Light-enhanced resistance to Magnaporthe grisea infection in the rice Sekiguchi lesion mutants

The rice sl mutant showed two types of responses to Magnaporthe grisea infection by light treatments. One was an sl-mutant-type response characterized by Sekiguchi lesion expression under light waves of 400-700 nm, and the other was a wild-type response characterized by blast and/or necrotic spot lesion expression in the dark or at wavelength between 290 and 330 nm. There was a large difference in the resistance to M. grisea infection between the mutant- and wild-type responses in the rice sl mutant. When the mutant-type response was induced in the rice sl mutant, the disease resistance was enhanced relative to that in the wild-type response. Enhanced resistance was demonstrated by two components: (a) the number of Sekiguchi lesions was reduced relative to that of blast or necrotic lesions; (b) sporulation of M. grisea was not induced in Sekiguchi lesions. The enhanced resistance was dependent on light of 400-700 nm.