Cultural and morphological features of <i>Fusarium oxysporum</i> and <i>Fusarium brachygibbosum</i> species associated with garden strawberry plants

Abstract

This study is focused on two micromycetes of the genus Fusarium: the complex species F. oxysporum and F. brachygibbosum Padwick isolated from strawberry roots from different regions of Russia. Studies were performed in 2021-2022 on samples of symptomatic plants collected in the Republic of Crimea and Voronezh Oblast. The micromycetes were studied by means of a combination of classical biological methods and molecular genetic approaches with decoding of nucleotide sequences. The subject of the work was to study the biological features of F. oxysporum and F. brachygibbosum Padwick. The work included the study of macro- and micro features of the target objects. The following cultural features were determined: structure and coloring of aerial and substrate mycelium, character of colony surface, growth rate, sporulation of fungi, pigmentation of structures and nutrient media on the studied media. The species F. brachygibbosum from planting material of strawberry originating from the Republic of Crimea was isolated and identified for the first time. As a result of studies of different composition of nutrient media, it was found that potato-glucose agar (PGA) 2 % is the most optimal nutrient medium for growth and sporulation of target isolates. It was determined that the addition of citric acid to PGA altered the macro features of the mycelium of F. brachygibbosum. Universal sites of several genes (internal transcribed spacer, actin gene, elongation translation factor gene) were studied for species identification of F. oxysporum and F. brachygibbosum. Variable gene sites for identification of the species identity of Fusarium isolates were determined. It was revealed that ITS1-5.8S-ITS2 and TEF sites could be used for interspecific differentiation of Fusarium wilts.