Root development is a complex process involving phytohormones and transcription factors. Our previous research has demonstrated that BcWRKY33A is significantly expressed in Bok Choy roots under salt stress, and heterologous expression of BcWRKY33A increases salt tolerance and promotes root development in transgenic Arabidopsis. However, the precise molecular mechanisms by which BcWRKY33A governs root development remain elusive. Here, we investigated the role of BcWRKY33A in both root elongation and root hair formation in transgenic Bok choy roots. Our data indicated that overexpression of BcWRKY33A stimulated root growth and stabilized root hair morphology, while silencing BcWRKY33A prevented primary root elongation and resulted in abnormal root hairs morphology. Meanwhile, our research uncovered that BcWRKY33A directly binds to the promoters of BcLRP1 and BcCOW1, leading to an upregulation of their expression. In transgenic Bok choy roots, increased BcLRP1 and BcCOW1 transcript levels improved primary root elongation and root hair formation, respectively. Additionally, we pinpointed BcWRKY25 as a NaCl-responsive gene that directly stimulates the expression of BcWRKY33A in response to salt stress. All results shed light on the regulatory mechanisms governing root development by BcWRKY25-BcWRKY33A-BcLRP1/BcCOW1 module and propose potential strategies for improving salt tolerance in Bok choy.

中文翻译：

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BcWRKY25-BcWRKY33A-BcLRP1/BcCOW1模块促进根部发育，提高白菜的耐盐性


根发育是一个涉及植物激素和转录因子的复杂过程。我们前期的研究表明，BcWRKY33A在盐胁迫下在白菜根中显着表达，并且BcWRKY33A的异源表达增加了转基因拟南芥的耐盐性并促进根部发育。然而，BcWRKY33A 控制根发育的精确分子机制仍然难以捉摸。在这里，我们研究了 BcWRKY33A 在转基因白菜根的根伸长和根毛形成中的作用。我们的数据表明，BcWRKY33A 的过度表达刺激根生长并稳定根毛形态，而沉默 BcWRKY33A 则阻止初生根伸长并导致根毛形态异常。同时，我们的研究发现BcWRKY33A直接与BcLRP1和BcCOW1的启动子结合，导致它们的表达上调。在转基因白菜根中，BcLRP1 和 BcCOW1 转录水平的增加分别改善了初生根伸长和根毛形成。此外，我们将 BcWRKY25 确定为 NaCl 响应基因，可直接刺激 BcWRKY33A 的表达以响应盐胁迫。所有结果揭示了 BcWRKY25-BcWRKY33A-BcLRP1/BcCOW1 模块控制根发育的调控机制，并提出了提高白菜耐盐性的潜在策略。