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Single and mixed arbuscular mycorrhizal fungal species inocula have a different effect on the growth and oxidative stress defense in Lolium perenne exposed to phenol and polynuclear aromatic hydrocarbons

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Jan 13, 2021 version files 35.30 KB

Abstract

Arbuscular mycorrhizal fungi (AMF) are ubiquitous mutualistic plant symbionts which promote plant growth and protect them from abiotic stresses. Studies on AMF-assisted phytoremediation have shown that AMF can increase plant tolerance to the presence of hydrocarbon contaminants by improving plant nutrition status and mitigating oxidative stress. This work aimed to evaluate the impact of single-species or mixed-species AMF inocula, obtained from the contaminated environment (Funneliformis caledonium, Diversispora varaderana, Claroideoglomus walkeri), on a growth, oxidative stress (DNA oxidation and lipid peroxidation) and activity of antioxidative enzymes (superoxide dismutase, catalase, peroxidase) in Lolium perenne cultured in a substrate contaminated with 0/0 - 30/120 mg phenol/polynuclear aromatic hydrocarbons (PAHs) kg-1. The assessment of AMF resistance to the presence of contaminants was based on mycorrhizal root colonization, spore production, the level of oxidative stress and antioxidative activity in AMF spores. In contrast to the mixed-species AMF inoculum, single AMF species significantly enhanced the growth of host plants cultured in the contaminated substrate. Their effect on the level of oxidative stress and the activity of antioxidative enzymes in plant tissues differed between the AMF species. Changes in the level of oxidative stress and the activity of antioxidative enzymes in AMF spores in response to contamination also depended on AMF species. Although, the concentration of phenol and PAHs had a negative effect on the production of AMF spores, low (5/20 mg phenol/PAHs kg-1) and substrate (15/60 mg phenol/PAHs kg-1) contamination stimulated the mycorrhizal colonization of roots. Among the studied AMF species, F. caledonium was the most resistant to phenol and PAHs and showed the highest potential in plant growth promotion. Adverse effects of mixed AMF inoculum on L. perenne growth might result from the competitive associations between the AMF species and excessive development of C. walkeri. Presented results might contribute to the development of functionally customized strategies of AMF-assisted phytoremediation with indigenous AMF inocula, adapted to form mycorrhizal associations in the presence of contaminants, which might enhance phytoremediation more effective than commercial AMF inocula.