Question

Explain the steps involved in the formation of root nodule.

Answer 1

There are many different type of reactions and interactions occur during the formation of root nodules. The Rhizobium is a soil bacterium which is known to have symbiotic association with the legume plants. There are formation of nodules in the roots of this plant by the bacterium. The bacterium penetrates the cells of the root, divide in the cortical cells and the form the colonies.

The bacteria first gets attached to the root hairs and then enter the epidermal cells. The root hairs are invaded by the bacteria. The bacteria then moves into the cortex of the root. The bacteria get transformed into rod-shaped cells which are known as the bacteroides. The cells in the cortex undergo division, leading to the formation of root nodules. The nodules finally get connected with the vascular tissues of the roots for the purpose of nutrient exchange.