Survey of the sanitary status of ancient native grapevine cultivars from Apulia (Italy) by real-time PCR

A study of the sanitary status of ancient native grapevine cultivars and biotypes of Apulia (Italy) was performed in the framework of the project Re.Ge.Vi.P. ("Recovery of Apulian grape germplasm"), A total of 80 native table and wine grapes (the majority of which described in historical pre-philloxera reports) were recovered throughout the Apulian territory and their dormant canes used for virus screening by ELISA for the presence of Grapevine virus A (GVA), Grapevine virus B (GVB), Grapevine leafroll-associated virus-1, -2 and -3 (GLRaV-1, -2 and -3), Grapevine fanleaf virus (GFLV), Grapevine fleck virus (GFkV) and Arabis mosaic virus (ArMV), using commercial kits (Agritest s.r.l., Italy). Certified plant propagation material of grapevine should be free of these viruses according to the Italian Law. Selected accessions were propagated and those positive for single or multiple virus infections were submitted to sanitation. Overall, at least three plantlets deriving from distinct apex excisions (totally 242) were transferred to the greenhouse after acclimatization and were tested after 60 days by REALTIME-RT-PCR for all the viruses above indicated Over 242 apexes tested, GFLV and GFKV were the most frequently detected viruses showing 9.5% and 8.2% of infection rate, respectively, followed by GVA (4.9%), GRLaV3 (2.9%) and GVB (1.6%). Furthermore, all plants reacted negatively to GLRaV-1, GLRaV-2 as well as ArMV which is known to be rare in the Mediterranean area, also because the low occurrence of its vector, Xyphinema diversicaudatum. Mixed infections by more than one virus were found in some plants assuming the failure of sanitation procedure to eliminate these viruses. The persistence of infection by GVA, GVB, GLRaV3 and GFkV in some apexes, which was not detected by the preliminary ELISA screening of source plants, underlines the higher sensitivity of Realtime-RT-PCR to detect these viruses.