M. Bousalem, D. Fargette, Agnès Pinel, J. Dubern and J. Berthaud
The vegetative multiplication of yam (Dioscorea sp.), the virus transmission by vectors and the frequent exchanges of infected plant material favour the spread of viral diseases. Yam
Mosaic Potyvirus is the most important virus described so far on yam. The study presented here is an evaluation of the molecular variability of YMV. Thirty isolates from different geographical areas and from different species and cultivars of yam were studied. The isolates were collected on three species, D. alata, D. cayenensis-D. rotundata. D. trifida. The regions of interest (NIB / CP / 3′-UTR) were amplified by PCR and sequenced. The phylogenetical analysis (cladistic parsimony method) distinguished nine groups. Comparative analysis with several poty viruses showed that, as for YMV, CP and 3′ UTR regions were highly variable. The thirty isolates analyzed were considered as strains of the same virus, although some were very distant one from each other. Links with geographical diversity and host species were established.