Secondary metabolism response to inoculation with arbuscular mycorrhizal fungi in artichoke seedlings

Artichoke is one of the world's oldest medicinal plants known for its pharmacological potential. Recommended for its actions, antioxidant, diuretic and choleretic, the extract of the leaves is widely used as phytotherapy. These properties are due to the high total polyphenol content and flavonoids present in the leaves. Both phenolic compounds content, as its antioxidant activity, may change depending on the hybrid used, phenological stage and crop management. Therefore, the use of arbuscular mycorrhizal (AM) fungi in artichoke crop has been studied as an alternative to increase the amount and the functionality of these compounds. Thus, the objective of this study was to evaluate how mycorrhizal infection changes the amount of total polyphenols and antioxidant activity of leaf extracts of four artichoke hybrids, at seedling production stage. To determine total polyphenols content and antioxidant activity, aqueous extracts of artichoke leaves of four hybrids ('Concert F1', 'Madrigal F1', 'Opal F1' and 'Symphony F1') inoculated and non-inoculated with AM fungi were used. A commercial product formulated on the basis of hyphae and spores of Paraglomus brasilanum, Rhizophagus clarus, Glomus deserticola, Rizophagus intraradices, Glomus monosporum, Funneliformis mosseae and Gigaspora margararita was used for inoculation. The treatments were arranged in a factorial 4 (hybrid) × 2 (inoculated and non-inoculated) in a complete randomized block design with three replications. All data were submitted to ANOVA and means were compared by Tukey's test (P≤0.05). The content of total polyphenols was featured in the extracts of 'Madrigal' hybrid (292.36 mg GAE L-1) and 'Concerto' (286.5 mg GAE L-1) inoculated with AM fungi. Highest antioxidant capacity was measured in extracts of the non-inoculated hybrids with the exception of the extract obtained from hybrid 'Madrigal'. Inoculation with AM fungi changes total polyphenols content and antioxidant capacity depending on the hybrids.