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Aims: The protective role of fungal endophytes in plants under stress by hydrocarbons is yet poorly understood. The influence of the endophytic fungus Lewia sp. on growth and oxidative stress control in plants of Festuca arundinacea exposed to a hydrocarbon mixture (HCM) was evaluated. Methods: Plants of F. arundinacea were inoculated or not with Lewia sp. to establish endophytic association. After 15 days, the plant growth, oxidative stress, and activity of antioxidant enzymes were analyzed in associated and unassociated plants. Then, both groups of plants were exposed for 7 days to a HCM (800 mg kg) in a model soil. The effect of the HCM was assessed in the plants through the same variables as mentioned above. Results: Endophytic association was established after 15 days. The fungus enhanced plant growth, as well as HO and malondialdehyde concentration, and decreased glutathione S-transferase (GST) activity. Lewia sp. decreased the HO concentration in plants exposed to the HCM and increased the activity of superoxide dismutase and peroxidases, while significantly decreasing GST activity. Conclusions: This study demonstrates the positive role of Lewia sp. in promoting growth and alleviating oxidative stress in F. arundinacea exposed to hydrocarbons. [ABSTRACT FROM AUTHOR]

Background and aims: The selective inoculation of specific hydrocarbon-degrading microbes into the plant rhizosphere offers a useful means for remediating hydrocarbon-contaminated soils. The effect of inoculating a seed-borne filamentous fungus ( Lewia sp.) on hydrocarbon removal by Festuca arundinacea and its growth was studied on perlite (model soil) and soil, both spiked with hydrocarbons. Methods: A hydrocarbon mixture (1,500 mg kg) of two polycyclic aromatic hydrocarbons (PAH), phenanthrene and pyrene, blended with hexadecane (1.0:0.5:0.5 weight) was used. Greenhouse experiments were carried out for 45 days. Inoculated and non-inoculated plants were grown in dark cylindrical glass pots containing perlite or soil. Results: Inoculation with Lewia sp. stimulated (100 %) root growth in spiked perlite. Inoculated plants showed higher phenanthrene removal (100 %) compared to non-inoculated plants in perlite and soil. Pyrene removal by inoculated plants was 37-fold higher than that by non-inoculated plants in perlite; in soil, pyrene removal by inoculated plants (97.9 %) differed significantly from that of non-inoculated plants (91.4 %). Accumulation of pyrene in roots (530.9 mg kg of dry roots) was promoted in perlite. Conclusions: Our results demonstrate that Lewia sp. (endophytic fungus) improved the efficiency of PAH removal by F. arundinacea, on both perlite and soil, stimulating pyrene accumulation in roots. [ABSTRACT FROM AUTHOR]