Genetic diversity and symbiotic efficiency of Rhizobium leguminosarum nodulating faba bean (Vicia faba)

We performed this search on Rhizobium leguminosarum bacteria that fix nitrogen symbiotically with faba bean. We selected twenty-five isolates from different locations in menofia governorate. we characterized the selected isolates, morphologically, biochemically, and molecularly to detect their diversity and symbiotic effectiveness. Moreover, we planted faba bean in pots experiment and inoculated them with all isolates in three replicates each. We measured plant fresh and dry weigh, nodules fresh and dry weigh. Moreover, measured total nitrogen content to detect their symbiotic efficiency. Least symbiotic efficiency appeared in isolates numbers RL 9(87.95), RL15(84.77), RL13(73.98) and RL12 (78.46). Highest symbiotic efficiency appeared in isolate numbers RL21(169.3), RL23(138.72) and RL25 (132.85). Morphological characterization of all isolates is motile, negative to gram stain and positive to fucshin stain. Biochemical characterization for all isolates came to be tolerate NaCl at various concentration (0, 0.5, 1, 2 and 4%) and able to grow over a wide range of pH (4-9). Isolates are able to utilize various sugars (Glucose, Fructose, Sucrose, Lactose, Sorbitol, Mannose, and Maltose) as sole carbon sources. All tested isolates are acid producers. Moreover, they are able to hydrolyse starch but not able to hydrolyse urea exept isolates (RL4 and RL16). Rhizobium leguminosarum isolates came to be either tolerant to tested antibiotics. Biodiversity of tested Rhizobium leguminosarum isolates were detected by using rep-PCR marker technique. The highest polymorphism among R. leguminosarum isolates was revealed by BOX-A1 primer (88.3%), followed by that revealed by ScoT-12 primer (87.5%). However, the lowest polymorphism was 68.75% resulted from application of rep-16 primer.16s rRNA sequence used to study genetic diversity between isolates. NifH amplification in 25 tested Rhizobium leguminosarum isolates showed the same molecular weight which came to be 336bps