Research PGR: The Temperature-Immunity Nexus: Activation of Immunity by Low Temperature

植物病害通常会对作物生产力造成重大损失。因此，植物生物学研究的一个基本目标是确定赋予植物病原体免疫力的基因，并确定它们如何在响应环境刺激时受到调节。关于免疫基因的性质以及它们在应对病原体攻击时是如何被调节的，我们已经了解了很多；也就是说，对生物压力的反应。然而，最近的研究已经确定，免疫基因也可以被诱导以应对非生物应激，即低温。在这项提案中，研究人员将研究温度与免疫的关系：植物免疫是如何受温度调节的。这种现象受到的关注相对较少，但在作物和其他植物物种中已经观察到，表明这可能是一种未得到充分重视的高度保守的“先发制人”生存策略；也就是说，植物免疫被激活是对非生物胁迫的反应，否则有可能增加植物对病原体感染的易感性。鉴于人们对气候变化的日益关注以及这些变化可能对作物生产力产生的负面影响，了解免疫基因的非生物调控和生物调控之间的联系非常重要，因为这些信息有可能用于开发新的方法来增强植物对环境胁迫的适应能力。拟南芥钙调素结合转录激活因子（CAMTA）转录因子是水杨酸（SA）介导的免疫的主要调节因子。在中等温度（约22℃）下生长的健康植物中，CAMTA蛋白抑制sa免疫基因的表达。然而，当植物暴露于病原体——一种生物压力，或者正如该研究小组最近所证明的那样，低温（约4摄氏度）——一种非生物压力下，CAMTA“刹车”就会“失效”，导致防御基因的诱导。该项目的一个基本目标是确定拟南芥CAMTA3蛋白的抑制活性是如何受温度调节的。特别是，将使用生化，蛋白质组学，遗传学和基因组学方法的组合来确定：1)CAMTA3蛋白如何在中等温度下抑制靶基因的表达；2)低温如何抑制CAMTA3的抑制活性；3)低温以外的非生物因素是否会使CAMTA3制动器失活。该项目的另一个重要组成部分是将拟南芥中CAMTA对免疫基因调控的研究扩展到一系列重要作物物种，并确定植物对低温和其他非生物胁迫的免疫调控在多大程度上是保守的。综上所述，这些调查的结果有望扩展我们对控制植物宿主防御机制的基本生命规则的认识。该奖项由植物基因组研究计划和植物生物相互作用计划共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Plant diseases routinely cause significant losses in crop productivity. Thus, a fundamental goal of plant biology research is to identify genes that impart immunity against plant pathogens and to determine how they are regulated in response to environmental stimuli. Much has been learned about the nature of immunity genes and how they are regulated in response to pathogen attack; i.e., in response to biotic stress. However, recent studies have established that immunity genes can also be induced in response to abiotic stress, namely cold temperatures. In this proposal, the investigators will study this temperature-immunity nexus: how plant immunity is regulated by temperature. This phenomenon has received relatively little attention, but has been observed in crop and other plant species indicating that it may be an underappreciated highly conserved “preemptive” survival strategy; i.e., that plant immunity is activated in response to an abiotic stress that otherwise has the potential to increase the susceptibility of the plant to infection by pathogens. Given the ever-increasing concerns about climate change and the possible negative effects that these changes could have on crop productivity, it is of great importance to understand the connectivity between abiotic and biotic regulation of immunity genes as such information has the potential to be used to develop novel approaches to enhance plant resilience to environmental stresses.The Arabidopsis Calmodulin-binding Transcription Activator (CAMTA) transcription factors are master regulators of salicylic acid (SA)-mediated immunity. In healthy plants grown at moderate temperature (ca. 22C), the CAMTA proteins repress expression of SA-immunity genes. However, when plants are exposed to pathogens—a biotic stress—or, as has recently been demonstrated by this research team, low temperature (ca. 4C)—an abiotic stress—the CAMTA “brake” is “disabled” resulting in the induction of defense genes. A fundamental goal of this project is to determine how the repression activity of the Arabidopsis CAMTA3 protein is regulated by temperature. In particular, a combination of biochemical, proteomic, genetic and genomic approaches will be used to determine: 1) how the CAMTA3 protein represses expression of target genes at moderate temperature; 2) how low temperature suppresses CAMTA3 repression activity; and 3) whether abiotic factors other than low temperature can inactivate the CAMTA3 brake. An additional integral component of this project is to extend the studies on CAMTA regulation of immunity genes in Arabidopsis to a range of important crop species and to determine the extent to which regulation of immunity in response to low temperature and other abiotic stresses is conserved in plants. Taken together, the results from these lines of investigation promise to expand our knowledge of the basic Rules of Life that govern host defense mechanisms in plants.This award was co-funded by the Plant Genome Research Program and Plant Biotic Interactions Program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.