Key message

LRRop-1, induced by DOF6 transcription factor, negatively regulates abiotic stress responses during Arabidopsis seed germination. The lrrop-1 mutant has reduced ABA signaling, which is part of the underlying stress-remediation mechanism.

Abstract

The large family of leucine-rich repeat (LRR) proteins plays a role in plant immune responses. Most LRR proteins have multiple functional domains, but a subfamily is known to possess only the LRR domain. The roles of these LRR-only proteins in Arabidopsis remain largely uncharacterized. In the present study, we have identified 44 LRR-only proteins in Arabidopsis and phylogenetically classified them into nine sub-groups. We characterized the function of LRRop-1, belonging to sub-group V. LRRop-1 encodes a predominantly ER-localized LRR domain-containing protein that is highly expressed in seeds and rosette leaves. Promoter motif analysis revealed an enrichment in binding sites for several GA-responsive and stress-responsive transcription factors. The lrrop-1 mutant seeds showed enhanced seed germination on medium containing abscisic acid (ABA), paclobutrazol and NaCl compared to the wild type (WT), demonstrating higher abiotic stress tolerance. Also, the lrrop-1 mutant seeds have lower levels of endogenous ABA, but higher levels of gibberellic acid (GA) and jasmonic acid-Ile (JA-Ile) compared to the WT. Furthermore, lrrop-1 mutant seeds imbibed with ABA exhibited reduced expression of ABA-responsive genes compared to similarly treated WT seeds, suggesting suppressed ABA signaling events in the mutant. Furthermore, chromatin immunoprecipitation (ChIP) data showed that DNA BINDING1 ZINC FINGER6 (DOF6), a negative regulator of seed germination, could directly bind to the LRRop-1 promoter and up-regulate its expression. Thus, our results show that LRRop-1 regulates ABA-mediated abiotic stress responses during Arabidopsis seed germination.

中文翻译：

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LRR-only 蛋白在拟南芥种子萌发过程中调节脱落酸介导的非生物胁迫反应。

关键信息

由 DOF6 转录因子诱导的LRRop-1在拟南芥种子萌发过程中负调控非生物胁迫反应。lrrop -1突变体减少了 ABA 信号，这是潜在的压力修复机制的一部分。

抽象的

富含亮氨酸重复 (LRR) 蛋白的大家族在植物免疫反应中发挥作用。大多数 LRR 蛋白具有多个功能结构域，但已知一个亚家族仅具有 LRR 结构域。这些 LRR-only 蛋白在拟南芥中的作用在很大程度上仍未得到表征。在本研究中，我们在拟南芥中鉴定了 44 种 LRR-only 蛋白，并在系统发育上将它们分为九个亚组。我们表征了LRRop-1的功能，属于 V 亚组。LRRop-1编码一种主要定位于 ER 的 LRR 结构域的蛋白质，该蛋白质在种子和莲座叶中高度表达。启动子基序分析揭示了几种 GA 响应和应激响应转录因子的结合位点富集。与野生型 (WT) 相比，lrrop-1突变体种子在含有脱落酸 (ABA)、多效唑和 NaCl 的培养基上表现出增强的种子发芽率，表现出更高的非生物胁迫耐受性。此外，与WT 相比， lrrop-1突变种子的内源 ABA 水平较低，但赤霉酸 (GA) 和茉莉酸-Ile (JA-Ile) 水平较高。此外，lrrop-1与类似处理的 WT 种子相比，吸收 ABA 的突变种子表现出 ABA 反应基因的表达降低，这表明突变体中的 ABA 信号传导事件受到抑制。此外，染色质免疫沉淀 (ChIP) 数据显示，种子萌发的负调节因子 DNA BINDING1 ZINC FINGER6 (DOF6) 可以直接与LRRop-1启动子结合并上调其表达。因此，我们的研究结果表明，LRRop-1 在拟南芥种子萌发过程中调节 ABA 介导的非生物胁迫反应。