Salt stress activates defence responses in plants, including changes in leaf surface structure. Here, we showed that the transcriptional activation of cutin deposition and antioxidant defence by the R2R3‐type MYB transcription factor AtMYB49 contributed to salt tolerance in Arabidopsis thaliana . Characterization of loss‐of‐function myb49 mutants, and chimeric AtMYB49‐SRDX‐ overexpressing SRDX49 transcriptional repressor and AtMYB49 ‐overexpressing (OX49 ) overexpressor plants demonstrated a positive role of AtMYB49 in salt tolerance. Transcriptome analysis revealed that many genes belonging to the category “cutin, suberin and wax biosyntheses” were markedly up‐regulated and down‐regulated in OX49 and SRDX49 plants, respectively, under normal and/or salt stress conditions. Some of these differentially expressed genes, including MYB41 , ASFT , FACT and CYP86B1 , were also shown to be the direct targets of AtMYB49 and activated by AtMYB49. Biochemical analysis indicated that AtMYB49 modulated cutin deposition in the leaves. Importantly, cuticular transpiration, chlorophyll leaching and toluidine blue‐staining assays revealed a link between increased AtMYB49‐mediated cutin deposition in leaves and enhanced salt tolerance. Additionally, increased AtMYB49 expression elevated Ca²⁺ level in leaves and improved antioxidant capacity by up‐regulating genes encoding peroxidases and late embryogenesis abundant proteins. These results suggest that genetic manipulation of AtMYB49 may provide a novel way to improve salt tolerance in plants.

中文翻译：

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R2R3-MYB转录因子AtMYB49通过调节角质层的形成和抗氧化防御来调节拟南芥的耐盐性。

盐胁迫会激活植物的防御反应，包括叶片表面结构的变化。在这里，我们证明了R2R3型MYB转录因子AtMYB49的角质素沉积的转录激活和抗氧化剂防御作用有助于拟南芥的耐盐性。功能丧失的myb49突变体以及嵌合的AtMYB49-SRDX过表达的SRDX49转录阻遏物和AtMYB49过表达（OX49）的过表达植物的表征证明了AtMYB49的积极作用耐盐性。转录组分析显示，在正常和/或盐胁迫条件下，OX49和SRDX49植物中分别属于“角质，木栓质和蜡质生物合成”类别的许多基因分别显着上调和下调。这些差异表达基因中的一些，包括MYB41，ASFT，FACT和CYP86B1，也被证明是AtMYB49的直接靶标，并被AtMYB49激活。生化分析表明，AtMYB49调节叶片中的角质沉积。重要的是，表皮蒸腾作用，叶绿素浸出和甲苯胺蓝染色分析揭示了AtMYB49介导的角质在叶片中的沉积增加与盐分耐受性之间的联系。此外，AtMYB49表达的增加通过上调编码过氧化物酶的基因和晚期胚胎发生的丰富蛋白质而提高了叶片中Ca ^2+的水平，并提高了抗氧化能力。这些结果表明AtMYB49的基因操作可能提供一种提高植物耐盐性的新方法。