Question

What would happen if you forget to add cytokinin to the culture medium?
A) Callus will not develop shoot buds
B) Callus will not develop root buds
C) Callus will stop differentiating
D) Both A and B

Answer 1

Hint: Cytokinin is a very important plant growth hormone. It is widely used in plant tissue culture in the media where the callus is grown. It promotes mitosis thus, inducing cell division.

Complete answer: Formation of callus in the process of tissue culture:
In the callus culture, a media is prepared and the explant is placed in the media, where the cells divide rapidly in the media. Within 7-10 days, the callus is formed. The callus is the undifferentiated mass of cells. As the callus grows, it starts absorbing nutrients from the media. Due to this reason, subculturing is done. After this, the callus is subjected to the cytokinin media. This accelerates the process of shoot formation. The callus is subjected to the auxin media as well. This accelerates the growth of roots in the callus. The callus develops shoot in the presence of the cytokinin because it is a plant hormone that plays an important role in the cell division mechanism. It helps in organ differentiation (shoot, stems, and leaves). Thus, if we forget to add cytokinin to the culture medium, then the callus will not develop shoot buds.
Hence, the correct answer is option A.

Note: Cytokinin is also known as kinetin. It was discovered by Skoog when he was working on the tobacco pith culture. Later on, Miller isolated it from the DNA of the Herring sperm cells. The first natural cytokinin was obtained from Zea mays known as the zeatin.