Induction of clovamide by jasmonic acid in red clover.

The effect of jasmonic acid (JA) on the secondary metabolism of 5-day-old red clover seedlings was investigated. Induction of the formation of four compounds was found in roots after treatment with 50 microM JA for 48 h, while no induction was observed in the shoots. These compounds, whose formation was induced by JA addition, were isolated and identified as caffeoyl DOPA (clovamide), caffeoyltyrosine, p-coumaroyl DOPA and p-coumaroyltyrosine, by ion-spray MS and 1H NMR analyses, and by chemical synthesis. Among them, clovamide was the most abundant, while the other amides represented only a minor portion. Clovamide started to increase in amount 24-36 h after treatment and reached a maximum after 96 h (2.81 nmol/mg fr. wt.). The induction of their formation was observed even with 5 microM of JA, and the amount increased with concentrations up to 100 microM. Treatment with 1 mM CuCl2, which elicits accumulation of the phytoalexin maackiain in red clover, caused a decrease in clovamide amount.