Capparis spinosa- a new host of Cucumber mosaic virus in Italy

Abstract

In spring 2004, a survey was conducted to investigate the phytosanitary status of caper ( Capparis spinosa ) crops in Sicily, the Eolie Islands (Salina and Lipari) and Pantelleria. Two viruses have previously been isolated from caper in Salina (Campo et al ., 2000): Caper latent virus (CapLV, genus Carlaviruses , family Flexiviridae ) (Gallitelli & Di Franco, 1987) and Pittosporum vein yellowing virus (PVYV, genus Nucleorhabdovirus , family Rhabdoviridae ) (Nuzzaci et al ., 1993) . Crude sap taken from collected leaf samples was used to mechanically inoculate the experimental host species Chenopodium quinoa , C. amaranticolor , Nicotiana benthamiana and N. glutinosa . Some samples from the Eolie crops produced chlorotic local lesions on Chenopodium spp. a few days post-inoculation and severe systemic mosaic leaf malformations and shoestringing on Nicotiana spp., resembling symptoms caused by C ucumber mosaic virus (CMV, genus Cucumovirus , family Bromoviridae ). ELISA, using a CMV-specific rabbit polyclonal antiserum (ISPaVe-CMV22), detected the presence of the virus in samples from Salina and Lipari. To characterize the virus isolates, total RNA was extracted from caper leaves (Qiagen, RNeasy Plant Mini Kit) and was analysed in a one-step RT-PCR using primer sets CMV-CPI or CMVCPII (Lumia et al ., 2001), specific to I and II subgroups of CMV, respectively. An amplified product of the expected size was mostly commonly obtained when CMV-CPI primers were used (672 bp), and less frequently with CMV-CPII primers (674 bp). In a few samples both subgroups were detected. During the spring, CMV was detected in plants showing reddish mottle, vein yellowing and yellow rings or spots, and in caper plants without symptoms that showed interveinal leaf chlorosis on a few basal shoots later in summer. Plants with yellowing disorder were found to be infected with both CMV and PVYV. No CMV-infected plants were detected in Pantelleria. This is the first report of Capparis spinosa as a natural host of CMV and adds a new plant family, Capparaceae, to the already wide virus host range.