Fine Structural Analysis of Brefeldin A-Induced Compartment Formation After High-Pressure Freeze Fixation of Maize Root Epidermis: Compound Exocytosis Resembling Cell Plate Formation during Cytokinesis |
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| Authors: | G Hause J Samaj D Menzel F Baluska |
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| Institution: | 1.Microscopy Unit; Biocenter; Martin-Luther-University Halle-Wittenberg; Halle, Germany;2.Institute of Cellular and Molecular Botany; Reinische Friedrich-Wilhelms-Universität; Bonn, Germany;3.Institute of Plant Genetics and Biotechnology; Slovak Academy of Sciences; Nitra, Slovak Republic;4.Institute of Botany; Slovak Academy of Sciences; Bratislava, Slovak Republic |
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| Abstract: | Formation of large perinuclear brefeldin A (BFA)-induced compartments is a characteristic feature of root apex cells, but it does not occur in shoot apex cells. BFA-induced compartments have been studied mostly using low resolution fluorescence microscopy techniques. Here, we have employed a high-resolution ultrastructural method based on ultra rapid freeze fixation of samples in order to study the formation of BFA-induced compartments in intact maize root epidermis cells in detail. This approach reveals five novel findings. Firstly, plant TGN/PGN elements are not tubular networks, as generally assumed, but rather vesicular compartments. Secondly, TGN/PGN vesicles interact with one another extensively via stalk-like connections and even fuse together via bridge-like structures. Thirdly, BFA-induced compartments are formed via extensive homotypic fusions of the TGN/PGN vesicles. Fourthly, multivesicular bodies (MVBs) are present within the BFA-induced compartments. Fifthly, mitochondria and small vacuoles accummulate abundantly around the large perinuclear BFA-induced compartments.Key Words: brefeldin A, BFA-induced compartments, golgi, endosomes, root apex |
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