The morphogenesis of lobed plant cells in the mesophyll and epidermis: organization and distinct roles of cortical microtubules and actin filaments

Authors

  • Emmanuel Panteris,

    1. University of Athens, Faculty of Biology, Department of Botany, Athens GR−15784, Greece
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  • Basil Galatis

    Corresponding author
    1. University of Athens, Faculty of Biology, Department of Botany, Athens GR−15784, Greece
      Author for correspondence: Basil Galatis Tel: +30 210 7274646 Fax: +30 210 7274702 Email: bgalatis@biol.uoa.gr
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Author for correspondence: Basil Galatis Tel: +30 210 7274646 Fax: +30 210 7274702 Email: bgalatis@biol.uoa.gr

Summary

The morphogenesis of lobed plant cells has been considered to be controlled by microtubule (MT) and/or actin filament (AF) organization. In this article, a comprehensive mechanism is proposed, in which distinct roles are played by these cytoskeletal components. First, cortical MT bundles and, in the case of pavement cells, radial MT arrays combined with MT bundles determine the deposition of local cell wall thickenings, the cellulose microfibrils of which copy the orientation of underlying MTs. Cell growth is thus locally prevented and, consequently, lobes and constrictions are formed. Arch-like tangential expansion is locally imposed at the external periclinal wall of pavement cells by the radial arrangement of cellulose microfibrils at every wall thickening. Whenever further elongation of the original cell lobes occurs, AF patches assemble at the tips of growing lobes. Intercellular space formation is promoted or prevented by the opposite or alternate, respectively, arrangement of cortical MT arrays between neighboring cells. The genes that are possibly involved in the molecular regulation of the above morphogenetic procedure by MT and AF array organization are reviewed.

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