The effects of light and photo- and protein-synthetic inhibitors on the Sekiguchi lesion formation by Magnaporthe grisea in rice cv. Sekiguchi-asahi

The significance of light irradiation in Sekiguchi lesion (SL) formation by infection with Magnaporthe grisea on rice cv. Sekiguchi-asahi was investigated. When the leaf blades of cv. Sekiguchi-asahi inoculated with M. grisea spores were kept under different wavelengths of light, SLs were formed under visible light regardless of the compatibility between fungal race and cv. Sekiguchiasahi. On the contrary, typical blast and/or nectrotic spot lesions were formed under near ultraviolet radiation from the black light fluorescent lamps and near infrared radiation from infrared fluorescent lamps. The effective wavelength for light-dependent SL formation was 400-700 nm. Furthermore, the longer the wavelength of radiation, the bigger were the SLs. Such light-dependent induction of the SL was suppressed by pretreatment of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and cycloheximide (CY). These results suggested that photosynthetic and protein synthetic activities were involved in SL formation.