Response of glutathione conjugation system to soil borneRhizoctoniainfection of okra

Abstract

Okra seedlings tolerated soil-borne Rhizoctonia infection in strain dependent manner. No connection was revealed between pathogenicity of strains and their origin or taxonomic position. However, the okra proved to be susceptible to strains highly pathogenic to other host plants as well. R. zeae, a species new to European flora, was as aggressive to okra as the most potent R. solani strains. The effect of Rhizoctonia infection was more prominent on mass accumulation in hypocotyls than in cotyledons. The protein content and glutathione S-transferase activity increased in parallel with the evolution of disease syndrome. Metalaxyl, an acetanilide type systemic antioomycete fungicide induced glutathione S-transferase activity in cotyledons with 24 hours a phase, and this induction was more outstanding in symptomless seedlings grown in Rhizoctonia infested soil. It might be concluded, that the stress response of plants in tolerant host/parasite pair takes effect at higher level than in susceptible relationships.