The carcinoembryonic antigen (CEA) family contains a large number of glycoproteins belonging to the immunoglobulin superfamily. Here, we investigate whether the gene conversions occurring between primate CEA-related genes are adaptive. Our results show that primate CEA-related genes are subject to frequent and repeated gene conversion events. Furthermore, gene conversions occur most frequently between nearby genes sharing similar sequences, are not more frequent in Ig-like V-type 1 domains than in the Ig-like C2-type 1 domains and dN/dS ratio tests shown that both these domains evolve either neutrally or under purifying selection. Our results therefore suggest that CEA-related genes evolve under purifying selection and the frequent gene conversion events we observed likely represent selectively neutral events between genes having similar sequences and functions.

-Durum wheat (Triticum turgidum) is one of the most important cereal crops in the world and the staple food for the Tunisian population. The main growing areas of durum wheat are located in the Northern part of the country, which is characterised by a sub humid climate favourable for fungal spoilage of grain such as Alternaria species. These species are able to produce plant pathogenic as well as toxic metabolites. For mycological analysis, the agar test was used. After mycelial growth, the Alternaria species were inoculated on potato carrot agar media. A PCR-based assay followed by a sequencing step allowed the identification of Alternaria alternata; Alternaria tenuissima and Alternaria japonica from grains.

Fusarium pseudograminearum is one of the major pathogens causing crown rot of wheat in the semi-arid and arid areas in Tunisia. In this study, the molecular diversity of 74 isolates of F. pseudograminearum representing three populations from Tunisia and a set of isolates from the world collection was investigated. The potential mycotoxin-producing ability was tested by PCR using primer pairs specific for the Tri3, Tri7 and Tri13 genes. Results indicated that all the isolates are potentially DON and ⁄ or 3-AcDON producers. The mating-type idiomorphs were identified using diagnostic PCR primer for MAT1-1 and MAT1-2. Both mating types were recovered from the same region and in some cases from the same field. Restriction analysis of the nuclear ribosomal DNA (nrDNA) intergenic spacer region (IGS) revealed 11 haplotypes, five of which were identified in the world collection. The analysis of population structure using the combined IGS and MAT data revealed that the total gene diversity (H T = 0.108) was mostly attributable to diversity within populations (H S = 0.102) and that the genetic differentiation among the four populations was low (G ST = 0.09). The analysis of molecular variance (amova amova) showed that 15% of the variability was between the Tunisian populations and the world collection. These findings indicate that quarantine measures should be in place to limit the introduction of new populations of F. pseudograminearum into Tunisia.

The application of beneficial microorganisms can enhance the growth of crops and increase their yields. In this context, we analysed the growth and development responses of six legume species inoculated by the mycorrhiza-based bio-fertilizer "Stanes Symbion ® VAM Plus" in greenhouse conditions. The effect of inoculation by Symbion VAM on legumes growth and development depends on the species and the cultivar used. A significant increase of shoot fresh weight, number of nodules and root dry weight was observed in common bean, pea and alfalfa, respectively. The most positive effect of inoculation was observed with the A17 Medicago truncatula line, which showed an increase in shoot and root dry weights, in nodule and pod numbers, and an early blooming. However, chickpea and lentil inoculated plants didn't show any increase for all measured growth and development traits. This positive effect of inoculation on A17 line by the Symbion VAM biofertilizer was associated with important mycorrhiza root colonization (21 to 40%) in comparison to the other legume cultivars at 50 days post inoculation. This study suggests that the success of inoculation with mycorrhiza-based inoculants depends on several factors including the density of inoculants in infective propagules and the length of legume life cycle.