MYB103 is required for FERULATE-5-HYDROXYLASE expression and syringyl lignin biosynthesis in Arabidopsis stems

Authors

  • David Öhman,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
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    • These authors contributed equally to this paper.

  • Brecht Demedts,

    1. Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Universiteit Gent, Gent, Belgium
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    • These authors contributed equally to this paper.

  • Manoj Kumar,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
    Current affiliation:
    1. Faculty of Life Sciences, University of Manchester, Manchester, UK
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  • Lorenz Gerber,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
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  • András Gorzsás,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
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  • Geert Goeminne,

    1. Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Universiteit Gent, Gent, Belgium
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  • Mattias Hedenström,

    1. Department of Chemistry, Umeå University, Umeå, Sweden
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  • Brian Ellis,

    1. Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
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  • Wout Boerjan,

    1. Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Universiteit Gent, Gent, Belgium
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  • Björn Sundberg

    Corresponding author
    • Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
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(e-mail bjorn.sundberg@slu.se).

Summary

The transcription factor MYB103 was previously identified as a member of the transcriptional network regulating secondary wall biosynthesis in xylem tissues of Arabidopsis, and was proposed to act on cellulose biosynthesis. It is a direct transcriptional target of the transcription factor SECONDARY WALL ASSOCIATED NAC DOMAIN PROTEIN 1 (SND1), and 35S-driven dominant repression or over-expression of MYB103 modifies secondary wall thickness. We identified two myb103 T-DNA insertion mutants and chemically characterized their lignocellulose by pyrolysis/GC/MS, 2D NMR, FT-IR microspectroscopy and wet chemistry. The mutants developed normally but exhibited a 70–75% decrease in syringyl (S) lignin. The level of guaiacyl (G) lignin was co-ordinately increased, so that total Klason lignin was not affected. The transcript abundance of FERULATE-5-HYDROXYLASE (F5H), the key gene in biosynthesis of S lignin, was strongly decreased in the myb103 mutants, and the metabolomes of the myb103 mutant and an F5H null mutant were very similar. Other than modification of the lignin S to G ratio, there were only very minor changes in the composition of secondary cell-wall polymers in the inflorescence stem. In conclusion, we demonstrate that F5H expression and hence biosynthesis of S lignin are dependent on MYB103.

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