Fusarium graminearum PKS14 is involved in orsellinic acid and orcinol synthesis

Simon Hartung Jørgensen, Rasmus John Normand Frandsen, Kristian Fog Nielsen, Erik Lysøe, Teis Esben Sondergaard, Reinhard Wimmer, Henriette Giese, Jens Laurids Sørensen

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    Abstract

    The available genome sequences show that the number of secondary metabolite genes in filamentous fungi vastly exceeds the number of known products. This is also true for the global plant pathogenic fungus Fusarium graminearum, which contains 15 polyketide synthase (PKS) genes, of which only 6 have been linked to products. To help remedy this, we focused on PKS14, which has only been shown to be expressed during plant infections or when cultivated on rice or corn meal (RM) based media. To enhance the production of the resulting product we introduced a constitutive promoter in front of PKS14 and cultivated two of the resulting mutants on RM medium. This led to the production of two compounds,
    which were only detected in the PKS14 overexpressing mutants and not in the wild type or PKS14 deletion mutants. The two compounds were tentatively identified as orsellinic acid and orcinol by comparing spectroscopic data (mass spectroscopy and chromatography) to authentic standards. NMR analysis of
    putative orcinol isolated from the PKS14 overexpressing mutant supported our identification. Orcinol and orsellinic acid, not previously detected in Fusarium, have primarily been detected in lichen fungi.
    Orsellinic acid is hypothesized to be the PKS release product which is transformed to orcinol through decarboxylation. Phylogenetic analyses of PKSs placed PKS14 in a subclade of known OA synthases.
    Expression analysis by microarray of 55 experiments identified seven genes near PKS14 that were expressed in a similar manner. One of the seven genes encodes a predicted carboxylase, which could be responsible for transforming orsellinic acid to orcinol.
    Original languageEnglish
    JournalFungal Genetics and Biology
    Volume70
    Pages (from-to)24-31
    Number of pages8
    ISSN1087-1845
    DOIs
    Publication statusPublished - 2014

    Keywords

    • Secondary metabolites
    • Polyketide synthase 14
    • Overexpression
    • Regulation
    • Fusarium

    Cite this

    Jørgensen, S. H., Frandsen, R. J. N., Nielsen, K. F., Lysøe, E., Sondergaard, T. E., Wimmer, R., Giese, H., & Sørensen, J. L. (2014). Fusarium graminearum PKS14 is involved in orsellinic acid and orcinol synthesis. Fungal Genetics and Biology, 70, 24-31. https://doi.org/10.1016/j.fgb.2014.06.008