Molecular Identification of Rhizobium Isolates Nodulating Faba Bean Plants in Egyptian Soils

Abstract

Eleven isolates of Rhizobium leguminosarum symbiovar. Viciae were isolated from root nodules of Vicia faba L. cultivated in 11 fields and represent different governorates in Egypt. The genetic diversity among the isolates was studied using the 16S rRNA gene partial sequence. The phylogenetic analysis formed two groups of isolates and the values of genetic distances were variable among the studied isolates. The highest value of genetic distance was between the isolates RL6 of North Sinai and RL8 of Dakhalia, while the lowest value was between isolates RL9 of Giza and RL10 of Sharkia. The isolates were evaluated for their tolerance to heavy metals using concentrations of 0.5, 1 and 2 mM of heavy metals (Cu, Pb and Zn). The ability to resist the heavy metals decreased with increase in concentration. At the highest concentration (2 mM), No growth was obtained with addition of Zn and Mn to the growth media, however only 27% of isolates could survive with the same concentration of Pb.