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Asymmetric cytokinesis guide the development of pseudomonads in Rhynchospora pubera (Cyperaceae)

Authors

  • Juca Abramo Barrera San Martin,

    1. Laboratory of Electron Microscopy and Microanalysis, PROPPG, State University of Londrina, 86051990 Londrina, Brazil
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  • Celia Guadalupe Tardeli de Jesus Andrade,

    1. Laboratory of Electron Microscopy and Microanalysis, PROPPG, State University of Londrina, 86051990 Londrina, Brazil
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  • Alexandra Antunes Mastroberti,

    1. Laboratory of Plant Anatomy, Botany Department, Biosciences Institute, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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  • Jorge Ernesto de Araújo Mariath,

    1. Laboratory of Plant Anatomy, Botany Department, Biosciences Institute, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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  • André Luís Laforga Vanzela

    Corresponding author
    • Laboratory of Biodiversity and Ecosystems Restorations, State University of Londrina, 86051990 Londrina, Brazil
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Corresponding author: e-mail: andrevanzela@uel.br

Abstract

The late stages of microsporogenesis in the family Cyperaceae are marked by the formation of an asymmetrical tetrad, degeneration of three of the four nuclei resulting from meiosis and the formation of pseudomonads. In order to understand the cytological changes involved in the development of pseudomonads, a combination of 11 different techniques (conventional staining, cytochemistry procedures, immunofluorescence, FISH and transmission electron microscopy: TEM) were used to study the later stages of microsporogenesis in Rhynchospora pubera. The results demonstrated the occurrence of two cytoplasmic domains in the pseudomonads, one functional and the other degenerative, which are physically and asymmetrically separated by cell plate with an endomembrane system rich in polysaccharides. Other changes associated with endomembrane behaviour were observed, such as a large number of lipid droplets, vacuoles containing electron-dense material and concentric layers of endoplasmic reticulum. Concomitant with the isolation of degenerative nuclei, the tapetal cells also showed evidence of degeneration, indicating that both tissues under programmed cell death (PCD), as indicated by immunofluorescence and TEM procedures. The results are significant because they associate cellular polarisation and asymmetry with different cytoplasmic domains, and hence open new possibilities for studying cellular compartmentalisation and PCD.

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