Journal Article

Analysis of Early Processes in Wound-Induced Vascular Regeneration using <i>TED3</i> and <i>ZeHB3</i> as Molecular Markers

Chikako Nishitani, Taku Demura and Hiroo Fukuda

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 1, pages 79-90
Published in print January 2002 | ISSN: 0032-0781
Published online January 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf008
Analysis of Early Processes in Wound-Induced Vascular Regeneration using TED3 and ZeHB3 as Molecular Markers

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  • Plant Sciences and Forestry

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Interruption of the vascular bundles of Zinnia internodes induced transdifferentiation of cells into tracheary elements (TEs) or sieve elements (SEs) within 4 d of wounding. The early stage of the regeneration processes was analyzed using two molecular marker genes, TED3 and ZeHB3, which are expressed specifically in TE precursor cells and immature phloem cells, respectively. An increase in the numbers of TED3 and ZeHB3 mRNA-expressing cells always preceded an increase in the numbers of TEs and SEs formed. The earliest sign of vascular differentiation was the appearance 24 h after wounding of a layer(s) of TED3 mRNA-expressing cells in the inter- and intrafascicular cambial-like regions along the severed vascular bundles. In contrast, the number of ZeHB3 mRNA-expressing cells decreased dramatically along the severed bundles 24 h after wounding, and increased again 36 h after wounding. These results clearly indicate that xylem and phloem differentiation are not synchronized during vascular regeneration. Treatment with 10–3 M colchicine abolished the expression of ZeHB3 mRNA in pith parenchyma, but not TED3 mRNA; this suggests that cell division is a prerequisite for the transdifferentiation of pith parenchymal cells into immature phloem cells expressing ZeHB3. In contrast, transdifferentiation of pith parenchymal cells to TE precursor cells does not require preceding cell division. However, the inhibition of cell division prevented the formation of both radial files of TEs and the cambial-like layer(s) of TED3 mRNA-expressing cells, and, ultimately, vascular regeneration altogether. These results imply that wound-induced cambial-like activity in and between severed vascular bundles is essential for vascular regeneration.

Keywords: Key words: Cell division — Sieve element — Tracheary element — Vascular regeneration — Wound — Zinnia.; Abbreviations: TE, tracheary element; SE, sieve element.

Journal Article.  6179 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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