Programmed cell death during the formation of rhytidome and interxylary cork in roots of Astragalus membranaceus (Leguminosae)
Programmed cell death during the formation of rhytidome and interxylary cork in roots of Astragalus membranaceus (Leguminosae)
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黄芪（豆科）根部节纹和木栓形成过程中的程序性细胞死亡
DOI：
10.1002/jemt.23696
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发表时间：
2021-01-17
影响因子：
2.5
通讯作者：
Peng, Huasheng
中科院分区：
文献类型：
--
作者：
Han, Xiaojing;Zhou, Yafu;Peng, Huasheng
细胞程序性死亡（Programmed cell death， PCD）是植物在生物或非生物胁迫下发生的一种高度调控和活跃的细胞死亡过程，在整个植物生命过程中起着至关重要的作用。本研究旨在提供黄芪根木栓形成的发育解剖学特征。并随后显示细胞形态学证据表明PCD参与了皱膜和木栓间的发育。利用光镜研究了蒙古黄芪多年生鲜主根的皱皮壳和间木栓的发育解剖，利用荧光显微镜和透射电镜研究了皱皮壳和间木栓发育过程中的PCD。组织学上观察到，根次生韧皮部和木质部的薄壁细胞恢复了分生组织的能力，并发育为皱皮室和木质部间栓。细胞学上观察到细胞核畸形、液泡消失、线粒体变性、囊泡充盈等超微结构特征。在根中，韧皮部薄壁细胞的细胞核在初潮期至初潮期呈末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）阳性，而在成熟期呈4′，6‐二氨基- 2‐苯基吲哚二盐化（DAPI）阴性。在木质部薄壁细胞的TUNEL实验中，从木质部早期到木质部软木形成阶段均表现出阳性特征，而在木质部成熟期则表现出DAPI‐阴性特征。凝胶电泳显示DNA的切割是随机的。我们的研究结果表明，节律丘和木栓的形成参与了PCD过程。
Programmed cell death (PCD) plays a critical role throughout the lives of plants, it is regarded as a highly regulated and active process of plant cell death during the times of biotic or abiotic stress. This study aims to provide developmental anatomical characteristics of the interxylary cork formation in the roots of Astragalus. membranaceus var. mongholicus, and to subsequently show cytomorphological evidence that PCD is involved in the development of rhytidome and interxylary cork. The developmental anatomy of rhytidome and interxylary cork of the perennial fresh main root of A. membranaceus var. mongholicus was studied using light microscopy, whereas the PCD in the development of rhytidome and interxylary cork was studied using fluorescence microscopy and transmission electron microscopy. Histologically, it was observed that the parenchyma cells of secondary phloem and xylem in roots recovered their meristematic ability, and later developed into rhytidome and interxylary cork. Cytologically, ultrastructural characteristics such as nucleus malformation, vacuole disappearance, mitochondrial degeneration, and vesicle filling were observed. In roots, the nucleus of the phloem parenchyma cells were terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling (TUNEL)‐positive from the pre‐rhytidome stage to the formation of rhytidome stage and 4′,6‐diamidino‐2‐phenylindole dihydrochloride (DAPI)‐negative during the mature rhytidome stage. The TUNEL assay of the xylem parenchyma cells showed positive characteristics from the early stage of interxylary cork formation to the interxylary cork formation stage, whereas DAPI‐negative characteristics were observed in the mature interxylary cork. Gel electrophoresis showed that DNA cleavage was random. Our results indicated that the formation of the rhytidome and interxylary cork involved the PCD process.