Auxin
/ˈɔk.sɪn/
Definition
Auxin is a class of plant hormones that regulate growth and development. Produced mainly in shoot tips and young leaves, it moves through tissues and helps control cell elongation, root initiation, apical dominance, and bending toward light or gravity. Its effects depend on concentration and location, which distinguishes it from nutrients or general growth stimulants.
Role and Significance
- Shoot tip control: Auxin produced near shoot tips helps maintain apical dominance, which suppresses some side buds and directs growth upward. When the tip is removed, branching often increases because that control is reduced.
- Bending toward light and gravity: Uneven auxin distribution causes cells on one side of a stem or root to elongate differently. This drives phototropism, growth toward light, and gravitropism, growth in response to gravity.
- Root initiation in cuttings: In horticulture, auxin is used in some rooting products to encourage adventitious roots, meaning roots that form from stems or leaves rather than from an existing root system.
- Fruit and tissue development: Auxin helps regulate cell elongation, vascular tissue formation, and aspects of fruit set and early fruit growth. Its effects often depend on tissue type, concentration, and interaction with other plant hormones.
Related Terms
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