Rhizospheric And Root Endopytic Microbial Communities Structure Research Of Dominant Plants On The Littoral Zones Of Saline-alkali Lakes In Arid Regions

Worldwide studies have found that salinity is a major environmental factor affecting the composition of microbial communities.Saline-alkali lakes are a special type of extreme saline-alkali ecosystem.Previous studies have mainly focused on the effects of salinity and alkalinity on microbial composition of the water bodies and sediments of saline-alkali lakes.However,little information is available on the effects of salinity and alkalinity on microbial composition in the root and root endophytes.The saline-alkali lake ecosystem plays an extremely important role in the utilization of water resources and ecological environment protection in arid and semi-arid areas.To explore the mechanism of the rhizosphere and root endophytic microorganisms in helping dominant plants to resist high salinity stress in the saline-alkali lake and the littoral zones,it has important scientific value and practical application significance for understanding the mechanism of stability maintenance of saline-alkali lake ecosystems.In this study,high-throughput sequencing technology was used to investigate the rhizosphere and root endophytic bacterial and fungal community structure and diversity of different dominant plants along the saline-alkali gradient.A variety of bioinformatics methods were used to explore the mechanism of rhizosphere and root endophytic microorganisms in assisting plant adaptation to high salinity stress.Research results indicates:(1)In extreme saline-alkali environment,salinity was not the mainenvironmental factor affecting microbial diversity.The composition of the microbial community was affected by both soil environmental factors and plant species.The influence of soil environmental factors on rhizosphere microorganisms was greater than that of root endophyte.(2)Mantel test analysis further revealed that the rhizosphere bacterial and fungal communities of dominant plants were most significantly affected by Mg²⁺in the Ejinur Salt Lake,while Cl^-and plant species had the most significant effects on root endophytic bacterial and fungal communities;The community composition of rhizosphere and root endophytic bacteria and root endophytic fungi of dominant plants were most significantly affected by SOC in the littoral zones of the Sunite Alkali Lake,while the rhizosphere fungal were most significantly affected by CO₃^2-.(3)There were significant differences in the microbial dominant groups enriched by different dominant plants in the littoral zone of saline-alkali lakes.The dominant genera enriched by dominant plants in the littoral zones of the Salt Lake include:Marinobacter,Palleronia,Ilumatobacter and Penicillium,while the dominant genera of dominant plants in the littoral zones of the Alkali Lake are:Bacillus,Halomonas and Preussia.These microorganisms all have certain salinity-tolerant or growth-promoting characteristics,so they may play a very important role in assisting the dominant plants to resist the high salinity stress environment in the littoral zones.(4)The analysis of the microbial network interaction pattern revealed that the microorganisms between the rhizosphere and root endophytes can be regulated by synergistic and antagonistic relationships,assisting the dominant plants to better adapt to the extreme saline-alkali environment.The screened keystones with salinity-tolerant and growth-promoting properties can assist host plants to adapt to extreme saline-alkali environments,such as Pseudomonas in the littoral zone of salt lakes and Sphingomonas in the littoral zone of alkaline lakes,etc.The results showed that salinity was not the main environmental factor on affecting microbial diversity in extreme saline-alkali environment.Environmental factors and enriched dominant microbial taxa were significantly different in the rhizosphere and root endophytic microbial composition of dominant plants in the littoral zones of saline-alkali lakes.The screened keystones taxa played an important role in better adaptation of host plants to extreme saline-alkali environments.The results of this study are of great significance and practical value for excavating the potential saline-alkali stress-resistant microbial resources in the littoral zones of saline-alkali lakes,and also provides a theoretical basis for the development and utilization of saline-alkali lake resources.