Generalist arbuscular mycorrhizal fungi dominated heavy metal polluted soils at two artisanal and small − scale gold mining sites in southeastern Ecuador

Abstract

Background Artisanal and small-scale gold mining activities are producing contamination with heavy metals and metalloids (HMM) into soils and water worldwide. The HMM are considered as one of the major abiotic stresses due to their long-term persistence in soil. In this context, arbuscular mycorrhizal fungi (AMF) confer resistance to a variety of abiotic plant stressors including HMM. However, little is known regarding the diversity and composition of AMF communities in heavy metal polluted sites in Ecuador. Methods In order to investigate the AMF diversity, root samples and associated soil of six plant species were collected from two sites polluted by heavy metals, located in Zamora-Chinchipe province, Ecuador. The AMF 18S nrDNA genetic region was analyzed and sequenced, and fungal OTUs were defined based on 99% sequence similarity. Results were contrasted with AMF communities from a natural forest and from reforestation sites located in the same province and with available sequences in GenBank. Results The main pollutants in soils were Pb, Zn, Hg, Cd and Cu with concentrations exceeding the soil reference value for agricultural use. Molecular phylogeny and OTU delimitation showed 19 OTUs, the family Glomeraceae was the most OTU-rich followed by Archaeosporaceae, Acaulosporaceae, Ambisporaceae and Paraglomeraceae. Most of the OTUs (11 of 19) have been found at other locations worldwide, 14 OTUs were proven from nearby non-contaminated sites in Zamora-Chinchipe. Conclusion Our study showed that there are no specialized OTUs at the studied HMM polluted sites, but rather generalists adapted to a wide variety of habitats. Their potential role in phytoremediation approaches remains to be investigated.

Arbuscular mycorrhizal fungal diversity and association networks in African tropical rainforest trees

“…The most abundant AM fungus genus was Glomus, aligning with previous studies on AM fungal composition in forest communities across the globe (Chen et al 2017;Sheldrake et al 2017Sheldrake et al , 2018Boeraeve et al 2019a;Ji et al 2020;Touré et al 2020;Suárez et al 2023). The most abundant OTUs corresponded to taxa that have been found in (sub)tropical regions before.…”

“…While some of the tree species have been microscopically examined before for the presence of mycorrhizal structures (Onguene and Kuyper 2001; Bechem et al 2018), to our knowledge, this was the first time that their AM fungal communities were determined using molecular methods. The most abundant AM fungus genus was Glomus , aligning with previous studies on AM fungal composition in forest communities across the globe (Chen et al 2017; Sheldrake et al 2017, 2018; Boeraeve et al 2019a; Ji et al 2020; Touré et al 2020; Suárez et al 2023). The most abundant OTUs corresponded to taxa that have been found in (sub)tropical regions before.…”

Arbuscular Mycorrhizal Fungi with different life strategies in an ancient and abandoned Pb-Zn-Ag mine in Andes Mountain

“…However, PCA results revealed associations between mycorrhizal fungal traits and certain parameters of each area. The Exp 1 area was distinguished by its high spore density, whereas Exp 2 exhibited the lowest AM fungal richness compared to the off-mine area.Consistent with previous research conducted in mines(Zarei et al 2008;Suárez et al 2023), mining exerted in uence on these fungal traits, particularly in the heavily impacted area (Exp 2).…”

Arbuscular Mycorrhizal Symbiosis of Viola Baoshanensis at Baoshan Pb/Zn Mine in China

“…Hyperaccumulators with associated AMF are promising for restoration of lands polluted by HMs (Wang et al, 2021;Raklami et al, 2022), and the appropriate combination of hyperaccumulators and AMF is very important (Vogel-Mikuš et al, 2006;Miransari, 2011). Indigenous AMF from long-term polluted sites have been found more suitable than non-native ones, therefore knowledge of native AMF is relevant for phytoremediation (Sánchez-Castro et al, 2017;Suárez et al, 2023). Therefore, roles of the dominant AMF in the remediation needs further investigation, and molecular techniques should be used to identify the AMF species colonized in the roots of V. baoshanensis for unraveling the mechanisms associated with restoration.…”