Study On The Growth-promoting And Taxonomy Of Endophytic Bacteria Isolated From Ligusticum Chuanxiong Hort.

The endophytic bacteria living inside plants can promote plant growth,which can be used to develop microbial fertilizer,with the advantages promotion plant growth,reduce fertilizer use,and reduce soil compaction,etc.In this paper,Ligusticum chuanxiong Hort.were collected from Pengzhou,Sichuan province as materials,and the endophytic bacteria in roots,stems and leaves were isolated.According to the morphological,physiological and biochemical characteristics,as wellas anal-ysis of 16 S rDNA sequences,identification of endophytic bacteria.Dissolution circle method was used to determine inorganic phosphorus and potassium dissolving ability;the Ashby medium method was used to determine the nitrogen fixing ability;the Iron bacteria medium method was used to determine the capability of utilizing ferric ammonium salt;Salkowski colorimetricmethod was used to determine IAA production;Preliminary screening of endophytic bacteria with potential for promoting growth.Then,the plantpromote growth ability was evaluated by pot experiments.The results were as follows:1.22 strains endophytes had been isolated from roots,stems and leaves of Ligusticum chuanxiong Hort.with the method of trituration.Among them,18 were isolated from roots,2 from stems and 2 from leaves.2.According to the morphological,physiological and biochemical characteristics,as well as analysis of 16 Sr DNA sequences,22 endophytic bacteria were identified,these strains belonged to 5 distinet bacterial genera,including Brevibacterium,Methanobacterium,Sporosarcina,Bacillus and Paenibacillus.The most dominant genus was Bacillus,accounting for 81.8%.3.The obtaincd bacerial endophytes were screned for their multifaceted beneficial,including the production of IAA,thecapacity of phosphate solubilizating,dissolved potassiumas,nitrogen fixation and utilization of ferric ammonium salt.The results showed that many of the strains displayed positive results in these assays(IAA: 12/22;phosphate solubilizating: 2/22;potassium solubilizating: 0;nitrogen fixation: 6/22;utilization of ferric ammonium salt: 10/22).4.Six producing endophytic bacteria is Lcl-2?Lcr-15?Lcr-16?Lcs-2?Lcr-17 and Lcr-18.Then,stems node of Ligusticum chuanxiong Hort.were cultivated by pot experiment in greenhouse,and the tested strains were used as inoculants,which was carried out to evaluate the growth-promoting efficient of these 6 strains.The results showed that all tested strains could promote the growth of Ligusticum chuanxiong Hort.,to some content.Among them,the contents of chlorophyll b,carotenoid,total chlorophyll,soluble sugar,soluble protein and inorganic phosphorus in the treatment group had pretty significant difference compared with control group.There were significant differences in plant height,chlorophyll a and nitrate nitrogen content between the treatment group and the control group.Through data analysis,it was found that strain Lcs-2,Lcr-16,Lcr-18 had the strongest effect on growth of Ligusticum chuanxiong Hort.