The formation of root nodules in plants takes place through many steps. In details, the Rhizobium bacteria form colonies and attached to the root hairs and epidermal cells. Eventually, these root hairs become curled due to bacterial invasion. Thus, leads to an infection into cortex of the root by bacteria. As a result, cortex and pericycle cells undergo division which leads to the formation of root nodules.

Soyabean is a legume associated symbiotically with Rhizobium. Rhizobium requires symbiotic association with the root nodules of legumes to fix nitrogen, others can fix nitrogen independently.