Abstract
In legumes, the number of nodules is controlled by a feed back system, called autoregulation. However, the postulated regulation signaling compound has not been identified. In this study, we examined the effect of brassinolide (BL) and BL synthesis inhibitor, brassinazole by application on the leaves or roots of soybean wild type (Enrei) and super-nodulating mutant (En6500) to know whether BL has any systemic effect on nodule regulation.
The foliar application of BL at 1day after rhizobia inoculation reduced nodule number of super-nodulating mutants while not reduced in wild type Enrei. The injection of BL on the root bases also retarded nodulation in En6500 but not in Enrei. On the other side, application of brassinazole to the leaves of Enrei or into their culture media increased the nodule numbers compared to the untreated plants. These data indicated that BL may control the nodule formation systemically in soybean plant.
