A wheat (Triticum aestivum L., near isogenic line of Hamlet) O-methyltransferase (OMT) was previously reported as a putative caffeic acid OMT (TaCOMT1), involved in lignin biosynthesis, based on its high sequence similarity with a number of graminaceous COMTs. The fact that the putative TaCOMT1 exhibits a significantly high sequence homology to another recently characterized wheat flavone-specific OMT (TaOMT2), and that molecular modeling studies indicated several conserved amino acid residues involved in substrate binding and catalysis of both proteins, prompted an investigation of its appropriate substrate specificity. We report here that TaCOMT1 exhibits highest preference for the flavone tricetin, and lowest activity with the lignin precursors, caffeic acid/5-hydroxyferulic acid as the methyl acceptor molecules, indicating that it is not involved in lignin biosynthesis. We recommend its reannotation to a flavone-specific TaOMT1 that is distinct from TaOMT2. Crown
Bibliographical noteFunding Information:
This work was supported by grants from the Natural Sciences and Engineering Research Council (NSERC) of Canada to R.K.I., and partially supported by the Technology Development Program for Agriculture and Forestry, Ministry of Agriculture and Forestry, Republic of Korea to Y.W.S. We wish to thank Dr. Y. Fukushi, Hokkaido University, Japan, for the synthesis of the tricetin methyl ether derivatives, and Professor Yoongho Lim, Dept. of Bioscience and Biotechnology, Konkuk University, S. Korea, for molecular modeling of TaOMT2 and production of Fig. 5 .
- Biochemical characterization
- Flavone-specific O-methyltransferase
- Triticum aestivum L.
ASJC Scopus subject areas
- Plant Science