Cytokinines

Cytokinins are a class of plant hormones that play a crucial role in plant growth and development. They are primarily involved in promoting cell division, also known as cytokinesis, hence their name. Cytokinins are synthesized mainly in the root tips and then transported upwards to other parts of the plant, including stems and leaves.

These hormones work in conjunction with other plant hormones, particularly auxins, to regulate various developmental processes. The ratio of auxins to cytokinins is a key factor in determining cell fate. For example, a high auxin to cytokinin ratio generally promotes root formation, while a low ratio favors shoot development. Cytokinins also influence shoot formation, bud outgrowth, and delay senescence, the process of aging in plants, by preventing the breakdown of chlorophyll and proteins.

Naturally occurring cytokinins are adenine derivatives, with zeatin being a prominent example. Synthetic cytokinins, such as kinetin and benzyladenine, are also widely used in agriculture and horticulture for their ability to stimulate plant growth and improve crop yields. They are applied in tissue culture techniques to induce cell proliferation and regenerate whole plants from small tissue samples. Research continues to explore the diverse roles of cytokinins in plant physiology, including their involvement in nutrient allocation, stress responses, and the regulation of gene expression.