Methyl jasmonate induces lauric acid omega-hydroxylase activity and accumulation of CYP94A1 transcripts but does not affect epoxide hydrolase activities in Vicia sativa seedlings

Treatment of etiolated Vicia sativa seedlings by the plant hormone methyl j asmonate (MetJA) led to an increase of cytochrome P450 content. Seedlings t hat were treated for 48 h in a 1 mM solution of MetJA stimulated omega-hydr oxylation of 12:0 (lauric acid) 14-fold compared with the control (153 vers us 11 pmol min(-1) mg(-1) protein, respectively). Induction was dose depend ent. The increase of activity (2.7-fold) was already detectable after 3 h o f treatment. Activity increased as a function of time and reached a steady level after 24 h. Northern-blot analysis revealed that the transcripts codi ng for CYP94A1, a fatty acid omega-hydroxylase, had already accumulated aft er 1 h of exposure to MetJA and was maximal between 3 and 6 h. Under the sa me conditions, a study of the enzymatic hydrolysis of 9,10-epoxystearic aci d showed that both microsomal and soluble epoxide hydrolase activities were not affected by MetJA treatment.