Assessment of arbuscular mycorrhizal fungi status and heavy metal accumulation characteristics of tree species in a lead–zinc mine area: potential applications for phytoremediation

Abstract

To select suitable tree species associated with arbuscular mycorrhizal fungi (AMF) for phytoremediation of heavy metal (HM) contaminated area, we measured the AMF status and heavy metal accumulation in plant tissues in a lead-zinc mine area, Northwest China. All 15 tree species were colonized by AM fungi in our investigation. The mycorrhizal frequency (F%), mycorrhizal colonization intensity (M%) and spore density (SP) reduced concomitantly with increasing Pb and Zn levels; however, positive correlations were found between arbuscule density (A%) and soil total/DTPA-extractable Pb concentrations. The average concentrations of Pb, Zn, Cu and Cd in plant samples were 168.21, 96.61, 41.06, and 0.79 mg/kg, respectively. Populus purdomii Rehd. accumulated the highest concentrations of Zn (432.08 mg/kg) and Cu (140.85 mg/kg) in its leaves. Considerable amount of Pb (712.37 mg/kg) and Cd (3.86 mg/kg) were concentrated in the roots of Robinia pseudoacacia Linn. and Populus simonii Carr., respectively. Plants developed different strategies to survive in HM stress environment: translocating more essential metals (Zn and Cu) into the aerial parts, while retaining more toxic heavy metals (Pb and Cd) in the roots to protect the above-ground parts from damage. According to the translocation factor (TF), bioconcentration factor (BCF), growth rate and biomass production, five tree species (Ailanthus altissima (Mill.) Swingle, Cotinus coggygria Scop., P. simonii, P. purdomii, and R. pseudoacacia) were considered to be the most suitable candidates for phytoextraction and/or phytostabilization purposes. Redundancy analysis (RDA) showed that the efficiency of phytoremediation was enhanced by AM symbioses, and soil pH, Pb, Zn, and Cd levels were the main factors influencing the HM accumulation characteristics of plants.

Comparisons of Soil Properties, Enzyme Activities and Microbial Communities in Heavy Metal Contaminated Bulk and Rhizosphere Soils of Robinia pseudoacacia L. in the Northern Foot of Qinling Mountain

“…Zn is an essential metal for plant growth and plays an important role in photosynthesis and enzyme composition for protein synthesis [46]; however, Pb is a non-essential element and has toxic effects on plant growth (membrane damage and oxidative stress) [47]. Therefore, plants may develop their own strategy to survive in HM polluted soil: reducing availability of toxic HM (Pb) in rhizosphere and preventing the translocation of Pb from soil to the aerial parts of plants, which was consistent with our previous study [24,31]. Various studies have indicated that plant root exudates could react with HM ions and affected metal solubility, mobility and phytoavailability [48].…”

“…In our previous investigation, R. pseudoacacia had been identified as lead/zinc tolerant dominant tree species widely distributed in HM contaminated soils in Feng County [24]. This tree was considered as a suitable candidate for phytoremediation owing to its developed root system, high biomass productivity, environmental stress tolerance and ability of atmospheric nitrogen fixation [24][25][26].…”

“…This tree was considered as a suitable candidate for phytoremediation owing to its developed root system, high biomass productivity, environmental stress tolerance and ability of atmospheric nitrogen fixation [24][25][26].…”

Diverse Metabolic Capacities of Fungi for Bioremediation

“…Mumtaz et al [83] demonstrated the potential of fungi like Aspergillus, Cryptococcus, Penicillium and Curvularia for bioremediation of uranium contaminated soils which was attributed to their uranium binding ability. Symbiotic association of AM fungi with the roots of plants promoted immobilization of heavy metals and hence provided ability to plants to grow in metal-contaminated soils as observed in case of enhanced Cd tolerance of plants [84,85]. Further enhancement in remediation potential of toxic compounds by fungi could be achieved by certain pre-treatments.…”

Subcellular Compartmentalization and Chemical Forms of Lead Participate in Lead Tolerance of Robinia pseudoacacia L. with Funneliformis mosseae

“…R. pseudoacacia is frequently found in HM contaminated areas and it may serve as an indicator of Pb pollution (Serbula et al, 2012). R. pseudoacacia plants are well grown and commonly colonized by AMF such as F. mosseae in the Qiandongshan lead–zinc polluted area (Yang et al, 2015b,c). Recent studies have shown that photosynthesis and antioxidant enzymes (e.g., superoxide dismutase and ascorbate peroxidases) in the leaves of R. pseudoacacia are enhanced by F. mosseae under Pb stress (Yang et al, 2015a).…”