Response Mechanism Of Pteris Vittate Microbiome To Arsenic Pollution

Arsenic contamination in soil is one of the hot issues attracting wide attention at present.As an arsenic hyperaccumulation plant,Pteris vittata has strong potential for phytoremediation of arsenic-contaminated soil.In addition to plant arsenic absorption and arsenic detoxification capabilities,plant microbiome,especially root related microorganisms,are also closely related to arsenic transformation and metabolism,which is of great significance to arsenic transformation in Pteris vittata.However,the response mechanism of Pteris vittata plant microbiome to arsenic is still unclear.The current studies on the rhizosphere and root endosphere microbial community of Pteris vittata mainly focus on the pure culture system,which tends to ignore the influence of other microorganisms and environmental factors in the microbial community,and greatly underestimate the diversity of root functional microorganisms.Therefore,this study combined geochemical characteristics,high-throughput sequencing,metagenomic sequencing and molecular bioinformation methods to analyze the community diversity and community structure of the rhizosphere and root endosphere microbial community of hyperaccumulator Pteris vittata and nonhypercumulant plants(Artemisia argyi Levl and Eupatorium adenophora Spreng)from multiple perspectives.The response of microorganisms to arsenic in the rhizosphere and endosphere was further investigated.In addition,stable isotope probing technique was applied to identify potential arsenic oxidizing bacteria in the rhizosphere and roots of Pteris vittata.The main conclusions are as follows:1.Significant divergence existed among microbial communities of Pteris vittata,Artemisia argyi Levl and Eupatorium adenophora Spreng growing in high arsenic environment,whether rhizosphere or endosphere.Arsenic is mainly concentrated in fronds of Pteris vittata,while in nonhypercumulant plant Artemisia argyi Levl,arsenic is mainly concentrated in roots.Compared with(Artemisia argyi Levl and Eupatorium adenophora Spreng),the arsenic hyperaccumulation plant Pteris vittata has higher diversity and stability in rhizosphere microbial community.A variety of arsenic-resistant bacteria and plant-promoting bacteria,including KD4-96,Gemmatimonadaceae,Solirubrobacteraceae,Gaiellaceae and Nitrososphaeraceae,were significantly enriched in the rhizosphere microbial community of Pteris vittate compared with the other two nonhypercumulant plants.Rhodomicrobiaceae,Hyphomicrobiaceae,Rhizobiales＿Incertae＿Sedis and Frankiaceae related microorganisms were significantly enriched in the roots of Pteris vittata growing in high arsenic pollution soil.2.The correlation and response mode between various heavy metal(loid)s factors and rhizosphere or root endosphere bacteria were investigated based on the 16 S rRNA amplicon sequencing technology.The concentrations of Arsenic,antimony and chromium were the main influencing factors of the rhizosphere microbial community of Pteris vittata.Among them,the relative abundance of Gemmatimonadaceae,Geodermatophilaceae,Micrococcaceae,Nitrososphaeraceae,Rhodomicrobiaceae and Nocardioidaceae was positively correlated with arsenic concentration in rhizosphere soil.The concentrations of zinc,antimony and arsenic were the main factors affecting the root microbial community,and Rhodomicrobiaceae,Streptomycetaceae and Halomonadaceae showed a significant positive correlation with the arsenic content in the root of Pteris vittata.The influence of heavy metal components on the rhizosphere microbial community of Pteris vittata was greater than that of the rhizosphere microbial community,and the host plants could reduce the environmental disturbance to the rhizosphere microbial community.3.The As(Ⅲ)oxidation gene aioA is a key gene that drives arsenic oxidation by microorganisms in the rhizosphere and roots endosphere of Pteris vittata.The microorganisms related to Burkholderiales such as Hydrogenophaga are the main autotrophic arsenic oxidizing bacteria in the rhizosphere of Pteris vittata.They not only possess arsenic oxidizing ability,but also possess various metal resistance and plant growth promoting potential.Hydrogenophaga and Shinella-related microorganisms were the potential autotrophic arsenite oxidizing bacteria in the roots of Pteris vittata.