| Symbiotic nodulation of leguminous plants by rhizobia has been a focus of interest for many years. This interest is mainly due to a unique communication circuitry between a rhizobium species and its host plant that is required for successful nodulation. This work was initiated to further understand the intricate communication involved in compatible rhizobium-host legume symbioses. Previous work identified a unique molecule, bradyoxetin, in Bradyrhizobium japonicum that was shown to play a role in the regulation of the bacterial genes involved in nodulation. From this study, we hypothesized that this type of molecule may also have a role in nodulation by other species of rhizobium. The rhizobia Sinorhizobium meliloti and Mesorhizobium loti were used in testing this hypothesis. Through early work done with nodulation genetics, it was found that an extract made from soybean seedlings was able to repress the nodulation genes similar to what was seen with the feedback inhibition by the bacterial derived Nodulation factor. This was surprising due to the fact that the Nodulation factor is a lipochito-oligosaccaride molecule and no such molecule has ever been found in plants. Therefore, we attempted to isolate and characterize the plant compound responsible for the observed activity in rhizobia. |
