High salinity, one of the most widespread abiotic stresses, inhibits photosynthesis, reduces vegetation growth, blocks respiration and disrupts metabolism in plants. In order to survive their long‐term lifecycle, trees, such as Populus species, recruit the abscisic acid (ABA) signaling pathway to adapt to a saline environment. However, the molecular mechanism behind the ABA‐mediated salt stress response in woody plants remains elusive. We have isolated a WRKY transcription factor gene, PalWRKY77, from Populus alba var. pyramidalis (poplar), the expression of which is repressed by salt stress. PalWRKY77 decreases salt tolerance in poplar. Furthermore, PalWRKY77 negatively regulated ABA‐responsive genes and relieved ABA‐mediated growth inhibition, indicating that PalWRKY77 is a repressor of the ABA response. In vivo and in vitro assays revealed that PalWRKY77 targets the ABA‐ and salt‐induced PalNAC002 and PalRD26 genes by binding to the W‐boxes in their promoters. In addition, overexpression of both PalNAC002 and PalRD26 could elevate salt tolerance in transgenic poplars. These findings reveal a novel negative regulation mechanism for the ABA signaling pathway mediated by PalWRKY77 that results in more sensitivity to salt stress in poplar. This deepens our understanding of the complex responses of woody species to salt stress.

中文翻译：

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PalWRKY77转录因子负调控胡杨的耐盐性和脱落酸信号传导

高盐度是最普遍的非生物胁迫之一，可抑制光合作用，减少植物生长，阻止呼吸并破坏植物的新陈代谢。为了维持其长期生命周期，树木（例如胡杨树）会募集脱落酸（ABA）信号传导途径，以适应盐碱环境。但是，ABA介导的盐胁迫在木本植物中的分子机制仍然难以捉摸。我们已经从白杨（Populus alba var）中分离出WRKY转录因子基因PalWRKY77。锥体小叶杨（白杨），其表达被盐胁迫抑制。PalWRKY77降低了杨树的耐盐性。此外，PalWRKY77负调控的ABA反应基因和缓解的ABA介导的生长抑制，表明PalWRKY77是ABA反应的阻遏物。体内和体外试验表明，PalWRKY77通过与启动子中的W-box结合，靶向ABA和盐诱导的PalNAC002和PalRD26基因。另外，PalNAC002和PalRD26的过表达均可提高转基因杨树的耐盐性。这些发现揭示了由PalWRKY77介导的ABA信号传导途径的新型负调控机制，该机制导致对杨树盐胁迫的敏感性更高。这加深了我们对木质物种对盐胁迫的复杂反应的理解。