Elsevier

Developmental Biology

Volume 215, Issue 2, 15 November 1999, Pages 407-419
Developmental Biology

Regular Article
Cell Cycling and Cell Enlargement in Developing Leaves of Arabidopsis

https://doi.org/10.1006/dbio.1999.9443Get rights and content
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Abstract

Cell cycling plays an important role in plant development, including: (1) organ morphogenesis, (2) cell proliferation within tissues, and (3) cell differentiation. In this study we use a cyclin::β-glucuronidase reporter construct to characterize spatial and temporal patterns of cell cycling at each of these levels during wild-type development in the model genetic organism Arabidopsis thaliana (Columbia). We show that a key morphogenetic event in leaf development, blade formation, is highly correlated with localized cell cycling at the primordium margin. However, tissue layers are established by a more diffuse distribution of cycling cells that does not directly involve the marginal zone. During leaf expansion, tissue proliferation shows a strong longitudinal gradient, with basiplastic polarity. Tissue layers differ in pattern of proliferative cell divisions: cell cycling of palisade mesophyll precursors is prolonged in comparison to that of pavement cells of the adjacent epidermal layers, and cells exit the cycle at different characteristic sizes. Cell divisions directly related to formation of stomates and of vascular tissue from their respective precursors occur throughout the period of leaf extension, so that differing tissue patterns reflect superposition of cycling related to cell differentiation on more general tissue proliferation. Our results indicate that cell cycling related to leaf morphogenesis, tissue-specific patterns of cell proliferation, and cell differentiation occurs concurrently during leaf development and suggest that unique regulatory pathways may operate at each level.

Keywords

Arabidopsis
cell cycling
cell enlargement
cyclin
leaf development

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1

To whom correspondence should be addressed at Department of Botany, University of Toronto, Toronto, ON M5S 1A1. Fax: (416) 978-5878. E-mail: [email protected].