Definition

1. Noun:
   • A class of plant hormones: Cytokinins are a specific group of plant hormones (phytohormones).
   • Promotes cell division: Their primary function is to stimulate and regulate cell division (cytokinesis) in plant roots and shoots.
   • Delays leaf senescence: They work to slow down the aging process in leaves, helping them stay green and functional for longer.

Usage Examples

• Noun:
  • The application of cytokinin to the plant tissue culture medium encouraged rapid cell proliferation.
  • Scientists are studying how cytokinins interact with auxins to control plant growth.
  • One effect of cytokinin is the delay of leaf yellowing.

Advanced Usage

• "Cytokinin-to-auxin ratio": A critical concept in plant biology referring to the balance between these two hormones, which determines whether plant cells form roots or shoots.

  • The cytokinin-to-auxin ratio in the medium dictates the developmental fate of the callus.

• "Cytokinin signaling pathway": The series of molecular events by which a plant cell detects and responds to the presence of cytokinins.

  • Mutations in the receptor can disrupt the entire cytokinin signaling pathway.

Variants and Related Words

• Cytokinin (adj. form: cytokinin): The word itself is primarily used as a noun. The related adjective is often "cytokinin-related" or "cytokinin-like".
• Kinetin: A specific, synthetic type of cytokinin often used in laboratory experiments.
• Zeatin: A natural cytokinin found in plants like corn.

Synonyms

• Phytohormone / Plant hormone: A broader term for any hormone produced by plants, including cytokinins, auxins, and gibberellins.
• Growth regulator: A substance that controls the growth processes of a plant.

Notes on Meaning

• Cytokinins are specifically named for their role in cytokinesis (cell division). They are not general growth promoters but have very specific functions related to cell division and senescence.
• They often work in opposition or concert with other hormones like auxin (which promotes cell elongation) and abscisic acid (which promotes senescence and stress responses).

Noun

1. any of a class of plant hormones that promote cell division and delay the senescence of leaves