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A cytoskeletal basis for wood formation in angiosperm trees: the involvement of cortical microtubules

Chaffey, N, Barnett, J.R and Barlow, P.W (1999) 'A cytoskeletal basis for wood formation in angiosperm trees: the involvement of cortical microtubules.' Planta, 208 (1). pp. 19-30. ISSN 1432-2048

Abstract

Rearrangements of cortical microtubules (CMTs) during the differentiation of axial secondary xylem elements within taproots and shoots of Aesculus hippocastanum L. (horse-chestnut) are described. A correlative approach was employed using indirect immunofluorescence microscopy of α-tubulin in 6- to 10-μm sections and transmission electron microscopy of ultrathin sections. All cell types – fibres, vessel elements and axial parenchyma – derive from fusiform cambial cells which contain randomly oriented CMTs. At the early stages of development, fibres and axial parenchyma cells possess helically arranged CMTs, which increase in number as secondary wall thickening proceeds and simple pits develop. In contrast, incipient vessel elements are distinguished by the marking out of sites of bordered pits; these sites first appear as microtubule-free regions within the reticulum of randomly oriented CMTs that characterises their precursor fusiform cambial cells. Subsequently, the ring of CMTs which develops at the periphery of the microtubule-free region decreases in diameter as the over-arching pit border is formed. Like bordered pits, large-diameter, non-bordered pits (contact pits) which develop between vessel elements and adjacent contact ray cells originate as microtubule-free regions and are also associated with development of a ring of CMTs at the periphery. In the case of contact pits, however, there is no reduction in the diameter of the CMT ring during pit development. Tertiary cell wall thickenings are also a feature of vessel elements and appear to form at sites where bands of laterally associated, transversely oriented CMTs, separated from each other by microtubule-free zones, are found. Later, these bands of CMTs become narrower, and separate into pairs of microtubule bundles located on each side of the developing wall thickening. Development of perforations between vessel elements is also associated with the presence of a ring of CMTs at their periphery.

Item Type: Article
Keywords: Aesculus (wood formation), Cytodifferentiation, Microtubule, Secondary vascular tissue, Xylem
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QK Botany
Divisions: College of Liberal Arts
Date Deposited: 20 Jul 2015 11:54
Last Modified: 29 Apr 2016 14:12
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