Read the passage given below and answer the following question. As traditional breeding techniques failed to keep pace with demand and to provide sufficiently fast and efficient systems for crop improvement, another technology called tissue culture got developed. It was learnt by scientists, during 1950s, that whole plants could be regenerated from any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media. It is important to stress here that the nutrient medium must provide a carbon source such as sucrose and also inorganic salts, vitamins, amino acids and growth regulators like auxins, cytokinins etc. By application of these methods it is possible to achieve propagation of a large number of plants in very short durations. Many important food plants like tomato, banana, apple, etc., have been produced on commercial scale using this method. Another important application of the method is the recovery of healthy plants from diseased plants. Even if the plant is infected with a virus, the meristem is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc. Scientists have even isolated single cells from plants and after digesting their cell walls have been able to isolate naked protoplasts. Isolated protoplasts from two different varieties of plants – each having a desirable character – can be fused to get hybrid protoplasts, which can be further grown to form a new plant.

What is protoplast?

Plant cell with wall Animal cell with wall Plant cell without cell wall Animal cell without wall

Plant cell without cell wall

Protoplasts are isolated cells produced by removing the surrounding cell wall either by mechanical means or by the use of cell wall degrading enzymes. Removal of the cell wall leaves the protoplast surrounded by the plasmalemma membrane.