Genetic Diversity of Microsymbionts of Legumes Lathyrus pratensis L., Vicia cracca L., Trifolium repens L., and Astragalus schelichowii Turcz. Growing Near Norilsk in Arctic Russia

The paper studies the genetic diversity of microorganisms isolated from root nodules of wild populations of the legumes Lathyrus pratensis L., Vicia cracca L., Trifolium repens L., and Astragalus schelichowii Turcz. collected near Norilsk (Arctic Russia). The taxonomic position of the 19 isolates obtained was determined by sequencing the 16S rRNA gene (rrs). The isolates were assigned to four genera of the order Hyphomicrobiales: Rhizobium, Pararhizobium, Bosea and Tardiphaga. Nine fast-growing isolates belonged to the genera Rhizobium and Pararhizobium. ITS region sequencing clarified the species identity of 6 rhizobial isolates. Isolates from V. cracca nodules were identified as Pararhizobium sp., P. herbae. Microsymbionts from T. repens were assigned to Rhizobium sp. and to the species R. beringeri, while isolates from L. pratensis were identified as P. herbae and R. beringeri. Symbiotic nodA and nodC genes were found in the Rhizobium strains P8/5-2, P9/1-1 and P9/3-2 from L. pratensis and T. repens nodules, nodA gene was detected in the Pararhizobium strains P7/3-1, P7/4-1, P7/5-1 from V. cracca nodules. Nine out of ten slow-growing isolates were assigned to the genus Bosea. Three isolates from the nodules of V. cracca were assigned to the species B. psychrotolerans. Six isolates from the nodules of A. schelichowii were identified as B. vaviloviae, B. lathyri and Bosea sp. The strain P22/3-5 isolated from the nodule of A. schelichowii was identified as Tardiphaga robiniae. Simultaneous presence of strains belonging to different genera of the order Hyphomicrobiales was detected in the nodules of V. cracca and A. schelichowii.