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.

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Background Grey mould caused by Botrytis cinerea Pers. (teleomorph Botryotinia fuckeliana (de Bary) Whetzel) is one of the most destructive fungal diseases of Mediterranean crops. In Algeria, few studies have been made on the economic impact of this disease. Nevertheless, it is practically present in all tomato and strawberry greenhouses, as well as in prospected vineyards in the north and south of the country. The complexity of chemical control of this disease has led to search for Trichoderma strains that are effective in biological control. Results Fifteen isolates of Trichoderma spp. were obtained from vigorous and healthy plants (tomatoes, strawberries, and vines) rhizosphere, and from a commercial bio-compost (Bio-composte®), then identified as T. afroharzianum (four isolates), T. gamsii (four isolates), T. longibrachiatum (three isolates), T. atroviride (one isolate), T. brevicompactum (one isolate), T. breve (one isolate), and T. lixii (one isolate) on the basis of DNA sequence analysis of four genes (ITS, tef1, rpb2, and acl1). In vitro biocontrol tests revealed that four Algerian isolates of Trichoderma spp. (TAtC11, TGS7, TGS10, and TBS1) had a high antagonistic activity against B. cinerea, the mycelial growth has been reduced by 62 to 65% in dual-culture technique, by 62.31 to 64.49% in volatile compounds test, and a high inhibition of germling growth was recorded by TBS1 isolate with 90.68% in Culture filtrates test. Biocontrol tests carried out on tomato plants with T. brevicompactum (TBS1), T. atroviride (TAtC11), and T. lixii (TLiC8) against B. cinerea (BCT04) showed that TBS1 inoculation significantly reduced the incidence of disease by 64.43 and 51.35% in preventive and curative treatment, respectively. Conclusion The present study revealed the first report of T. brevicompactum, T. breve, and T. lixii in Algeria, and it also contributes to the promotion of the use of native strains of Trichoderma in biological control leading to a better preservation of soil microbial diversity.

The aim of these studies is to develop a method for early detection of Rigidoporus lignosus (Basidiomycete, Polyporaceae), the causative agent of white root disease of rubber tree. Two polyclonal sera were produced against soluble mycelial proteins of two R. lignosus isolates, one from Africa (FCI2), the other from Asia (FID2). The specificity of the antisera was tested using isoelectric focusing (IEF)/Western-blot and DAS-ELISA. The two sera recognized all 20 R. lignosus isolates from various geographical origins. The banding patterns obtained by Western-blot enabled a distinction to be made between isolates from Africa and those from Asia. In DAS-ELISA and Western-blot analyses, strong cross reactions were observed with R. ulmarius. Only slight reactions were observed in Western-blot analysis to R. lineatus and P. noxius, both causative agents of root rot in Hevea. These cross reactions were not observed under our DAS-ELISA analysis conditions. Finally, no cross reactions were obtained with 9 other Polyporaceae or Hevea root pathogen species. The sensitivity threshold of the DAS-ELISA method was 5 ng ml-1 of R. lignosus protein. An initial approach to using the DAS-ELISA test for the detection of R. lignosus in infected plants was carried out on artificially inoculated root samples. The DAS-ELISA protocol enabled detection of R. lignosus in the root systems of diseased plants. Moreover, no cross reaction was observed with healthy plant extracts.

The present study was carried out to ascertain the genetic status of soybean and maize crops introduced in Algeria and to test local and imported products containing maize and soybean for the presence of genetically modified organisms (GMO into the food and feed chain). Samples from crops and processed food products were selected, randomly sampled and screened by polymerase chain reaction (PCR) for the presence of the 35S cauliflower mosaic virus promoter (P35S CaMV) and the Agrobacterium tumefaciens nopaline synthase (nos) terminator, commonly found in transgene cassettes. Results showed that GMOs were absent in all crop samples, but present in 29 food and feed samples. These analyses are discussed for the efficiency of the Algerian regulation and the absence of labelling and traceability mechanisms within the country.