The karrikin (KAR) receptor and several related signaling components have been identified by forward genetic screening, but only a few studies have reported on upstream and downstream KAR signaling components and their roles in drought tolerance. Here, we characterized the functions of KAR UPREGULATED F-BOX 1 (KUF1) in drought tolerance using a reverse genetics approach in Arabidopsis (Arabidopsis thaliana). We observed that kuf1 mutant plants were more tolerant to drought stress than wild-type (WT) plants. To clarify the mechanisms by which KUF1 negatively regulates drought tolerance, we performed physiological, transcriptome, and morphological analyses. We found that kuf1 plants limited leaf water loss by reducing stomatal aperture and cuticular permeability. In addition, kuf1 plants showed increased sensitivity of stomatal closure, seed germination, primary root growth, and leaf senescence to abscisic acid (ABA). Genome-wide transcriptome comparisons of kuf1 and WT rosette leaves before and after dehydration showed that the differences in various drought tolerance-related traits were accompanied by differences in the expression of genes associated with stomatal closure (e.g. OPEN STOMATA 1), lipid and fatty acid metabolism (e.g. WAX ESTER SYNTHASE), and ABA responsiveness (e.g. ABA-RESPONSIVE ELEMENT 3). The kuf1 mutant plants had higher root/shoot ratios and root hair densities than WT plants, suggesting that they could absorb more water than WT plants. Together, these results demonstrate that KUF1 negatively regulates drought tolerance by modulating various physiological traits, morphological adjustments, and ABA responses and that the genetic manipulation of KUF1 in crops is a potential means of enhancing their drought tolerance.

中文翻译：

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KARRIKIN UPREGULATED F-BOX 1 对拟南芥的耐旱性产生负调节。

karrikin (KAR) 受体和一些相关信号元件已通过正向遗传筛选鉴定出来，但只有少数研究报道了 KAR 上下游信号元件及其在耐旱性中的作用。在这里，我们使用反向遗传学方法表征了拟南芥 (Arabidopsis thaliana) 中 KAR UPREGULATED F-BOX 1 (KUF1) 在耐旱性中的功能。我们观察到 kuf1 突变体植物比野生型 (WT) 植物更能耐受干旱胁迫。为了阐明 KUF1 负向调节耐旱性的机制，我们进行了生理学、转录组和形态学分析。我们发现 kuf1 植物通过减少气孔孔径和角质层渗透性来限制叶片水分流失。此外，kuf1植物表现出气孔关闭的敏感性增加，种子发芽、初生根生长和叶子衰老至脱落酸 (ABA)。脱水前后kuf1和WT莲座叶的全基因组转录组比较表明，各种耐旱相关性状的差异伴随着气孔关闭（例如OPEN STOMATA 1）、脂质和脂肪酸相关基因表达的差异代谢（例如蜡酯合成酶）和 ABA 响应性（例如 ABA 响应元素 3）。kuf1突变体植物比野生型植物具有更高的根/冠比和根毛密度，表明它们比野生型植物能够吸收更多的水。总之，这些结果表明 KUF1 通过调节各种生理性状、形态调整、