Effect of amino acid supplementation, elicitation and LEDs on Hylocereus costaricensis callus culture for the enhancement of betalain pigments

Abstract Hylocereus costaricensis more popularly known as the purplish-red pitaya or dragon fruit belongs to the Cactaceae family. The present study analyzes the effect of amino acids, elicitors, and light quality to improve callus proliferation, enhance betalain content and antioxidant profiles through elicitation and amino acid supplementation. The treatments that stimulated the highest total betalain content in red callus cultures were 50 µM tyrosine that produced a 1.6-fold increase (11.28 ± 0.38 mg/g DM) in betalain content and 200 µM leucine that produced 2.56-fold increase (18.13 ± 5.98 mg/g DM) in betalain content. Elicitation of yellow callus cultures with 100 mg/L yeast extract enhanced betalain content by 2-fold without affecting callus biomass. Betalain content could also be improved by 1.23-fold with 20 µM silver nitrate (12.51 ± 0.55 mg/g DM) while callus dry mass and total phenolic content were elevated at 40 µM silver nitrate. The utilization of light was a promising strategy for increased production of secondary metabolites in callus cultures of H. costaricensis. Both yellow and red callus cultures incubated under red LED lights enhanced total betalain content by 3.8- fold (11.64 ± 0.54 mg/g DM) and 4.8-fold (9.42 ± 1.48 mg/g DM), significantly higher (p