Interaction between faba bean cultivars and the Rhizobium leguminosarum strains: Symbiotic N2 fixation and protein profiles under salt stress

Abstract

The efficiency of eight Rhizobium leguminosarum strains isolated from root nodules of Faba bean plants which were collected from different Governorate in Egypt has been examined. After inoculation of faba bean seeds with each Rhizobium strain individually, we measured the growth promotion, nodule formation and plant protein profile under different concentration of sodium chloride salt stress. The interactions between salt tolerant and sensitive faba bean cultivars and Rhizobium strains under NaCl stress were found to be significant. Nitrogen fixation efficiency varied among the eight Rhizobium strains. The protein profile using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for both faba bean cultivars revealed that Rhizobium strains numbers RL1, 2, 4 and RL 8 showed high level of salt tolerance under 40 and 80 mM NaCl in both faba bean cultivars. Rhizobium strains improved the salt tolerance, as is clearly observed in number of nodules and the amount of N 2 fixation. It is known that stress affects the growth, metabolic activity and symbiotic efficiency of Rhizobium with faba bean plant but in this study we found that Rhizobium strains numbers RL2 and RL 3 showed high efficiency of N 2 fixation and growth promotion in both faba bean cultivar.