Molecular and pathogenic characterization of Fusarium oxysporum f. sp. pisi isolates obtained from Turkey

Fusarium oxysporum f. sp. pisi (Fop) is a highly destructive root rot pathogen for the pea (Pisum sativum L.) plant. In this study, the presence of F. oxysporum isolates was detected during the 2020–2021 growing season in plants showing symptoms of root rot in provinces of Turkey (Bursa, Afyonkarahisar, İzmir and Aydın) important for pea production. The pathogen was identified by its colony growth on various media, morphological characteristics and, molecular characterization based on DNA sequencing and SCoT markers. The pathogenicity of 183 isolates obtained from the roots of disease symptomatic plants was tested after artificial inoculation of pruned roots of seedlings by dipping in a conidia suspension of the isolates. Disease severity was scored and the length of brown lesions on the stem, extending from the base, was measured for each isolate. The isolates showed very large variation (0%-80%) for disease severity. A total of 50 isolates showing high stem-lesion lengths within different disease severity ranges were selected and evaluated for their effect on plant growth parameters such as plant height, number of seeds per pod and number of pods per plant. There were significant positive correlations between the reduction (%) in plant height and lesion length, and disease severity. These isolates can potentially cause yield losses in Turkey's pea cultivation based on the measured stem lesions which could be an indication of the pathogenicity of different Fop isolates. New information about pathogenic variability in Fop isolates from Turkey will be valuable for detecting races of this pathogen and resistance of pea genotypes.