INVESTIGATION ON OCCURRENCE OF TRICHO-, FOVEA- AND CAPILLOVIRUSES IN ANCIENT FRUIT TREE CULTIVARS IN CAMPANIA

During a survey of ancient local fruit tree cultivars, the occurrence of Apricot pseudo chlorotic leaf spot virus (APCLSV), a recently described Trichovirus closely related to Apple chlorotic leaf spot virus (ACLSV) (Liberti et al., 2005a), was investigated. Samples were collected from 361 symptomatic and asymptomatic trees and analyzed by nested RT-PCR. APCLSV was detected in 7 of 112 apricot, 1 of 29 peach and 2 of 26 plum trees. All apple, pear and cherry trees tested negative for APCLSV. Compared with those in databanks, the sequences of APCLSV PCR products showed an average pairwise divergence of 11.6% (nt) and 4.5% (aa). The majority of isolates clustered with those characterized by Liberti et al. (2005a), but three additional divergent clusters could be identified. These results significantly extend our knowledge of the variability of APCLSV and suggest that contrary to ACLSV, APCLSV could be restricted to stone fruit hosts. Forty-eight samples were also screened for the presence of viruses belonging to the Trichovirus, Foveavirus and Capillovirus genera by PDO Nested RT-PCR (Foissac et al., 2005). The results revealed a very high prevalence of ACLSV in all species tested. Additional viruses detected include Cherry green ring mottle virus (CGRMV, 2 of 4 cherry trees), Apricot latent virus (ALV, 1 of 14 apricot trees), Cherry virus A (CVA, 6 of 14 apricot, 1 of 6 plum and 1 of 4 cherry trees), Apple stem pitting virus (ASPV, 4 of 9 apple and 1 of 8 pear trees) and Apple stem grooving virus (ASGV, 1 of 9 apple and 1 of 8 pear trees). This is the first record for APCLSV on peach in Campania and of CVA in Italy. These results provide information on the prevalence of Fovea-, Tricho- and Capilloviruses in old local cultivars and extend our knowledge on the diversity of these agents.