Question

F. Skoog observed that callus proliferated from the internodal segments of tobacco stem when auxins was supplied with one of the following except :

• A. Extract of Vascular tissues
• B. Coconut milk
• C. Abscisic acid
• D. Yeast Extract

Answer 1

The Correct Option is C

F. Skoog was a prominent plant physiologist who conducted extensive research on the factors that encourage callus formation and plant growth. Callus is a mass of undifferentiated plant cells that forms when plant tissues are cultured in vitro, often in response to wounding. Auxins, a class of plant hormones, are crucial in initiating callus formation. However, for effective callus proliferation, auxins need to be combined with certain other substances that can act as additional growth promoters or cytokinin sources.

Let's analyze each option provided:

• Extract of Vascular Tissues: These extracts may contain naturally occurring cytokinins and other growth factors that can enhance cell division and growth, promoting callus formation.
• Coconut Milk: Known to contain cytokinins, coconut milk is a common additive in plant tissue culture as it supports cell division and differentiation.
• Yeast Extract: It provides vitamins and other nutrients that can support plant tissue culture growth, often aiding in callus formation.
• Abscisic Acid: Unlike the others, abscisic acid is a plant hormone that acts primarily as a growth inhibitor, playing roles in stress responses and dormancy rather than promoting growth or callus formation.

Thus, the substance that does not act synergistically with auxins to promote callus proliferation is Abscisic Acid. This substance is known for its role in inhibiting growth processes, which is contrary to what is needed for callus proliferation.

Therefore, the correct answer is Abscisic Acid.