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First Report of Alfalfa mosaic virus in Lavandula officinalis

For several years, in ornamental nurseries in the Mediterranean area of Spain, stunting and yellow leaf spotting have been observed in young plants of Lavandula officinalis. Symptoms eventually disappeared as the plants matured. During the summer of 2003, the number of plantlets affected and the intensity of symptoms increased significantly. Symptomatic plants tested positive using enzyme-linked immunosorbent assay (ELISA) (Phyto-Diagnostics, INRA, France) for the presence of Alfalfa mosaic virus (AMV). ELISA results were verified using reverse transcription-polymerase chain reaction (RT-PCR). Total RNA extracts from symptomatic plants were analyzed using primers designed specifically for the coat protein region of AMV utilizing sequence data from GenBank Accession No. AF215664: AMVcoat-F: GT GGT GGG AAA GCT GGT AAA and AMVcoat-R: CAC CCA GTG GAG GTC AGC ATT. The thermocycling schedule was as follows: reverse transcriptase step at 50°C for 30 min, first PCR cycle at 94°C for 2 min, 35 cycles each of 30 s at 94°C, 30 s at 54°C, 30 s at 72°C, followed by a final extension at 72°C for 10 min. A 700-pb PCR product of the expected size was obtained from plants that were positive for AMV using ELISA. The two systems provide for rapid detection of AMV in L. officinalis. A regular screening program will assist in providing virus-free plants to ornamental nurseries. These results demonstrate the presence of AMV in L. officinalis. Alfalfa (Medicago sativa L.) is a typical source of AMV. However, because the nurseries where L. officinalis is grown are not in the vicinity of alfalfa fields, we suggest the source of the infection originated in the propagation material. AMV has currently been reported in L. officinalis only in Italy and France (1). To our knowledge, this is the first report of AMV in L. officinalis in Spain.

Reference: (1): A. Garibaldi et al. Ed. Edagricole-Edisioni Agricole della Calderini s.r.l., Bologna, 2000.