Allen N S, Bennett M N
Department of Botany, North Carolina State University, Raleigh 27695-7612, USA.
Scanning Microsc Suppl. 1996;10:177-86; discussion 186-7.
Confocal and video micrographs of living and fixed alfalfa roots, onion epithelial and pear pollen cells illustrate the architecture of the cytoskeleton and endoplasmic reticulum in plant cells. Fixation of plant tissues to preserve cytoplasmic structure poses special problems. When possible, emphasis should be placed on the imaging of structures in stained living cells over time. The early events that occur when Nod factors or bacteria elicit nodule formation in alfalfa roots will illustrate several approaches to plant cell fixation, staining and imaging. The first observable events after Nod factor stimulation occur in root hairs and are changes in rates of cytoplasmic streaming, nuclear movements, and changes in the shape of the vacuole. Within ten minutes, the endoplasmic reticulum shifts position towards the tip of the root hair. For comparison, the endoplasmic reticulum localization in pollen tubes and onion epithelial cells will be illustrated. The actin cytoskeleton undergoes a series of changes over a twelve hour period. These changes in the cytoskeleton are spatially and temporally correlated with the observed growth changes of the root hairs. This dynamic change of the actin filament and endoplasmic reticulum and associated secretory vesicles in these root hairs suggests a mechanism for the observed root hair growth changes.
共聚焦显微镜和视频显微镜拍摄的活体和固定的苜蓿根、洋葱上皮细胞和梨花粉细胞的显微照片，展示了植物细胞中细胞骨架和内质网的结构。固定植物组织以保存细胞质结构存在特殊问题。只要有可能，就应着重对染色的活细胞中的结构进行长时间成像。苜蓿根中根瘤菌因子或细菌引发根瘤形成时发生的早期事件，将说明植物细胞固定、染色和成像的几种方法。根瘤菌因子刺激后最早可观察到的事件发生在根毛中，表现为细胞质流动速率、细胞核运动以及液泡形状的变化。十分钟内，内质网会向根毛尖端移动。作为对比，还将展示花粉管和洋葱上皮细胞中内质网的定位。肌动蛋白细胞骨架在十二小时内会发生一系列变化。这些细胞骨架的变化在空间和时间上与观察到的根毛生长变化相关。这些根毛中肌动蛋白丝、内质网及相关分泌小泡的动态变化，提示了观察到的根毛生长变化的一种机制。
