Light-dependent induction of Sekiguchi lesion formation by Bipolaris oryzae in rice cv. Sekiguchi-asahi

The effect of light irradiation on Sekiguchi lesion formation induced by infection with Bipolaris oryzae on rice sl mutants was investigated. Although the Sekiguchi lesions formed exclusively under daylight fluorescent lamps, brown spots and necrotic spot lesions formed in the dark. The Sekiguchi lesions were larger than the brown spot lesions. When leaf blades inoculated with B. oryzae were irradiated through band-pass filters of BPB-45, BPB-50, BPB-55, and BPB-60, Sekiguchi lesions were formed regardless of the BPB filters' wavelengths. Under black-light lamps, near-infrared fluorescent lamps, or in the dark, however, brown spot lesions were induced by B. oryzae. The effective wavelength region for light-dependent Sekiguchi lesion formation was 400-700 nm. Furthermore, there was a direct correlation between the length of the radiation wavelengths and the size of the Sekiguchi lesions.