| Plant rhizosphere bacteria and seed endophytic bacteria are important components of plant microbiome.Research on community composition of plant rhizosphere bacteria and seed endophytic bacteria and screening of functional strains is of great significance for further research on species composition of plant microorganisms,promoting plant growth and improving plant stress resistance.In this study,Cupressus gigantea endemic to Tibet was taken as the research object,and high-throughput sequencing was used to study the community composition of bacteria in rhizosphere soil and endophytic bacteria in seeds.Traditional culture method was used to isolate and screen functional plant growth promoting bacteria.The functional strains were inoculated on the plants,and the growth promotion effect of the bacterioides was verified by plate test and pot experiment.The drought resistance ability of the bacterioides on the non-host plants was verified by natural water control method,so as to explore the functional strains resources of the Cupressus gigantea,the following results are obtained:(1)The bacterial community in rhizosphere soil was rich in diversity and varied greatly in composition.The results showed that: at phylum level,the dominant bacterial phylum(>10%)were Actinobacteriota and Proteobacteria;At the genus level,the relative abundance of norank＿f＿67-14,Norank＿f＿xanthoaceae,Mycobacterium and Streptomyces in rhizosphere soil is higher,and the relative abundance of norank＿f＿67-14 is the highest.It was6.16%.The bacterial community diversity of endophytic seeds was rich,and the community composition was different.The results showed that Proteobacteria was the dominant bacterial phylum at the phylum level.At the genus level,the relative abundance of endophytic bacteria of Azohydromonas,Ralstonia,Erysipelatoclostridium and Dechloromonas was high,and the relative abundance of Azohydromonas was the highest,accounting for 31.43%.(2)372 strains of culturable bacteria were isolated and screened from rhizosphere soil of Cupressus gigantea,and 79 strains of culturable bacteria were isolated and screened from seeds of Cupressus gigantea.Among them,20 strains had the ability of nitrogen fixation,ACC deaminase,IAA production and phosphorus solubilization.Among them,15 were rhizosphere bacteria,5 were seed endophytic bacteria,15 were potassium solubilizing bacteria,and 17 were iron carriers.The results showed that the rhizosphere bacteria strains Z-5-1 and Z-5-3 were identified as Achromobacter spanius,and strains Z-5-2,Z-5-5,Z-5-6and Z-5-7 were identified as Klebsiella oxytoca.Strains Z-5-4 and X-3-5 were Enterobacter ludwigii,and strain X-5-1 were Stenotrophomonas indicatrix.Strains X-5-2 and X-4-3 were identified as Enterobacter cloacae,and strain P4-4-1 was identified as Pseudomonas putida.Strain GYMS-4-6 was identified as Peribacillus frigoritolerans,and strain YJ-6-9 was identified as Serratia liquefaciens.P4-4-2 was identified as Bacillus subtilis.The endophytic bacteria CZ-T-12,CZ-R-18,CZ-T-22 and CZ-N-28 were identified as Alcaligenes faecalis,and CZ-8-17 was identified as Bacillus subtilis.(3)The growth promoting effect of functional strain was verified by plate test and pot experiment.Different strain treatments significantly promoted the seedling growth of non-host plants,rape and barley.Different strain treatments had different growth promoting effects on barley and rape,and different growth promoting strains were screened in the dish test and pot test.In the dish experiment,strain P4-4-2 had significant effect on barley and rape.The results of pot experiment showed that 9 functional strains had significant growth promotion effect on green plants,and 14 strains had good growth promotion effect on rape plants in terms of different measurement indexes.(4)The inoculation of multifunctional strains can promote the growth and enhance the drought resistance of non-host plants in rape and highland barley seedlings under drought stress.Different strains had different growth promotion effects and drought resistance ability,and the growth promotion ability and drought resistance ability of strains under different drought conditions were also different.The strains Z-5-1,Z-5-3 and CZ-R-18 inoculated under mild drought condition,Z-5-3 and X-4-3 under moderate drought condition,and CZ-R-18,YJ-6-9 and Z-5-6 under severe drought condition showed significant growth promotion and drought resistance.Under mild and moderate drought conditions,the inoculation strains of CZ-R-18 and CZ-T-12,and under severe drought conditions,the inoculation strains of X-4-3 and YJ-6-9had significant growth promotion and drought resistance on highland barley seedlings.Inoculation of rhizosphere bacteria Z-5-3,Z-5-6,X-4-3,YJ-6-9 and endophytic seed bacteria CZ-T-12 and CZ-R-18 showed significant effects in moderate and severe drought.Cupressus gigantea’s rhizosphere bacteria and seed endophytic bacteria community is rich in diversity,and the rhizosphere bacteria and seed endophytic bacteria have a variety of functional properties.The inoculation functional strains play a good role in promoting the growth of non-host plants highland barley and rape,and the inoculation strains can promote the growth of highland barley and rape plants and resist drought under drought stress,so the development potential is great. |
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