Abstract WRKY transcription factors (TFs) are key regulators in numerous plant biological processes and responses to stresses. Although a group III tomato WRKY, SlWKRY81, is induced by some biotic stressors, its role in drought response remains largely unknown. Here, we unveiled a critical role of SlWKRY81 in regulation of drought response by using agronomic, bioinformatics, genetic and pharmacological approaches. Drought gradually increased the transcript levels of SlWRKY81 and impaired leaf water potential and membrane stability in tomato. Analysis of plant phenotypes revealed that silencing of SlWRKY81 in tomato enhanced tolerance to drought, while its overexpression in Arabidopsis resulted in an opposite phenotype. Notably, the enhanced drought tolerance in SlWRKY81-silenced tomato plants was closely associated with a rapid and increased stomatal closure. Furthermore, such stomatal response in the SlWRKY81-silenced plants was sensitive to abscisic acid alongside drought-induced enhanced accumulation of H2O2 in the guard cells. The results suggest that SlWRKY81 acts as a negative regulator of stomatal closure by suppressing SlRBOH1-derived H2O2 accumulation, which attenuates plant tolerance to drought. These results may have potential implications on improving plant drought tolerance through genetic manipulation.

中文翻译：

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番茄 WRKY81 通过调节保卫细胞 H2O2 介导的气孔关闭作为耐旱性的负调节剂

摘要 WRKY 转录因子 (TFs) 是众多植物生物过程和胁迫响应的关键调节因子。尽管第 III 组番茄 WRKY SlWKRY81 是由一些生物胁迫因素诱导的，但其在干旱反应中的作用仍然未知。在这里，我们通过使用农艺学、生物信息学、遗传学和药理学方法揭示了 SlWKRY81 在调节干旱反应中的关键作用。干旱逐渐增加了 SlWRKY81 的转录水平，并损害了番茄的叶水势和膜稳定性。植物表型分析表明，番茄中 SlWRKY81 的沉默增强了对干旱的耐受性，而其在拟南芥中的过度表达导致了相反的表型。尤其，SlWRKY81 沉默的番茄植物中增强的耐旱性与快速和增加的气孔关闭密切相关。此外，SlWRKY81 沉默植物中的这种气孔响应对脱落酸敏感，同时干旱诱导的保卫细胞中 H2O2 的积累增强。结果表明，SlWRKY81 通过抑制 SlRBOH1 衍生的 H2O2 积累作为气孔关闭的负调节因子，从而减弱植物对干旱的耐受性。这些结果可能对通过遗传操作提高植物耐旱性具有潜在意义。结果表明，SlWRKY81 通过抑制 SlRBOH1 衍生的 H2O2 积累作为气孔关闭的负调节因子，从而减弱植物对干旱的耐受性。这些结果可能对通过基因操作提高植物耐旱性具有潜在意义。结果表明，SlWRKY81 通过抑制 SlRBOH1 衍生的 H2O2 积累作为气孔关闭的负调节因子，从而减弱植物对干旱的耐受性。这些结果可能对通过基因操作提高植物耐旱性具有潜在意义。