“Flavescence dorée” strains in selected Italian wine-producing areas

The study of the genetic variability of phytoplasmas is a tool to clarify their epidemiology and to implement an effective management of their associated diseases. “Flavescence dorée” (FD), a threatening disease of grapevine associated to phytoplasmas belonging to 16SrV-C and -D subgroups (Martini et al., 1999) and its insect vector(s), is(are) distributed within the most important European wine-producing areas. This quarantine disease has severe effects on both vineyard productivity and landscape management and, despite the efforts to contain the pathogen dissemination, the disease is epidemic in several viticultural areas of northern Italy. During the past 30 years FD phytoplasmas belonging to both ribosomal groups were detected in several viticultural areas of Italy (Angelini et al., 2018), however sequencing of non-ribosomal genes, such as secY, map and rpsC, allowed the identification variants within the FD phytoplasma populations that seems in several cases consistent with an increased bacterium virulence (Bertaccini et al., 2021; Contaldo et al., 2021). From 2018 to 2022 focused surveys were conducted in FD infected vineyards to verify molecular variability of the FD phytoplasma strains and their relationship with outbreaks.