| Antimony is potentially toxic and carcinogenic,and has been listed as a priority pollutant by various organizations in the world.Once it enters the environment,it will cause certain damage to the biosphere.In this paper,Iris L.was used as pot experiment material,16S rRNA and metagenomic sequencing technology were used to study the different concentrations of 0 mg·kg-1（CK）,10 mg·kg-1（L10）,50 mg·kg-1（L50）,100 mg·kg-1（L100）,200 mg·kg-1（M200）,500 mg·kg-1（M500）,1000mg·kg-1（H1000）,2000 mg·kg-1（H2000）antimony stress Influence on the physiological growth of Iris L.and the structure of rhizosphere microbial community.In order to clarify the response of Iris L.and rhizosphere microorganisms to antimony stress,and to provide a theoretical basis for the development of plant-microbe joint restoration methods for soil and water sources in contaminated areas,the research results show that:（1）Compared with CK,the chlorophyll content of Iris L.in each treatment group showed an overall downward trend,decreasing by 8.43%,10.59%,14.62%,16.81%,21.285%,26.43%,respectively,indicating that antimony has an inhibitory effect on the synthesis of chlorophyll in Iris L..There are significant differences in the net photosynthetic rate of Iris L.under different concentrations of antimony stress.The changes of Pn,Tr,Ci,Gs of Iris L.are basically the same,and the overall trend is decreasing,which is expressed as CK>L100>M200>M500>H1000>H2000.It shows that by adjusting the stomatal conductance,Iris L.can change the intensity of transpiration,maintain its own osmotic pressure balance,and reduce the impact of antimony stress.As the concentration of antimony treatment increased,the Fv/Fm and Fm/Fo of Iris L.showed an overall downward trend,and there were significant differences among the treatments（P<0.05）.Fo,F,and NPQ are on the rise.It shows that antimony stress will affect the photosynthesis of Iris L.and destroy the physiological health of Iris L..Compared with the control group,the total root length between treatments showed a downward trend.Compared with the control group,CK was reduced by 26.80%,39.06%,45.72%,56.07%,78.24%,81.98%.The number of root tips in the treatment group was compared with the control group.Decline:51.14%,57.43%,44.36%,69.08%,84.66%,86.79%.As the concentration of antimony increases,there is a significant difference between L50 and L100,and a significant difference between L100 and M200,M500,H1000,and H2000（P<0.05）.The results showed that too high antimony content in the soil is not conducive to the growth of Iris L.root system,and too high antimony content seriously inhibits root growth.With the increase of antimony concentration,the antimony content of the aboveground and underground parts of Iris L.showed an upward trend,but TF<1.The BF of each treatment group was0.17,0.36,0.67,1.51,2.53,2.98 times of the CK of the control group.The enrichment coefficient increased with the increase of antimony concentration,but the increase was slower.It shows that Iris L.has a certain enrichment effect on antimony,and it is mainly enriched in the roots of Iris L..（2）Using 16S rRNA sequencing technology to analyze the bacterial community structure in the rhizosphere soil of Iris L.In this experiment,the bacteria in the rhizosphere soil samples of 21 Iris L.were mainly divided into 36 phyla,102 classes,271 orders,476 families,and 915 Genus.Through NR species annotation and evolution analysis,it is found that the bacterial communities in the rhizosphere soil samples of Iris L.under different antimony stresses roughly originate from 6 groups:Proteobacteria,Bacteroides,Chlorocurve,Actinomycetes,Bacillus Phylum,the abundance of most of the bacteria phyla decreased with the increase of antimony concentration.There are a certain number of unidentified species,and the evolutionary trend is not obvious,but the genetic distance of the known community evolution is relatively short,and the genetic relationship is relatively close.Through the KEGG function annotation analysis,the pathway level 1-3 metabolic pathways of the soil bacteria in the rhizosphere of Iris L.were 6,41,and 300 respectively.Under different antimony stress treatments,the types of metabolic pathways in each group were similar,and their abundance values were different.Among them,41 metabolic pathways have significant differences under different antimony stress treatments.In terms of metabolism,including photosynthesis-antenna protein,oxidative phosphorylation,etc.;in terms of environmental information processing,ion channels,bacterial toxicity,etc.,the abundance values of the above metabolic pathways with the increase of antimony concentration are lower than the control group,indicating antimony stress Bottom,the metabolic function potential of the soil bacterial community in the rhizosphere of Iris L.is inhibited.（3）Using metagenomic sequencing to analyze the effects of antimony stress on the structure and diversity of soil microbial communities in the rhizosphere of Iris L.,8kingdoms,122 phyla,225 classes,438 orders,751 families,and 2200 genera were detected.9984 species.The CK group had the most peculiar orders with 13 species,followed by the treatment group L50,with 11 species,and the H2000 with the least peculiar eyes,with only 5 species.Through the NR species annotation,it was found that with the increase of antimony concentration,the proportion of Proteobacteria and Xanthomonas in the rhizosphere soil of Iris L.showed an upward trend,and the proportion of Actinomycetes and Brachyrhizobium showed a downward trend.It can be seen that antimony is in to a certain extent,it changed the microbial community structure in the rhizosphere soil of Iris L..Through COG function annotation,it is related to amino acid transport and metabolism（10.12%,9.95%,9.72%）,translation of ribosomal structure and biogenesis（5.11%,5.11%,4.90%）,energy production and transformation（9.15%,8.86%）,8.81%),carbohydrate transportation and metabolism（5.82%,5.71%,5.70%）and other related COG functions decrease with the increase of antimony concentration.Transport and metabolism of nucleotides and metabolism of inorganic ions（5.55%,5.79%,5.90%）,DNA replication,recombination and repair（5.74%,5.86%,5.92%）,cell wall/membrane biogenesis（4.67%）,4.92%,4.95%),transcription（4.32%,4.33%,4.36%）,coenzyme transport and metabolism（2.64%,2.71%,2.73%）and other related COG functions increase with the increase of antimony concentration.Through KEGG analysis,it was found that with the increase of antimony concentration,the abundance of metabolic pathways related to organic matter accumulation in microorganisms decreased,indicating that antimony stress would inhibit the accumulation of microorganism organic matter.The increase in the abundance of metabolic pathways related to bacterial secretion system,steroid biosynthesis,carbon metabolism,etc.indicates that microorganisms will make corresponding adjustments after antimony stress to adapt to environmental stress.Through the correlation analysis of environmental factors,it was found that Azotobacter,Monk,Acidobacter,Agrobacterium,etc.have better adaptability to heavy metal antimony stress,while Pseudoxanthomonas,Microbacteria,and slow-growing rhizoma Bacteria and other genera have a negative influence on antimony stress.The number of viruses in the H2000 treatment group was significantly higher than that in the control group CK,indicating that these genes related to energy production and transformation,DNA replication,recombination and repair can be exchanged between species through viruses,so that microorganisms in the entire environment can actively respond to heavy metal antimony Coercion. |
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