Abstract
A study of the diversity of endophytic diazotrophs in sweet potato (Ipomoea batatas L.) revealed the presence of bradyrhizobia within the stems and storage roots. The strain AT1, Bradyrhizobium spp. isolated from sweet potato, showed no ability to form root nodules in soybean, azuki bean, cowpea, groundnuts, lupinus and Aeschynomene indica. On the other hand, colonization of inoculated AT1, evaluated by the PCR targeted to nifH genes, was detected in soybean stems. Colonization in the stems after inoculation of AT1 to the roots was also detected in rice, maize and sunflower. These results suggest that bradyrhizobia isolated from sweet potatoes possess the ability for colonizing in the wide range of plant species. Inoculation of bradyrhizobia, MAFF210318 having nifH sequence highly similar to that expressed in the sweet potatoes, improved the chlorophyll contents in the leaves of sweet potatoes, suggesting the endophytic nitrogen fixation by infected bradyrhizobia.
