EPIDEMIOLOGICAL AND MOLECULAR ASPECTS OF ALFALFA MOSAIC VIRUS OCCURRENCE IN LAVANDULA VERA CROPS OF LIGURIA

From 2008 to 2010, an epidemiological study on the spread of Alfalfa mosaic virus (AMV) in some Lavandula vera crops located in Liguria Region (Albenga area) has been carried out. In fact, this non-persistent aphid-born virus, represents one of the most dangerous and economically important pathogens involving both growth and ornamental appearance of this aromatic species. In 2008 and 2009 numerous inspections were made at several lavender producers with accurate examination of pot-plants before blooming; AMV was serologically and molecularly detected by applying DAS-ELISA and PCR tests respectively, associated to stunting and yellow mosaic leaf symptoms. Considering that L. vera is propagated by shoots and that mother-plants (10-12 years old) growth at borders of pot-plants crops, in 2010 serological analyses were carried out to control ligurian propagation materials. Some mother-plants of L. vera showing leaf mosaic symptoms resulted AMV infected. One isolate of AMV from affected mother-plants was molecularly characterized and compared with previously characterized Italian lavender isolates of AMV, including a second one found infecting in 2010 L. vera “None Blue” in Emilia-Romagna Region. Results indicated that both these two isolate of AMV-L. vera (from Liguria and Emilia-Romagna) belonged to subgroup I, according with restriction profiles of the coat protein gene and phylogenetic relationships with other AMV isolates belonging to subgroups I and II. As prevention measures, mother-plants could be selected by periodic visual inspections and serologically tested for AMV presence. Virus-free shoots used as propagation material and large crop rotation periods are the most effective type of control.