| In recent years,Pinus sylvestris has encountered many serious problems,such as pests and diseases,damage to the soil environment and poor seedling growth.After the use of chemical methods for control,people gradually realize that their excessive use also brings a series of serious environmental pollution problems,which makes people have to turn their attention to more environmentally friendly biological control methods.For example,the use of beneficial microorganisms in the rhizosphere,as an important probiotic group in the plant rhizosphere,plays an irreplaceable role in promoting plant growth and improving stress resistance.On this premise,in order to cope with Pinus sylvestris blight disease,this study took the rhizosphere bacteria ZB155 isolated from the rhizosphere soil of Pinus sylvestris as the research object.After strain identification,its biocontrol potential was determined by its performance in vitro and inoculation experiments,and the co-culture system was attempted with other excellent probiotic strains.The results were as follows:(1)Strain ZB155 was identified as Burkholderia ambifaria in the genus Burkholderia by morphology,characteristics observation,physiological and biochemical indexes determination and16 S r RNA gene sequencing.Strain ZB155 was active in phosphorus solubilization,IAA production,pathogen plate confrontation and fermentation broth confrontation experiments,and produced broad-spectrum inhibition against a variety of pathogens.Illumina Hiseq×10 platform was used to analyze the whole genome of strain ZB155.It was found that the genome of strain ZB155 included several genes related to metabolism and biological regulation and the 20 secondary metabolic gene clusters of strain ZB155 included several antibiotic anabolic gene clusters.Abundant secondary metabolic gene cluster analysis results also confirmed the biocontrol potential of ZB155.(2)Inoculated with ZB155 and inoculated with Rhizoctonia Solani,it was found that inoculation with ZB155 could effectively control the occurrence of Rhizoctonia solani in Pinus sylvestris seedlings.The average incidence of Rhizoctonia solani inoculated with ZB155 was30.27%,and the average incidence of Rhizoctonia solani inoculated with ZB155 was 75.33%.By measuring the growth indexes of Camphor pine seedlings,nutrient indexes and enzyme activities of rhizosphere soil,and physiological indexes of seedling resistance,it was found that the mean seedling height,ground diameter,fresh weight and dry weight of strain ZB155 increased by 24.43%,10.15%,23.39% and 17.42%,respectively.The mean of soil available N,total P,available P,total K and available K increased by 57.57%,32.53%,103.84%,33.11% and 23.52%,respectively.The activities of β-1,3-glucanase,chitinase,superoxide dismutase,catalase and peroxidase of inoculated seedlings increased by 40.13%,48.35%,14.16%,12.36% and 149.64%,respectively.It was proved that strain ZB155 had significant effects on growth promotion and disease resistance of Pinus sylvestris.(3)To explore the in vitro interaction effect of strain ZB155 with other excellent probiotics and try to construct a co-culture system,so as to exert more efficient biocontrol ability.The most compatible strain of Trichoderma Virens ZT05 was selected from a variety of beneficial rhizosphere microorganisms previously isolated in the laboratory by the plate face-off method.After that,strain ZB155 and Trichoderma Virens ZT05 were treated with fermentation broth at different concentrations under in vitro conditions.To explore the effects of the two strains on the growth of each other and the antagonistic ability of N.solanum.The results showed that compared with blank control,colony diameter,biofilm formation,spore germination rate and bacteriostatic rate were mainly mutually promoted at low concentrations,and only showed an inhibitory effect at high concentrations.Finally,the co-culture of the two strains was carried out,and it was found that the inhibition rate was significantly improved under the co-culture condition.Under the in vitro conditions,it was proved that the co-culture system established by mutually compatible strains has obvious advantages over a single-root probiotic.In conclusion,Burkholderia bidirectional strain ZB155 has the ability to promote the growth of Pinus sylvestris,improve the resistance to Pinus sylvestris,enrich the selection of strains for the prevention and control of Pinus sylvestris,and provide the corresponding experimental data of in vitro and inoculation.In addition,the co-culture system of Trichoderma aeruvium ZT05-Burkholderia bidirectional ZB155 constructed in this study also showed efficient biocontrol performance,which provided a preliminary basis and reference for the later inoculation experiment and even the production and development of efficient compound bacterial agent. |
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