Cytokinins

Definition

Cytokinins are a class of plant hormones that promote cell division, shoot formation, and the growth of lateral buds. They play a vital role in plant tissue culture and micropropagation by influencing various physiological processes such as cell differentiation and growth, which are essential for the successful development of plant tissues in vitro.

5 Must Know Facts For Your Next Test

1. Cytokinins are synthesized mainly in the roots and then transported to other parts of the plant, where they exert their effects on growth and development.
2. These hormones help delay leaf senescence, thereby promoting longevity and vitality in plants.
3. Cytokinins can be used in plant tissue culture to induce the formation of shoots from callus tissue, making them essential for cloning plants.
4. They work synergistically with auxins to regulate various developmental processes, including the balance between root and shoot growth.
5. Synthetic cytokinins are often used in agricultural practices to enhance crop yield and improve the quality of fruits and vegetables.

Review Questions

• How do cytokinins interact with other plant hormones to influence plant growth and development?
  • Cytokinins interact with other plant hormones like auxins and gibberellins to coordinate various aspects of plant growth and development. For instance, while cytokinins promote shoot development and cell division, auxins tend to favor root formation. The balance between these hormones is crucial; an excess of cytokinins can lead to excessive shoot growth at the expense of roots, while an excess of auxins can inhibit shoot formation. This interplay is especially important in processes like tissue culture where a controlled environment is needed for optimal plant regeneration.
• Discuss the role of cytokinins in micropropagation and how they contribute to successful tissue culture techniques.
  • Cytokinins play a critical role in micropropagation by promoting the proliferation of shoots from cultured tissues. In tissue culture techniques, cytokinins are often added to the growth medium to stimulate cell division and shoot formation from callus or explants. This leads to the generation of multiple new shoots which can then be rooted and acclimatized into whole plants. The ability of cytokinins to delay senescence also helps maintain healthy tissues during culture, ensuring higher success rates in producing viable plants.
• Evaluate the impact of synthetic cytokinins on agricultural practices and their implications for sustainable farming.
  • Synthetic cytokinins have significant implications for agricultural practices by enhancing crop yields and improving fruit quality through regulated growth responses. Their application can lead to more efficient use of resources by promoting uniformity in growth patterns and extending harvest times. However, while they offer benefits such as increased productivity, reliance on synthetic hormones raises questions about sustainability and environmental impact. Overuse may lead to imbalances in natural hormone levels within ecosystems, highlighting the need for responsible application and further research into alternatives that align with sustainable farming practices.

Related terms

Auxins: Auxins are another class of plant hormones that regulate growth processes such as cell elongation and root formation, often working in conjunction with cytokinins.

Gibberellins: Gibberellins are plant hormones that promote stem elongation, seed germination, and flowering, contributing to overall plant growth and development.

Micropropagation: Micropropagation is a technique used to grow plants from small tissue samples in a controlled environment, heavily relying on plant hormones like cytokinins for successful tissue development.