Isolation, race determination and molecular characterization of Fusarium oxysporum f. sp. melonis in Bushehr province

In spring 2018, yellowing and wilting symptoms were observed on melon plants, Janna variety, in Dashti county, Bushehr province, southern Iran. In order to identify the causal agent of disease, infected tissues were transferred to the laboratory and five fungal isolates were isolated. Based on the morphological characteristic and sequence data of three different loci (ITS, EF-1α, and IGS), the fungi were identified as Fusarium oxysporum f. sp. melonis . The disease assay and race determination were performed in greenhouse using three melon differential hosts including Cha-T (no resistance gene), Cha-Fom1 (contains Fom1 resistance gene) and Cha-Fom2 (contains Fom2 resistance gene). The results of bio-assay experiment reveald that these isolates are belonged to race 1.2 of Fusarium oxysporum f. sp. melonis. According to the phylogenetic analysis, the isolates from Bushehr and the other Iranian isolates belonging to VCG0134 were clustered in the same linage and there were no nucleotide differences between them based on DnaSp analysis. Although F. oxysporum f. sp. melonis is known as a fungal pathogen of melon in cold and temperate regions, the presence of this pathogen in the tropical region of Iran is reporting for the first time in this study.