Vineyards in western and center regions of Algeria were surveyed for the Grapevine leafroll-associated virus 2 (GLRaV-2). Analyses by DAS-ELISA and Reverse Transcription Polymerase Chain Reaction (RT-PCR) reveal 15, 8% prevalence. The genetic diversity of the GLRaV-2 population was studied by phylogenetic analyses of the HSP70h gene region of seven samples sequenced in this study and other sequences downloaded from GenBank. Results reveal segregation of the GLRav-2 population into six distinct groups. An estimation of the ratio of non-synonymous substitutions per non-synonymous site to synonymous substitutions per synonymous site indicated that HSP70h gene evolve under positive selection. Similarity plot constructed with representative sequence from each group confirmed previous results.  All Algerian isolates belong to group PN. As far as we know, this is the first characterization of GLRaV-2 isolates from Algeria.

Grapevine rupestris stem pitting‐associated virus (GRSPaV) is one of the most widespread grapevine viruses and is transmitted mainly by grafting. GRSPaV presence was tested in 487 samples representative of the Tunisian grapevine germplasm (including autochthonous, table, wine, wild grape, and rootstock varieties) from different Tunisian regions. GRSPaV infection was detected in 51.3% of samples from different Tunisian regions, among which the table grapevine cultivars were the most commonly infected (68.7%). Genetic variability of GRSPaV isolates from wild and cultivated grapevines was assessed by sequencing the partial capsid protein (CP) gene of 19 Tunisian isolates and 1 Italian GRSPaV isolate from Sicily, and the partial RNA‐dependent RNA polymerase (RdRp) gene of 13 Tunisian GRSPaV isolates. According to phylogenetic analysis of CP nucleotide sequences obtained in this study and sequences retrieved from GenBank, Tunisian isolates fell into four phylogenetic groups already described (I, II, III, and IV) and two new phylogenetic groups (VI and VIII). Phylogenetic analysis of the partial RdRp gene revealed that Tunisian isolates of GRSPaV are distributed into four phylogroups. This study highlights the importance of regular monitoring of GRSPaV infections in Tunisia, with special regard to those grapevine accessions employed in conservation and selection programmes. In particular, the presence of new GRSPaV genetic variants and infection of wild grapevines must be taken into account in order to choose a correct control strategy.

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 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.

Several grapevine viruses were reported in Algeria and especially in grapevine germplasm collection, therefore it is a great challenge to free these varieties from virus infection before any breeding programs. Our study focused on the development of chemotherapy on autochthonous varieties collected in the grapevine germplasm collection of ITAFV. All these varieties were tested by DAS-ELISA and the presence of GLRaV-3 and GFLV was confirmed in all used samples for the sanitation. After 8 weeks of shoot tips in vitro culture in a modified M S medium containing ribavirin, DAS-ELISA test revealed that GLRaV-3 was completely eliminated and GFLV to a significant rate.

Algeria is a country known for a varietal variety of Citrusfruits, which are susceptible to serious pathologies such as stubborn disease (Spiroplasma citri), causing significant economic losses. The current study was conducted in order to investigate the possible existence of different Spiroplasma citri strains in Algeria. Samples of fresh leaves and orange-tree fruits (Citrus sinensis L.) with stubborn symptoms were detected in Boumerdes and Blida province. Identification of the causative agent (Spiroplasma citri) was ensured by ELISA and PCR techniques. DNA extracted from symptomatic samples were used as a template for amplification of products of 675 bp using primer pairs Spiralin (Sc1 / Sc1-) and (SpiF / SpiR) by PCR. Furthermore, the spiralin gene was cloned and sequenced. About 18,23% of the samples, showing clear-cut stubborn symptoms, were ELISA-positive. Molecular characterization by sequence analysis has identified two Algerian isolates with 99% homology between them. Spiroplasma citri Isolate 12 (OQ078580) and Spiroplasma citri isolate 14 (OQ068387). Phylogenetic tree showed that the Algerian Spiroplasma citriisolates are more closely related to the Egypt, Israel, than those isolated from Iran and Corse.