cytokinineja

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, which is essential for the formation of new tissues and organs. Cytokinins are synthesized mainly in the root tips and are then transported upwards to other parts of the plant.

These plant hormones work in conjunction with auxins, another important group of plant hormones. The ratio of auxins to cytokinins is a key factor in determining the pattern of plant development, influencing processes such as shoot and root formation, leaf senescence, and flowering. For example, a high cytokinin to auxin ratio generally promotes shoot formation, while a low ratio favors root formation.

Beyond their role in cell division, cytokinins also influence other physiological processes in plants. They help delay leaf senescence, the aging and eventual death of leaves, by inhibiting protein breakdown and maintaining chloroplast integrity. This can extend the period of photosynthesis. Cytokinins can also impact nutrient mobilization, stress responses, and the formation of vascular tissues.

The chemical structures of cytokinins vary, but they often contain an adenine moiety. Naturally occurring cytokinins include zeatin, isopentenyladenine (IPA), and kinetin. Synthetic cytokinins are also used in agriculture and horticulture to promote growth and improve crop yields. Understanding the functions of cytokinins is vital for comprehending plant biology and for developing strategies to optimize plant cultivation.