Study On The Response Characteristics Of Non-rhizosphere,rhizosphere And Endophytic Microorganisms To Soil Arsenic Pollution In Pteris Vittata L.

Arsenic contamination in soil has become one of the global environmental problems due to extensive mining and industrial activities.As the first discovered arsenic hyperaccumulator in the world,Pteris Vittata L.has been considered as an ideal plant for arsenic pollution soil remediation.The absorption and transport process of arsenic in P.Vittata is regulated by many factors,among which the endophytic bacteria play a promotion role.However,the response mechanism of microorganisms to arsenic enrichment in P.Vittata is still not well studied.In order to explore the response mechanism of P.Vittata endogenous microorganisms to arsenic pollution,this project used9 kinds of P.Vittata and P.Vittata pots with different arsenic pollution sites as experimental objects,respectively,using 16S r RNA high-throughput sequencing,metagenomic sequencing and other means combined with statistical and bioinformatics analysis methods to characterize the diversity of microbial community structures related to P.Vittata under the influence of different arsenic contamination,the distribution of arsenic content in the root of P.Vittata,and the identification of microbial arsenic-related functional genes in P.Vittata roots.To explore the universality of the metabolic potential of endomic microorganisms of P.Vittata and the interaction mechanism between P.Vittata-microorganisms and arsenic.The main findings of the study are as follows:（1）The enrichment ability of P.Vittata on arsenic is mainly manifested in the absorption of arsenic by stem and leaf,and the results show that when the soil As pollution concentrations are 250mg·kg^-1 and 500 mg·kg^-1,the concentration of stem and leaf As of P.Vittata is much higher than that of root As,and the concentration coefficients of stem and leaf As of P.Vittata are 99.99 and66.83,respectively.（2）The analysis of microbial community diversity showed that the microbial community structure of Centipede grass in the same location on the nine different arsenic contaminated sites was small,while the non-rhizosphere,rhizosphere and intra-root microbial community diversity of Centipede grass were significantly different（P<0.05）.In addition,there are similar phenomena in pot experiments:the difference in microbial community structure in the same part under the stress of arsenic concentration is not obvious,while the diversity of microbial communities between the rhizosphere soil,roots and stems and leaves of centipede grass under the same arsenic concentration stress has significant differences（P<0.05）.It shows that there is a specific selectivity between centipede grass-microorganisms and is universal.The difference in microbial community structure in the relevant parts of centipede grass has little to do with the size of arsenic stress,and is mainly related to the location of microorganisms.（3）A group of core and key microorganisms growing in P.Vittata roots on sites with different arsenic contamination concentrations were identified,namely Rhizobiales,Burkholderiales,Saccharimonadales and Alphaproteobacteria,Actinobacteriota.And identified the core microorganisms in the rhizosphere soil,in the roots and stems and leaves of P.Vittata in potting experiments with different arsenic concentrations,namely Xanthobacteraceae uncultured,KD4-96and Vicinamiales uncultured;Rhizobium,Devosia and Ohtaekwangia;stenotrophomonas.These beneficial microorganisms,which are highly tolerant to arsenic and can promote plant growth and development,play an important role in the mechanism of action of P.Vittata super-cumulative arsenic function.（4）The sequencing analysis of microbial metagenomics in P.Vittata roots in the field successfully assembled 20 high-quality（completeness>60%,contamination<15%）metagenomic assembled genomes（MAG）,and identified 9 functional genes involved in As metabolism in these magnums,namely ACR3,aio A,arr A,ars A,ars B,ars C,ars D,ars M and ars R.At the same time,it was found that a large number of As metabolic function genes were encoded in the core microorganisms and key microorganisms in the P.Vittata roots.This is further evidence that P.Vittata can enrich specific arsenic-resistant microorganisms in large quantities and promote the superaccumulation effect of P.Vittata on arsenic.