| Soil heavy metal pollution is a serious environmental problem,and cadmium(Cd)is one of the most toxic heavy metal elements found in soil.Soil heavy metal cadmium pollution has the characteristics of concealment,long-term and irreversibility,that is,soil heavy metal cadmium pollution is difficult to distinguish with the naked eye,it is necessary to detect the soil cadmium pollution indicators,and it is difficult to repair,which is permanent pollution.In the soil,Cd has a strong fluidity and solubility,enabling it to be easily absorbed by plants and accumulated in cells.Cadmium enters the human body through the food chain and accumulates mainly in the kidneys and liver,leading to liver and kidney organ failure.A combined plant-microbial remediation technology is a priority for the efficient treatment of heavy metal pollution in soil,but there is relatively little research on the combined remediation system for Cd pollution.In this study,Salix matsudana Koidz,which has a fast growth rate,large biomass,and high cumulative capacity of heavy metals,was selected as the enrichment plant.However,since Salix matsudana Koidz is a deciduous tree,the planting density should not be too large.So we have also selected creeping bentgrass as the alternative enrichment plant to achieve the remediation effect via the maximum utilization of the soil area.Arbuscular mycorrhizal fungi(AMF),which are in direct contact with the soil and plant roots,can help the plant to absorb the minerals in the soil and promote plant growth.Therefore,after successively selecting Salix matsudana Koidz and creeping bentgrass as host plants.By analyzing the changes in the abundance and differentiation of AMF microbiota in different Cd-contaminated areas in the field,a fungus of the Glomeraceae family was found to be a key dominant fungi of AMF,and the key fungal strain in the plant symbiotic AMF was identified as Funneliformis mosseae(FM).By analyzing the correlation between Cd and other environmental factors in the samples collected in the field where the soil contained excessive Cd content,the Cd content was found to be positively correlated with total organic carbon(TOC),p H and phosphorus(P)content,but negatively correlated with K content.In order to verify whether FM is a key AMF related to Cd accumulation,a series of pot and soil cultivation simulation experiments were conducted to measure the content of Cd,nutrient elements and enzyme activity in roots,stems and leaves of the two kinds of plants.The results showed that FM could help Salix matsudana Koidz and creeping bentgrass to enrich Cd in soil.To explore the response mechanism of the Salix matsudana Koidz – FM or creeping bentgrass – FM symbiotic system to cadmium stress,we further examined the content of various essential nutrient elements in different parts of the plants.The correlation between FM and these nutrient elements was analyzed,and the role of FM in the symbiotic systems with plants on Cd accumulation and Cd toxicity was finally determined.The results showed that: 1)FM promoted the plants’ absorption of P and other elements and increased plant biomass;2)There may be a competitive relationship between Cd and K,Zn in the aboveground parts of Salix matsudana Koidz and creeping bentgrass;3)Cd content in soil was positively correlated with P content and negatively correlated with K content,and the correlation between Cd and P and K in soil was also adapted in the aerial part of plants;4)FM affected the activity of plant antioxidant enzymes mainly by promoting the activity of ascorbate peroxidase(APX),thereby reducing the content of reactive oxygen species(ROS)induced in the plants by Cd stress.It is worth noting that the current study was constrained by the objective conditions,and thus,the ability of FM to help plants effectively enrich cadmium in the soil in field plant-microbial symbiosis systems needs to be further verified.However,the current results could be useful for microbial agent development suitable for field applications. |
PDF Full Text Request