Plant sources, techniques of production and uses of tar: A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Throughout history, Humans have always used tar for different purposes such as gluing materials, waterproofing, and conserving wood, but today, it is also used in medicines and cosmetics. Many countries around the world, Norway and Morocco to name a few, obtain tar from endemic trees. In a process of dry distillation, the organic material, endemic trees in this case, is exposed to a high temperature with a restricted amount of oxygen. Eventually, it cracks the large molecules in the matter and turns it into tar. AIM OF THE REVIEW: This review article sheds light on tar production and the species that have been used in the process. Equal emphasis is placed on its uses, chemical composition, and toxicity. MATERIALS AND METHODS: Meta-analysis (PRISMA) guidelines have been used to review this article. The review is put together from various articles, theses, documents in "Science Direct", "Hal (Archive ouvert)", "Web of knowledge" without limitation date. RESULTS: It turns out that tar can be produced by 18 tree taxonomic families, notably Cupressaceae, Pinaceae, and Betulaceae. As for the production techniques, two methods are considered: Per ascensum and Per descensum, which can take different forms. The chemical composition of tar consists of acids, phenols, and aromatic hydrocarbons. The uses of tar have changed over time, while its toxicity is strongly related to its chemical composition. CONCLUSIONS: The different species used in tar production have been highlighted in this research review. Equal importance has been given to its methods of extraction, uses and its chemical components. We hope that future studies will focus more on these species used to produce tar in other biological activities.

The endemic Chamaecytisus albidus is nodulated by symbiovar genistearum of Bradyrhizobium in the Moroccan Maamora Forest.

Out of 54 isolates from root nodules of the Moroccan-endemic Chamaecytisus albidus plants growing in soils from the Maamora cork oak forest, 44 isolates formed nodules when used to infect their original host plant. A phenotypic analysis showed the metabolic diversity of the strains that used different carbohydrates and amino acids as sole carbon and nitrogen sources. The isolates grew on media with pH values ranging from 6 to 8. However, they did not tolerate high temperatures or drought and they did not grow on media with salt concentrations higher than 85 mM. REP-PCR fingerprinting grouped the strains into 12 clusters, of which representative strains were selected for ARDRA and rrs analyses. The rrs gene sequence analysis indicated that all 12 strains were members of the genus Bradyrhizobium and their phylogeny showed that they were grouped into two different clusters. Two strains from each group were selected for multilocus sequence analysis (MLSA) using atpD, recA, gyrB and glnII housekeeping genes. The inferred phylogenetic trees confirmed that the strains clustered into two divergent clusters. Strains CM55 and CM57 were affiliated to the B. canariense/B. lupini group, whereas strains CM61 and CM64 were regrouped within the B. cytisi/B. rifense lineage. The analysis of the nodC symbiotic gene affiliated the strains to the symbiovar genistearum. The strains were also able to nodulate Retama monosperma, Lupinus luteus and Cytisus monspessulanus, but not Phaseolus vulgaris or Glycine max. Inoculation tests with C. albidus showed that some strains could be exploited as efficient inocula that could be used to improve plant growth in the Maamora forest.

Diversity and spatial genetic structure of natural Moroccan Quercus susber L. assessed by ISSR markers for conservation.

Morocco is one of the most important regions of the world in terms of Quercus suber L. number and variation. This species is in decline due to several factors, which can lead to permanent loss of this resource. It would be essential to evaluate the genetic diversity in order to conserve maximum genetic variability of this species. The genetic diversity and differentiation of 16 sites from five regions representing the entire range of Moroccan Cork Oak were assessed. Twenty-three ISSR primers used generated 985 polymorphic fragments with an average of 42.8 bands per primer and showed 100% of polymorphism. The 173 individuals revealed a moderate level of genetic diversity at species level (I = 0.27, He = 0.161). The AMOVA showed that the highest level of diversity occurred within populations (64%), this was also confirmed by the coefficient of differentiation (Gst = 0.47). The estimated gene flow (Nm = 0.56) and the Mantel test revealed a significant correlation between geographic and genetic diversity (r = 0.266; p = 0.001). This genetic structure was further shown by the topology of the UPGMA, sPCA and STRUCTURE analysis. In addition, a core collection of 34 genotypes was established representing the essential diversity detected. This research advocates populations and individuals to preserve in order to improve and conserve this resource in the future.