Journal Article

Isolation and Characterization of a Novel Peroxidase Gene <i>ZPO-C</i> Whose Expression and Function are Closely Associated with Lignification during Tracheary Element Differentiation

Yasushi Sato, Taku Demura, Ken Yamawaki, Yukina Inoue, Seiichi Sato, Munetaka Sugiyama and Hiroo Fukuda

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 4, pages 493-503
Published in print April 2006 | ISSN: 0032-0781
Published online April 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcj016
Isolation and Characterization of a Novel Peroxidase Gene ZPO-C Whose Expression and Function are Closely Associated with Lignification during Tracheary Element Differentiation

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  • Biochemistry
  • Molecular and Cell Biology
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In an attempt to elucidate the regulatory mechanism of vessel lignification, we isolated ZPO-C, a novel peroxidase gene of Zinnia elegans that is expressed specifically in differentiating tracheary elements (TEs). The ZPO-C transcript was shown to accumulate transiently at the time of secondary wall thickening of TEs in xylogenic culture of Zinnia cells. In situ hybridization indicated specific accumulation of the ZPO-C transcript in immature vessels in Zinnia seedlings. Immunohistochemical analysis using anti-ZPO-C antibody showed that the ZPO-C protein is abundant in TEs, especially at their secondary walls. For enzymatic characterization of ZPO-C, 6×His-tagged ZPO-C was produced in tobacco cultured cells and purified. The ZPO-C:6×His protein had a peroxidase activity preferring sinapyl alcohol as well as coniferyl alcohol as a substrate, with a narrow pH optimum around 5.25. The peroxidase activity required calcium ion and was elevated by increasing Ca2+ concentration in the range of 0–10 mM. An Arabidopsis homolog of ZPO-C, At5g51890, was examined for expression patterns with transgenic plants carrying a yellow fluorescent protein (YFP) gene under the control of the At5g51890 promoter. The YFP fluorescence localization demonstrated vessel-specific expression of At5g51890 in the Arabidopsis roots. Taken collectively, our results strongly suggest that ZPO-C and its homologs play an important role in lignification of secondary cell walls in differentiating TEs.

Keywords: Arabidopsis; Lignification; Peroxidase; Tracheary element differentiation; Zinnia elegans; ZPO-C; AP, alkaline phosphatase; BA, 6-benzyladenine; BSA, bovine serum albumin; CA, coniferyl alcohol; CaMV, cauliflower mosaic virus; NAA, naphthalenacetic acid; NLS, nuclear localization signal; PBS-T, phosphate-buffered saline–Tween-20; PCD, programmed cell death; pI, isoelectric point; 5′RACE, 5′ rapid amplification of cDNA ends; RT–PCR, reverse transcription–PCR; SA, sinapyl alcohol; TE, tracheary element; YFP, yellow fluorescent protein

Journal Article.  7181 words.  Illustrated.

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

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