Improvement of common bean (Phaseolus vulgaris) nodulation by selected rhizobial strain from Egyptian soils through genotypic characterization, symbiotic effectiveness and competitiveness under salt stress conditions

To maximize the symbiotic nitrogen fixation of common bean (Phaseolus vulgaris) under egyptian soil conditions, twelve rhizobial isolates were isolated from root nodulated common bean. These isolates were physiologiacl characterized to test the more effeicient strains in nitrogen fixation, to select strains more adapted to environmetal stresses such as salinity, alkalinity, temperature. The adapted strains were selected to study the competitiveness of these strains against the standard strain CIAT 899 marked with gus gene under normal conditions, stress of salinity and stress of alkalinity. These strains were also characterized using molecular biology techniques such as REP-PCR, ARDRA of 16S and 23S rDNA, plasmid profiles analysis, sequencing of full length of 16S rDNA, hybridization with nifH gene and amplification of nodC gene. Strain EBRI 26 and Sinorhizobium meliloti strain 2010 were selected as salt tolerant strains to study the proteins involeved in salt tolerance by 2D proteom analysis and MALDI-Tof mass spectrometry