Research On The Rhizosphere Bacterial Structure And Spatial Distribution Suaeda Salsa In Semi-arid Region

Suaeda salsa vegetation zone which is a stable and adaptive community in the saline zone of the lakeside,has a unique value to Daihai Lakeside ecosystem.Inter-root is the link between plant roots and soil environment.In this thesis,high-throughput sequencing technology was used to research the inter-root bacterial community of suaeda salsa,revealing the spatial and temporal distribution patterns of soil microorganisms in the inter-root of suaeda salsa and their distribution mechanisms and factors,predicting the functions of inter-root microorganisms,and providing a theoretical basis for the subsequent study of the interaction between the inter-root and soil microorganisms of suaeda salsa.The main research conclusions are followed:(1)Due to the physicochemical properties in the spatial and temporal distribution,the suaeda salsa inter-root soil of different areas p H ranged from 8.20 to 9.45,water content from 8.3% to 22.6%,and conductivity from 0.78 to 3.78.p H,water content,and conductivity showed some spatial heterogeneity in the inter-root soil physicochemical properties.There were significant differences in the growth of suaeda salsa in each site,including significant differences in density and plant height(p < 0.05).Seasonal variation mainly led to changes in inter-root soil water content,bulk density and conductivity of suaeda salsa.Soil nutrients were significantly affected by seasonal changes,among which soil organic matter,total nitrogen,ammonia nitrogen,total phosphorus and fast-acting phosphorus showed a trend of decreasing and then increasing,while fast-acting nitrogen and nitrate nitrogen also showed some changes in seasonal dynamics but no consistent pattern was observed.The physical and chemical properties of inter-rooted soils were correlated with the growth and development of suaeda salsa,among which p H and conductivity were most significantly related to the height of suaeda salsa.(2)The inter-rhizosphere soil of suaeda salsa is rich in microbial resources,and 16 S r RNA gene sequencing annotated a total of 46 phyla,132 orders,506 families,and 1481 genera of bacteria,with Proteobacteria,Cyanobacteria,and Actinobacteriota as The average relative abundance of the dominant phyla was 54.21%.The dominant bacteria at the genus level mainly included Halomonas and Planctomyces.The soil bacterial community showed a certain dynamic distribution pattern with seasonal changes.The species diversity of inter-rhizosphere bacteria in autumn was significantly greater than that in spring and summer(p < 0.05).Among the inter-rhizosphere bacterial communities of suaeda salsa,the phylum Thick-walled Bacteria and the phylum Bacteroidetes were more sensitive to seasonal changes.Seasonal changes in soil nutrients,water content and temperature caused by seasonal changes had important effects on the seasonal dynamics of the inter-rhizosphere soil microbial community of suaeda salsa,where fast-acting phosphorus and soil water content were the main factors determining the seasonal distribution of the inter-rhizosphere soil bacterial community.(3)A total of 57 sub-functional taxa from seven types of metabolic pathways were identified in the gene sequences of alkali pong inter-rhizosphere bacteria,and Carbohydrate metabolism,Amino acid metabolism,Energy metabolism and Membrane transport were the major metabolic functional groups in the bacterial community.The results of the relative abundance of functional microorganisms showed that the spatial and temporal variation of functional genes related to carbon and nitrogen was obvious with the change of seasons.Alkali pong inter-root bacteria were annotated to 51,56,and 59 ecological functional groups in spring,summer,and autumn,respectively,with Chemoheterotrophy and Aerobic chemoheterotrophy,and Hydrocarbon degradation,Nitrate＿reduction were common dominant taxa in all seasons of the bacterial ecological functional groups.Phototrophy was the dominant ecological functional group in spring,Fermentation was the dominant ecological functional group in summer,and Nitrate respiration was the dominant ecological functional group in autumn.