Identification of fungi inhabiting underground plant parts of soybean [Glycine max (L.) Merrill] in two developmental stages

Abstract

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.

Identification and Pathogenicity of Fusarium Isolated from Soybean in Poland

“…Fungal isolates included in this study were obtained in June and July 2019 from soybean plants grown from uncoated seeds in the experimental field located in Makowisko (50°2′43″ N, 22°47′10″ E, podkarpackie voivodeship, southeast Poland) [ 14 ]. Soil and weather conditions in this experiment have been described by Jarecki et al [ 29 ].…”

“…Both ML trees formed four well-supported clades. Clade 1 included six isolates (14)(15)(16)(17)(18)(19) and NCBI records of F. graminearum. Clade 2 included four isolates (10)(11)(12)(13) and NCBI records of F. culmorum.…”

“…Fusarium root rot was first reported in Iowa in 1953 and F. oxysporum was the predominant fungus isolated from symptomatic soybean roots. Soybean root rot caused by this species has also been widely reported in China [ 11 ] and is the most frequently isolated Fusarium species from field grown soybean plants in Poland [ 12 , 13 , 14 ]. Moreover, F. oxysporum is associated with Fusarium wilt or blight and can cause a range of symptoms, including damping-off, cortical decay and vascular discoloration in soybean plants.…”

“…At present, this species is recognized as a primary pathogen of soybean, responsible for root rot, and for pre- and post-emergence damping-off in several countries on both American continents [ 17 ]. It is also isolated from soybean seeds as well as plants grown in Poland [ 14 , 20 ]. Moreover, F. graminearum has the ability to produce trichothecene mycotoxins, which significantly reduce seed germination [ 20 , 21 ].…”

“…However, Zeng et al [ 23 ] consider this pathogen to be one of the major causal agents of soybean root rot in three provinces in China. There are few reports of the detection of this species on soybean seed and plants in Poland [ 12 , 13 , 14 , 20 , 24 ] The pathogenicity of F. culmorum isolates is closely linked to production of mycotoxins, including the trichothecenes [ 25 ].…”