Question

The hormonal theory of balanced growth and regulation was proposed by

• A. Murashige and Skoog
• B. Skoog and Miller
• C. Philips and Gamborg
• D. White

Hint:

Remember:
Auxin = Rooting.
Cytokinin = Shooting.
The balance determines the fate of the tissue. This is the "Golden Rule" of the plant tissue culture lab.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question refers to a fundamental principle in plant physiology and tissue culture regarding how different ratios of hormones regulate the development of specific plant organs.
Detailed Explanation:

• The Auxin-Cytokinin Ratio:
In 1957, Folke Skoog and Carlos Miller published a classic paper showing that organogenesis (the formation of roots and shoots) in tobacco pith callus is controlled by the balance between two plant growth regulators: Auxin and Cytokinin.

• The Theory of Balanced Growth:
They proposed that:
1. High Auxin to Cytokinin ratio $\rightarrow$ Promotes Root formation (Rhizogenesis).
2. High Cytokinin to Auxin ratio $\rightarrow$ Promotes Shoot formation (Caulogenesis).
3. Equal/Intermediate ratios $\rightarrow$ Promotes unorganized Callus growth.

• Impact:
This discovery provided a logical framework for regenerating whole plants from single cells or tissue explants, making it a cornerstone of modern plant biotechnology.

• Analyzing other options:
Murashige and Skoog: Known for the MS medium, but the hormonal balance theory was specifically Skoog and Miller's work.
Gamborg: Known for the B5 medium.

Step 2: Final Answer:
The hormonal theory of balanced growth (organogenesis) was proposed by Skoog and Miller.