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Bidens pilosa frequently forms a symbiotic association with arbuscular mycorrhizal fungi (AMF). This plant species can grow in Pb-polluted soils, accumulating Pb in its tissues. The aims of the study were to determine whether Pb accumulated in the tissues of B. pilosa can be transferred to the soil through AMF and to compare the role of AMF communities that have a history of exposure to the contaminant with those that have never been exposed. The experiment combined plants with and without Pb accumulated in their tissues, and inoculated with AMF collected from the rhizosphere of B. pilosa in soils contaminated and not contaminated with Pb. The results showed that AMF participate in the removal of Pb that had entered the plant and release it into the soil, as evidenced by the presence of Pb in the AMF spores and in the glomalin produced by AMF. We propose that Pb accumulation in AMF spores would be a protection mechanism that interrupts Pb uptake by the plant; however, that mechanism would not be fully exploited in detoxification, whereas the production of Pb-enriched glomalin could be an important detoxification mechanism to eliminate Pb already taken up by plants. AMF with a history of Pb exposure achieved only higher rates of root colonization, while AMF without previous exposure showed higher Pb concentration in the spores and higher glomalin production, and successfully removed Pb from both the roots and aboveground parts of the plant. The use of AMF communities not adapted to Pb may be a more effective option for microbe-mediated phytoremediation methods in which detoxification mechanisms are desirable., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Salazar M.J. reports financial support was provided by Fund for Scientific and Technological Research. Becerra A.G. reports financial support was provided by Fund for Scientific and Technological Research. Salazar M.J. reports financial support was provided by National Scientific and Technical Research Council. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The impact of lead (Pb) pollution on native communities of arbuscular mycorrhizal fungi (AMF) was assessed in soil samples from the surroundings of an abandoned Pb smelting factory. To consider the influence of host identity, bulk soil surrounding plant roots soil samples of predominant plant species (Sorghum halepense, Bidens pilosa, and Tagetes minuta) growing in Pb-polluted soils and in an uncontaminated site were selected. Molecular diversity was assessed by sequencing the 18S rDNA region with primers specific to AMF (AMV4.5NF/AMDGR) using Illumina MiSeq. A total of 115 virtual taxa (VT) of AMF were identified in this survey. Plant species did not affect AMF diversity patterns. However, soil Pb content was negatively correlated with VT richness per sample. Paraglomeraceae and Glomeraceae were the predominant families while Acaulosporaceae, Ambisporaceae, Archaeosporaceae, Claroideoglomeraceae, Diversisporaceae, and Gigasporaceae were less abundant. Acaulosporaceae and Glomeraceae were negatively affected by soil Pb, but Paraglomeraceae relative abundance increased under increasing soil Pb content. Overall, 26 indicator taxa were identified; four of them were previously reported in Pb-polluted soils (VT060; VT222; VT004; VT380); and five corresponded to cultured spores of Scutellospora castaneae (VT041), Diversispora spp. and Tricispora nevadensis (VT060), Diversispora epigaea (VT061), Glomus proliferum (VT099), and Gl. indicum (VT222). Even though AMF were present in Pb-polluted soils, community structure was strongly altered via the differential responses of taxonomic groups of AMF to Pb pollution. These taxon-specific differences in tolerance to soil Pb content should be considered for future phytoremediation strategies based on the selection and utilization of native Glomeromycota.

Heavy metal (HM) pollution of soils is one of the most important and unsolved environmental problems affecting the world, with alternative solutions currently being investigated through different approaches. Arbuscular mycorrhizal fungi (AMF) are soil inhabitants that form symbiotic relationships with plants. This alleviates HM toxicity in the host plant, thereby enhancing tolerance. However, the few investigations that have addressed the presence of metals in the fungus structures were performed under experimental conditions, with there being no results reported for Pb. The current study represents a first approximation concerning the capability of spores to accumulate Pb in the AMF community present in a Pb polluted soil under field conditions. Micro X-ray fluorescence was utilized to obtain a direct observation of Pb in spores, and the innovation of total reflection X-ray fluorescence was applied to obtain Pb quantification in spores. The AMF community included species of Ambisporaceae, Archaeosporaceae, Gigasporacea, Glomeraceae and Paraglomeraceae, and was tolerant to high Pb concentrations in soil. Pb accumulation in AMF spores was demonstrated at the community level and corroborated by direct observation of the most abundant spores, which belonged to the Gigasporaceae group. Spore Pb accumulation is possibly dependent on the AMF and host plant species., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background and aims: Algae and Cyanobacteria species that grow in contaminated sites can accumulate high concentrations of heavy metals. In this work it was proposed to a) characterize the community of algae and Cyanobacteria and b) evaluate the effect of lead (Pb) on the composition of algae present in the rhizosphere of plants capable to accumulate Pb in Córdoba province. M&M: Soil samples were taken from the rhizosphere of Sorghum halepense, Bidens pilosa and Tagetes minuta at sites with different levels of Pb. In the laboratory, the soil was sown in capsules with sterilized Watanabe medium. The cultures grew 9 weeks. The algae and Cyanobacteria were identified over the time and the final relative frequency analyzed. Results: In contaminated soils, 24 species of Cyanobacteria, Chloroplastida and Xanthophyceae were identified. The heterocytous cyanobacteria Cylindrospermum muscicola, Nostoc commune and Calothrix clavata registered a relative mean frequency (between 21 and 60%). Trebouxia parmeliae (Chloroplastida) and Vaucheria sp. (Xanthophyceae) were present in soils with the highest level of Pb. Most of the species were concentrated in the lowest levels of Pb. Conclusions: A negative effect of Pb on the species richness of algae and Cyanobacteria was observed in the rhizosphere of the evaluated plants. Based on the composition of the community of algae and Cyanobacteria in the soil, two groups are determined and could be considered tolerant and non-tolerant communities of Pb contamination. [ABSTRACT FROM AUTHOR]

In this study, the content of Pb, the physico-chemical and biological parameters in soils, and the metal transfer to vegetative and reproductive Sorghum bicolor plants were evaluated along with their relationship with the toxicological risk of crop consumption. To carry this out, soil and sorghum samples at different growth stages were collected near to a former battery recycling plant. The results showed that the concentrations of Pb in soils at several sites were above the maximum permissible levels. Metal bioavailability was not directly related to the pH, OM% or EC, while no association between metals and the different genera of fungi was observed. Sorghum crops accumulated Pb mainly in the roots in all of the growth stages, and therefore presented low levels of Pb in aerial parts without toxicological risk due to direct consumption. Taken together, our results revealed that sorghum could be employed as a potential phytostabilizator of lead in soils associated with crop production. However, further studies are necessary to extend these findings. [ABSTRACT FROM AUTHOR]