Response of 3 Arabidopsis clones to 41 strains of eight Rhizoctonia species was studied in model experiments. The seed germination was decelerated in most of the cases, although the inhibitory effect varied within large limits. The pre-emergence damping off and root neck rot leading to damping off were the most frequent symptoms of disease syndrome caused by toxic metabolites. The clone transformed with cDNA clone overexpressing gstf4 gene exhibited significantly improved tolerance as compared to parental one, meanwhile the sensitivity of Dmannose pyrophosphorylase/mannose-1-pyrophosphatase deficient clone dramatically increased. Strains of R. solani of AG-2, AG-4 and AG-7 and Athelia rolfsii produced the most toxic metabolites, however, no strict relationships were revealed between taxonomic position of Rhizoctonia strains and toxicity of their metabolites.