Glomalin-related soil protein (GRSP) in metal sequestration at Pb/Zn-contaminated sites

PURPOSE: Glomalin-related soil protein (GRSP), secreted by arbuscular mycorrhizal fungi (AMF), contributes to heavy metal sequestration in polluted soils and sediments. The objective of this study was to investigate metal sequestration by GRSP associated with the plants Miscanthus sinensis, Cyperus rotundus, and Pteris vittata. MATERIALS AND METHODS: A total of 45 rhizosphere soil and plant root samples were collected from three plants at two Pb/Zn mining polluted and non-polluted sites in China. Soil samples were analyzed for total and bioavailable heavy metal (Cr, Cu, Cd, Pb, Zn, As, Sb, and Ni) concentration, chemical properties (SOC, TN, TP, TS, Olsen-P, and available K), and GRSP concentration. The contribution of GRSP-bound metals and its sequestration potential were calculated to assess the metal sequestration ability of GRSP. RESULTS AND DISCUSSION: Mycorrhizal root colonization of P. vittata was significantly higher than that of M. sinensis and C. rotundus at three sites. P. vittata also exhibited significantly more GRSP accumulation than the other two plants in soil. The significant negative correlation between GRSP and the combined indicators of eight bioavailable (r = − 0.60, p < 0.001) or total (r = − 0.39, p < 0.01) metals’ concentration was found. Averaged across the polluted sites, in P. vittata soil, GRSP showed a higher contribution to sequestering most heavy metals (Cu, Cd, Pb, Zn, As, Sb, and Ni), compared with that in M. sinensis and C. rotundus soil, although the sequestration potential descended in the order of C. rotundus > P. vittata > M. sinensis. CONCLUSIONS: AMF-P. vittata symbiosis presented higher contribution to sequestering most metals by GRSP in the contaminated sites when compared with the plants M. sinensis and C. rotundus. This study sheds light on the ecological function of GRSP sequestration of metals associated with mycorrhizal plants, and its contribution to reducing metal bioavailability in polluted sites.