HORT640 - Metabolic Plant Physiology
Secondary products derived from aromatic amino acids
Eugenol and isoeugenol
The sweet fragrance of Clarkia breweri is due to 8 to 12 volatile compounds, including 4 phenylpropanoids; eugenol, isoeugenol, methyleugenol and isomethyleugenol. Eugenol and isoeugenol are thought to be derived from the lignin precurors ferulic acid or coniferyl alcohol. Methylation of eugenol to methyleugenol and isoeugenol to isomethyleugenol is catalyzed by an S-adenosylmethionine-dependent O-methyltransferase (IEMT). The IEMT cDNA has 70% identity to SAM:caffeic acid
O-methyltransferase. The protein encoded by the IEMT cDNA is able to use eugenol and isoeugenol as substrate, but not caffeic acid (Wang et al, 1997).
Clarkia flowers also produce methylsalicylate (MeSA) [derived by methylation of the carboxyl group of salicylic acid (SA), catalyzed by SAM:salicylic acid carboxyl methyltransferase], and benzylacetate [derived by condensation of benzyl alcohol with acetyl-CoA, catalyzed by acetyl-CoA:benzylalcohol acetyltransferase] (Dudareva et al, 1998).
Dudareva N, Raguso RA, Wang J, Ross JR, Pichersky E 1998 Floral scent production in Clarkia breweri. III. Enzymatic synthesis and emission of benzenoid esters. Plant Physiol. 116: 599-604.
Wang J, Dudareva N, Bhakta S, Raguso RA, Pichersky E 1997 Floral scent production in Clarkia breweri (Onagraceae). II. Localization and developmental modulation of the enzyme S-adenosyl-L-methionine:(iso)eugenol O-methyltransferase and phenylpropanoid emission. Plant Physiol. 114: 213-221.
| PubMed Search | Entrez Protein Search | ISI Web of Knowledge Search | Scirus Search |