Most of WRKY transcription factors play important roles in plant development, protection against disease, and response to abiotic stress; however, their roles in lily are largely unknown. Transcriptome analysis in lily (Lilium longiflorum) led to the identification and isolation of a WRKY-IIe gene, LlWRKY22, which was found to be activated at high temperature and play a positive role in thermotolerance regulation. LlWRKY22 expression was continuously activated by heat stress. We further found that LlWRKY22 protein localized to the nucleus and exhibited transactivation activity in both yeast and plant cells, and that its C terminus contributed to its transactivation activity. Meanwhile, overexpression of LlWRKY22 in lily improved thermotolerance and activated the expression of heat-related LlDREB2B gene; however, silencing of LlWRKY22 exerted the opposite effects. Further analysis revealed that LlWRKY22 directly activated the expression of LlDREB2B by binding to two tandem W-box elements on its promoter. Simultaneously, we also found that LlWRKY22 can directly bind its own promoter, thereby activating its own expression and forming a positive regulatory loop. Combined, our findings demonstrated that LlWRKY22 may be a new regulator of heat stress response and positively participates in the establishment of thermotolerance by activating itself and LlDREB2B.

中文翻译：

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Lily WRKY 因子 LlWRKY22 通过 LlDREB2B 的自动激活和激活促进耐热性

大多数 WRKY 转录因子在植物发育、疾病保护和对非生物胁迫的反应中发挥着重要作用；然而，他们在百合中的角色在很大程度上是未知的。百合 (Lilium longiflorum) 的转录组分析导致 WRKY-IIe 基因 LlWRKY22 的鉴定和分离，该基因在高温下被激活并在耐热性调节中发挥积极作用。LlWRKY22 表达被热应激持续激活。我们进一步发现 LlWRKY22 蛋白定位于细胞核并在酵母和植物细胞中均表现出反式激活活性，并且其 C 末端有助于其反式激活活性。同时，LlWRKY22在百合中的过表达提高了耐热性并激活了与热相关的LlDREB2B基因的表达；然而，LlWRKY22 的沉默产生了相反的效果。进一步分析表明，LlWRKY22 通过与其启动子上的两个串联 W-box 元件结合直接激活 LlDREB2B 的表达。同时我们还发现LlWRKY22可以直接结合自身的启动子，从而激活自身的表达，形成正调控环。综合起来，我们的研究结果表明，LlWRKY22 可能是一种新的热应激反应调节剂，并通过激活自身和 LlDREB2B 积极参与耐热性的建立。从而激活其自身的表达并形成正向调节循环。综合起来，我们的研究结果表明，LlWRKY22 可能是一种新的热应激反应调节剂，并通过激活自身和 LlDREB2B 积极参与耐热性的建立。从而激活其自身的表达并形成正向调节循环。综合起来，我们的研究结果表明，LlWRKY22 可能是一种新的热应激反应调节剂，并通过激活自身和 LlDREB2B 积极参与耐热性的建立。