01/08/2026
🌿 Cytokinins: The Cell Division Hormones
Cytokinins are a group of plant growth regulators that primarily stimulate cell division (cytokinesis). They are mainly synthesized in the root apical meristems and transported to other parts of the plant through the xylem. Cytokinins play an essential role in shoot growth, leaf expansion, delay of senescence, nutrient mobilization, and overall plant development.
The first naturally occurring cytokinin to be identified was Zeatin, which is abundant in maize (corn) kernels.
🌱 Site of Synthesis
🔹 Produced mainly in the root apical meristems.
🔹 Also synthesized in developing fruits, seeds, and young leaves.
🔹 Transported from roots to shoots through the xylem.
🧬 Types of Cytokinins
🌿 Natural Cytokinins
🔹 Zeatin – The most common naturally occurring cytokinin.
🔹 Isopentenyl adenine (iP).
🧪 Synthetic Cytokinins
🔹 Kinetin.
🔹 Benzylaminopurine (BAP or BA).
🌍 Functions of Cytokinins
🌱 1. Stimulate Cell Division
🔹 Promote cytokinesis in actively growing tissues.
🔹 Essential for plant growth and development.
🌿 2. Promote Shoot Growth
🔹 Stimulate the growth of axillary buds.
🔹 Encourage branching by reducing apical dominance.
🍃 3. Delay Leaf Senescence
🔹 Slow down the aging of leaves.
🔹 Maintain chlorophyll content and photosynthetic activity for a longer time.
🌾 4. Promote Nutrient Mobilization
🔹 Help transport nutrients to actively growing tissues.
🔹 Support the development of young leaves, fruits, and seeds.
🧫 5. Tissue Culture
🔹 Widely used in plant tissue culture.
🔹 A high cytokinin-to-auxin ratio promotes shoot formation.
🌾 Agricultural Applications
🔹 Enhance branching in crop plants.
🔹 Delay leaf yellowing after harvest.
🔹 Improve micropropagation in tissue culture.
🔹 Increase crop productivity and plant vigor.
🔹 Promote shoot regeneration in horticultural plants.
⚠️ Key Facts
🔹 Cytokinins work opposite to auxins in controlling apical dominance.
🔹 They interact with auxins, gibberellins, ethylene, and abscisic acid (ABA) to regulate plant growth.
🔹 The auxin-to-cytokinin ratio determines whether roots or shoots develop in plant tissue culture.
🌟 Did You Know?
🌽 Zeatin, the first naturally occurring cytokinin discovered, was isolated from immature maize (corn) kernels. Cytokinins are widely used in plant tissue culture to produce large numbers of healthy plants from a small piece of tissue.
💬 Which plant hormone is best known for stimulating cell division and delaying leaf senescence—Auxin, Gibberellin, or Cytokinin? Share your answer in the comments!
