Down-regulation of the maize and Arabidopsis thaliana caffeic acid O-methyl-transferase genes by two new maize R2R3-MYB transcription factors

Plant Mol Biol. 2006 Dec;62(6):809-23. doi: 10.1007/s11103-006-9058-2. Epub 2006 Aug 29.


The maize (Zea mays L.) caffeic acid O-methyl-transferase (COMT) is a key enzyme in the biosynthesis of lignin. In this work we have characterized the involvement of COMT in the lignification process through the study of the molecular mechanisms involved in its regulation. The examination of the maize COMT gene promoter revealed a putative ACIII box, typically recognized by R2R3-MYB transcription factors. We used the sequence of known R2R3-MYB factors to isolate five maize R2R3-MYB factors (ZmMYB2, ZmMYB8, ZmMYB31, ZmMYB39, and ZmMYB42) and study their possible roles as regulators of the maize COMT gene. The factors ZmMYB8, ZmMY31, and ZmMYB42 belong to the subgroup 4 of the R2R3-MYB family along with other factors associated with lignin biosynthesis repression. In addition, the induction pattern of ZmMYB31 and ZmMYB42 gene expression on wounding is that expected for repressors of the maize COMT gene. Arabidopsis thaliana plants over-expressing ZmMYB31 and ZmMYB42 down-regulate both the A. thaliana and the maize COMT genes. Furthermore, the over-expression of ZmMYB31 and ZmMYB42 also affect the expression of other genes of the lignin pathway and produces a decrease in lignin content of the transgenic plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Down-Regulation / genetics
  • Gene Expression Regulation, Enzymologic / genetics
  • Gene Expression Regulation, Plant / genetics
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Lignin / metabolism
  • Methyltransferases / genetics*
  • Methyltransferases / metabolism
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Phenotype
  • Phylogeny
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plants, Genetically Modified
  • Promoter Regions, Genetic / genetics
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Stress, Mechanical
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism*
  • Zea mays / enzymology*
  • Zea mays / genetics
  • Zea mays / metabolism


  • Plant Proteins
  • Protein Isoforms
  • Transcription Factors
  • Green Fluorescent Proteins
  • Lignin
  • Methyltransferases
  • caffeate O-methyltransferase