Molecular characterization of alfalfa mosaic virus (AMV) isolates from officinal plants

Seven new AMV (Alfalfa mosaic virus) isolates from officinal plants have been characterized at molecular level. Isolates were from symptomatic plants of Lavandula hybrida (three varieties of lavandins), Lavandula x alardii (one hybrid) and single plants of Lippia citriodora, Ocimum basilicum and Symphytum tuberosum. In all instances symptoms consisted in a more or less extended yellow bright mosaic of the leaves. The nucleotidic and aminoacidic sequences of the coat protein (CP) and movement protein (MP) have been determined for each of them. Phylogenetic relationships conducted on the CP and MP set of sequences showed that all isolates belonged to subgroup I of AMV isolates with the exception for that from the “Sumiens” variety of L. hybrida which was related to subgroup II of AMV isolates. Data were confirmed by RFLPs of the amplicons corresponding to the CP and MP. Since subgroup II have been detected so far only in France, the detection of a subgroup II isolate in Italy could be explained with the accidental introduction of infected vegetative propagate material form France where the “Sumiens” variety was constituted several years ago. The possibility of the diffusion of subgroup II isolates in Italy and related consequences are discussed.