The Characteristic Of Phyllosphere And Rhizosphere Microbial Community Of Bohtriochloa Ischaemum In Copper Tailings Area

Plant-microbial combined remediation is an important method for contaminated soil remediation in industrial and mining areas,which has become one of the key research contents in the field of restoration ecology.The microbial of phyllosphere and rhizosphere are the two important components of plant microorganisms.It not only affects the physiological and ecological characteristics of plants,but also affects the physical and chemical properties of soil.Thus,it is the great scientific significance and guidance for ecological restoration to explore the characteristics of vegetation microbial communities in mining areas.In this study,the Shibahe tailing dam of northern copper mine was selected as the experimental site in Yuanqu County,Shanxi Province.The phyllosphere and rhizosphere microbial of Bohtriochloa ischaemum were selected as the objects in copper tailing dam.The dynamic characteristics were analyzed about the physical and chemical properties of the soil in the process of plant-microbial combined remediation.The phyllosphere and rhizosphere microbial were based on the High-throughput sequencing of the variable regions of 16 Sr DNAV4-V5,ITS I and ITS II,and the statistical methods were used such as correlation analysis,Mantel test,RDA analysis and co-occurrence network graph,and analyzed the composition and diversity of microbial communities in phyllosphere and rhizosphere of B.ischaemum.This study revealed the main ecological factors affecting the microbial community characteristics of B.ischaemum in different periods,and provides the theoretical basis for improving the efficiency of plant-microbial remediation in the mining area.The study arrived at the following results:1.Dynamic characteristics of soil physical and chemical properties and enzyme activity under different recovery years of the copper tailings dam(1)With the increase of the recovery years,the copper was accumulated.The contents of arsenic and cadmium increased and then decreased,and reached a stable level at the later stage gradually.There was no significant difference in the content of zinc in soil with the recovery years.(2)There was a significant negative correlation between catalase and the ratio of carbon and nitrogen(C/N),and urease with soil water content and total nitrogen content were significantly positive correlation and significant positive correlation.2.Characteristics of microbial community structure in rhizosphere soil of B.ischaemum in different seasons(1)Except for C/N,ammonium nitrogen(NH4+-N)and nitrate nitrogen(NO3--N)in rhizosphere soil of B.ischaemum,other soil physical and chemical factors showed a significant seasonal difference.(2)The dominant phylums of bacteria and fungi communities were Proteobacteria and Ascomycota in the rhizosphere microbial community structures of B.ischaemum in different seasons,respectively.The maximum numbers of OTU were occurred in summer and spring in rhizosphere bacteria and fungi of B.ischaemum,respectively,while the lowest number was appeared in autumn.(3)The ecological factors affecting bacteria and fungi were different in rhizosphere soil of B.ischaemum in different seasons.In spring and winter,NH4+-N,NO3--N and catalase were the main influencing factors of bacterial and fungal communities.In autumn,the common influencing factors were total sulfur content,soil water content,soil temperature and urease.3.Characteristics of microbial Community structure in the phyllosphere of B.ischaemum at different growth stages(1)Proteobacteria and Ascomycota were the dominant phylums of bacterial and fungal in phyllosphere microbial communities in B.ischaemum at different growth stages,respectively.(2)The numbers of OTU were the highest at seedling and tillering in the bacterial and fungal communities.(3)The correlations were analyzed between phyllosphere microorganisms and physiological indexes of leaves showed that the contents of total nitrogen and total sulfur content were highly positively correlated with Cyanobacteria and Acidobacteria in mature stage in bacterial community,respectively.Moreover,there was a significant positive correlation between total carbon content and Zygomycota at tillering stage in fungal communities.(4)In the phyllosphere microbial communities of B.ischaemum,the total sulfur content and C/N were the main influencing factor at seedling and mature stage,respectively.Main conclusions:(1)With the increase of the recovery years,the soil nutrient content increased.(2)The highest diversity of rhizosphere microbial communities of B.ischaemum was shown in summer.(3)The diversity was the highest in the phyllosphere bacterial and fungal communities at seedling and tillering of B.ischaemum.