What is tissue culture? Explain how new plants are obtained by this technique?

The technique of culturing tissue on a nutrient medium and aseptic condition in laboratories is called tissue culture. Tissue culture technique is widely used in raising new plants. In this technique, a small piece of tissue is cut from a plant. This tissue is placed on a nutrient medium under suitable conditions. The tissue grows into an unorganised mass called callus. In the second stage, a portion of this callus is placed in another medium, which induces differentiation in the cells of the callus. As a result plantlets are produced. These plantlets are transplanted in pots or soil and new plants are raised. This technique is successfully applied to raise new plants of orchids, chrysanthemum, asparagus and other plants.

Tissue culture;
(A) A piece of tissue placed on a nutritive medium.
(B) Tissue grows into a callus.
(C) A piece of callus grown on another medium where cell differentiation occurs.
(D) Plantlets develop from the piece of callus.