Kelompok Hormon Sitokinin

Summary

This lecture focuses on cytokinins, a group of plant hormones that promote shoot growth while inhibiting root, flower, and fruit development. The lecturer explains the key characteristics and benefits of different cytokinin types, including BAP, TDZ, and kinetin, highlighting their applications in plant propagation and tissue culture. The session also covers the interplay between cytokinins, auxins, and gibberellins, emphasizing how these hormones can be combined to achieve desired results. Additionally, practical examples of cytokinin use in plant growth, including enhancing shoot proliferation and somatic embryo production, are discussed. The lecture provides valuable insights for optimizing plant growth techniques.

Takeaways

• 😀 Cytokinins are plant hormones that support shoot growth but inhibit or kill roots, flowers, and fruits when in high concentrations.
• 😀 The application of cytokinin hormones must be targeted to the specific plant area to ensure desired results.
• 😀 Cytokinins and auxins can weaken each other when combined, but this can be mitigated by using gibberellins in low concentrations to enhance shoot growth.
• 😀 Gibberellins help accelerate cell division and support the rapid growth of shoots when combined with cytokinins.
• 😀 When combining different cytokinins, the effects are synergistic, meaning they enhance each other's effectiveness.
• 😀 There are various types of cytokinins, each with unique characteristics, such as BAP, TDZ, and 2iP, which affect shoot growth and other factors.
• 😀 BAP (Benzylaminopurine) is a potent cytokinin commonly used in tissue culture to support strong shoot growth.
• 😀 TDZ (Thidiazuron) is an expensive but powerful cytokinin that promotes large, vigorous shoots and is often used to rejuvenate plants.
• 😀 The cytokinin kinetin supports shoot growth and calus formation, while 2iP increases the number of shoots but can result in taller plants.
• 😀 Cytokinins can be used to enhance the growth of somatic embryos, particularly in bulbs, tubers, and other types of vegetative reproduction.
• 😀 In practical applications, cytokinin hormones can be combined with other substances to enhance specific growth outcomes, such as larger, thicker, or more uniform leaves.

Q & A

What are cytokinins and what is their main function in plants?

Cytokinins are a group of plant hormones that primarily support the growth of shoots and buds, promoting the development of new shoots. They can also inhibit root, flower, and fruit growth when applied in high concentrations.

How does cytokinin interact with other hormones, like auxin and gibberellin?

Cytokinins tend to inhibit the action of auxins when combined, which can lead to weakened growth. However, combining cytokinins with gibberellins at low concentrations helps overcome this inhibition and accelerates shoot growth by enhancing cell division.

What happens when cytokinins are applied at high concentrations?

At high concentrations, cytokinins can inhibit the growth of roots and kill them. They are useful in certain applications like inducing rapid shoot growth or embryo formation, but too high a concentration can be harmful.

How do cytokinins affect plant tissue culture?

In plant tissue culture, cytokinins like benzylaminopurine (BAP) and thidiazuron (TDZ) are often used to stimulate the growth of shoots. TDZ, for example, is particularly effective at producing larger, more vigorous shoots compared to other cytokinin types.

What is the role of TDZ in cytokinin applications?

TDZ (thidiazuron) is known for its potent ability to stimulate large, robust shoot growth. It is a high-cost but highly effective cytokinin, commonly used in advanced tissue culture practices.

What are some specific types of cytokinins and their effects?

Some common types of cytokinins include BAP, TDZ, 2IP, and kinetin. BAP is effective in promoting general shoot growth, TDZ produces large shoots, 2IP leads to many tall shoots, and kinetin promotes callus formation along with shoots.

How does cytokinin concentration affect the growth of lateral shoots?

When applied at concentrations around 2 mg/liter, cytokinins stimulate the growth of lateral shoots, promoting a bushier, more branched plant. Higher concentrations can further enhance lateral shoot proliferation.

How do cytokinins help in somatic embryo formation?

Cytokinins, when applied in high concentrations (100-300 mg/liter), can induce somatic embryo formation. This is useful for regenerating plants from tissues like tubers, bulbs, or rhizomes, where somatic cells develop into embryos.

What is the advantage of using cytokinin in propagating ornamental plants like Sansiviera?

Cytokinins are used in propagating ornamental plants like Sansiviera by stimulating shoot growth from leaf cuttings, even when no natural buds are present. High concentrations of cytokinin can significantly speed up the regeneration process.

How does the combination of cytokinin and gibberellin enhance plant growth?

When combined, cytokinin and gibberellin work synergistically to promote rapid shoot development. Gibberellin accelerates cell division, while cytokinin stimulates shoot growth, leading to faster and stronger plant development.