Arbuscular Mycorrhizal Fungi Increase the Phenolic Compounds Concentration in the Bark of the Stem of Libidibia Ferrea in Field Conditions

Background Libidibia ferrea is a species particular to the caatinga presenting medicinal properties for containing bioactive compounds. The use of Arbuscular Mycorrhizal Fungi (AMF) can increase the production of biomolecules in the legume leaves; however, no light has been shed on the role of symbiosis in maximizing metabolites production in the bark of L. ferrea stem. Objective The aim was to select AMF that are efficient at increasing the production of phenolic compounds with medicinal properties in the bark of the L. ferrea stem. Methods The experiment was designed in randomized blocks with four inoculation treatments (plants pre-inoculated with Claroideoglomus etunicatum, with Gigaspora albida, with Acaulospora longula, and non-inoculated plants - control) with six repetitions. Thirteen months after the transplanting, the plants were pruned and the bark of the stem was collected; subsequently, this plant material was dried in a chamber. After the drying process, fractions of the bark of the stem were macerated in methanol. The extracts were further used for analyses of the biomolecules. Results The flavonoids concentration had an increase of, respectively, 236% and 186% in relation to the control for the treatments with A. longula and C. etunicatum; plants inoculated with A. longula had an increase of 47% in total tannins concentration compared with the non-inoculated control - a benefit that the proanthocyanidins did not present. Conclusion Applying inoculation with A. longula may be an alternative to increase the production of biomolecules of the secondary metabolism in the bark of the L. ferrea stem in field conditions.