Programmed cell death in plant development

程序性细胞死亡（PCD）是一种基因激活的过程，在这个过程中，选定的细胞组织自己的毁灭。PCD在所有真核生物王国中普遍存在，单细胞和多细胞生物都利用它作为正常发育的一部分或对外界刺激的反应。在植物中，PCD是生长和生存所必需的，可以由发育调节或环境诱导。发育型PCD的一个独特例子是蕾丝植物叶片的穿孔（孔）形成。这些孔位于纵脉和横脉之间，使叶子呈格状。在穿孔形成过程中，离散的细胞亚群经历PCD，而相邻的细胞保持完整。蕾丝植物原产于马达加斯加，在水族馆条件下很难生长。我成功地开发了一种无菌培养系统，用于蕾丝植物的发育性PCD。就信号通路和分子机制而言，我们仍然不知道在叶片发育的特定阶段是什么线索触发了PCD。我描述了水生植物穿孔形成过程中的细胞死亡过程，并表明这种水生植物是研究体内发育性PCD的理想模型系统。因此，我研究的长期目标是利用花边植物叶片形态发生作为模型系统，对发育性PCD的机制有一个基本的了解。这将通过以下目标来实现：植物PCD关键调控因子及信号通路的鉴定。2. 自噬在植物PCD中的作用。3. 通过遗传转化表征PCD过程中细胞器动力学。4. 花青素和其他酚类化合物与蕾丝植物PCD有关的研究。5. PCD细胞与NPCD细胞差异表达基因的鉴定。这些结果将帮助我们确定动物和植物PCD之间是否存在共同的机制，或者它们是否独立进化。

Programmed cell death (PCD) is a genetically-enabled process in which select cells organize their own destruction. PCD is ubiquitous in all eukaryotic kingdoms and is employed by both unicellular and multicellular organisms as part of normal development or in response to external stimuli. In plants, PCD is necessary for growth and survival and can either be developmentally regulated or environmentally induced. A unique example of developmental PCD is perforation (hole) formation in lace plant leaves. These holes are situated equidistantly between longitudinal and transverse veins, giving leaves a lattice-like pattern. During perforation formation, discrete subpopulations of cells undergo PCD while adjacent cells remain intact. Lace plant is native to Madagascar and difficult to grow in aquarium conditions. I have successfully developed a sterile culture system to work on developmental PCD in lace plant. We still do not know what cues trigger PCD at a specific stage of leaf development, so far as the signaling pathways and the molecular mechanisms are concerned. I have characterized the cell death process during perforation formation in lace plant and showed that this aquatic plant is an ideal model system to study developmental PCD in vivo. Therefore, the long term objective of my research is to achieve a fundamental understanding of the mechanisms involved in developmental PCD using lace plant leaf morphogenesis as a model system. This will be achieved through the following objectives: 1. Identification of key regulators and signaling pathways in lace plant PCD. 2. Determination of the role of autophagy during lace plant PCD. 3. Characterization of organelle dynamics during PCD via genetic transformation. 4. Investigation of anthocyanin and other phenolic compounds involved in lace plant PCD. 5. Identification of differentially expressed genes between PCD cells and NPCD cells. These results will help us to determine whether there are common mechanisms between animal and plant PCD or whether they evolved independently. Research in plant PCD has garnered remarkable interest in the past 20 years; however, the signaling pathways, molecular mechanisms, and genes involved in developmentally regulated PCD are still largely unknown. The proposed research will permit my lab group to advance the understanding of various mechanisms involved in plant PCD in a novel way that is unique not only in Canada, but internationally.