Arbuscular mycorrhizal fungi increase gallic acid production in leaves of field grown Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz

Abstract

Because arbuscular mycorrhizal fungi (AMF) has been shown to induce concentration increases of pharmaceutically useful phytochemicals in some Brazilian semi-arid native plants, the current study examined whether mycorrhizal inoculation increased the production of bioactive compounds, especially gallic acid, in field grown Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz plants. Seedlings were inoculated with Claroideoglomus etunicatum (W.N. Becker & Gerd.) C. Walker & A. Schüßler, Acaulospora longula Spain & N. C. Schenck, Gigaspora albida N. C. Schenck & G. S. Sm. or non-inoculated (control) and, seven months after transplanting, examined for growth parameters, chlorophyll, phenols, tannins and gallic acid concentrations, mycorrhizal colonization and rhizosphere AMF spore density. Plants inoculated with C. etunicatum had 21% higher gallic acid concentrations than control plants while those inoculated with G. albida had higher total chlorophyll concentrations. Mycorrhizal technology employing C. etunicatum can constitute an alternative to increase gallic acid production in field grown L. ferrea plants.

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

“…In accordance with the results by Silva et al [27], who studied the concentration of phenols in leaves of L. ferrea , seven months after the transplanting, the concentration of phenols in the bark of the stem did not differ among the treatments (Table 2 ). In contrast, Riter Netto et al [19] developed a study using screens and reported an increase in the foliar content of total phenols in Passiflora alata Curtis inoculated with C. etunicatum , Rhizophagus intraradices , and mixed inoculum ( Rhizophagus clarus and Gigaspora margarita ) in relation to the non-inoculated control.…”

“…Similar results were recorded in inoculated C. forskohlii in field conditions with the density of the spores in the mycorrhized plants presenting differences in relation to the plants in the control treatment without inoculation and containing vermicompost [25]. Silva et al [27] recorded results that differ from our study considering that the density of the spores in the rhizosphere of L. ferrea, in field conditions, did not differ among the inoculation treatments. The higher production of these propagules in the soil guarantees new colonization sites in the L. ferrea since favorable conditions may cause the spores to germinate and colonize the host [40].…”

“…Other studies with legumes had also reported such benefit with the inoculated AMF favoring the increase of species and, in contrast with our study, producing more mycorrhizal structures than the control treatment [37]. However, in seedlings of Inga vera , legume occurring in the caatinga, mycorrhized with A. longula , G. albida , and C. etunicatum [38] as well as in inoculated L. ferrea established in the field [27], the inoculation with AMF did not result in difference in the root diameter in relation to the non-inoculated control. This benefit may be associated with the presence of arbuscules in the inoculated roots since such structure favors the exchange of nutrients in the roots [39], resulting in greater development.…”

“…In L. ferrea established in the field, the foliar concentration of tannins presented no difference caused by mycorrhization [27], such records are different from ours considering that the inoculation provided increase in the concentration of tannins in the bark of the stem of L . ferrea.…”

“…Furthermore, the increase in the concentration of these biomolecules can be caused by the increase in the concentration of precursors of these compounds, such as the gallic acid, which can be optimized through mycorrhizal inoculation in L. ferrea [27]; in addition, the activity of key-enzymes such as chalcone synthase, which benefits the formation of flavonoids, can be increased with a few inoculated treatments [20]. …”