Rice Research Institute and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China.
Institute for Bioscience and Biotechnology Research & Department of Plant Science and Landscape Architecture, University of Maryland, Rockville, Maryland, 20850, USA.
J Integr Plant Biol. 2021 Feb;63(2):378-392. doi: 10.1111/jipb.13025.
Study on the regulation of broad-spectrum resistance is an active area in plant biology. RESISTANCE TO POWDERY MILDEW 8.1 (RPW8.1) is one of a few broad-spectrum resistance genes triggering the hypersensitive response (HR) to restrict multiple pathogenic infections. To address the question how RPW8.1 signaling is regulated, we performed a genetic screen and tried to identify mutations enhancing RPW8.1-mediated HR. Here, we provided evidence to connect an annexin protein with RPW8.1-mediated resistance in Arabidopsis against powdery mildew. We isolated and characterized Arabidopsis b7-6 mutant. A point mutation in b7-6 at the At5g12380 locus resulted in an amino acid substitution in ANNEXIN 8 (AtANN8). Loss-of-function or RNA-silencing of AtANN8 led to enhanced expression of RPW8.1, RPW8.1-dependent necrotic lesions in leaves, and defense against powdery mildew. Conversely, over-expression of AtANN8 compromised RPW8.1-mediated disease resistance and cell death. Interestingly, the mutation in AtANN8 enhanced RPW8.1-triggered H O . In addition, mutation in AtANN8 led to hypersensitivity to salt stress. Together, our data indicate that AtANN8 is involved in multiple stress signaling pathways and negatively regulates RPW8.1-mediated resistance against powdery mildew and cell death, thus linking ANNEXIN's function with plant immunity.
广谱抗性调控的研究是植物生物学中的一个活跃领域。抗白粉病 8.1（RPW8.1）是少数几种引发过敏反应（HR）以限制多种致病感染的广谱抗性基因之一。为了解决 RPW8.1 信号如何被调控的问题，我们进行了遗传筛选，并试图鉴定增强 RPW8.1 介导的 HR 的突变。在这里，我们提供了证据，将 annexin 蛋白与拟南芥中对白粉病的 RPW8.1 介导的抗性联系起来。我们分离并表征了拟南芥 b7-6 突变体。b7-6 在 At5g12380 基因座的点突变导致 annexin 8（AtANN8）中的一个氨基酸取代。AtANN8 的功能丧失或 RNA 沉默导致 RPW8.1 的表达增强、叶片中 RPW8.1 依赖的坏死损伤以及对白粉病的防御。相反，AtANN8 的过表达削弱了 RPW8.1 介导的抗病性和细胞死亡。有趣的是，AtANN8 中的突变增强了 RPW8.1 触发的 H2O2。此外，AtANN8 的突变导致对盐胁迫的敏感性增加。总之，我们的数据表明 AtANN8 参与多种应激信号通路，并负调控 RPW8.1 介导的对白粉病和细胞死亡的抗性，从而将 annexin 的功能与植物免疫联系起来。
