SEQUENCE AND EXPRESSION OF A CAFFEIC ACID O-METHYL TRANSFERASE CDNA HOMOLOG IN THE TROPICAL FORAGE LEGUME STYLOSANTHES HUMILIS

The isolation and characterisation of a cDNA encoding a caffeic acid O -methyl transferase cDNA homologue (COMT) from Stylosanthes humilis ar e described. The clone is 1391 nucleotides in length, with an open rea ding frame encoding a predicted protein of 366 amino acids. Cluster an alysis of the deduced amino acid sequence revealed extensive homology to other published O-methyl transferase sequences. Maximum levels of h omology were seen with COMTs from alfalfa (87%) and aspen (84%). South ern analysis suggested that this enzyme is encoded by two genes in S. humilis. The mRNA is most strongly expressed in stem tissue, with inte rmediate levels of expression in young leaves and roots, and does not appear to be induced upon fungal infection or wounding.