The successful use of Bradyrhizobium japonicum as an inoculant on soybean in dependent upon the number of effective bacteria that are present as well as the ability of the bacteria to colonize the soil and to interact with the host plant. This proposal sets out to accomplish 2 major objectives. The first is to complete the optimization of a PCR based assay (culture independent) to enable the quantification of B. japonicum in soil samples in a matter of days. The second part of this proposal initiates a program of study using this assay, with other culture independent approaches, to determine how and where B. japonicum populations develop following inoculation onto a field. It is hoped that this information will be useful in developing better commercial inoculums.
