Responses Of Endophytic Diversity And Community On Salt Gradient Stress By Borszczowia Aralocaspica

Halophytes were an important guarantee for the safety and health of desert ecosystem,and their endophytes were of great value in enhancing the environmental adaptability of host plants.Borszczowia aralocaspica belonged to the genus Borszczowia of Chenopodiaceae.As panicum miliaceum,it had extremely strong saline-alkali resistance and barren resistance,and was the main constructive species in the Gulbantonggut Desert.However,there was no report on the response of endophytic bacterial diversity and community structure under different gradient salt stress.In this study,the in-situ soil desalination of B.aralocaspica was prepared for different salt gradients,and the composition evolution of endophytic bacteria in different development stages of B.aralocaspica was detected to understand the response of endophytic bacteria diversity to salt gradients and provided theoretical basis for improving plant salt tolerance by using microorganisms.(1)In order to know whether the preparation of salt gradient soil had an impact on its microbial community,this study used high-throughput sequencing technology to analyze the microbial diversity of four kinds of prepared salt gradient soils and in-situ soil.The results showed that there was no significant difference in microbial diversity among salt gradient soils,and the microbial community structure in each sample was consistent and had no significant change,but the abundance of each group changed slightly,which laid an experimental foundation for planting B.aralocaspica in salt gradient soils.(2)The results of high-throughput sequencing showed that there were 771 genera of endophytic bacteria distributed in 29 phyla.Proteobacteria had the highest relative abundance,followed by Actinobacteria,Firmicutes and Bacteroidetes,all of which belonged to the dominant phyla.The relative abundance of Kushneria was the highest,followed by Halomonas,Gillisia,Marinobacter and Planococcus,all of which were dominant bacteria.Different developmental stages and different tissues have different effects on the diversity of endophytic bacteria.At different development stages,the change rule of diversity was: seedling stage > flowering stage > mature stage > seed setting stage;In different tissues,the diversity of endophytic bacteria in flowers was the highest,followed by leaves,stems and roots,and the diversity of endophytic bacteria in fruits was the lowest.(3)Combing the high-throughput sequencing data of cultures and wild plants,their endophytic bacteria were distributed in 38 phyla and 1112 genera.Proteobacteria had the highest relative abundance,while Actinobacteria,Firmicutes and Bacteroidetes had lower relative abundance.Halomonas and Pseudomonas had a high proportion,while Ralstonia and Kushneria had low relative abundance,which were dominant bacteria,but they showed different changes under the influence of salt gradient stress.The relative abundance of Halomonas increased with the increase of salt gradient at seedling stage and growth stage.The abundance in roots of Ralstonia was extremely low,but the relative abundance in stems,leaves and flowers gradually increased in 20% and 50% of the cultivated samples.Salt stress has no significant effect on the diversity and community composition of endophytic bacteria in different development stages,but it will cause a large number of unique species in different development stages.It has a significant impact on the community structure and diversity of endophytic bacteria in different tissues.Root,stem,leaf and flower tissues were rich in endophytic bacteria under high salinity.The abundance of some groups increased with the increase of salt gradient,but the response of some groups were just the opposite.The results showed that salt stress will make the plants of B.aralocaspica have richer diversity of endophytic bacteria.By analyzing the regular changes of community structure,we can better understand the synergy between the endophytic bacteria of halophytes and the adaptation of host stress,which was of great development value for screening of salt-tolerant and growth-promoting strains,it was also a new species resources.