Lermontova, Irkutsk, 664033 Russia Acknowledgements: Authors are thankful to SIPPB SB RAS employees L.E. Makarova for her help in organizing the expedition to the Chivyrkuy Gulf Coast and A.A. Kiseleva for plant identification. <...> Supported in part by Russian Science Foundation (Agreement number 14-26-00094) (sequencing of the isolates from ) A b s t r a c t Rhizobia are Gram-negative soil microorganisms that form intracellular nitrogen-fixing symbiosis with leguminous plants. <...> Investigations of symbiotic systems with the participation of endemic or relict species have a particular importance for understanding of the evolution of plantmicrobe interactions. <...> The purpose of our work was to create a representative collection of microsymbionts of endemic Baikal legumes, as well as to estimate their biodiversity. <...> The study of taxonomic positions of 69 isolates from root nodules and , was conducted. <...> For primary identification of these isolates the methods of ITS-RFLP analysis was used that divided strains into 33 groups with identical DNAprofile. <...> Then the taxonomy positions of isolates were determined by the 16S rRNA gene ( and ITS region sequencing. <...> Phylogenetic analysis revealed the considerable genetic diversity among microsymbionts of plants studied. <...> Rhizobial isolates belonged to 5 genera: ), and (family and (family ), and ). <...> In addition, non-rhizobial isolates belonging to the genera , were obtained. <...> It is known that some species of these genera may be present in the nodules of legumes, but also be inhabitants of rhizosphere or phyllosphere of different plants. <...> The presence of atypical rhizobial microsymbionts in the studied plants was noted, which may indicate the active formation of relationships between partners in the legumerhizobial systems of Baikal region. <...> Keywords: legumes of Baikal region, taxonomy of rhizobia, ribosomal genes sequencing. <...> Nodule bacteria ( ) belong to a large genetically diverse group of Gram-negative soil microorganisms that form intracellular nitrogen-fixing symbiosis with legumes. <...> Investigations of symbiotic systems with the participation of endemic or relict species have a particular importance for understanding of the evolution of plant-microbe interactions. <...> These unique objects include Baikal legumes, such as low-growing vetchling ( ), a Late Pleistocene relict of the South Siberian-Severouralsk area [2]; Mongolian milk vetch ( ), a rare medicinal plant [3, 4]; Baikal endemics Baikal pea ( ) and forest oxytrope ( Few data on ) [5] these microorganisms belonging to different <...>