EVALUATION OF SCLEROTINIA BOREALIS AND S. NIVALIS AS A POTENTIAL TOXIN PRODUCER

Effective pathogenesis by the fungus Sclerotinia spp. requires the secretion of oxalic acid, but, this compound has no specific activity to host plants. Some studies were conducted to determine whether oxalate aids pathogen compatibility, but indicated that the inhibitory effects of oxalate are largely independent of both its acidity and its affinity for Ca2+. Other chemicals must be considered, but the current information about Sclerotinia's toxins is limited. Three isolates of Sclerotinia borealis and S. nivalis were studied to examine the possible toxin production and its effect on virulence. After 5 days of germinated seeds incubation, screening experiments revealed small difference in toxin production by the isolates, and significant difference in sensitivity of the tested plants. The isolates were less toxic to putative host plants - cereals, and highly toxic to tomatoes, brassicas, and other vegetables, rarely affected by those pathogens. Five putative toxin-coding genes were revealed in analysis of complete genome of S. borealis F-4128. This indicates that a possible action of several toxins is involved in the phytotoxicity of the phytopathogens.