Rhizobiums is one of the most important bacteria in the soil. The symbiotic intraction between the rhizobia and leguminous plants is a highly sophisticated process with exchange of biochemical signals between two partners which leads to molecular nitrogen fixation. Genetic characterization of symbiotic rhizobium and its compatibility with the host legume is the most important factor to determinant the nodulation competitiveness of different strains, therefore, identification of genetic diversity among the different rhizobia in the soils, the frequency of strains and detection of compatible strains with different host species is very important. Sainfoin due to desirable features such as high nutritional value, lack of bloat in cattle, maintain soil fertility, resistance to drought, salinity, cold and pests such as Hypera postica was cultivation especially is regions where there is no possibility of alfalfa and clover cultivation. The symbiont sainfoin rhizobiums have shown a high heterogeneity and the relationships between symbiotic rhizobium strains with host species related to geographic region is unknown. The West of Isfahan province (Friedan and Fereydoonshahr) and neighboring regions of Lorestan province (Azna and Aligudarz) are important areas of sainfoin cultivation and it is essential to identify symbiotic rhizobium species nodulating sainfoin in these regions. Therefore, in this study, Keywords: Rhizobium , molecular ltr"
