Identification and Characterization of Potato spindle tuber viroid infecting tomato in Italy

Potato spindle tuber viroid (PSTVd), a quarantine plant pathogen in Europe, was detected in tomato plants in northern Italy. Infected plants, showing shortened internodes, deformed and necrotic leaves, and abnormal fruit maturation, were growing close to symptomless Solanum jasminoides plants also infected by PSTVd. Molecular characterization of field isolates, biological assays and sequence analyses support the likelihood of PSTVd transmission to tomato plants from the neighbouring infected S. jasminoides plants. These data provide the first evidence of the risk of PSTVd spread from symptomless ornamental Solanaceae to susceptible horticultural crops when prophylactic measures are not enforced, suggesting that occasional PSTVd outbreaks in tomato crops reported from several European countries in the last two decades could have a similar origin. This report appears also to be the first of PSTVd infections of tomato in Italy.