Question

What are the steps involved in formation of a root nodule?

Answer 1

Nodule Formation

• Nodules are the small outgrowths on roots.

• Involves interaction between the roots of the host plant and Rhizobia that multiply and colonise the roots, attaching themselves to the root hair cells and the epidermal cells

• Root hair curls and bacteria infest there, and finally, reach the cortex, where it starts nodule formation.

• An infection thread carries the bacteria to the cortex. In the next step, the bacteria get released from the thread and invade the cortex cells.

• Specialised nitrogen-fixing cells differentiate and form the nodules.

• Nodules establish a direct vascular connection with the host for exchange of nutrients.