Stimulation of secondary metabolites biosynthesis in plants by cold plasma and electromagnetic field

Abstract

Seed treatment with non-thermal or cold plasma (CP) or electromagnetic field (EMF) improves agricultural performance of crops, leads to stimulation of germination, biomass production, and disease resistance. However, a detailed molecular mechanism of mentioned effects is still missing, preventing the possibility of controlled modulation of plant. Besides of improved adaptivity and higher yield of treated plants, the quality of plant production and the concentrations of valuable secondary metabolites can be increased by CP and EMF. We reported, for the first time, that seed treatment with physical stressors led to substantial increase in amounts of chemical constituents and antioxidant activity in leaves of medicinal plant Echinacea purpurea: the amount of cichoric acid increased up to 3.8-fold, amount of vitamin C – up to 1.9 fold, and radical scavenging activity - up to 2-fold. CP and EMF had strong stimulating effect on steviol glycosides (SGs), used as natural sweeteners, accumulation in Stevia rebaudiana. The concentration of rebaudioside A, the most preferable of SGs as sweetener without bitter aftertaste, was increased 1.5-fold and the concentration of stevioside, the second most abundant SG, was increased 7-11-fold depending on treatment duration. Seed treatment with CP induced substantial changes of the amount and ration of izoflavones formononetin and biochanin A (BA) in leaves of Trifolium pratens. Therefore, it can be concluded that short time pre-sowing treatment of seeds with CP and EMF can be a powerful tool for the enhancement of biosynthesis/accumulation of secondary metabolites in plants and can have an economic benefit.