Aspects of mycorrhizal colonization in adaptation of sweet marjoram (Origanum majorana L.) grown on industrially polluted soil

The current study reveals the effects of mycorrhization on heavy metal uptake and accumulation, antioxidant potential, and essential oil composition of Origanum majorana L., grown on soil polluted with industrial Cd and Pb. Two strains of Claroideoglomus claroideum (EEZ 54 and EEZ 55) were isolated from soil that is naturally rich in metals. EEZ 35 (Funneliformis mosseae) was isolated from a place with industrial contamination. The percentage of mycorrhizal colonization with the EEZ 54 strain was higher than those of the other strains; there was no significant difference between EEZ 55 and EEZ 35. The highest value of the total identified essential oils was observed in plants inoculated with EEZ 35, where Pb accumulated in the roots. Mycorrhizal colonization led to a change in the content of the main compounds of marjoram essential oil. The EEZ 54 and EEZ 55 strains, isolated from areas with naturally high levels of metals, significantly reduced Pb accumulation in marjoram shoots and roots as compared with nonmycorrhizal plants. Antioxidant activity in marjoram aerial parts increased as a result of inoculation with EEZ 54 and EEZ 35 arbuscular mycorrhizal fungi strains due to the elevated levels of phenolic compounds.