Cyclic nucleotide-gated ion channel (CNGC)-mediated signal transduction and hormonal crosstalk in plant natural immunity

背景：由于全球人口的增长，增加粮食产量是世界上一个紧迫的问题。然而，尽管广泛使用可能危害环境的农用化学品，每年仍有大量农产品因植物病害而损失。因此，了解植物免疫并找到增强植物自然抗性的方法是未来粮食生产安全和健康环境的关键。到目前为止，我们已经证明了环核苷酸门控离子通道CNGC11和12在植物免疫中发挥重要作用，并分析了它们的结构-功能关系。我们还使用了一个CNGC突变体来检测信号串扰。在动物中，CNGCs影响视觉和嗅觉信号转导，并受钙传感器蛋白calmodulin （CaM）的调节。然而，在植物中，CNGCs的调节因子及其下游信号转导级联在很大程度上仍然未知。研究目标和概述：我研究的长期目标是在分子水平上理解环境胁迫与病原体感染的信号转导途径和网络。为此，在未来的5年里，我们将：1)识别和表征cngc介导的信号转导成分，2)研究cngc的调控，以及3)研究激素串扰和环境对植物免疫的影响。对于目的1，我们鉴定了rdd1，它是CNGC2零突变体dnd1（无死亡防御1）的一个抑制因子，它表现出自身免疫表型。因此，RDD1可能作用于CNGC2介导的抗病信号的下游或影响CNGC2信号的信号级联。这项工作将在分子水平上研究RDD1在cngc介导的抗性信号传导中的作用。此外，我们确定了另外五种抑制因子，我们将对其进行表征和鉴定。第二部分讨论了中国对天然气天然气的监管。动物CNGC研究表明，CaM结合负向调控CNGC；然而，CaM对植物CNGCs的调控尚不清楚。在本研究中，我们将确定植物CNGCs中的CaM结合域，并表征它们在病原体感染时的结合动力学。目的III研究水杨酸（SA）、脱落酸（ABA）和生长素之间的串扰。SA是植物免疫过程中重要的信号分子，SA、ABA和生长素之间的复杂串扰对植物抗病性有重要影响。这表明一个协调的信号网络允许植物分配资源来对抗病原体，应对非生物胁迫并维持生长。此外，我们目前的数据表明，环境因素影响CNGC信号。为了确定这种串扰的关键节点，我们对ABA和sa诱导蛋白进行了酵母双杂交分析，发现了几种可能介导串扰的候选相互作用。在本文中，我们将分析这些候选药物的分子机制，并进行SA与生长素信号传导成分之间的相互作用组分析。预测意义：本提案的结果将显著有助于我们了解cngc介导的植物免疫应答。此外，植物免疫中的激素串扰与环境条件有关，已成为一个重要的研究课题。目前，尽管大量使用昂贵的农用化学品，但植物病害仍造成每年重大的农产品损失。此外，不稳定的气候条件可能增加疾病暴发的频率。因此，拟议的计划将对农业研究产生重大影响，以提高植物的抗病性，促进人类社会的可持续发展。

BACKGROUND:Due to global population growth, increasing food production is an urgent issue in the world. However, significant amounts of agricultural products are lost annually due to plant disease in spite of the extensive usage of agrochemicals that may harm the environment. Thus, the understanding of plant immunity and finding ways to enhance natural resistance of plans is the key for security of food production and a healthy environment in the future. To date, we have shown that the cyclic nucleotide-gated ion channels CNGC11 and 12 play significant roles in plant immunity and we have analyzed their structure-function relationships. We also used a CNGC mutant to examine signal crosstalk. In animals, CNGCs affect visual and olfactory signal transduction and are regulated by the calcium sensor protein calmodulin (CaM). However, in plants, the regulators of CNGCs and their downstream signal transduction cascades remain largely unknown. RESEARCH OBJECTIVE AND OUTLINE:The long-term goal of my research is to understand the signal transduction pathways and networks integrating environmental stresses with pathogen infection at the molecular level. To this aim, over the next 5 years we will: I) Identify and characterize components of CNGC-mediated signal transduction, II) Investigate the regulation of CNGCs, and III) Investigate hormonal crosstalk and environmental effects on plant immunity.For aim I, we identified rdd1, a suppressor of the CNGC2 null mutant dnd1 (defense no death1), which displays an autoimmune phenotype. Thus, RDD1 likely acts downstream of CNGC2-mediated disease resistance signaling or on a signaling cascade that affects CNGC2 signaling. The proposed work will investigate the involvement of RDD1 in CNGC-mediated resistance signaling at the molecular level. Furthermore, we identified five additional suppressors, which we will characterize and identify. Aim II addresses regulation of CNGCs by CaM. Animal CNGC research showed that CaM binding negatively regulates CNGCs; however, the regulation of plant CNGCs by CaM remains unclear. In this proposal, we will determine the CaM binding domains in plant CNGCs and characterize their binding kinetics upon pathogen infection.Aim III addresses the crosstalk between salicylic acid (SA), abscisic acid (ABA) and auxin. SA is a key signaling molecule in plant immunity and the complex crosstalk among SA, ABA and auxin strongly influences disease resistance. This suggests a coordinated signaling network allowing plants to allocate resources to fight pathogens, respond to abiotic stresses and maintain growth. In addition, our current data indicate that environmental factors affect CNGC signaling. To identify the key nodes in this crosstalk, we conducted a yeast two-hybrid analysis of ABA- and SA-inducible proteins and discovered several candidate interactions that may mediate crosstalk. In this proposal, we will analyze molecular mechanisms of these candidates and conduct another interactome analysis between SA and auxin signaling components.PREDICTED SIGNIFICANCE:The outcome of this proposal will significantly contribute to our understanding of CNGC-mediated plant immune responses. Furthermore, hormonal crosstalk in plant immunity has emerged as an important topic, since it is related to environmental conditions. Currently, plant diseases cause significant annual losses of agricultural products, despite the extensive use of costly agro-chemicals. In addition, unstable climate conditions may increase the frequency of disease outbreaks. Thus, the proposed program will significantly impact agricultural research to improve plant disease resistance for a sustainable human society.