Construction Of Core Flora To Promote The Growth Of Elymus Sibiricus And Diversity Of AAPB In Rhizosphere Soil

Elymus sibiricus is recognized as an excellent grass forage with good comprehensive performance.It plays an important role in livestock development and ecological establishment,and is often used as the preferred germplasm for forage breeding.Although promising results have been achieved in the breeding of Elymus sibiricus,the current cultivation and breeding of Elymus sibiricus is only based on traditional methods,resulting in slow progress in the selection and breeding of its new varieties,which need further improvement in terms of grass yield,quality and resistance to stress in order to meet the needs of livestock development.In this paper,we used high-throughput sequencing technology and bioinformatics analysis to analyze the composition of the rhizosphere microorganisms of Elymus sibiricus;Co Net analysis was used to predict the composition of the rhizosphere core flora of Elymus sibiricus.Then,the rhizosphere microorganisms were isolated,and the rhizosphere core flora was synthesized and inoculated back.Finally,the core flora that can promote the growth and improve the quality of Elymus sibiricus was obtained.The aim is to provide new ways and basis for the breeding of Elymus sibiricus.By analyzing the community structure of Aerobic anoxygenic phototrophic bacteria(AAPB)in the rhizosphere of Elymus sibiricus,the mechanism of AAPB in the growth and development of Elymus sibiricus was further understood,which laid a theoretical foundation for further exploring the mechanism of AAPB in the rhizosphere of Elymus sibiricus on its growth and development.The conclusions are as follows :(1)The dominant phylum of bacteria in the rhizosphere soil of Elymus sibiricus: Proteobacteria,Actinobacteriota,Chloroflexi,Acidobacteriota and Bacteroidota;the dominant families were Sphingomonadaceae,Micrococcac-eae and Beijerinckiaceae.The dominant phylum of nitrogen-fixing bacteria : Proteobacteria and Cyanobacteria;the dominant families were Rhodospirillaceae,Nostocaceae,unclassified＿o＿＿Rhizobiales,Alcaligenaceae,Pseudomonadaceae and Methylococcaceae.The dominant phylum of AAPB: Proteobacteria and Chloroflexi;the dominant families were Bradyrhizobiaceae,Methylococcaceae,Rhodospirillaceae,Erythrobacteraceae,unclassified＿o＿＿Burkholderiales,Rhodobacteraceae,Caulobacteraceae and Roseiflexaceae.(2)Synthetic bacteria can promote the growth and development of Elymus sibiricus.In this paper,Co Net network analysis predicted that the common key families of rhizosphere bacteria and nitrogen-fixing bacteria in Elymus sibiricus were Rhodospirillaceae,Nostocaceae,Methylococcaceae and Pseudomonadaceae.Azospirillum brasilense of Rhodospirillaceae,Nostoc commune of Nostocaceae,Methylococcus capsulatus of Methylococcaceae and Pseudomonas hunanensis of Pseudomonadaceae formed the core syntrophic flora,which promoted the growth of Elymus sibiricus and significantly increased the protein content in the leaves of Elymus sibiricus.(3)The relationship between soil physicochemical factors and AAPB community structure.Among the soil physical and chemical factors,p H was significantly positively correlated with Methylococcaceae and significantly negatively correlated with Rhodobacteraceae and Nocardioidaceae.Available phosphorus has a relatively high correlation with rhizosphere microorganisms.Available phosphorus has a very significant positive correlation with Rhodobacteraceae in soil microorganisms,and has a significant negative correlation with Methylobacteriaceae and Pseudonocardiaceae.They may be important bacteria that affect the absorption of phosphorus in the rhizosphere.The AAPB flora in the rhizosphere of Elymus sibiricus was mainly composed of Bradyrhizobiaceae,Methylobacteriaceae and Rhodospirillaceae at the family level.