Role of aromatic aldehyde synthase in wounding/herbivory response and flower scent production in different Arabidopsis ecotypes

Authors

  • Michael Gutensohn,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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    • These authors contributed equally to this article.

  • Antje Klempien,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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    • These authors contributed equally to this article.

  • Yasuhisa Kaminaga,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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    • These authors contributed equally to this article.

  • Dinesh A. Nagegowda,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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    • Present address: Central Institute of Medicinal and Aromatic Plants, P.O. CIMAP, Lucknow 226015, India.

  • Florence Negre-Zakharov,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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    • Present address: Department of Plant Sciences, University of California, Davis, CA 95616, USA.

  • Jung-Hyun Huh,

    1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, 408 Latham Hall, AgQuad Lane, Blacksburg, VA 24061, USA
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  • Hongli Luo,

    1. Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA
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  • Renate Weizbauer,

    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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  • Tesfaye Mengiste,

    1. Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA
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  • Dorothea Tholl,

    1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, 408 Latham Hall, AgQuad Lane, Blacksburg, VA 24061, USA
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  • Natalia Dudareva

    Corresponding author
    1. Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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(fax +1 765 494 0391; e-mail dudareva@purdue.edu).

Summary

Aromatic l-amino acid decarboxylases (AADCs) are key enzymes operating at the interface between primary and secondary metabolism. The Arabidopsis thaliana genome contains two genes, At2g20340 and At4g28680, encoding pyridoxal 5′-phosphate-dependent AADCs with high homology to the recently identified Petunia hybrida phenylacetaldehyde synthase involved in floral scent production. The At4g28680 gene product was recently biochemically characterized as an l-tyrosine decarboxylase (AtTYDC), whereas the function of the other gene product remains unknown. The biochemical and functional characterization of the At2g20340 gene product revealed that it is an aromatic aldehyde synthase (AtAAS), which catalyzes the conversion of phenylalanine and 3,4-dihydroxy-l-phenylalanine to phenylacetaldehyde and dopaldehyde, respectively. AtAAS knock-down and transgenic AtAAS RNA interference (RNAi) lines show significant reduction in phenylacetaldehyde levels and an increase in phenylalanine, indicating that AtAAS is responsible for phenylacetaldehyde formation in planta. In A. thaliana ecotype Columbia (Col-0), AtAAS expression was highest in leaves, and was induced by methyl jasmonate treatment and wounding. Pieris rapae larvae feeding on Col-0 leaves resulted in increased phenylacetaldehyde emission, suggesting that the emitted aldehyde has a defensive activity against attacking herbivores. In the ecotypes Sei-0 and Di-G, which emit phenylacetaldehyde as a predominant flower volatile, the highest expression of AtAAS was found in flowers and RNAi AtAAS silencing led to a reduction of phenylacetaldehyde formation in this organ. In contrast to ecotype Col-0, no phenylacetaldehyde accumulation was observed in Sei-0 upon wounding, suggesting that AtAAS and subsequently phenylacetaldehyde contribute to pollinator attraction in this ecotype.

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