Preparation of fluorescent labeled nodule bacteria strains of wild legumes for their detection in vivo and in vitro

A series of expression vectors containing TurboGFP and TurboRFP genes of fluorescent proteins under the control of the T5 phage constitutive promoter was created for a vital staining of nodule bacteria. These vectors were either obtained using the broad host range pBBRI replicon for labeling of strains, where a marker gene was expressed from a transformed plasmid, or they were prepared using the pRL765 gfp plasmid for labeling of strains via the introduction of genes of fluorescent proteins into the bacterial chromosome. Transformation was shown to be the most convenient method of transfer of constructions into cells of nodule bacteria, as there exists the possibility of spontaneous plasmid mobilization and, consequently, its transition from cells of labeled strains into other soil bacteria if the mob locus is present in vectors needed for conjugation. Fluorescent labeled strains of Rhizobium sp., Mesorhizobium sp., Ensifer (Sinorhizobium) sp., Bradyrhizobium sp., Phyllobacterium sp., and Agrobacterium sp. were prepared using the obtained vector constructions. The suitability of the obtained strains for both in vivo and in vitro experiments was demonstrated.