Question

In plant tissue culture higher concentration of cytokinin generally promotes-

• A. Root regeneration
• B. Shoot regeneration
• C. Leaf primordia
• D. Flower initiation

Hint:

Memorize the "hormone ratio rule": High {C}ytokinin \(\rightarrow\) {S}hoots ({C}ytokinin for {C}aulogenesis) High {A}uxin \(\rightarrow\) {R}oots ({A}uxin for {R}hizogenesis)

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Plant organogenesis (the formation of organs) in tissue culture is primarily controlled by the balance of two key classes of plant hormones: auxins and cytokinins. The question asks about the effect of a high concentration of cytokinin.
Step 2: Detailed Explanation:
The ratio of auxin to cytokinin in the culture medium is a critical determinant of cellular differentiation:
High cytokinin to auxin ratio: This condition generally stimulates cell division and promotes the differentiation of shoots from a callus or explant. This process is called caulogenesis.
High auxin to cytokinin ratio: This condition typically promotes the formation and growth of roots. This process is called rhizogenesis.
Intermediate ratio: A balanced level of both hormones often leads to the proliferation of an undifferentiated mass of cells called a callus.
Therefore, a higher concentration of cytokinin is used to induce shoot regeneration.
Step 3: Final Answer:
In plant tissue culture, a higher concentration of cytokinin generally promotes shoot regeneration.