Genetic diversity of rhizobial endophytes from nodules of <i>Oxytropis czekanowskii</i> Jurtz. Growing in Norilsk

BACKGROUND: Legumes can play a key role in the formation of highly productive pasture phytocenoses and have significant potential for introduction in the Arctic regions of the Russian Federation for the purpose of sustainable development of northern livestock farming. One of the key properties of legumes is the formation of a mutually beneficial nitrogen-fixing symbiosis with nodule bacteria (rhizobia), which facilitates the fixation of atmospheric nitrogen and provides plants with available nitrogen compounds, thereby increasing the productivity of phyto- and agrocenoses. Oxytropis czekanowskii Jurtz. is a rare subendemic species of perennial legume growing in Yakutia and Taimyr. AIM: The aim of the work was to create a collection and study the rhizobial endophytes from nodules of O. czekanowskiigrowing in Norilsk (Krasnoyarsk Territory). MATERIALS AND METHODS: Rhizobial strains were isolated from root nodules of plants by a standard technique using mannitol-yeast nutrient medium YMA after sterilization of nodules for 1 min in 96% ethanol. The taxonomic position of the isolates was studied using sequencing and phylogenetic analysis of 16S rDNA and ITS region sequences. RESULTS: A high genetic diversity of the isolates was shown, assigned to six genera and four families of the order Hyphomicrobiales: Mesorhizobium (family Phyllobacteriaceae), Neorhizobium, Pararhizobium and Agrobacterium (family Rhizobiaceae), Bosea (family Boseaceae) and Tardiphaga (family Bradyrhizobiaceae). Based on the analysis of 16S rRNA genes and the ITS region, isolates P10/4-1 and P10/5-2 were assigned to the species Neorhizobium vignae, isolates P10/1-1 and P10/5-1 to the species Pararhizobium herbae, while isolate P10/3-1 was identified as Mesorhizobium qingshengii. At the same time, the strains Bosea sp. P10/2-3, P10/1-3 and P10/4-4, which showed a low level of similarity with the closest type strain, can potentially be attributed to a new species of microorganisms. CONCLUSION: Thus, wild northern legumes are a unique source of valuable genetic resources of cold-resistant nodule and endophytic bacteria, promising for the creation of highly productive perennial pasture and hay cereal-legume phytocenoses in the extreme soil and climatic conditions of the Arctic.