Journal Article

Antifungal Properties of Haem Peroxidase from <i>Acorus calamus</i>

MODHUMITA GHOSH

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 98, issue 6, pages 1145-1153
ISSN: 0305-7364
Published online October 2006 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcl205
Antifungal Properties of Haem Peroxidase from Acorus calamus

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims Plants have evolved a number of inducible defence mechanisms against pathogen attack, including synthesis of pathogenesis-related proteins. The aim of the study was to purify and characterize antifungal protein from leaves of Acorus calamus.

Methods Leaf proteins from A. calamus were fractionated by cation exchange chromatography and gel filtration and the fraction inhibiting the hyphal extension of phytopathogens was characterized. The temperature stability and pH optima of the protein were determined and its presence was localized in the leaf tissues.

Key Results The purified protein was identified as a class III haem peroxidase with a molecular weight of approx. 32 kDa and pI of 7·93. The temperature stability of the enzyme was observed from 5 °C to 60 °C with a temperature optimum of 36 °C. Maximum enzyme activity was registered at pH 5·5. The pH and temperature optima were corroborated with the antifungal activity of the enzyme. The enzyme was localized in the leaf epidermal cells and lumen tissues of xylem, characteristic of class III peroxidases. The toxic nature of the enzyme which inhibited hyphal growth was demonstrated against phytopathogens such as Macrophomina phaseolina, Fusarium moniliforme and Trichosporium vesiculosum. Microscopic observations revealed distortion in the hyphal structure with stunted growth, increased volume and extensive hyphal branching.

Conclusions This study indicates that peroxidases may have a role to play in host defence by inhibiting the hyphal extension of invading pathogens.

Keywords: Acorus calamus; haem peroxidase; antifungal; hyphal inhibition; thermal stability; localization; epidermal cells; xylem lumen

Journal Article.  4758 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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