Abstract
A novel virus infecting yams (Dioscoreaspp.), tentatively named "yam asymptomatic virus 1" (YaV1), was characterized and sequenced from an asymptomaticD. alataplant from Vanuatu. Sequence comparisons and phylogenetic analysis showed that YaV1 is a novel ampelovirus and has the smallest genome among "subgroup 1" members. RT-PCR-based screening of a yam germplasm collection conserved in Guadeloupe showed that YaV1 is prevalent inD. alata,D. bulbifera,D. cayennensissubsp. rotundata,D. esculentaandD. trifidaaccessions but causes no apparent symptoms. Additional phylogenetic analysis revealed a low variability of YaV1 in Guadeloupe in a limited part of the genome, and suggested the occurrence of plant-to-plant transmission.