Question

Which of the following hormone is preferred for rooting in plant tissue culture?
(A). IAA
(B). BAP
(C). Kinetin
Choose the correct answer from the options given below:

• A. (A) only.
• B. (B) only.
• C. (C) only.
• D. (A), (B) and (C).

Hint:

Keep the hormone balance simple: Auxin (IAA, IBA, NAA) = Rooting; Cytokinin (BAP, Kinetin, Zeatin) = Shooting.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Plant organogenesis in tissue culture is controlled by the ratio of auxins to cytokinins in the growth medium.
This principle was established by Folke Skoog and Carlos Miller, who demonstrated that a high auxin-to-cytokinin ratio promotes root development (rhizogenesis), while a high cytokinin-to-auxin ratio promotes shoot development (caulogenesis).

Step 2: Detailed Explanation:
Let us evaluate each of the given hormones:
- IAA (Indole-3-acetic acid): This is a naturally occurring auxin.
Auxins stimulate cell division, elongation, and adventitious root initiation in cultured tissues.
Therefore, auxins like IAA, IBA, and NAA are added to the culture medium to induce rooting.
- BAP (6-Benzylaminopurine): This is a synthetic cytokinin.
Cytokinins promote cell division and shoot bud differentiation.
They are used to induce shoot development, not root development.
- Kinetin: This is another cytokinin that promotes shoot organogenesis.
Because rooting specifically requires an auxin-dominated environment, only the auxin IAA (A) is preferred for inducing root growth in tissue culture.

Step 3: Final Answer:
Hence, the correct option is (A).