The main antioxidants present in plant extracts—quercetin, β-carotene, gallic acid, ascorbic acid, hydroxybenzoic acid, caffeic acid, catechin and scopoletin—are able to synthesize silver nanoparticles when reacting with a Ag NO₃ solution. The UV-visible absorption spectrum recorded with most of the antioxidants shows the characteristic surface plasmon resonance band of silver nanoparticles. Nanoparticles synthesised with ascorbic, hydroxybenzoic, caffeic, and gallic acids and scopoletin are spherical. Nanoparticles synthesised with quercetin are grouped together to form micellar structures. Nanoparticles synthesised by β-carotene, were triangular and polyhedral forms with truncated corners. Pentagonal nanoparticles were synthesized with catechin. We used Fourier-transform infrared spectroscopy to check that the biomolecules coat the synthesised silver nanoparticles. X-ray powder diffractograms showed the presence of silver, AgO, Ag₂O, Ag₃O₄ and Ag₂O₃. Rod-like structures were obtained with quercetin and gallic acid and cookie-like structures in the nanoparticles obtained with scopoletin, as a consequence of their reactivity with cyanide. This analysis explained the role played by the various agents responsible for the bio-reduction triggered by nanoparticle synthesis in their shape, size and activity. This will facilitate targeted synthesis and the application of biotechnological techniques to optimise the green synthesis of nanoparticles.

Several studies have reported glacial refugia and migration pathways for different pine species in the Iberian Peninsula, all of them based on a single‐species approach. In this paper, chloroplast microsatellites (cpSSRs) are used to compare population genetic structure and diversity estimates for interspecific pairs of populations located along a cline from southwestern (latitude 36°32′ N, longitude 5°17′ W) to northeastern Spain (latitude 42°14′ N, longitude 2°47′ E) in two widely distributed Mediterranean pines, Pinus halepensis Mill. and Pinus pinaster Ait. Some cpSSRs were shared between species, facilitating comparison of levels of gene diversity at the species level and inferences about within and among species differentiation. P. pinaster showed a much higher number of variants (29) and haplotypes (69) than P. halepensis (20 and 21, respectively). Moreover, genetic diversity estimates for interspecific pairs of populations along the cline were negatively correlated. Three main causes may explain the differences between species in the present‐day distribution of genetic diversity: (1) the distribution of genetic variability before the Quaternary glaciations, with an earlier presence of P. pinaster in the Iberian Peninsula and a late spread of P. halepensis from eastern and central Europe, (2) the location of the Holocene glacial refugia and the migration pathways from these refugia to the present‐day range (from northeast to southwest in P. halepensis and from southwest to northeast and northwest in P. pinaster) and (3) the interactions between species during the postglacial spread.

In Quercus suber, cork oak, a Mediterranean forest tree of economic and social interest, rapid production of isogenic lines and clonal propagation of elite genotypes have been achieved by developing in vitro embryogenesis from microspores and zygotic embryos respectively. Despite its high potential in tree breeding strategies, due to their recalcitrancy, the efficiency of embryogenesis in vitro systems in many woody species is still very low since factors responsible for embryogenesis initiation and embryo development are still largely unknown. The search for molecular and cellular markers during early stages of in vitro embryogenesis constitutes an important goal to distinguish, after induction, responsive from non-responsive cells, and to elucidate the mechanisms involved in embryogenesis initiation for their efficient manipulation. In this work, we have performed a comparative analysis of two embryogenesis pathways derived from microspores and immature zygotic embryos in cork oak in order to characterize early markers of reprogrammed cells in both pathways. Rearrangements of the cell structural organization, changes in epigenetic marks, cell wall polymers modifications and endogenous auxin changes were analyzed at early embryogenesis stages of the two in vitro systems by a multidisciplinary approach. Results showed that early embryo cells exhibited defined changes of cell components which were similar in both embryogenesis in vitro systems, cellular features that were not found in non-embryogenic cells. DNA methylation level and nuclear pattern, proportion of esterified pectins in cell walls, and endogenous auxin levels were different in embryo cells in comparison with microspores and immature zygotic embryo cells from which embryos originated, constituting early embryogenesis markers. These findings suggest that DNA hypomethylation, cell wall remodeling by pectin esterification and auxin increase are involved in early in vitro embryogenesis in woody species, providing new evidences of the developmental pattern similarity between both embryogenesis pathways, from microspores and immature zygotic embryos, in woody species.