Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India.
Plant Cell Rep. 2021 Nov;40(11):2151-2171. doi: 10.1007/s00299-021-02710-8. Epub 2021 May 17.
MiWRKY53 is expressed in response to various stresses and hormones. Although it is localized in the nucleus, it shows no transcriptional activation. Role of SA-mediated plant defence response is demonstrated. WRKY transcription factors are one the largest gene families in plants involved in almost every process in plants including development, physiological processes, and stress response. Salicylic acid (SA) is key regulator of biotic stress against various pathogens in plants acting via its multiple mechanisms to induce defence response. Herein, we have identified and functionally validated WRKY53 from mulberry (Morus indica var. K2). MiWRKY53 expressed differentially in response to different stress and hormonal treatments. MiWRKY53 belongs to group III of WKRY gene family, localized in nucleus, and lacks transcriptional activation activity in yeast. Hormone responsive behaviour of MiWRKY53 Arabidopsis overexpression (OE) transgenics preferentially was noted in root growth assay in response to Salicylic acid (SA). Arabidopsis overexpression plants also displayed alteration in leaf phenotype having wider leaves than the wild-type plants. PR-1 transcripts were higher in MiWRKY53 Arabidopsis OE plants and they displayed resistance towards biotrophic pathogen Pseudomonas syringae PstDC3000. MiWRKY53 Mulberry OE transgenics also depicted SA-responsive behaviour. Several hormones and stress-related cis-acting elements were also identified in the 1.2-Kb upstream regulatory region (URR) of MiWRKY53. Functional characterization of full-length promoter region revealed that it is induced by SA and further analysis of deletion constructs helped in the identification of minimal promoter responsible for its inducibility by SA. Altogether, the findings from this study point towards the SA preferential behaviour of MiWRKY53 and its function as regulator of plant defence response through SA-mediated mechanisms.
MiWRKY53 响应各种胁迫和激素而表达。尽管它定位于核内，但没有表现出转录激活。证明了水杨酸（SA）介导的植物防御反应的作用。WRKY 转录因子是植物中最大的基因家族之一，涉及植物的几乎所有过程，包括发育、生理过程和应激反应。水杨酸（SA）是植物中各种病原体生物胁迫的关键调节剂，通过其多种机制诱导防御反应。在此，我们从桑树（Morus indica var. K2）中鉴定并功能验证了 WRKY53。MiWRKY53 对不同胁迫和激素处理的反应存在差异表达。MiWRKY53 属于 WRKY 基因家族的第 III 组，定位于核内，并且在酵母中缺乏转录激活活性。MiWRKY53 拟南芥过表达（OE）转基因植物在根生长测定中对水杨酸（SA）的激素响应行为优先，表现为根生长增强。与野生型植物相比，拟南芥过表达植物的叶片表型也发生了改变，叶片更宽。PR-1 转录物在 MiWRKY53 拟南芥 OE 植物中更高，它们对生物营养性病原体丁香假单胞菌 PstDC3000 表现出抗性。MiWRKY53 桑树 OE 转基因植物也表现出对 SA 的响应行为。在 MiWRKY53 的 1.2-Kb 上游调控区（URR）中还鉴定了几个激素和应激相关的顺式作用元件。全长启动子区域的功能表征表明，它被 SA 诱导，进一步的缺失构建体分析有助于鉴定负责其对 SA 诱导性的最小启动子。总之，这项研究的结果表明 MiWRKY53 对 SA 的偏好行为及其通过 SA 介导的机制作为植物防御反应调节剂的功能。
