Potentiation of Phytoalexin Accumulation in Elicitor-treated Epicotyls of Pea (Pisum sativum) by a Diacylglycerol Kinase Inhibitor

When epicotyl tissues of pea were treated with a diacyl- glycerol (DAG) kinase inhibitor (R59022), enhanced induction of the phytoalexin accumulation occurred which was induced by fungal elicitor. The marked induction was associated with a sustained accumulation of phenylalanine ammonia-lyase (PAL)-mRNA and the consequent increase in PAL activity. These results sug- gest that inhibition of DAG breakdown leads to increased induction of phytoalexin accumulation and support the hypothesis that DAG kinase negatively regulates the signal transduction.