Question

The breakdown product of DNA (capable of inducing cell division) which was later identified as cytokinin is

• A. trans-Zeatin
• B. Kinetin
• C. Benzyladenine
• D. Thidiazuron

Hint:

"Kinetin" was discovered by autoclaving herring sperm DNA. Its name is derived from "cytokinesis," representing its ability to promote cell division in plant tissues. It is a synthetic purine-type cytokinin.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The discovery of cytokinins was closely tied to search for compounds that could stimulate cell division (mitosis) in plant tissue cultures.

Step 2: Detailed Explanation:
In 1955, Carlos Miller and Folke Skoog isolated a highly active cell-division-promoting substance from autoclaved herring sperm DNA.
This active compound (6-furfurylaminopurine) was a degradation product of DNA formed when the deoxyribose sugar and adenine base reacted under heat and pressure.
They named this newly identified compound Kinetin because of its ability to induce cytokinesis (cell division) in tobacco pith tissue.
Kinetin was the first identified member of the plant hormone class now known as Cytokinins.
Later, trans-Zeatin (A) was isolated from maize endosperm as the first naturally occurring plant cytokinin, while Benzyladenine (C) and Thidiazuron (D) are synthetic cytokinins used in tissue culture.

Step 3: Final Answer:
The DNA breakdown product that was identified as the first cytokinin is Kinetin, which corresponds to option (B).