Improving production of plant secondary metabolites through biotic and abiotic elicitation

Abstract Plants need to counter continuous threats posed by the environment, such as pathogen attacks (fungi, viruses, insects, nematodes) and harsh physical conditions (drought, salinity, temperature, exposure to UV radiation). Plants recognize the threat signals through their receptors and sensors and activate defense responses to stabilize against these stresses. The responses include accumulation of secondary metabolites. Enhanced synthesis of secondary metabolites, called elicitation ensures the survival, persistence and competitiveness of the plant. Secondary metabolites include volatile oils, flavonoids, alkaloids, glycosides, tannins, resins etc that have been successfully exploited for vital sources for food additives, flavors, and industrially important pharmaceuticals. The improved production of the secondary metabolites through elicitation has unlocked a new area of research that could have significant economic benefits for the pharmaceutical and therapeutic (including neutraceutical) industry. The present review discusses about the different elicitation methods through various biotic (proteins, carbohydrates, plant growth promoting rhizobacteria, fungus, hormones) and abiotic elicitors (heavy metals, low and high temperature, light, salt, drought) that could bring about increased yield of secondary metabolites especially in medicinal plants beneficial to the medicinal and aromatic industry.