Cytokinin – Definition & Detailed Explanation – Botanical Glossary

I. What is Cytokinin?

Cytokinins are a class of plant hormones that play a crucial role in regulating various physiological processes in plants. They are known for their ability to promote cell division, stimulate shoot and root growth, delay senescence, and regulate nutrient uptake. Cytokinins are essential for plant growth and development, as they interact with other hormones to coordinate plant responses to environmental stimuli.

II. History and Discovery of Cytokinin

The discovery of cytokinins dates back to the 1950s when scientists observed that coconut milk had a stimulatory effect on plant cell division. This led to the isolation and identification of the first cytokinin, zeatin, by Miller and Skoog in 1955. Since then, numerous other cytokinins have been identified, including isopentenyladenine (IPA), kinetin, and dihydrozeatin.

III. Functions of Cytokinin in Plants

Cytokinins play a diverse range of roles in plants, including promoting cell division, regulating shoot and root growth, delaying leaf senescence, and enhancing stress tolerance. They also interact with other hormones, such as auxins, to coordinate plant growth and development. Cytokinins are involved in various physiological processes, including seed germination, leaf expansion, flower development, and fruit ripening.

IV. Types of Cytokinins

There are several types of cytokinins found in plants, including zeatin, isopentenyladenine, kinetin, and dihydrozeatin. These cytokinins differ in their chemical structure and biological activity. Zeatin is one of the most common cytokinins found in plants and is known for its role in promoting cell division and shoot growth. Isopentenyladenine is another important cytokinin that regulates root growth and development.

V. Sources of Cytokinin in Plants

Cytokinins are synthesized in various parts of the plant, including the roots, shoots, and seeds. They are also found in plant tissues, such as leaves, stems, and fruits. Cytokinins can be produced endogenously by plants or applied exogenously as growth regulators. Some plants have the ability to convert inactive forms of cytokinins into active forms, allowing them to regulate their own growth and development.

VI. Role of Cytokinin in Plant Growth and Development

Cytokinins play a crucial role in plant growth and development by regulating cell division, shoot and root growth, and nutrient uptake. They interact with other hormones, such as auxins, to coordinate plant responses to environmental stimuli. Cytokinins also play a role in stress tolerance, as they help plants adapt to changing environmental conditions. Overall, cytokinins are essential for plant growth, development, and survival.