Abstract:
Fusarium wilt of melon is a destructive fungal disease throughout the world. In this
study, the evolutionary relationships among isolates of different formae speciales of
Fusarium oxysporum was examined, with a special emphasis on the forma specialis
melonis. Bootstrapped maximum likelihood analysis of the elongation factor-1α (EF-1α)
sequence was conducted on 16 Iranian and 11 foreign isolates of F. o. melonis that
included representatives of different vegetative compatibility groups (VCGs 0130-0136).
The tree inferred from the dataset resolved five evolutionary lineages that were correlated
with the F. o. melonis VCGs, with the exception of VCGs 0130 and 0131, which could not
be differentiated with EF-1α sequences. Furthermore, based on EF-1α sequences, specific
associations were found between F. o. melonis VCGs and the other formae speciales whose
sequences were obtained from the GenBank. Taken together, these results support a
polyphyletic origin for F. o. melonis, meaning that the ability of this forma specialis to
cause disease on melon has emerged multiple times.
Keywords: Cucumis melo, Iran, Polyphyletic, VCG
