Study On The Interaction Between AM Mycorrhizal Fungi,PGPR Probiotics And Rhizobium

In order to investigate the interaction between Arbuscular mycorrhizal Fungi(AMF),Glant Growth Promoting Rhizobacteria(PGPR)and Rhizobium,this study was carried out by wet sieve decantation-sucrose centrifugation.The AMF was screened from the rhizosphere of the dominant vegetation of the alpine degraded grassland in the Qilian Mountains.It was identified by morphology and 18 s RNA sequencing,and expanded by the oat pot experiment method.Oats and Alfalfa were studied and the interaction between AMF and PGPR was studied by pot experiment.The experiment was set up with 12 treatments: CK(inactivated live bacteria),VAF1(AMF1: Rhizophagus intraradices),VAF2(AMF2,screening of this study),R(oats potted experiment for biocontrol Phyllobacterium ifriqiyense,alfalfa pot experiment are Ensifer fredii),PGPR(Azotobacter sp.,Pseudomonas sp.,Bacillus mycoides mixed strain),VAF1+PGPR,VAF2+PGPR,VAF1+R,VAF2+R,PGPR+R,VAF1+PGPR+R,VAF2+PGPR+R.Agronomic traits,root morphology,root physiological and biochemical,rhizosphere soil physicochemical properties and soil enzyme activities were measured at 60 d.Principal component analysis combined with score and cluster analysis was used to define the interaction of AMF-PGPR or AMF-PGPR-Rhizobium in the rhizosphere of oats and alfalfa.The results show:(1)An arbuscular mycorrhizal fungus(AMF2)was isolated and screened.AMF2 was identified by morphology and gene sequencing as Rhizophagus intraradices,GenBank serial number MK311327.(2)Oat test showed that single and mixed inoculation of AMF and PGPR had different effects on the growth of oat seedlings.After inoculation with AMF2,PGPR mixed bacteria and biocontrol bacteria,the growth promotion effect of oats was the best,compared with the other 11 treatments;the oat plant height was increased by 16.05% compared with the control CK,but the plant dry matter accumulation decreased;chlorophyll a chlorophyll b And carotenoids decreased by 2.29%,25.66% and 15.99%,respectively;at the same time,the physiological and biochemical effects on roots were significant,root activity,amylase,peroxidase,catalase,soluble protein and sugar increased,respectively.2.19,2.61,0.86,0.15,4.5 and 0.85 times,superoxide dismutase,free proline,malondialdehyde and cellulose content were significantly reduced by 37.37%,58.58%,64.06% and 27.71%,respectively;AMF2,PGPR Mixed strains and biocontrol bacteria are the best combination of strains that promote oat growth.(3)Pot experiments of alfalfa showed that AMF,PGPR strain and Rhizobium single and mixed inoculation had different degrees of inhibition on seedling growth;inoculation of AMF1,PGPR mixed strain and Rhizobium compared with control,I felt agronomic traits at seedling stage(plant height 26.07%,stem diameter 12.40%),but promote root growth and dry matter accumulation;at the same time reduce root physiological and biochemical indicators,root activity,invertase,malondialdehyde,cellulose,soluble protein and sugar decreased by 36.68%,58.97%,3.15%,3.86%,1.33% and 16.00%.Compared with the rest of the treatment,the inoculation of AMF1,PGPR mixed strain and Rhizobium had the weakest inhibitory effect on seedling growth.(4)(single,mixed)inoculation of AMF,PGPR on oats and(single,mixed)inoculation of AMF,PGPR and rhizobium have different effects on rhizosphere soil,but the overall trend is to promote soil improvement.Among them,oat test showed that AMF1,PGPR mixed bacteria and biocontrol bacteria combination were the most effective compared with control CK,the latter increased soil available nutrients and enzyme activities,among which available nitrogen,phosphorus,potassium and catalase,urease and sucrose.The enzyme activities increased by 19.81%,59.31%,26.36%,3.59%,112.79% and 24.33%,respectively.The sputum test showed that AMF1,PGPR mixed strain and Rhizobium had the best soil improvement effect compared with the control CK,increased soil total nutrient,effective nutrient and enzyme activity,and increased total potassium,nitrogen and available phosphorus.K is 3.59.%,20.33%,16.39% and 8.41% also increased phosphatase,urease and sucrase by 38.69%,60.49% and 32.96%,respectively.(5)The results of PCA analysis of 36 indicators of oatmeal showed that the comprehensive scores of the five treatments were higher than the control,and the scores of AMF2,PGPR and biocontrol bacteria were the highest,which were higher than 29.21% of the control group.Indicating that the oat root is AMF2,the PGPR strain and the biocontrol bacteria can interact to promote oat growth.After cluster analysis,it was found that the control treatment and inoculation of AMF1,AMF2,PGPR and AMF1 + PGPR were at the same level,indicating that the mixed relationship between AMF1 and PGPR mixed on oat root was weak;the remaining treatment found AMF2 and PGPR mixed strain,biological control bacteria There is mutual inhibition in the rhizosphere of oats.(6)The results of PCA analysis of 35 indicators in the alfalfa test showed that the scores of AMF1,PGPR mixed bacteria and Alternaria rhizogenes or AMF mixed vaccination were higher than the control group,which increased by 9.20%,33.05% and 64.63%,respectively.The highest score of the inoculated AMF1,PGPR mixed strain and Rhizobium was 34.72.Cluster analysis showed that AMF1 + PGPR + Rhizobium was treated in the first stage,AMF was inoculated in the second stage,and the remaining treatment was in the third stage,indicating that AMF2 and PGPR mixed strains and Rhizobium had certain mutual inhibition in the rhizosphere.In summary,R.intraradices and Azotobacter sp.,Pseudomonas sp.,Bacillus mycoides mixed in oats promote oat growth,AMF2,PGPR mixed bacteria and Anti-bacteria is the best combination of strains to promote oat growth;AMF2,growth-promoting strains and Ensifer fredii have inhibitory effects in the rhizosphere of oats,among which AMF1,PGPR mixed strains and rhizobium are the best to promote alfalfa growth combination.