A collection of rhizobial strains isolated from root nodules of the narrowly endemic legume species Oxytropis erecta, O. anadyrensis, O. kamtschatica, and O. pumilio originating from the Kamchatka Peninsula (Russian Federation) was obtained. Analysis of the 16S ribosomal RNA gene sequence showed a significant diversity of isolates belonging to families Rhizobiaceae (genus Rhizobium), Phyllobacteriaceae (genera Mesorhizobium, Phyllobacterium), and Bradyrhizobiaceae (genera Bosea, Tardiphaga). A plant nodulation assay showed that only strains belonging to genus Mesorhizobium could form nitrogen-fixing nodules on Oxytropis plants. The strains M. loti 582 and M. huakuii 583, in addition to symbiotic clusters, possessed genes of the type III and type VI secretion systems (T3SS and T6SS, respectively), which can influence the host specificity of strains. These strains formed nodules of two types (elongated and rounded) on O. kamtschatica roots. We suggest this phenomenon may result from Nod factor–dependent and –independent nodulation strategies. The obtained strains are of interest for further study of the T3SS and T6SS gene function and their role in the development of rhizobium-legume symbiosis. The prospects of using rhizobia having both gene systems related to symbiotic and nonsymbiotic nodulation strategies to enhance the efficiency of plant-microbe interactions by expanding the host specificity and increasing nodulation efficiency are discussed.

从狭义特有豆科植物根瘤中分离根瘤菌的集合棘万寿菊，O. anadyrensis，O. kamtschatica，和O. pumilio获得从堪察加半岛（俄罗斯联邦）始发。在16S核糖体RNA基因序列分析表明属于家庭分离的显著多样性根瘤菌（属根瘤菌），Phyllobacteriaceae（属慢生根瘤菌，Phyllobacterium）和慢生根瘤菌科（属氧化包西氏，Tardiphaga）。一种植物结瘤试验表明，只有菌株属于属中慢生根瘤菌可以形成上固氮根瘤棘植物。菌株M.洛蒂582和M. huakuii 583，除了共生簇，III型所具有的基因和VI型分泌系统（T3SS和T6SS，分别地），这可以影响菌株的宿主特异性。这些菌株在O. kamtschatica上形成两种类型的结节（伸长的和圆形的）根。我们认为，这种现象可能是由依赖于Nod因子和独立于Nod因子的根瘤策略引起的。获得的菌株对于进一步研究T3SS和T6SS基因的功能及其在根瘤菌-豆科植物共生发展中的作用具有重要意义。讨论了使用具有与共生和非共生结瘤策略相关的基因系统的根瘤菌通过扩大宿主特异性和增加结瘤效率来提高植物-微生物相互作用效率的前景。