SEROLOGICAL GROUPING OF INDIGENOUS-BRADYRHIZOBIUM SP (ARACHIS) ISOLATED FROM VARIOUS SOILS OF THAILAND

ELISA and antibody adsorption tests were applied to determine the mini mal somatic antigen constitution of 243 strains of Bradyrhizobium sp. (Arachis) using 12 antisera. The 243 indigenous bradyrhizobial isolate s were from 15 sites in four regions of Thailand. A total of 29 serogr oups were identified. Most (80%) of the isolates tested had at least o ne heat-stable antigen in common with strain 280A, forming a so-called 280A serocluster. At 11 of 15 sites tested, 53 to 100% of the isolate s fell into one or two predominant serogroups. The serological propert ies of the indigenous bradyrhizobia were not related to the cropping h istory of the cultivated fields from which they were isolated.