Background: The possibility of changing the properties of rhizobial bacteria by giving them the ability to regulate the expression of additionally introduced genes into them is an urgent task both for fundamental science and for applied agrobiology, since this will make it possible to obtain microsymbionts with desired properties. An expression construct using the rhizobia regulatory system was created in this work. The rhizobia nodD gene encodes a regulatory protein that, in the presence of plant inducers, flavonoids, activates the transcription of nod-genes involved in the early stages of the formation of legume-rhizobium symbiosis. Materials and methods: A vector construct containing the nodD gene from Rhizobium leguminosarum bv. trifoli under the regulation of its own promoter and the gfp gene under the regulation of the nodA gene promoter from the same rhizobia was obtained. Neorhizobium galegae CIAM 0702 were transformed with the vector construct. Results: It has been shown that in recombinant strains synthetic flavonoids are capable of inducing expression of gfp gene to varying degrees. Conclusion: In the future, the results can be used to obtain rhizosphere microorganisms with a controlled synthesis of growth-stimulating and protective substances.

Background An analysis of the spatial distribution of some taxonomically and ecologically related legumes in the Ural showed a nontrivial spatial distribution of related species of the genus Oxytropis DC of the Orobia Bunge section within the Uchalinsky uplands. Despite the similarities in ecology, these species practically do not grow together. Explicit spatial segregation of closely related plants over a relatively small area allows this phenomenon to be used as a convenient model for studying the effect of segregation of closely related legume species on the genetic composition of their nodule bacteria. Materials and methods The genetic diversity of nodule bacteria entering into symbiosis with O. kungurensis, O. baschkiriensis, O. approximata and O. gmelinii plants was studied. In addition, the polymorphism of their symbiotic genes has also been analyzed. Results Phylogenetic characteristics of nodule bacteria endemic for the Southern Ural belonging to 4 species of leguminous plants of the genus Oxytropis of the section Orobia: O. kungurensis, O. baschkiriensis, O. approximata, O. gmelinii which are characterized by spatial separation of the growth sites, also called plant segregation, are given. It was shown that all of them belong to the genus Mesorhizobium despite certain phylogenetic differences of bacteria. Analysis of the symbiotic genes of the analyzed strains revealed a lack of congruence of their phylogeny with the core part of the genome. It was found that the microsymbionts of O. baschkiriensis plants differ in the phylogeny of nod-genes from nodule bacteria of other plants of the Oxytropis genus and are close to microsymbionts of plants of the Lupinaster genus growing in the Southern Urals. Conclusion Acquisition of the property to enter into symbiosis with nodule bacteria of plants of the genus Lupinaster may turn out to be an adaptive mechanism that arose as a result of segregation of O. baschkiriensis from other species of Oxytropis