Phenotypic and Genotypic Diversity of Rhizobia Nodulating Faba Bean from Various Egyptian Locations

Abstract

Thirteen Rhizobial isolates from root nodules of Faba beans (Vicia faba L.) were obtained from eleven governorates, representing different agro-ecological, agro-climatic and soil conditions in Egypt. A polyphasic approach, including phenotypic and genotypic techniques were used to study their diversity. Rhizobium isolates were examined for their ability to tolerate salt stress and antibiotic resistance. We used four NaCl concentrations ranging from 0.1%, 1%, 3% and 5% in liquid media and plates, moreover we used 24 different antibiotic disks to determine resistance or sensitive among the tested isolates on plates. The obtained results after salt tolerance and antibiotic response of the R. leguminosarium strains showed that the isolate No. RL9 was the superior strain for salt tolerance . The following strains for salt tolerance were the isolates (RL4) and (RL12), although the isolate No. RL11 was the superior strain for antibiotic resistant then isolates No. RL 13 and Rh3. Growth of all isolates were inhibited above 3% NaCl except five isolates RL4, RL9, RL10, RL12 and RL 13. Also the antibiotic resistance of the isolated strains showed a high level of resistance against Cefoxitin (FOX30) and Cefuroxime (Cxm30). The genetic diversity was studied using RAPD-PCR technique and we used specific primer (nodC) amplification. In this study we found that OPE15 and OPG04 primers showed the highest polymorphism level among the tested isolates, however OPJ20 and OPC06 primers showed the lowest polymorphism level.