Survey of viral infections in spontaneous grapevines from natural environments in Sicily

The presence of nine of the most economical important grapevine viruses was surveyed in eight spontaneous grapevine populations from natural areas of Sicily. Arabis mosaic virus (ArMV), Grapevine fanleaf virus (GFLV), Grapevine leafroll-associated virus 1, 2 and 3 (GLRaV-1, -2 and -3), Grapevine virus A and B (GVA, GVB), Grapevine rupestris stem pitting-associated virus (GRSPaV) and Grapevine fleck virus (GFKV) infections were assessed by molecular and serological methods in 73 vines collected in summer 2013 and winter 2013-2014. Reverse transcription-multiplex PCR detected nine GRSPaV- and one GFLV-infected plants in five and one grapevine populations, respectively, while no ArMV, GLRaV-1, GLRaV-2, GLRaV-3, GVA, GVB, GFKV infections were detected. ELISA tests on dormant wood confirmed the result of the molecular detection. The relationship of Sicilian wild grapevine isolates with isolates from grapevines of different geographic origin was investigated through sequencing of the complete coat protein (CP) region of GRSPaV, and partial CP and homing protein (HP) domains of GFLV. Pairwise comparison among the Sicilian GRSPaV CP sequences showed identity scores ranging from 81.67% to 99.87% and from 92.66% to 100% at nucleotide (nt) and amino acid level (aa), respectively. For GFLV, the CP sequence showed identity ranges from 84.28% to 90.48% (nt) and from 89.39% to 97.11% (aa); higher variability was obtained analysing the HP domain with identity scores ranging from 68.42 to 93.28% (nt) and from 58.02% to 93.23% (aa). According to phylogenetic analyses, GRSPaV and GFLV isolates from Sicilian wild grapevines clustered with isolates from cultivated grapevines without any correlation between isolate distribution and their geographic origin.