The Guard Cell as a Paradigm to Dissect the Role of the Actin Cytoskeleton in Plant Immunity

植物通过利用一些预先形成的和可诱导的信号传导过程来响应环境；有趣的是，许多这些回答都有一些共同的特征。例如，植物对水分供应限制和病原体感染所施加的压力的反应是关闭气孔——叶片表面专门的气孔，气孔不仅在气体交换中起作用，而且是许多病原体的主要进入点。因此，在关闭气孔时，植物限制了水分的流失以及潜在致病微生物的进入。与激素调节人类细胞过程的方式大致相同，植物激素已被证明可以控制植物对环境变化的反应，包括上述对环境和致病性应激源的反应。该项目的长期目标是确定植物胁迫信号如何被调节和转导以引发植物免疫反应。为了做到这一点，目前的工作将利用植物气孔作为一个易于处理的标记，以了解细胞中的化学变化是如何被感知和最终转导来调节细胞运动、结构和形状的物理和机械变化的。有了这些知识，研究人员将确定植物用来监测环境潜在威胁的主要成分，而且，对这些变化做出快速反应。这项研究的最终目标是揭示植物赖以生存的机制，并通过传播更广泛的影响，将这些数据传达给社会，以教育公众在粮食生产和安全领域。肌动蛋白因其在所有真核生物中定义细胞形状和驱动细胞器和大分子运动的作用而闻名。此外，作为植物和动物免疫系统的一个组成部分，肌动蛋白细胞骨架已被证明对多种病原体衍生的激发子有反应。然而，肌动蛋白在植物免疫中的作用机制尚不清楚。本研究将利用pi实验室最近开发的方法和资源，利用气孔保护细胞作为实验范例和一系列定量细胞生物学和遗传学方法，确定肌动蛋白作为植物免疫网络关键组成部分的贡献和作用。植物气孔保护细胞是一种有吸引力的、可调节的、与生物相关的细胞类型，可以进一步研究肌动蛋白动力学在植物免疫中的作用。本文描述的工作将定义基本生理过程（例如，激素信号，病原体感知）与宿主免疫反应之间的关系。该项目的预期影响是：1)阐明动态响应和功能的过程，作为细胞之间的切换，病原体，免疫和激素信号；2)控制细胞骨架组织和气孔保护细胞动力学的关键植物调控节点的磷酸化调控和病原体靶向；3)肌动蛋白在关键的气孔信号通路中的作用。

Plants respond to the environment by utilizing a number of preformed and inducible signaling processes; interestingly, many of these responses share a number of common features. For example, plants respond to stresses imposed by limitations in water availability and pathogen infection by closing stomata- specialized pores on the leaf surface that not only function in gas exchange, but also are primary points of entry to many pathogens. Thus, in closing stomata plants restrict water loss as well as entry to potentially pathogenic microorganisms. Much in the same way that hormones regulate human cellular processes, plant hormones have been demonstrated to control plant response to changes in the environment, including the above noted response to environmental and pathogenic stressors. The long range goal of this project is to define how plant stress signals are regulated and transduced to elicit the plant immune response. To do this, the current work will use the plant stomata as a tractable marker to understand how chemical changes in a cell are perceived and ultimately transduced to regulate physical and mechanical changes in cellular movement, architecture, and shape. With this knowledge, the investigators will define the principle components that plants use to monitor their environments for potential threats, and moreover, to rapidly respond to these changes. The ultimate goal of this research is to uncover mechanisms that plants use to survive, and through dissemination of the Broader Impacts, to communicate these data to society to educate general public in the area of food production and security. Actin is well known for its roles in defining cell shape and powering movement of organelles and macromolecules in all eukaryotic organisms. Additionally, as a component of the immune system of both plants and animals, the actin cytoskeleton has been demonstrated to respond to a variety of pathogen-derived elicitors. However, the mechanism(s) underpinning the role of actin in plant immunity is lacking. This study will leverage recently developed methods and resources in the PIs' laboratories to define, using the stomatal guard cell as an experimental paradigm and a series of quantitative cell biology and genetic approaches, the contribution and role of actin as a key component of the plant immune network. Plant stomatal guard cells are an attractive, amenable, and biologically relevant cell type for further dissecting the role of actin dynamics in plant immunity. The work described herein will define the relationships that link basic physiological processes (e.g., hormone signaling, pathogen perception) to the host immune response. Anticipated impacts of this project are: 1) the elucidation of the processes that dynamically respond to and function as cellular switches between, pathogen, immunity, and hormone signaling; 2) the phospho-regulation and pathogen targeting of a key plant regulatory node that controls cytoskeletal organization and stomatal guard cell dynamics; and 3) a demonstration of a role for actin in critical stomatal-based signaling pathways.