Cytokinins

Definition

Cytokinins are a class of plant hormones that promote cell division and growth, playing crucial roles in various plant processes such as shoot and root development, as well as nutrient allocation. They work in conjunction with other hormones, influencing the balance of growth and differentiation in plants, which is essential for mineral uptake, transport, and overall physiological health.

5 Must Know Facts For Your Next Test

1. Cytokinins are primarily synthesized in the roots and are transported upwards to the shoots where they stimulate cell division.
2. They play a significant role in delaying leaf senescence (aging) by promoting chloroplast development and maintaining leaf vitality.
3. Cytokinins interact with auxins to regulate plant growth patterns, determining how resources are allocated within the plant.
4. In tissue culture, cytokinins are used to induce shoot proliferation and influence the growth of callus tissues.
5. The balance between cytokinins and auxins is crucial for establishing sink-source relationships in plants, affecting how photoassimilates are distributed.

Review Questions

• How do cytokinins interact with other plant hormones to regulate growth patterns?
  • Cytokinins work closely with auxins to regulate growth patterns within plants. While auxins primarily promote elongation and root development, cytokinins encourage cell division and shoot formation. This interaction is vital for maintaining a balance between different parts of the plant, ensuring that resources are allocated appropriately for optimal growth. Together, they influence apical dominance and overall plant architecture.
• Discuss the role of cytokinins in delaying leaf senescence and its importance in plant physiology.
  • Cytokinins play a crucial role in delaying leaf senescence by promoting the maintenance of chloroplasts and enhancing photosynthetic activity. This function is important as it allows leaves to continue producing energy through photosynthesis even as they age. By extending leaf life, cytokinins contribute to the overall health of the plant and support effective nutrient allocation during critical stages of growth and development.
• Evaluate the significance of cytokinins in plant tissue culture and how they impact micropropagation techniques.
  • Cytokinins are essential in plant tissue culture as they stimulate shoot proliferation from explants, which is a key factor in micropropagation techniques. By manipulating cytokinin concentrations, researchers can induce multiple shoots from a single piece of tissue, significantly increasing propagation efficiency. This ability not only aids in producing large numbers of identical plants quickly but also helps in preserving rare or endangered species through tissue culture methods. Their role underscores the importance of understanding hormone interactions for successful agricultural practices.

Related terms

Auxins: Auxins are another class of plant hormones that regulate various aspects of plant growth, particularly elongation and apical dominance.

Gibberellins: Gibberellins are hormones that promote stem elongation, seed germination, and flowering in plants.

Apical Dominance: Apical dominance refers to the phenomenon where the main central stem of a plant grows more vigorously than the side stems, regulated by hormone interactions including cytokinins.