Effects of Light Quality on Induction of Tryptamine-mediated Resistance in Lesion Mimic Mutant of Rice Infected with Magnaporthe grisea

The effective wavelength of light on Sekiguchi lesion formation, tryptamine accumulation, enzyme activities and hydrogen peroxide (H2O2) generation involved in light-induced resistance of rice (cv. Sekiguchi-asahi) infected with Magnaporthe grisea was determined by using band-pass filters (BPF). When the M. griseainoculated leaves were irradiated by BPF-filtered lights from daylight fluorescent lamps, Sekiguchi lesion development was enhanced by increasing the wavelength of visible light. The longer the radiation wavelength, the greater the tryptamine accumulation, the tryptophan decarboxylase and monoamine oxidase activities, and the H2O2 generation. By contrast, the longer the radiation wavelength of radiation, the greater the inhibition of catalase (CAT) activity. Among the visible lights, red light was the most effective for tryptamine pathway activation and CAT inhibition involved in light-induced resistance