Ques. 1AIPMT 2003
Differentiation of shoot is controlled by
- high auxin : cytokinin ratio
- high cytokinin : auxin ratio
- high gibberellin : auxin ratio
- high gibberellin : cytokinin ratio.
Answer
(2) high cytokinin : auxin ratio
Solution
In tissue culture (Skoog and Miller), the auxin : cytokinin ratio decides organ formation from callus: a high auxin : cytokinin ratio leads to root differentiation, while a high cytokinin : auxin ratio leads to shoot differentiation.
As per NCERT, cytokinins help to produce new leaves and promote adventitious shoot formation.
∴ Shoot differentiation is controlled by a high cytokinin : auxin ratio.
Answer: (2)