26 イネファイトアレキシン生産におけるジャスモン酸を軸とした細胞内シグナル伝達機構(口頭発表の部)

抄録

One of the most important defensive systems in plants against pathogen attack is the production of antimicrobial compounds called phytoalexins. We have demonstrated that accumulation of the flavonoid phytoalexin, sakuranetin is mediated by endogenous production of JA in stressed rice leaves, and also shown that sakuranetin production is strongly elicited by exogenously applied JA. We suggested that the further metabolism of JA into its amino acid conjugates would be needed to furnish the signal transduction pathway and showed the importance of amino acid conjugates of JA in phytoalexin production. On the mechanism(s) by which exogenously applied JA elicits phytoalexin production in rice leaves, we find that cytokinin (a plant hormone) counteracts the JA-inducible sakuranetin production, and ascorbic acid (free radical generator) accelerates the JA-inducible sakuranetin production. We speculate that active oxygen species (AOS) might be connected with the JA-inducible sakuranetin production from above results and observed that exogenously applied AOS elicit the sakuranetin production. We also find that methionine (an amino acid) also elicits phytoalexin production in rice. Studying of elicitation mechanism(s) by methionine in relation to JA is in progress in our laboratory.