Dehydration stress response is a complex mechanism in plants involving several factors and hormone signalling pathways. RAV1 is a member of the AP2/ERF family of transcription factors that works in various developmental pathways. Here we show that downregulation of RAV1 gene expression is important for efficient dehydration stress response. Interestingly, the B3-domain transcription factor ABI3 negatively regulates RAV1 expression. In absence of ABI3, RAV1 expression increases during dehydration stress compared to control. As a part of stress response, ABI3 occupancy increases in the RAV1 promoter region. Such regulation of RAV1 gene expression seems vital as absence of RAV1 leads to reduced water loss during dehydration stress and consequently faster recovery compared to wild type. rav1 mutant seedlings show more abundant root growth under control condition and higher primary root elongation compared to wild type when subjected to dehydration stress. Mutants also exhibit enhanced ABA sensitivity compared to wild type. At the transcript level, rooting genes like NAC1, ARF16, SLR and SLR-downstream genes like ARF7, PLT3, SHR show differential expression in rav1 mutant, compared to wild type. Additionally, ethylene-responsive genes ETR1, EIN2 and ERF1 also get differentially expressed in presence and absence of RAV1 under control and stress conditions. This indicates an altered ethylene response in the rav1 mutant. All these features render rav1seedlings better equipped for responding to dehydration stress. It thus becomes evident that ABI3 mediated regulation of RAV1 gene expression is a significant part of dehydration stress signalling for efficient stress management at the molecular and morphological level.

中文翻译：

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ABI3介导的RAV1基因表达的抑制促进拟南芥中有效的脱水胁迫反应。

脱水胁迫反应是植物中涉及多种因素和激素信号通路的复杂机制。RAV1是AP2 / ERF转录因子家族的成员，可在各种发育途径中发挥作用。在这里，我们显示RAV1基因表达的下调对于有效的脱水应激反应很重要。有趣的是，B3结构域转录因子ABI3负调节RAV1表达。与对照相比，在缺乏ABI3的情况下，脱水胁迫期间RAV1表达增加。作为应激反应的一部分，RAB1启动子区域中的ABI3占有率增加。RAV1基因表达的这种调节似乎至关重要，因为与野生型相比，缺少RAV1可以减少脱水胁迫期间的水分流失，因此恢复速度更快。与野生型相比，在干旱条件下，rav1突变苗在控制条件下显示出更丰富的根系生长，并且具有更高的原生根伸长。与野生型相比，突变体还表现出增强的ABA敏感性。在转录本水平上，与野生型相比，生根基因（如NAC1，ARF16，SLR和SLR下游基因，如ARF7，PLT3，SHR）在rav1突变体中显示差异表达。此外，在控制和胁迫条件下，无论是否存在RAV1，乙烯响应基因ETR1，EIN2和ERF1也会差异表达。这表明rav1突变体中乙烯反应的改变。所有这些功能使幼树更好地应对脱水压力。