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。发育性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。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发育性PCD的理想模型系统。蕾丝植物原产于马达加斯加，在水族馆条件下很难生长。我已经成功地开发了一种无性系培养的蕾丝植物系统来研究发育性PCD。我们仍然不知道在叶片发育的适当阶段是什么线索触发PCD，信号通路和分子机制。因此，我的总体目标是利用生物化学和显微技术，通过以下四种方法确定诱导穿孔的因素和调节穿孔的机制：1)研究在穿孔过程中肌动蛋白细胞骨架的变化；2)比较同一种植物的诱导PCD和发育PCD；3)制定蕾丝植物的稳态和瞬态转化方案；4)考察钙抑制剂对植物细胞死亡的影响。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 (holes) 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. 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. Lace plant is native to Madagascar and difficult to grow in aquarium conditions. I have successfully developed an axenically cultured lace plant system to work on developmental PCD. We still do not know what cues trigger PCD at the appropriate stage of leaf development, the signaling pathways, and the molecular mechanisms. Therefore, my overall aim is to identify factors inducing perforations and the mechanisms that regulate the PCD in lace plant using biochemical and microscopical techniques with four approaches: 1) To investigate changes in the actin cytoskeleton during lace plant PCD; 2) To compare induced and developmental PCD in the same plant species; 3) To develop both a stable and transient transformation protocol for lace plant; 4) To test the effect of calcium inhibitors on cell death in plants. These results will help us to determine whether there are common mechanisms between animal and plant PCD or whether they evolved independently.