Jasmonic acid elicits oxidative defense and detoxification systems in Cucumis melo L. cells

This study investigated whether a jasmonic acid (JA) elicitation strategy developed in a conventional cell suspension culture could evoke melon resistance mechanisms, including secondary metabolite production. Twenty one day cultured melon cell suspensions grown in MS1  medium were supplemented with JA at the concentrations of 0.5, 5.0 and 10 µmol. Melon cultures were sampled 24, 48 and 72 h post elicitation to evaluate different defense related factors such as antioxidant enzymes, ascorbate metabolism and phenolic compounds. Results suggest that melon cells respond to JA reprogramming the primary and secondary metabolism which will result in melon plantlets with enhanced resistance against diverse stress conditions through the production of specific bioactive molecules. Jasmonic acid elicited melon cells exhibited enhanced oxidative enzymes activities and ascorbic acid, coumarin and p-coumaric amounts were found without growth retardation. Induced  intracellular JA  functions as a signal transducer acting upstream to H2O2, which is a secondary messenger triggering jasmonic signaling cascades  by activating certain late genes that regulate the activity of catalase, peroxidase and de novo synthesis of five isozymes, ascorbic peroxidase detoxifying enzymes concomitant with ascorbate compound. Secondary metabolite production in melon cells seems to be activated upon JA exposure suggesting that this cell culture could be used as a source for rapid and increased production of coumarin, p-coumaric, ascorbic acid and likely other specific phenylpropanoids. These data provide further evidences for a role of jasmonic acid in the intracellular signal cascade that results in the accumulation of secondary compounds and ultimately induced melon resistance. This approach could assist further in understanding the metabolic mechanisms operating in melon cells under stress, and thus how to control them.