Phytoalexin production by amino acid conjugates of jasmonic acid through induction of naringenin-7-O-methyltransferase, a key enzyme on phytoalexin biosynthesis in rice (Oryza sativa L.).

Amino acid conjugates of jasmonic acid are found to elicit production of the flavonoid phytoalexin, sakuranetin in rice leaves. The elicitation is shown to arise from induction of naringenin 7-O-methyltransferase, a key enzyme of sakuranetin biosynthesis. The (-)-phenylalanine conjugate, one of the active compounds, is characterized by high activity for both sakuranetin and enzyme induction and low phytotoxicity against rice growth. Both (+)-enantiomers of the conjugates and free amino acids do not show any activity. The amino acid conjugate of jasmonic acid is speculated to be the later component in the signaling transduction chain in stressed rice plants.