Rapid Response of Suspension-cultured Parsley Cells to the Elicitor from Phytophthora megasperma var. sojae

Large and rapid increases in the activities of two enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase and 4-coumarate:CoA ligase, occurred in suspension-cultured parsley cells (Petroselinum hortense) treated with an elicitor preparation from Phytophthora megasperma var. sojae. Highest enzyme activities were obtained with an elicitor concentration similar to that required for maximal phenylalanine ammonialyase induction in cell suspension cultures of soybean, a natural host of the fungal pathogen.The changes in phenylalanine ammonia-lyase activity in parsley cells were caused by corresponding changes in the mRNA activity for this enzyme. Phenylalanine ammonia-lyase mRNA activity increased much faster and transiently reached a much higher level in elicitor-treated than in irradiated cell cultures. In contrast to irradiation, treatment of the cells with the elicitor did not induce the enzymes of the flavonoid glycoside pathway, as demonstrated for acetyl-CoA carboxylase and chalcone synthase. Induction of these enzymes by light was abolished by simultaneous application of the elicitor.