The occurrence of grapevine rugose wood disease in Algeria

Rugose wood disease constitutes one of the major grapevine disease complexes causing significant economic damage worldwide. It is widely distributed in all grapevine growing areas of the world and comprised of four individual syndromes, which may be caused by different viruses. These syndromes are Corky bark, LN 33 stem grooving, Kober stem grooving and Rupestris stem pitting (RSP). The present study focuses on the prevalence of three viruses associated with rugose wood complex (RWC) in Algeria. Field inspections and collection of symptomatic samples were conducted on autumn 2012 in the table wine and autochthone accession in the western and central regions of Algeria. A total of 202 samples were tested by RT-PCR using specific primers for Grapevine virus A (GVA), Grapevine virus D (GVD) and Grapevine rupestris stem pitting associated virus (GRSPaV). The results of RT-PCR indicated the presence of the viruses GVA, GVD and GRSPaV with 68,81% (139 out of 202 infected samples) total average infection rate. The results also indicated the predominance of GRSPaV compared to the prevalence of GVA and GVD with an infection rate of 57,92% vs. 36,63% (74 out of 202) and 2,97% (6 out of 202), respectively. Mixed infections of these three viruses were not observed in any of the samples analysed, however the mixed infection of GVA and GRSPaV was noted with a high rate of 26.73%. The grapevine cultivars; Kings Rubi, Carignan and Mersguerra were the most infected, while the Alicante Bouschet cultivar presented the lowest infection rate. To the best of our knowledge, the present study reports for the first time on the presence of GVD in Algeria

Prevalence and Genetic Diversity of Grapevine Virus D in Tunisia

The prevalence and the genetic diversity of grapevine virus D (GVD) isolates from rootstocks, wine and table grape varieties grown in Tunisia were studied. RT-PCR assays performed on the coat protein gene (CP) showed the presence of GVD in 31.5% of the 403 samples tested. The highest rate of infection was found in table grapes (56.5%), followed by autochthonous table grapes (24.1%), wine grapes (20.8%) and rootstocks (12.5%).  Sequences and phylogenetic analyses of the partial CP genes of 14 GVD isolates showed nucleotide identities that ranged from 84% to 99%. The  Tunisian GVD-isolates segregated in 3 phylogenetic groups together with international isolates reported in GenBank. The present study extends our  knowledge of the presence of GVD in Tunisian vines and on its genetic diversity, which is useful for developing broad-spectrum molecular  diagnostics (RT-PCR) capable of detecting the different isolates infecting vines