| Halophytes plays important guarantees for the health of desert ecosystems,while endophytes are important for plants environmental adaptation and resistance to adverse stimuli,and were also regulated by environmental factors,plant genotypes and organs.But the source of endophytes in halophytes and how they are collected remains a mystery of nature.In this study,the halophyte Borszczowia aralocaspica was used as the object,in situ,in situ and ectopic soil sterilization and non-sterilization treatment and sterilization substrates as materials,and the high-throughput sequencing technology was used as the means.The composition and evolution of endophytic bacteria in different tissues during growth were analyzed in order to reveal the source and recruitment of endophytic bacteria,and to improve the scientific basis for further understanding the relationship between endophytic bacteria and environment.(1)The results indicated that the abundance and diverse of endophytic bacteria were higher in primary habitat(FK)than the pthers.They were distributed in 31 phylum,785 genera and1858 OTUs.The dominant bacteria were Proteobacteria(60.99%),Actinobacteria(13.14%),Firmicutes(12.87%)and Bacteroidetes(11.24%).The dominant bacteria are Kushneria(25.86%),Halomonas(7.47%),Marinobacter(4.91%),Antarcticibacterium(4.25%),Planococcus(3.59%),unidentified genus of Enterobacteriaceae(3.08%),Nesterenkonia(2.06%),lactococcusla(2.01%),and the relative abundance of different tissues at different development stages is different.The relative abundance at different developmental stages was as follows: anthesis >seed-setting > seedling > growth stage.The results showed that the composition of endophytic bacteria were regulated at different growth stages in order to adapt to the environment.The diversity of endophytic bacteria in leaf tissues was significantly higher than that in roots and stems,confirming that these bacterial groups were airborne.(2)The endophytic bacteria of in situ soil sterilization(FKM)culture were distributed in 25 phyla and 558 genera,and the dominant bacteria were Pseudomonas,Marinobacter and Halomonas.And their proportion in different developmental stages and different tissues is different.There were 415 and 530 genera in seedling stage and growth stage,respectively,and 48 and 55 unique genera,respectively.The diversity of bacteria decreased in seedling stage,but increased in growth stage.There were 343,502 and 473 genera in roots,stems and leaves,respectively.The results showed that the diversity of tissues of the sterile in-situ soil culture strains,including Microbulbifer and Sinomicrobium,was less than that of the wild ones,suggesting that these endophytes came from the original soil.(3)Endophytic bacteria were distributed in 32 phylum and 512 genera in ectopic soil(MD).The dominant bacteria were Pseudomona and Allorhizobium-NeorhizobiumPararhizobium-Rhizobium.The proportion of Pseudomona was the lowest in roots and the highest in leaves,while Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium was opposite.Sharing analysis showed that there were 287 and 510 genera at seedling stage and growth stage,respectively,and 26 and 72 genera were unique to the genus.There were 352 genera in root,405 genera in stem and 453 genera in leaf,respectively.There were 34 endemic genera in the ectopic soil cultivation plants compared with the wild ones,including Rhodomicrobium,Niastella and Chloronema,which indicated that these endophytes originated from ectopic cultivated soil.(4)Endophytic bacteria were distributed in 19 phylum and 400 genera in ectopic sterilized soil(MDM).The dominant genera in seedling stage were Pseudomonas and Flavobacterium,accounting for 46.98% and 6.52,respectively.The dominant genera in the growth stage were Pseudomonas,Paenibacillus and Alkalobaciliaceae,accounting for 39.07%,22.06% and 5.23%,respectively.The results showed that Pseudomonas was derived from the seed of heterophyllum,and Paenibacillus and Alkalobaciliaceae were derived from airborne.(5)Endophytic bacteria were distributed in 21 phylum and 322 genera in MS medium with sterile substrate.The dominant genus Pseudomonas accounted for the highest proportion(34.02%),followed by Ralstonia(28.23%),Rhodococcus and Kushneria(6.64% and 6.00%).However,Marinobacter)and Antarcticibacterium,which were dominant in wild Borszczowia aralocaspica,were absent in MS culture medium.The results showed that these two genera are the main groups of host adapted to high salinity environment.The results showed that the community structure of endophytic bacteria was not only affected by vertical seed transmission,but also related to soil microbial community.The endophytic bacteria in aseptic soil(FKM and MDM)and aseptic substrate(MS)were relatively stable,but the relative abundance of endophytic bacteria increased,confirming that the group from vertical seed transmission was dominant in the absence of competition from exogenous microorganisms.The diversity and relative abundance of endophytic bacteria increased significantly in both in situ(FK)and in remote(MD)cultures without sterilized soil,confirming that endophytic bacteria were also derived from rhizosphere soil and airborne transmission.The results provided scientific basis for improving host environmental adaptability by using microbial strains. |
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