Arbuscular Mycorrhizal Fungi and Glomalin Play a Crucial Role in Soil Aggregate Stability in Pb-Contaminated Soil

Abstract

With the rapid development of industrialization and urbanization, soil contamination with heavy metal (HM) has gradually become a global environmental problem. Lead (Pb) is one of the most abundant toxic metals in soil and high concentrations of Pb can inhibit plant growth, harm human health, and damage soil properties, including quality and stability. Arbuscular mycorrhizal fungi (AMF) are a type of obligate symbiotic soil microorganism forming symbiotic associations with most terrestrial plants, which play an essential role in the remediation of HM-polluted soils. In this study, we investigated the effects of AMF on the stability of soil aggregates under Pb stress in a pot experiment. The results showed that the hyphal density (HLD) and spore density (SPD) of the AMF in the soil were significantly reduced at Pb stress levels of 1000 mg kg−1 and 2000 mg kg−1. AMF inoculation strongly improved the concentration of glomalin-related soil protein (GRSP). The percentage of soil particles >2 mm and 2–1 mm in the AMF-inoculation treatment was higher than that in the non-AMF-inoculation treatment, while the Pb stress increased the percentage of soil particles <0.053 mm and 0.25–0.53 mm. HLD, total glomalin-related soil protein (T-GRSP), and easily extractable glomalin-related soil protein (EE-GRSP) were the three dominant factors regulating the stability of the soil aggregates, based on the random forest model analysis. Furthermore, the structural equation modeling analysis indicated that the Pb stress exerted an indirect effect on the soil-aggregate stability by regulating the HLD or the GRSP, while only the GRSP had a direct effect on the mean weight diameter (MWD) and geometric mean diameter (GMD). The current study increases the understanding of the mechanism through which soil degradation is caused by Pb stress, and emphasizes the crucial importance of glomalin in maintaining the soil-aggregate stability in HM-contaminated ecosystems.

Fallow Land Enhances Carbon Sequestration in Glomalin and Soil Aggregates Through Regulating Diversity and Network Complexity of Arbuscular Mycorrhizal Fungi Under Climate Change in Relatively High-Latitude Regions

“…Therefore, changes in GRSP in the aggregate fraction may have a direct impact on aggregate stability. The results of this study showed that both EE-GRSP and T-GRSP were positively correlated MWD and GMD ( Supplementary Figure 5 ), which was consistent with most previous studies ( Wu et al, 2012 ; Li et al, 2022 ). However, the effect of GRSP on soil aggregate stability was greatly linked to the soil particle size.…”

“…Our research indicates that CC and LUC could regulate GRSP and soil aggregate stability mainly by regulating AMF diversity, network complexity, and growth parameters based on the results of random forest model ( Supplementary Figure 4 ). Importantly, GRSP was located in the core position to influence the stability of soil aggregates and was the most important factor for explaining soil aggregation ( Li et al, 2022 ). Therefore, changes in GRSP in the aggregate fraction may have a direct impact on aggregate stability.…”

Impact of symbiotic mycorrhiza interrelation in some soil biological parameters and growth of five cover crops

“…By comparing the results of soil protein (glomalin), concentration and biomass, can understand the direct correlation between them. Also, there are some similar reports to approve this (YANG et al, 2017;LI et al, 2022).…”

Microbial carbon use efficiency of litter with distinct C/N ratios in soil at different temperatures, including microbial necromass as growth component

“…Microbial necromass C (Liang et al 2020) or microbial residues (Joergensen and Wichern 2018) embraces all freshly synthesized microbial non-biomass metabolites that leave the cells, such as exo-enzymes (Burns et al 2013), extracellular polymeric substances (Redmile-Gordon et al 2014), e.g. the glomalin-related soil protein (Wright and Upadhyaya 1996;Spohn and Giani 2011;Li et al 2022), other secondary metabolites, e.g. antibiotics (Boruta 2018;Keller 2019), and dead tissue remains (Joergensen and Wichern 2018).…”