Effects of Low-Dose Kinetin, 2,4-D and Monochromatic Light Conditions on Flavonoid Content in Callus Culture of Dioscorea esculenta

Abstract

The callus culture of Dioscorea esculenta is a potential strategy to produce efficacious bioactive compounds in multiplied production. It can be carried out by applying plant growth regulators (PGR) and environmental modification, including light-emitting diodes (LEDs) exposure. This study aims to investigate the impact of PGR and the stimulatory effect of LEDs on flavonoid profiles in D. esculenta callus culture. The study was conducted using combination variations of 2,4-D (0.5 and 1 ppm), kinetin (0.5 and 1 ppm), and LEDs stimulatory conditions (light and dark). The results showed that flavonoids are the dominant compounds found in lesser yam cultures, which reached more than 78 % in all treatments-specifically, adding 0.5 ppm kinetin and 0.5 ppm 2,4-D to D. esculenta callus cultures significantly increased flavonoids production compared to single PGR treatment. This shows there is a synergistic activity induced by 2,4-D and kinetin. Furthermore, monochromatic light exposure also significantly affects flavonoid production. Analysis of 5 main flavonoids, isoflavones, flavanones, kaempferols, quercetin, and epigallocatechin, proved that monochromatic light significantly increased flavonoids production compared to callus cultures were kept in a growth room under 24 °C temperature in the dark condition. This study confirmed that equally combining 0.5 ppm of 2,4-D and 0.5 ppm of kinetin under monochromatic LEDs increases flavonoid production in D. esculenta callus cultures. Further research must be conducted to describe how the bioactive compound synthesis signaling pathway involving PGR and monochromatic LEDs improves plant quality in the pharmaceuticals’ role. HIGHLIGHTS Kinetin and 2,4-D at the same concentration of 0.5 ppm is an optimal combination to increase secondary metabolite production in esculenta callus culture Combining kinetin and 2,4-D at low concentrations significantly increased flavonoids, especially kaempferol, isoflavone, quercetin, flavanone, and epigallocatechin in esculenta callus culture Light condition significantly affects the production of flavonoids, especially kaempferol, isoflavone, quercetin, flavanone, and epigallocatechin There is evidence that kinetin and 2,4-D under light conditions work in a synergic effect on the biosynthesis of secondary metabolite compounds in esculenta callus cultures GRAPHICAL ABSTRACT