Effect of Wavelength and Light Intensity from Ultraviolet and Violet Light-emitting Diodes for Optimizing Vinblastine Production in the Leaves of Madagascar Periwinkle

Vinblastine accumulation in Madagascar periwinkle leaves is rapidly induced by ultraviolet A irradiation. This study aimed to elucidate the effects of light quality and intensity (wavelengths between 280 and 405 nm) on vinblastine accumulation. In the first experiment, leaves were incubated for 5 days under light-emitting diodes (LEDs) with five distinct peak wavelengths: 280, 310, 365, 385, and 405 nm. Vinblastine accumulation was observed only in leaves treated with 365- and 385-nm LEDs. The leaves were irradiated for 5 days in the second experiment with eight light intensities between 1 and 150 W·m −2 from 365- and 385-nm LEDs. The vinblastine concentration was maximized at 25 or 50 W·m −2 using 385-nm LEDs. These findings suggest that the optimal light conditions for vinblastine production in periwinkle leaves using LEDs are irradiation with 385-nm LEDs at an intensity of 25 W·m −2 for 5 days.