DISTRIBUTION OF THIABENDAZOLE RESISTANT HELMINTHOSPORIUM SOLANI STRAIN
Helminthosporium solani strains were isolated from potato tubers that were grown in Russia, Germany and the Netherlands. Thiabendazole was effective against the sensitive strains of H. solani (EC50< 7.3 mg/l); however, 8 studied strains from Russia and the Netherlands were found to be extremely resistant to it (EC50 > 1000 mg/l). The sequence of their β-tubulin gene contained a SNP mutation in 198 codon or 200 codon, translating to Gln (CAG) instead of Glu (GAG) or Tyr (TAC) instead of Phe (TTC), respectively. Resistant to thiabendazole strains were found in distant regions of Russia (Moscow, Kostroma, Kaluga district) and in the Netherlands. Resistance to thiabendazole of the Russian, European, and American strains had the same genetic background and was conferred by the same mutations.