Heat-induced Resistance of Sugarcane to Helminthosporium sacchari and Helminthosporoside

Sugarcane clones susceptible to eye spot disease became resistant to the pathogen or helminthosporoside activity during warm summer months. Exposure of plants to 30 to 35 C temperatures, hot water treatment of excised leaves from 30 to 50 C, preincubation of leaves in an N(2) atmosphere, or preincubation in the presence of protein synthesis inhibitors also induced resistance. Hot water-treated leaves reverted to a susceptible condition. Five to 15 C temperatures, an N(2) atmosphere, or protein synthesis inhibitors prevented this recovery. Results indicate that temperature may influence host tissue sensitivity to helminthosporoside, thus governing disease development throughout the year.