Question

You are given a tissue with its potential for differentiation in an artificial culture. Which of the following pairs of hormones would you add to the medium to secure shoots as well as roots ?

• A. IAA and gibberellin
• B. Auxin and cytokinin
• C. Auxin and abscisic acid
• D. Gibberellin and abscisic acid

Answer 1

The Correct Option is B

In plant tissue culture, the differentiation of roots and shoots from undifferentiated cells (callus) is regulated by the ratio of two key plant hormones:

• Auxins (like IAA, NAA) promote root formation.
• Cytokinins (like kinetin, BAP) promote shoot formation. 

By adjusting the auxin to cytokinin ratio in the medium:

• High auxin and low cytokinin favors root development.
• High cytokinin and low auxin favors shoot development.
• Balanced ratio may lead to callus formation or development of both organs.

Therefore, to induce both shoots and roots, a combination of auxin and cytokinin is used.