LED light improves shoot multiplication, steviol glycosides and phenolic compounds biosynthesis in Stevia rebaudiana Bertoni in vitro culture

Light-emitting diode (LED) lamps are efficient elicitors of secondary metabolites. To investigate the influence of LED light on steviol glycosides (SGs) and phenolic compounds biosynthesis, stevia shoots were cultured under the following LED lights: white-WL, blue-B, red-R, 70% red and 30% blue-RB, 50% UV, 35% red and 15% blue-RBUV, 50% green, 35% red and 15% blue-RBG, 50% yellow, 35% red and 15% blue-RBY, 50% far-red, 35% red and 15% blue-RBFR and white fluorescent light (WFl, control). RBG light stimulated shoots' biomass production. RBFR had a beneficial impact on stevioside biosynthesis (1.62 mg/g dry weight, DW), while RBUV favoured the production of rebaudioside A (3.15 mg/g DW). Neochlorogenic, chlorogenic, caffeic, 4-feruloylquinic, isochlorogenic A, rosmarinic acids and the flavonoid quercitrin were identified in the obtained material. A stimulatory effect of RBFR and RBUV on the biosynthesis of phenolic compounds was noted. LED light also influenced stomata appearance, stomata density, photosynthetic pigments, soluble sugar content and antioxidant enzyme activities in stevia shoots. This is the first report to provide evidence of the stimulating effect of LED light on biomass yield, SGs production and phenolic compounds in stevia shoot cultures.