The study of morpho-anatomical aspects, metabolic changes of proteins, antioxidant substances, as well as phenolic compounds in embryogenic callus (EC) and degenerative embryogenic callus (DEC) was the aim of the present investigation. Ability to form somatic embryos (SEs) was associated with the softness of the EC, which exhibited a white or creamy color and was composed of isodiametric cells containing dense cytoplasm, conspicuous nuclei and minimal vacuoles with observed mitotic activity. Furthermore, protein, reduced glutathione (GSH) and ascorbic acid (ASC) concentrations and the ratio between ASC and dehydroascorborbic acid (DHA) were increased significantly in the EC in comparison to the DEC. In addition, the phenolic extract of the EC was proved to have higher scavenging activity than the extract from the DEC. A loss of embryogenic competence in the DEC was correlated with the presence of more rigid clumps and such calli had a yellowish to brown color and no cell division could be observed in the cells of such aggregates as the cells had large vacuoles and they have very thick walls. Moreover, these morphological and anatomical observations of the DEC were accompanied by accumulations of the oxidized form of ascorbic acid (DHA), H2O2, total soluble phenolic compounds and overaccumulation of naringenin. Alternations in cellular metabolism can affect and regulate the morphogenesis of somatic embryos.

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.