Screening Of Dominant Rhizobia Strains In Aluminum-Tolerance And Aluminum-Sensitive Soybeans And Studying Their Influence Upon Rhizosphere Bacterial Community

Acid red soil is a typical soil type in South China.It has a pH value of acidity and the aluminum in it has serious toxicity,which is one of the important factors limiting the growth and yield of soybean.Soybeans are not only important food,oil,feed and energy crops,but also have an important role in improving the environment of harsh soil.As an important group of nitrogen-fixing bacteria in leguminous plants,rhizobia is of great value for research.Therefore,it is very important to select the superior aluminum tolerance rhizobia and to study the differences of rhizosphere microbial community in different soybeans under the condition of acid red soil.This study used typical acid soil in South China as growth medium,with two soybean genotypes BX10(aluminum tolerance type)and BD2(sensitive type)as the materials,which have different tolerances to aluminum toxicity.The rhizobia of effective nodμLation was screened from the nodμLes of two genotype soybean varieties.We identified them belonging to the genus Rhizobium by nodμLation test and 16S rDNA amplification,and performed the experiment of aluminum stress to obtain aluminum resistant strains R.T-1,which can grow well in the aluminum concentration of 250μmol/L.After the strain R.T-1 was physiologically characterized and its related indicators of quorum sensing were measured,we found that its quorum-sensing was very distinct.R.T-1 will provide the basis for the follow-up study on mechanism of aluminum tolerance and increasing the yield of soybean under acid-aluminum stress.Rhizosphere is the most important part for the interaction for material,energy and information exchange between plant roots and soil microbes.This study chose two soybean genotypes BX10(aluminum tolerance type)and BD2(sensitive type)as the materials,planted the soybean in acid soils by the rhizobox,and collected soil samples of different parts and roots,the total DNA of the microorganisms in the above samples was extracted.The V4 region of the 16S rDNA was analyzed by ILLUMINA MISEQ platform.The results of PCA analysis showed that there were some differences in the BX10 and BD2 between two-sides rhizosphere soils,rhizosphere soils and eluted rhizosphere soils.The soils of each part were annotated and analyzed from the phylum,the class,the order,the family,the genus and the species,the main dominant bacteria in the soils were Proteobacteria,Actinobacteria,Firmicutes,Bacteroidetes,Verrucomicrobia.In the BX10 rhizosphere soil,the relative abundunce of Janthinobacterium and Burkholderia were higher,the Burkholderia strain is important for promoting the growth of plants,Janthinobacterium has a strong acid resistance,it is inferred that the bacteria in the improved acid soil may have a certain role.It also lays a good foundation for the selection of rhizosphere microorganisms in different genotype soybeans.