First report of Little cherry virus 1 in cherry, plum, almond and peach in Italy

Little cherry disease (LChD) is a widespread disorder of ornamental, sweet and sour cherries. In sensitive cultivars, it results in the production of small, pale-coloured fruits with reduced sugar content and in the premature reddening or bronzing of the leaves. Little cherry virus-1 (LChV- 1) and Little cherry virus 2 (LChV-2), both members of the family Closteroviridae, are associated with this disease, but often induce symptomless infection. Assays for both viruses were made during a survey in 2006 and 2007 of the sanitary status of fruit trees in Apulia (southern Italy). Samples were collected in different commercial orchards from 22 sweet cherry, 13 plum, five almond, five peach, and two apricot trees. Total nucleic acids (TNA) were extracted from the leaves as described by Foissac et al. (2001) and used as template for Superscript III one-step RT-PCR with Platinum Taq DNA polymerase (Invitrogen, Carlsbad, CA, USA) using primer sets specific for LChV-1 or LChV-2 (Rott and Jelkmann, 2001). Whereas all samples were negative for LChV-2, a 419 bp fragment corresponding to part of the 3' non-translated region of LChV-1 RNA was amplified from five cherry, four plum, one almond and one peach tree samples. These results were obtained in several independent experiments. Trees of both native and imported cultivars were infected but LChV-1 was not associated with any particular field symptoms. To our knowledge, this is the first report of LChV-1 in Italy and of its natural occurrence in plum, almond and peach.