This paper concerns studies on rhizobia in Symbiosis with important legume soybean and peanut crops in China, following: 1) Summarized bio-diversity of rhizobia, including indigeneous population, isolation frequency, strain type, distribution, and strain-host promiscuity and compatibility from large and small samples. 2) Reviewed symbiont improvement in both sides of rhizobia and hosts, involving selection of effective rhizobial strains, evoluation and utilization of the host germplasm for symbiotic proper...