Identification and Pathogenicity of the Soybean Root Rot Pathogen in Arid Conditions

Soy is an important oilseed crop in Kazakhstan. However, its yield is significantly reduced due to an increase in the development of fungal diseases with soil infection. This study aims to identify the root rot pathogen in soybean varieties in Western Kazakhstan and assess its pathogenicity. Samples of soybean roots to determine the root rot pathogen were selected at the experimental plots of the Aktobe agricultural experimental station in 2021. Genetic analysis of isolates observed on potato dextrose agar medium from soybean root slices was carried out using the sequencing reaction of internal transcribed spacer region nucleotide sequences using the Big Dye Terminator protocol (applied biosystems) with a further comparison of data with the Gen bank database. A test for the pathogenicity of the identified isolates of the fungus was carried out. Statistical data processing was carried out using the R-studio software according to the nonparametric Kruskal Wallis test. Phylogenetic analysis of samples of soybean affected by root rot showed that the main biotic agent causing root rot was the imperfect fungus Fusarium equiseti. Sequencing of the highly informative internal transcribed spacer region of fungal isolates allowed identifying strains 1 and 2 belonging to the species Fusarium equiseti. The pathogenicity test established that isolates of the Fusarium equiseti fungus caused discoloration of seedlings and plant roots and necrosis in soybean seedlings.