The role of oxidative burst and cell wall in tomato interaction with various taxonomic groups of Rhizoctonia spp

Abstract In this research, interaction of multinucleate Rhizoctonia solani and a binucleate isolate of Rhizoctonia sp. (BNR) was investigated with using tomato as a susceptible host. The highest levels of O2−, H2O2, callose accumulation and superoxide dismutase activity were observed for the isolate of R. solani AG 3, which caused lower disease severity compared to highly pathogenic R. solani isolates belonging to AG 4 HG-I and AG 4 HG-II. Xanthine/xanthine oxidase treatment, which induced O2− production, increased the disease symptoms. Whereas, glucose/glucose oxidase, which increased H2O2, decreased the disease symptoms. Ascorbate, as an inhibitor of H2O2 accumulation, reduced callose deposition and increased the disease severity. Analyzing activity of cell wall degrading enzymes (pectinase and cellulase) produced by different fungi showed higher activity of these enzymes for the isolates with higher pathogenicity. Therefore, defense components of host plant and pathogenicity factors of fungi are both involved in the outcome of plant-fungi interaction.