First report of tomato leaf curl New Delhi virus in Lagenaria siceraria var. longissima in Italy

Abstract

During 2022, a new disease of bottle gourd, causing leaf mosaic and yellowing symptoms, was observed in a private garden in the Campania region, Southern Italy. Incidence of disease was high (up to 80% of plants with symptoms). Polymerase chain reaction (PCR) with coat protein specific primers to tomato leaf curl New Delhi virus (ToLCNDV) indicated association of a begomovirus with the disease. The sequence comparison and phylogenetic analysis of the complete DNA genome further revealed the virus as within ToLCNDV-ES strain. Nevertheless, phylogenetic relationships showed two distinctive subgroups among ToLCNDV-ES isolates, with subgroup I composed only of ToLCNDV-ES isolates identified in the Campania region, including the isolate found in bottle gourd. The possible evolutionary forces that determined evolution of the two subgroups within the ToLCNDV-ES strain, including the role of the vector and cultural practices, are briefly analyzed and discussed.