Genetic Structure and Molecular Variability of Grapevine Fanleaf Virus in Sicily

Grapevine fanleaf virus (GFLV) is one of the main causes of grapevine fanleaf degeneration disease (GFDD) and is present in almost all areas where grapevine is cultivated. In this work, we ascertained the presence and spread of GFLV in different commercial vineyards in four Sicilian provinces (Italy), and its genetic structure and molecular variability were studied. In detail, a total of 617 grapevine samples of 11 autochthonous grapevine cultivars were collected in 20 commercial vineyards. Preliminary screening by serological (DAS-ELISA) and molecular (RT-PCR) analyses for ArMV (arabis mosaic virus) and GFLV detection were conducted. Results obtained showed the absence of ArMV in all the samples analyzed, while 48 out of 617 samples gave positive results to GFLV, for a total of 9 out of 11 cultivars analyzed. Phylogenetic analyses carried out on the GFLV-CP gene of 18 Sicilian GFLV sequences selected in this study showed a certain degree of variability among the Sicilian isolates, suggesting a different origin, probably as a consequence of the continuous interchange of GFLV-infected propagating material with other Italian regions or viticultural areas located in other countries.