Species Diversity And Heavy Metal Tolerance Of DSE Fungi In Fengfeng Mining Area,Hebei Province

Fengfeng Mining Area,located in the southwest of Handan City,Hebei Province,is the main coal production base of Handan City.Overexploitation of mineral resources leads to serious pollution of heavy metals in soil and intensified destruction of vegetation.Soil samples and root samples from 0-20 cm and 20-40 cm soil layers of Ilex chinensis and Broussonetia papyrifera in Fengfeng mining area of Hebei Province were collected in October 2016 and 2017.The community composition,ecological distribution,heavy metal tolerance and inoculation effects of dark septate endophytes(DSE)were studied in order to provide basis for the effective utilization of DSE fungi resources and the promotion of vegetation restoration and ecological reconstruction in mining areas.The main test results are as follows:1.Both the roots of Ilex chinensis and Broussonetia papyrifera can be highly infected by DSE,forming typical dark septate mycelia and microsclerotia structure.The total colonization rates of DSE in the roots of plants in mining areas in 2016 and 2017 were 34% and 40%,respectively.The colonization rate of microbial sclerotia was negatively correlated with soil available nitrogen.The colonization rate of mycelium was positively correlated with total phosphorus and negatively correlated with temperature.The colonization rate of microorganisms was negatively correlated with temperature and organic carbon.The total colonization rate was positively correlated with soil total phosphorus,negatively correlated with heavy metal Zn and temperature.Colonization intensity was negatively correlated with soil organic matter and positively correlated with total phosphorus and available nitrogen.2.Eight DSEs were isolated and identified,namely Acrocalymma vagum,Scytalidium lignicola,Nothophoma quercina,Cochliobolus lunatus,Fusarium acuminatum,Neonectria radicicola,Pyrenochaetopsis indica and Peosporales sp.The dominant species were Acrocalymma vagum,Scytalidium lignicola and Fusarium acuminatum,with separation frequencies of 37.6%,17.43% and 11.93%,respectively.3.The mycelia of Scytalidium lignicola,Acrocalymma vagum,Cochliobolus lunatus and Pyrenochaetopsis indica strains under different concentrations of Cd and Zn stress showed darker color,shorter interval and wider hyphae.Some strains form a large number of hyphal circles,which induce sporulation,and the number of spores also increases.4.Superoxide dismutase(SOD),soluble protein,malondialdehyde(MDA),glutathione(GSH),melanin content and biomass of mycelium were determined under different concentrations of Cd and Zn stress liquid culture.Under the stress of Cd and Zn at different concentrations,the biomass of the tested strains increased first and then decreased with the increase of heavy metal concentration,while the biomass decreased.Some of the strains showed the trend of first rising,then falling and then rising.5.The correlation analysis between antioxidant indexes and chemical components showed that soluble protein and melanin of four DSEs were correlated with SOD,MDA and GSH under heavy metal stress,but the response mechanism of different strains to heavy metal stress was different.6.Acrocalymma vagum and Sytalidium lignicola were returned to non-host plants,Medicago sativa and Ammopiptanthus mongolicus,and cultivated in soil under Cd stress.It was found that after inoculation with DSE,they could grow healthily and form a good symbiotic relationship with Medicago sativa and Ammopiptanthus mongolicus.The colonization rate increased with the increase of heavy metal concentration,with an average total colonization rate of 43.89%.7.Under heavy metal stress,inoculation of DSE has a good growth promoting effect on plants,and can significantly promote plant height,root growth and biomass.DSE inoculation could promote the uptake of N and P,increase the chlorophyll content,and significantly enhance the accumulation of cadmium in plants.