First detection of Arbuscular mycorrhizal fungi (AMF) in the root system of plants growing under metallic trace elements stress in eastern Morocco at a polluted mining site and identification of spores in the soil

Abstract

Soil pollution has become a major environmental concern, particularly in industrialized regions. The role of accumulator and hyperaccumulator plants in the remediation of soils contaminated by mining activities is now well recognized. Consequently, optimizing the growth of plant species capable of thriving in such environments is essential for enhancing the uptake of heavy metals. This study aims to investigate the presence of vesicular-arbuscular mycorrhizal (VAM) fungi in the roots of plants growing in a metal-stressed area, and to isolate and identify fungal spores from a former mining site located in eastern Morocco. This site, which operated from 1945 to 1980, was dedicated to the processing and refining of lead and silver for over 33 years. The mining site was closed due to the depletion of local raw material sources. Following the collection of plant species from the area, a root staining procedure using trypan blue was carried out to accurately assess the frequency and intensity of mycorrhizal colonization in each species. Subsequently, fungal spore identification was conducted. The results revealed that all seven plant species were mycorrhizal, exhibiting high colonization frequencies over 80% for Diplotaxis erucoides and an intensity of 86% for Capsella bursa-pastoris. The arbuscular mycorrhizal (AM) fungal spores present in the soil of Oued El Heimer were predominantly from the genus Glomus, whereas Ambispora was the least represented. Overall, this study demonstrates that the mining site harbors a high diversity of AM fungi, which contribute to enhanced plant tolerance to trace metal elements. Furthermore, these fungi aid in soil remediation by immobilizing metal ions on plant roots, indicating significant fungal colonization in the area.