BESE Division 4700, King Abdullah University of Science and Technology (KAUST), Thuwal, Makkah 23955, Saudi Arabia.
Biological Sciences Department, College of Science & Arts, King Abdulaziz University, Rabigh 21911, Saudi Arabia.
Int J Mol Sci. 2024 Oct 30;25(21):11642. doi: 10.3390/ijms252111642.
LIM proteins are named after the initials of three proteins Lin-11, Isl-1, and MEC-3, which belong to a class of transcription factors that play an important role in the developmental regulation of eukaryotes and are also involved in a variety of life processes, including gene transcription, the construction of the cytoskeleton, signal transduction, and metabolic regulation. Plant LIM proteins have been shown to regulate actin bundling in different cells, but their role in immunity remains elusive. Mitogen-activated protein kinases (MAPKs) are a family of conserved serine/threonine protein kinases that link upstream receptors to their downstream targets. Pathogens produce pathogen-associated molecular patterns (PAMPs) that trigger the activation of MAPK cascades in plants. Recently, we conducted a large-scale phosphoproteomic analysis of PAMP-induced plants to identify putative MAPK targets. One of the identified phospho-proteins was WLIM2A, an Arabidopsis LIM protein. In this study, we investigated the role of WLIM2A in plant immunity. We employed a reverse-genetics approach and generated knockout lines using CRISPR-Cas9 technology. We also generated complementation and phosphosite-mutated expression lines in the background. The lines were compromised in their response to DC3000 but showed enhanced resistance to the necrotrophic fungus . Transcriptome analyses of mutants revealed the deregulation of immune hormone biosynthesis and signaling of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways. The mutants also exhibited altered stomatal phenotypes. Analysis of plants expressing variants of the phospho-dead or phospho-mimicking MAPK phosphorylation site showed opposing stomatal behavior and resistance phenotypes in response to DC3000 infection, proving that phosphorylation of WLIM2A plays a crucial role in plant immunity. Overall, these data demonstrate that phosphorylation of WLIM2A by MAPKs regulates responses to plant pathogens.
LIM 蛋白以 Lin-11、Isl-1 和 MEC-3 三种蛋白的首字母命名，它们属于一类转录因子，在真核生物的发育调控中发挥重要作用，还参与多种生命过程，包括基因转录、细胞骨架构建、信号转导和代谢调节。植物 LIM 蛋白已被证明可以调节不同细胞中的肌动蛋白成束，但它们在免疫中的作用仍不清楚。丝裂原活化蛋白激酶 (MAPK) 是一组保守的丝氨酸/苏氨酸蛋白激酶，它们将上游受体与下游靶标连接起来。病原体产生病原体相关分子模式 (PAMP)，触发植物中 MAPK 级联的激活。最近，我们对 PAMP 诱导的植物进行了大规模磷酸蛋白质组学分析，以鉴定潜在的 MAPK 靶标。鉴定出的磷酸化蛋白之一是拟南芥 LIM 蛋白 WLIM2A。在这项研究中，我们研究了 WLIM2A 在植物免疫中的作用。我们采用反向遗传学方法，利用 CRISPR-Cas9 技术生成 敲除系。我们还在 背景下生成了互补和磷酸化位点突变的 表达系。 系对 DC3000 的反应受损，但对坏死真菌 的抗性增强。 突变体的转录组分析显示免疫激素生物合成和水杨酸 (SA)、茉莉酸 (JA) 和乙烯 (ET) 途径信号的失调。 突变体还表现出改变的气孔表型。表达磷酸化缺失或磷酸化模拟 MAPK 磷酸化位点的 变体的植物分析表明，对 DC3000 感染的气孔行为和抗性表型表现出相反的反应，证明 WLIM2A 的磷酸化在植物免疫中起着至关重要的作用。总体而言，这些数据表明，MAPK 对 WLIM2A 的磷酸化调节植物对植物病原体的反应。
