Study of chloroplast stromules during PCD and inter-organellar communication

描述（由申请人提供）：在动物和植物中，需要各种类型的程序性细胞死亡（PCD）来去除正在死亡、感染或不再需要的细胞。植物先天免疫依赖于一种称为过敏反应（HR-PCD）的特殊类型的PCD来限制病原体并预防疾病。HR-PCD的激活和执行需要快速的细胞重编程和细胞内不同隔室之间的协调。有趣的是，我们的研究结果表明，在HR-PCD，叶绿体发出高度动态的管状延伸称为“基质”，物理连接叶绿体的细胞核，可能增加他们的沟通。关于小孢子形成所需的细胞机制或小孢子在任何生物过程中的精确功能知之甚少。本文提出的研究的具体目标是：1）采用候选、遗传和蛋白质组学方法来鉴定胚座诱导所需的新因子，并阐明它们在HR-PCD和先天免疫过程中的生物学作用。2)在HR-PCD过程中，基质在产生和传播促细胞死亡信号（如过氧化氢和水杨酸）过程中的功能将被揭示。3)使用先进的显微镜技术对叶绿体与核的关联进行深入研究，将揭示HR-PCD和先天免疫过程中细胞器间通信的重要性。这里概述的研究无疑将推进先天免疫领域，为研究人员提供一种新颖、有凝聚力的HR-PCD模型，该模型整合了叶绿体、线粒体和细胞核的基本功能，以及它们如何沟通以协调细胞重编程，从而导致HR-PCD和先天免疫。此外，这些研究将揭示更广泛的见解，在PCD和细胞器间的通信中的作用的基质。类似于在多模型系统中的研究，如人类细胞系，C。线虫、果蝇和酵母都增加了我们对PCD的理解，在植物中的拟议研究将增加对平衡细胞生死的保守和不同机制的新见解。

DESCRIPTION (provided by applicant): In both animals and plants, various types of programmed cell death (PCD) are required for the removal of cells that are dying, infected or no longer needed. Plant innate immunity relies on a specialized type of PCD called the hypersensitive response (HR-PCD) to restrict pathogens and prevent disease. Activation and execution of HR-PCD requires rapid cellular reprogramming and the coordination between different compartments within the cell. Interestingly, our results indicate that during HR-PCD, chloroplasts send out highly dynamic tubular extensions called "stromules" that physically connect chloroplasts to nuclei, possibly augmenting their communication. Very little is known about the cellular machinery required for stromule formation or the precise function of stromules during any biological process. The specific aims of the proposed research here will 1) employ candidate, genetic and proteomic approaches to identify novel factors required for stromule induction and will elucidate their biological role during HR-PCD and innate immunity. 2) The function of stromules during the generation and propagation of pro-cell death signals, such as hydrogen peroxide and salicylic acid, during HR-PCD will be revealed. 3) An in-depth study of chloroplast-to-nuclear associations using advanced microscopy techniques will shed light on the importance of inter-organellar communication during HR-PCD and innate immunity. The research outlined here will undoubtedly advance the field of innate immunity by providing researchers with a novel, cohesive model for HR-PCD that integrates the essential functions of chloroplasts, mitochondria and nuclei, and how they communicate to coordinate cellular reprogramming that leads to HR-PCD and innate immunity. Furthermore, these studies will reveal broader insights into the role of stromules in PCD and inter-organellar communication. Similar to how studies in multiple model systems, such as human cell lines, C. elegans, Drosophila and yeast, have all added to our understanding of PCD, the proposed studies here in plants will add new insight into conserved and divergent mechanisms that balance the life and death of a cell.