Archivio Journal of Plant Pathology

Abstract:

Rugose wood is a complex disease affecting grapevine worldwide. At present, at least six different viruses belonging to the family Betaflexiviridae are known to be associated with the disease (Saldarelli, 2014). Previous studies had shown that Grapevine virus A (GVA), Grapevine virus B (GVB) and Grapevine rupestris stem pitting associated virus (GRSPaV) are common in Tunisian grapevines (Martelli, 2014), whereas no information is available on the presence of Grapevine virus D (GVD). Therefore, a total of 140 samples from several cultivars, were collected from major Tunisian viticultural regions and tested for the presence of this virus by RT-PCR using the GVD-specific primers CP471C and CP7V (Abou-Ghanem et al., 1997). A 474 bp product corresponding to a fragment of the coat protein gene was amplified from 58 samples, accounting for an infection rate of 41.42%. The virus was present in all the surveyed areas and grape cultivars tested. The infection rate ranged from 11.7% (cv. Red Globe) to 88.8% (cv. Muscat RafRaf). To confirm the identity of the target virus, three RT-PCR products were cloned and sequenced. The Tunisian isolates shared 86-91% common nucleotides with the other GVD isolates from GenBank, and 72-73%, 60-62% and 53-55% nucleotide identity with GVA (JF754577), GVB (NC003602.1) and GVE (JX402759.1), respectively. To our knowledge, this is the first report on the occurrence of GVD in Tunisian grapevines. The infection rate of GVD (41.42%), which is close to that of GVA (47.2%) in the same samples, suggests the presence of common vectors for both viruses in Tunisian vineyards.