Morphology of Vavilovia formosa (Steven) Fed. Nodules Induced by Different Rhizobia Strains

The study of wild relatives of crop legumes offers an inexhaustible source of useful properties and microorganisms for agriculture. In this study, we morphologically examined vavilovia (Vavilovia formosa (Steven) Fed.) nodules induced by strains of Rhizobium ruizarguesonis RCAM1026, Rhizobium leguminosarum sv. viciae TOM, as well as R. leguminosarum sv. viciae strains Vaf-12 and Vaf-108, isolated from nodules of wild-type plants of V. formosa. The nodules induced by R. leguminosarum sv. viciae strain Vaf-12 maintained histological and ultrastructural organization typical for indeterminate nodules. Different ultrastructural abnormalities were revealed in nodules induced by the other strains. When using the R. leguminosarum sv. viciae strain Vaf-108, pinkish nodules formed, in which a senescence zone developed in four weeks after inoculation. Furthermore, small brownish pseudonodules were also formed. In the nodules induced by the R. leguminosarum sv. viciae strain TOM bacteroids rapidly degraded and were excluded from the cytoplasm into the vacuole. Nodules induced by the R. ruizarguesonis strain 1026 were characterized with excessive accumulation of starch grains in mature infected cells.