Impact of photon flux density and light spectral quality on biomass production and arbutin compound accumulation in Origanum majorana L. plantlets

Abstract

Light is one of the factors that in uence the growth, development and synthesis of secondary metabolites of different plant species in vitro. Origanum majorana is an aromatic plant belonging to a group of plants that produce arbutin, a substance of importance in the cosmetic industry. The objective of this study was to verify the effect of light intensity and wavelength on the growth and accumulation of arbutin in vitro in plantlets. Nodal segments were grown in MS culture medium under photon ux densities of 26, 51, 69, 94 and 130 µmol m − 2 s − 1 . In the light spectrum, nodal segments were grown under different light-emitting diodes LED: red; blue; a combination of blue and red light (30% B:70% R; 50% B:50% R; 70% B:30% R); and white, yellow and green. After 40 days, the growth, photosynthetic pigments and arbutin accumulation were evaluated by HPLC-DAD. The lowest light intensity (26 µmol m − 2 s − 1 ) provided a higher content of photosynthetic pigments, and the intensity of 94 µmol m − 2 s − 1 increased dry biomass accumulation. Greater accumulation of arbutin was observed under a higher light intensity of 130 µmol m − 2 s − 1 . Regarding the quality of light, different wavelengths did not signi cantly affect the number of shoots or shoot length. The white light spectrum stimulated a greater accumulation of dry biomass. The green light provided a greater accumulation of photosynthetic pigments. The amount of arbutin was in uenced by the different light spectra. The red spectrum promoted the highest arbutin content, and the yellow inhibited.