Adamakis Ioannis-Dimosthenis S, Eleftheriou Eleftherios P
Department of Botany, School of Biology, National and Kapodistrian University of Athens, 157 84 Athens, Greece.
Department of Botany, School of Biology, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
Plants (Basel). 2019 Mar 11;8(3):62. doi: 10.3390/plants8030062.
Previous studies have shown that excess tungsten (W), a rare heavy metal, is toxic to plant cells and may induce a kind of programmed cell death (PCD). In the present study we used transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) to investigate the subcellular malformations caused by W, supplied as 200 mg/L sodium tungstate (Na₂WO₄) for 12 or 24 h, in root tip cells of (pea), The objective was to provide additional evidence in support of the notion of PCD induction and the presumed involvement of reactive oxygen species (ROS). It is shown ultrastructurally that W inhibited seedling growth, deranged root tip morphology, induced the collapse and deformation of vacuoles, degraded Golgi bodies, increased the incidence of multivesicular and multilamellar bodies, and caused the detachment of the plasma membrane from the cell walls. Plastids and mitochondria were also affected. By TEM, the endoplasmic reticulum appeared in aggregations of straight, curved or concentric cisternae, frequently enclosing cytoplasmic organelles, while by CLSM it appeared in bright ring-like aggregations and was severely disrupted in mitotic cells. However, no evidence of ROS increase was obtained. Overall, these findings support the view of a W-induced vacuolar destructive PCD without ROS enhancement.
先前的研究表明，过量的钨（一种稀有重金属）对植物细胞有毒，并可能诱导一种程序性细胞死亡（PCD）。在本研究中，我们使用透射电子显微镜（TEM）和共聚焦激光扫描显微镜（CLSM）来研究以200 mg/L钨酸钠（Na₂WO₄）供应12或24小时所导致的、在豌豆根尖细胞中由钨引起的亚细胞畸形。目的是提供额外的证据来支持PCD诱导的概念以及活性氧（ROS）的假定参与。超微结构显示，钨抑制幼苗生长，扰乱根尖形态，诱导液泡塌陷和变形，降解高尔基体，增加多囊泡体和多层体的发生率，并导致质膜与细胞壁分离。质体和线粒体也受到影响。通过TEM观察，内质网呈现为直的、弯曲的或同心的扁平囊泡聚集体，经常包裹着细胞质细胞器，而通过CLSM观察，内质网呈现为明亮的环状聚集体，并且在有丝分裂细胞中严重破坏。然而，未获得ROS增加的证据。总体而言，这些发现支持了钨诱导液泡破坏性PCD而无ROS增强的观点。
