Atlantic Food and Horticulture Research Center, Agriculture and Agri-Food Canada, Kentville, Nova Scotia, B4N 1J5, Canada.
Am J Bot. 2009 May;96(5):865-76. doi: 10.3732/ajb.0800343. Epub 2009 Mar 20.
Programmed cell death (PCD) is required for many morphological changes, but in plants it has been studied in much less detail than in animals. The unique structure and physiology of the lace plant (Aponogeton madagascariensis) is well suited for the in vivo study of developmental PCD. Live streaming video and quantitative analysis, coupled with transmission electron microscopy, were used to better understand the PCD sequence, with an emphasis on the chloroplasts. Dividing, dumbbell-shaped chloroplasts persisted until the late stages of PCD. However, the average size and number of chloroplasts, and the starch granules associated with them, declined steadily in a manner reminiscent of leaf senescence, but distinct from PCD described in the Zinnia tracheary element system. Remaining chloroplasts often formed a ring around the nucleus. Transvacuolar strands, which appeared to be associated with chloroplast transport, first increased and then decreased. Mitochondrial streaming ceased abruptly during the late stages of PCD, apparently due to tonoplast rupture. This rupture occurred shortly before the rapid degradation of the nucleus and plasma membrane collapse, in a manner also reminiscent of the Zinnia model. The presence of numerous objects in the vacuoles suggests increased macro-autophagy before cell death. These objects were rarely observed in cells not undergoing PCD.
程序性细胞死亡（PCD）是许多形态变化所必需的，但在植物中，它的研究远不如在动物中详细。 lace 植物（Aponogeton madagascariensis）的独特结构和生理学非常适合活体研究发育中的 PCD。实时视频和定量分析，加上透射电子显微镜，用于更好地理解 PCD 序列，重点是叶绿体。分裂的哑铃形叶绿体一直持续到 PCD 的后期。然而，叶绿体的平均大小和数量，以及与之相关的淀粉颗粒，以类似于叶片衰老的方式但又不同于在 Zinnia 导管元件系统中描述的 PCD 方式稳步下降。残留的叶绿体通常在核周围形成一个环。似乎与叶绿体运输有关的液泡间连丝首先增加，然后减少。线粒体流在 PCD 的后期突然停止，显然是由于液泡膜破裂所致。这种破裂发生在细胞核和质膜迅速降解之前，这也类似于 Zinnia 模型。液泡中存在大量物体表明细胞死亡前发生了大量的巨自噬。在不经历 PCD 的细胞中很少观察到这些物体。
