Investigation on the phytosanitary status of major ornamental hibiscus species in Italy to assess virus infection

In 2010-11, a study examined symptomatic Hibiscus rosa-sinensis plants in a major wholesale nursery in central Italy for the presence of viruses. The observed symptoms were chlorotic spots or rings, chlorotic mottling, and in some cases, vein necrosis in older leaves and early leaf yellowing and drop. A total of 125 samples were collected from cultivated plants of different cultivars and 13 imported cutting lots imported from elsewhere in Europe, Africa or Asia. Additionally, leaf samples of H. moscheutos, H. syriacus and some wild species commonly used for breeding were included in this study. All samples were assayed for Hibiscus chlorotic ringspot virus, Hibiscus latent Singapore virus and Hibiscus latent Fort Pierce virus by single-step RT-PCR using specific primers designed to the coat protein gene for each virus. The obtained amplicons of the expected sizes were sequenced and analysed to confirm virus species identity. Further, the sequences were analysed and phylogenetically compared with available sequences of the same viral species in GenBank. The results showed that all three viruses are widely distributed in hibiscus in nurseries and commercial gardens surveyed in Italy and in imported cuttings. In this study, preliminary molecular characteristics of the isolates of the aforementioned viruses are also provided.