Pretreatment of parsley (Petroselinum crispum L.) suspension cultures with methyl jasmonate enhances elicitation of activated oxygen species

Suspension-cultured cells of parsley (Petroselinum crispum L.) were used to demonstrate an influence of jasmonic acid methyl ester (JAME) on the elicitation of activated oxygen species. Preincubation of the cell cultures for 1 d with JAME greatly enhanced the subsequent induction by an elicitor preparation from cell walls of Phytophtora megasperma f. sp. glycinea (Pmg elicitor) and by the polycation chitosan. Shorter preincubation times with JAME were less efficient, and the effect was saturated at about 5 micromolar JAME. Treatment of the crude Pmg elicitor with trypsin abolished induction of activated oxygen species, an effect similar to that seen with elicitation of coumarin secretion. These results suggest that JAME conditioned the parsley suspension cells in a time-dependent manner to become more responsive to elicitation, reminiscent of developmental effects caused by JAME in whole plants. It is interesting that pretreatment of the parsley cultures with 2,6-dichloroisonicotinic and 5-chlorosalicylic acid only slightly enhanced the elicitation of activated oxygen species, whereas these substances greatly enhanced the elicitation of coumarin secretion. Therefore, these presumed inducers of systemic acquired resistance exhibit a specificity different from JAME.