Role of Brown-Discolored Tissues around Blast Lesions in the Defence Reaction of Rice Plants against Pyricularia oryzae Cav.

Abstract

To investigate the water permeability of the brown-discolored marginal zone, artificial lesions were prepared by means of inoculation at heat-injured spots. These lesions formed sharp brown-discolored zone which seemed to barricade the parasite. Water content of these lesions decreased rapidly even under sufficient water supply, suggesting that the brown-discolored tissue inhibits the supply of water and water soluble nutrients to the fungus enclosed in the lesion.