Biochemical characterization of the jasmonic acid methyltransferase gene from wasabi ().

Methyl jasmonate and jasmonic acid play important roles as signaling molecules in regulating plant development and stress-related responses. Previous studies have shown that jasmonic acid carboxyl methyltransferase (JMT), which belongs to the SABATH methyltransferase gene family, catalyzes the transfer of methyl groups from -adenosyl-L-methionine to the carboxyl groups of jasmonic acid. In the present study, we used RNA-seq analysis to identify a putative JMT gene, , in wasabi (). The EujJMT proteins showed the highest similarity (89% identity) to JMT proteins of . Functional characterization of a recombinant EujJMT protein expressed in showed the highest level of activity with jasmonic acid among the different carboxylic acids tested. The apparent value of EujJMT using jasmonic acid as substrate was 62.6 µM, which is comparable to the values of known JMTs. Phylogenetic analysis suggested that EujJMT shares a common ancestor with the JMTs of and species and that the strict substrate specificity toward jasmonic acid is conserved among Brassicaceae JMTs.