Diversity and pathogenicity of the Fusarium fungi occurred in soybean mycobiota

Abstract

The aim of present study was to reveal the species composition of Fusarium fungi found in the soybean mycobiota from the various origins of Russia, as well as to characterize physiological and biochemical properties of isolates. Identi cation of the taxonomic status of 21 Fusarium strains isolated from seeds, stems and roots of soybeans was clari ed according to data using phylogenetic analysis of the nucleotide sequences of the gene of translation elongation factor 1α. Five fungal species have been identi ed: F. oxysporum (11 strains), F. equiseti (4), F. proliferatum (3), F. solani (2), as well one strain of F. commune, which was identi ed for the rst time in soybean mycobiota in Russia. The morphological and cultural characteristics of the isolates and their pathogenicity to leaves of two soybean varieties in the laboratory conditions were also analyzed. At the cultivation of Fusarium fungi on potato- sucrose agar medium, the optimal temperature range for the growth of all isolates has been established as 25-30 °C, at which the largest colony diameter 68,5-74,0 mm was found in F. equiseti and F. commune strains, and the smallest colonies (49,5-55,8 mm) was detected in F. solani strains. Three F. oxysporum strains and one F. commune strain, isolated from the stems, were characterized by high pathogenicity to the leaves of two soybean varieties. These strains caused the necrosis of leaves of the Isidor variety in the range of average length 16,7-21,7 mm, and the necrosis of leaves of the Selecta 201 variety in the range of 10,7-23,3 mm. At the same time, the most of the analyzed Fusarium strains (52-67 % depending on the soybean variety) were non-pathogenic. A high intraspeci c variability of pathogenicity to soybean leaves was noted among F. oxysporum and F. proliferatum strains