[A sinorhizobium fredll strain that effectively nodulate Medicago sativa]

Sinorhizobium fredii 042BS was isolated from root nodules of alfalfa (Medicago sativa) from Xinjiang Region. Nodulation experiments showed that both soybean and alfalfa were nodulated by 042BS effectively. The 16S rDNA PCR-RFLP analysis was carried out by four restriction endonucleases, and the restriction maps of strain 042BS were identical with those of S. fredii USDA205. The DNA G + C mol% of strain 042BS was 60.0. The DNA homology between 042BS and S. fredii USDA205 and USDA191 were 84.9% and 89.6%, respectively. To prove the capability of 042BS to nodulate both soybean and alfalfa, constitutively expressed green fluorescence protein gene(gfp) was introduced to 042BS, and the recombinant strain 042BSG was obtained. The reisolates from nodules of the soybean and alfalfa inoculated with 042BSG were observed using the confocal laser-scanning microscope, and the expressions of gfp were detected, respectively. 042BS showed various nodulation capacities with different alfalfa cultivars used.