Studies On The Species Diversity And Distribution Of Rhizobia Isolated From The Soil Gown Mimosa Spp.

In this study, a total of205rhizobia isolated from the soil that are from Yunnan,Hainanand Guangdong province. For researching their species diversity and the regularities ofspecies distribution, these isolates were analyzed by methods of16S rDNA-PCR RFLP, thesequences analysis of16S rRNA gene and the inoculation test.The results of the16S rDNA-PCR RFLP show that all of the text strains are divided intotwo groups such as group A and group B at the similarity of63%. The grpup A and the groupB stand of α-Rhizobia and β-Rhizobia respectively.The group A include168strains groupedwith the corresponding reference strains of Rhizobium, Siomrhizobium, Bradyrhizobium andMesorhizobium. In group A, the number of test isolates grouped with the type strainsRhizobium and Sinorhizobium is95and65, the residual strains grouped with the type strainsof Mersorhizobium. The group B consist of37isolates,which grouped with the type strains ofCupriavidus and Burkholderia. There are25strains belonged to the type strains ofCupriavidus.Based on the conclusion of the16S rDNA-PCR RFLP,32strains are selected for thestudy of the sequences analysis of16S rRNA gene and phylogenetic position analysis, whichdemonstrated that all of the test strains were distribute into two groups such as α-Rhizobiaand β-Rhizobia. The group of α-Rhizobia.includes23strains.During the group of α-Rhizobia,11test strains including the strain S293201belong to the branch of the gunus ofSinorhizobium, which are from Yunnan,Hainan and Guangdong province. The genusRhizobium(includeing the isolate S363202) contains7test strains came from Yunnan,Hainanand Guangdong province.The isolates S741301and S817105belong to the genus ofMersorhizobium,which are from Yunnan province.2isolates respectively belong to thebranch of Phyllobacterium and Ochrobactrum. Strains S741101in the branch ofBradyrhizobium is from Yunnan province.In the group of β-Rhizobia,4stains belong to thegenus of Burkholeria,which are fromYunnan and Hainan province. Belonged to the genus ofCupriavidus,5test strains isolated from Yunnan province.In the inoculation test, the strain S322101belonged to the genus of Burkholderia nodulewith the plant of Mimosa spp., while the other strains is not nodulation among the32isolatesselected. During the process of nodulation, the plant of Mimosa spp. are prefer to selectβ-Rhizobia and rare to nodule with α-Rhizobia. In order to find the reason why β-Rhizobia are not nodulation with the plant of Mimaso spp. in this study, we test the nodulation gene ofβ-Rhizobia. The results show that there is not existing in the strains besides the strainS322101.Thus, β-Rhizobia are not nodulation maybe due to the losing of the gene nodA.The content of the effective Phosphorus,the total Nitrogen, fast-effective Potassium andmoister were measured by the methods of Bray and so on.The results say that the content ofmoister is the most important factor for the distribution of the rhizobia during the four soilfactors, whose influence power is41.9％,the second factor is the content of the totalNitrogen,which possess the persents of the influence power is21.6％,the persents of theinfluence power about the effective Phosphorus is0.4％,which is the least important factoramong the four factor detected in this environment. In addition, researching the relationshipbetween the content of soil factors of rhizobia existing districts and the distribution ofrhizobia species belonged to different genus of Cupriavidus, Burkholderia, Sinorhizobium andRhizobium, which demonstrateds that the soil existing different genus of rhizobia containdifferent contant of soil factors.During the4different genus of Rhizobium, the content ofmoister, the effective Phosphorus and the total Nitrogen are the highest in the soil distributingthe rhizobia belong to the genus of Burkholderia, while the content of fast-effectivePotassium in that soil is lower than the soil distributing the rhizobia belong to the genus ofCupriavidus;In the soil exiting the rhizobia belong to the geuns of Cupriavidus,the contantof the factors of fast-effective Potassium and moister are the highest,but the contant of thefactor of the effective Phosphorus is the least; In the soil exiting the rhizobia pertain to thegeuns of Sinorhizobium,the content of the factors of moister and the total Nitrogen are theleast.During the soil of rhzobia belong to the genus of Rhizobium,the content of the factors ofthe effective Phosphorus is least.