Light emitting diode (LED)-induced alteration of oxidative events during in vitro shoot organogenesis of Curculigo orchioides Gaertn.

We propose that the alteration of oxidative events due to perturbation in steady-state level of reactive oxygen species (ROS), resultant of irradiation under lights of specific wavelength(s) generated by light-emitting diodes (LEDs), regulates shoot regeneration potential of Curculigo orchioides. The changes in the oxidative response induced by LEDs were studied, using red (630 nm), blue (470 nm) and their combination (1: 1) as light sources, by estimating the changes in endogenous hydrogen peroxide (H2O2) content, the level of lipid peroxidation and the activities of antioxidative enzymes during shoot organogenesis. After irradiating for 28 days, cultures illuminated under blue (BL) LED displayed significant (p<0.05) improvements in the percentage of shoot organogenesis and mean number of shoot buds per responding explants compared to other treatments including control (fluorescent light, 40 W, 300-700 nm). Red LED treatment was found to be inhibitory on shoot organogenesis. A detrimental influence of LED light radiation on shoot organogenesis and concomitant changes in the levels of ROS and antioxidative enzyme activities were observed. Acquisition of organogenic competence and the initiation of shoot buds under BL-LED appeared to be associated with the increased level of superoxide dismutase activity.