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
