Elicitor Signal Transduction Leading to the Production of Plant Secondary Metabolites

Abstract

Plant metabolites are highly effective as medicine with a higher efficacy and lower adverse effect. Two basic metabolites are obtained from nature, namely primary metabolites and secondary metabolites. Alkaloids, glycosides, terpenoids, flavonoids are the principal secondary metabolites, and also the primary source for the drug discovery and development. Elicitors are the substances which under stress conditions induce the biosynthesis of secondary metabolites of plants. Both biotic and abiotic elicitors are used in the process. Most common secondary metabolites Ferulic acid, cinnamic acid, vanillin, coumaric acid, silymarin, affinin, hypocrellin A, steroiside, menthone, piperitone, glycyrrhizic acid, colchicine, thiocolchicoside, phenolic acid, gymnemic acid, flavonoids are utilized the elicitation technique. Elicitors are two types such as: abiotic and biotic. Abiotic elicitors such as salicylic acid, methyl jasmonate, hydrogen peroxide, lanthanum, different hormones, light, gamma rays and controlled temperature are used to generate secondary metabolites of wheat grass, Thymus vulgaris, Silybum marianum, Shiraia bambusicola, Ajuga bracteosa, broccoli plant, etc. Biotic elicitors like chitosan, rhizobacteria, Rhizobium leguminosum, Aspergillus tenius, Agrobacterium tumefacians, carrageenan, Streptomyces, Rhizopus, dextran, yeast are used to develop or improvise secondary metabolites of Khus, Mentha pulegium, Tavernia cuneifolia, chickpea, -Vitis vinifera, Rumex gmelini Turcz, Cupressus lusitanica, etc. Some secondary metabolites of Coleus aromaticus Benth, Rhododendron tomentosum, Fagonia indica, Rauwolfia serpentine, Solanum khasianum, Ocimum tenuiflorum, Stevia rebaudiana etc. are used both abiotic and biotic elicitors.