Stimulating secondary compound accumulation by elicitation: Is it a realistic tool in medicinal plants in vivo?

Abstract

AbstractStimulating the production of secondary metabolites by elicitation seems to be an accepted tool in several in vitro cultures. In vivo application of chemical elicitation is, however, much less frequently discussed. The paper summarizes the experimental findings on the effects of jasmonic acid, methyl-jasmonate (MeJa) and salicylic acid (SA) treatments on medicinal and aromatic plants. Growth behaviour, yield, stress responses, essential oil (EO) and phenolic compounds are discussed. Exogenous application of MeJa or SA mostly by foliar spraying in concentrations between 10−4 and 4 mM, induced various changes in the plants. In most cases, the elicitation enhanced the volatile accumulation, although the opposite reaction was observed too. Numerous in vivo trials also demonstrated an altered EO composition. Positive effects of treatments on the concentration of phenolic type compounds were described, while in some cases the components exhibited contradictory behavior or no significant changes. Unfortunately, phenolic composition was rarely determined. There is evidence for the dose dependency of the reactions to both elicitors, but systematic studies on this issue are missing. Some results indicate that lower concentrations in replication may be at least as effective as higher ones. Changes in secondary metabolite accumulation may be induced by the elicitors directly or through other physiological processes. The in vivo results should be considered in the complex system of plant ontogenesis, environmental conditions, timing of the treatment, type of the elicitor and concentration. Research results indicate a promising aspect of chemical elicitation in vivo, but further well-designed studies are needed for the individual species.