First report of Fusarium sporotrichioides causing root rot of soybean in Canada and detection of the pathogen in host tissues by PCR

Soybean plants showing symptoms of root rot were collected from fields in Manitoba, Canada, in 2017, to determine the causal agent of the disease. Of 240 isolated strains, including some known as root rot pathogens, five were identified as Fusarium sporotrichioides Sherb. based on morphological characteristics. All five isolates were pathogenic when inoculated on soybean under controlled conditions, and resulted in typical root rot symptoms. In addition, shoot length, root length, and fresh weight were significantly reduced. A PCR-based diagnostic test was developed, which specifically amplified the Trichothecene gene cluster in F. sporotrichioides. The primer SPO1 amplified a 541 bp fragment in fungal isolates originally isolated from commercial soybean crops, and from artificially infected roots of soybean. Trichothecene (TRI) gene expression was detected in infected soybean roots using RT-PCR analysis with TRI gene-specific primers. This is the first report of F. sporotrichioides as one of causal agents of root rot in soybean in Canada.