Mycorrhizal induction of phenolic compounds and antioxidant properties of fungi and seedlings during the early steps of symbiosis

Abstract

Ectomycorrhizal (ECM) symbiosis plays a major role in nutrient cycling and the functioning of forest ecosystems. Trees with well-developed ectomycorrhizas are more resistant to environmental stresses such as drought and to biotic stresses such as root pathogens. The establishment of ECM symbiosis is triggered by signals produced by both partners. These signals lead to morphological changes and a complex development of specific structures in both the plant root and the fungus. The development of the ECM fungi, Paxillus involutus and Pisolithus arhizus, in the presence and the absence of the symbiont-Pinus pinaster-was evaluated as well as their antioxidant properties and phenolic compounds composition in response to the symbiotic association. ECM fungi grew less in the presence of P. pinaster, with P. arhizus being less affected in growth and thus being more adapted to this association. Protocatechuic acid was found only in P. involutus, while P. pinaster roots, both in association and isolated, proved to have other phenolic acids, such as p-hydroxybenzoic and p-coumaric acids. The symbiosis between P. involutus and P. pinaster had no major effects on the symbionts, while the association between P. arhizus and P. pinaster seems to generally decrease the antioxidant effects of both symbionts, despite the increase in p-coumaric and cinnamic acids in the ECM fungi.

Antioxidants in Pinus pinaster roots and mycorrhizal fungi during the early steps of symbiosis

“…However, the LDA results indicated that the slight differences found among those two elements are sufficient to discriminate them in two separate groups, either for P. arhizus ( Figure 5A), as for P. involutus. In both cases, the LDA defined two significant ( Overall, this study demonstrated the hypothesis suggested by Reis et al (2011Reis et al ( , 2012 which stated P. arhizus as more compatible with P. pinaster than P. involutus, since the antioxidant activity in the latter species increased from 48 to 72 h, while P. arhizus antioxidant properties decreased at the same period (indicative of less oxidative stress).…”

“…P. arhizus seemed to be more compatible with P. pinaster than P. involutus, since the antioxidant activity in the latter species increased after a 48 h period, while P. arhizus remained unaffected (Reis et al, 2011;Reis et al, 2012). Nevertheless, the mechanisms of antioxidants production are still unknown and, therefore, the present study was conducted during early steps of in vitro mycorrhization:…”

“…P. arhizus seemed to be more compatible with P. pinaster than P. involutus, since the antioxidant activity in the latter species increased after a 48 h period, while P. arhizus remained unaffected (Reis et al, 2011;Reis et al, 2012). The present study aimed to evaluate the effects of coculture period in the antioxidant properties and antioxidants (phenolics, tocopherols and sugars) production during early steps of in vitro mycorrhization: 0, 6 and 24 h. An additional period of 72 h was also studied in order to understand if the chemical response followed up the same trend detected in the earlier periods.…”

“…Therefore, the production and/or activity of antioxidants, including enzymes (e.g. superoxide 4 dismutase, catalase and peroxidase; Münzenberger et al, 1997;Baptista et al, 2007) or phenolic compounds, might increase in plant roots and/or mycelia (Münzenberger et al, 1995;Reis et al, 2011).…”

Effects of different culture conditions on biological potential and metabolites production in threePenicilliumisolates

“…Comparing the antioxidant activity of the mycelium and the culture medium on which it has been developed, generally, the mycelium revealed higher antioxidant potential, as reported by other studies with different species and culture media. [34][35][36] However, there was some antioxidant activity detected in culture media, which may suggest the release of some antioxidant compounds from the mycelia like phenolic compounds ( Table 5). …”