Fungi belonging to the Fusarium genus are commonly isolated from soybean plants and seeds but not all of them are pathogenic. The aim of this study was to compare the pathogenicity among different Fusarium isolates obtained from soybean plants with disease symptoms originating from an experimental field located in the southeast of Poland. Nineteen fungal isolates were selected for the pathogenicity assay, including eight isolates of F. oxysporum, six isolates of F. graminearum, four isolates of F. culmorum and one isolate of F. redolens. Species identification of these isolates was carried out using microscopic methods and sequencing of two genes: translation elongation factor 1-alpha (TEF1) and RNA polymerase second largest subunit (RPB2). To our knowledge, this is the first report of F. redolens being isolated from soybean in Europe. The pathogenicity test was set up by fungal inoculation of healthy soybean seeds of three cultivars: Abelina, Atlanta and Mavka. Symptoms were assessed seven days after inoculation. Disease area percentage of Fusarium inoculated seeds was significantly higher compared to uninoculated control. Nineteen isolates differed in their aggressiveness as the median disease area percentage ranged between 5.0 and 88.0% depending on isolate. The obtained isolates of four Fusarium species may be used in the future screening of soybean cultivars for resistance to these pathogens.

Fungi have the potential to colonize soybean seeds in the field, during their maturation in the pods and after harvest, during storage. The aim of this study was to identify fungi inhabiting soybean seeds after storage with varying germination capacity and to evaluate their chemical composition. The research material consisted of twelve soybean seed lots collected from the fields in southern Poland and stored over winter. The germination percentage of these lots ranged between 20.67% and 81.33%. The seeds were subjected to analyses of the main chemical components and mycological analysis. Fungal isolates were subjected to taxonomic identification using microscopic methods and DNA sequencing (using internal transcribed spacer region and secondary barcoding regions). A total number of 355 fungal isolates from 16 genera were identified, with Aspergillus, Alternaria, and Fusarium being the most common. Species were successfully identified in 94% of isolates. Twelve examined seed lots varied significantly in the number of isolated fungal species (from 1 to 17). Moreover, they also differed in the isolated species composition. Highly significant positive correlation was found between the number of Aspergillus psedudoglaucus isolates and the content of free fatty acids. In turn, the number of Fusarium spp. isolates correlated negatively with protein and nitrogen content. Similarly, highly significant negative correlation was found between the number of all fungal isolates and the 1000-seed weight, indicating that smaller seeds are more vulnerable to fungal infection. The results obtained in this study identify species of fungi which may be responsible for lowering quality of the seeds obtained in southern Poland.

Organic soybean seeds are susceptible to colonization by numerous fungal pathogens, which can reduce their germination capacity and nutritional quality. This study evaluated fungi transmitted by seeds and their effects on selected seed quality parameters, as well as the influence of variety, location and growing season. In total, 471 fungal isolates belonging to 24 genera and 37 species were obtained from three soybean varieties (Erica, Es Commandor and Cerez PZO) cultivated at two locations during the 2022–2023 seasons. All obtained isolates were identified based on ITS sequencing, and Fusarium isolates were further characterized to the species level using TEF and RPB2 markers. Fusarium spp. was the most frequently isolated genus, accounting for 35.7% of all isolates, followed by Alternaria spp. (15.9%) and Aspergillus spp. (11.9%). Fungal frequency and species diversity differed significantly between years. Seed germination capacity was significantly lower in 2023 than in 2022 and coincided with higher fungal colonization, lower spring temperatures, and increased rainfall. A significant negative Pearson’s correlation (r = −0.58, p < 0.05) was found between fungi abundance and seed oil content, indicating a direct impact of fungal colonization on nutritional quality. These results highlight the role of environmental conditions in seed-borne pathogen communities and the need for monitoring and seed health management to ensure soybean seed quality.

Soybean [Glycine max (L.) Merrill] plants are potential hosts for different pathogens. Soil-borne diseases, caused by pathogenic fungi, are considered to be the main reason for the loss of soybean yields worldwide. The aim of the research was to isolate fungi inhabiting underground parts of soybean in order to identify potential pathogens present in south-east Poland. Research material comprised of seven soybean cultivars grown in field in 2017-2019. Samples collected in three subsequent vegetative seasons constituted soybean plants with disease symptoms on cotyledons, stems and roots. Fragments of the infected plant tissues were subjected to mycological analysis. A total of 1692 pure fungal isolates were obtained from the sampled plants and almost 80% of these isolates were assigned to Fusarium genus. Among Fusarium spp. isolates, the most frequently detected species was F. oxysporum (71.3%). Other detected Fusarium species included: F. graminearum, F. culmorum, F. avenaceum, F. poae, F. solani (syn. Neocosmospora solani), F. sporotrichioides and F. fujikuroi. Other fungi accounted for approx. 19% of the obtained isolates and their main representatives were: Alternaria alternata, Trichoderma sp., Rhizoctonia solani, Mucor sp., Cladosporium sp. and Rhizopus sp. Comparison of these results with published data from other regions of Poland shows differences in prevalence of different species of soil-borne fungi.