs), of which 1,029 and 431 DEGs were only found in the JW9-6 and JW2372, respectively. Gene Ontology (GO) and MapMan annotations suggested that many DEGs were involved in various defense-related biological pathways, including cell wall integrity, hormone signaling, antioxidant system, heat shock proteins, and transcription factors. Compared to JW9-6, JW2372 contained more DEGs involved in the maintenance of the cell wall integrity, ABA, and ethylene signal transduction pathways. In addition, more DEGs encoding heat shock proteins were found in JW2372. Instead, transcription factors including ERF, MYB, NAC, and WRKY were found to be more differentially expressed in JW9-6 under salinity stress. Furthermore, expressions of nine randomly selected DEGs were verified by qRT-PCR analysis. This study contributes in new perspicacity into underlying the salt tolerance mechanism of a shrub willow at the transcriptome level and also provides numerous salt-tolerant genes for further genetic engineering and breeding purposes in the future.

中文翻译：

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转录组分析揭示了盐分胁迫下耐盐和耐盐灌木柳基因型的复杂防御机制。

盐胁迫是限制植物生长和生产力的最具破坏性的非生物胁迫之一。作为中度耐盐作物，灌木柳（Salixspp。）分布在世界各地，可以提供多种生物能源产品和环境效益。为了研究耐盐机理并筛选耐盐基因，在之后的三个时间点（0、2和12 h），两个灌木柳品种（一个盐敏感基因型JW9-6和一个耐盐基因型JW2372） NaCl处理用于RNA测序。基因型和时间点之间的比较分析显示1,706个差异表达基因（DEG），其中1,029和431个DEG仅分别在JW9-6和JW2372中发现。基因本体论（GO）和MapMan注释表明许多DEG参与了各种与防御相关的生物途径，包括细胞壁完整性，激素信号传导，抗氧化系统，热激蛋白和转录因子。与JW9-6相比，JW2372包含更多与细胞壁完整性，ABA和乙烯信号转导通路维持相关的DEG。另外，在JW2372中发现了更多的编码热激蛋白的DEG。取而代之的是，发现在盐分胁迫下，包括ERF，MYB，NAC和WRKY在内的转录因子在JW9-6中的表达差异更大。此外，通过qRT-PCR分析验证了九种随机选择的DEG的表达。这项研究为转录柳组在灌木柳的耐盐机理中发挥了新的作用，并为将来的遗传工程和育种目的提供了许多耐盐基因。在JW2372中发现了更多的编码热激蛋白的DEG。取而代之的是，发现在盐分胁迫下，包括ERF，MYB，NAC和WRKY在内的转录因子在JW9-6中的表达差异更大。此外，通过qRT-PCR分析验证了九种随机选择的DEG的表达。这项研究为转录柳组在灌木柳的耐盐机理中发挥了新的作用，并为将来的遗传工程和育种目的提供了许多耐盐基因。在JW2372中发现了更多的编码热激蛋白的DEG。取而代之的是，发现在盐分胁迫下，包括ERF，MYB，NAC和WRKY在内的转录因子在JW9-6中的表达差异更大。此外，通过qRT-PCR分析验证了九种随机选择的DEG的表达。这项研究为转录柳组在灌木柳的耐盐机理中发挥了新的作用，并为将来的遗传工程和育种目的提供了许多耐盐基因。