Read Auxin from Shoot Tip to Fruit
Auxin is made in young shoot tissues and coordinates elongation, branching, rooting, fruit set and directional growth.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Follow auxin’s major actions
Auxin made in shoot apices promotes elongation and apical dominance, stimulates roots on cuttings and can induce parthenocarpic fruit. It delays abscission in young leaves but can promote drop of older leaves.
Explain bending toward light
The coleoptile tip perceives unilateral light and sends a growth signal. Unequal auxin-driven elongation on the shaded side bends the shoot toward the light. IAA is a natural indole auxin.
Auxin and apical dominance
Auxin from the shoot apex suppresses axillary-bud outgrowth. Removing the apex or reducing auxin influence releases lateral buds; cytokinin generally promotes bud growth rather than causing apical dominance.
Auxin coordinates phototropism and apical dominance
The shoot tip perceives unilateral light and sends an auxin signal to the elongation zone, where unequal growth bends the shoot toward light. Auxin from the apex also suppresses axillary-bud growth; reducing that influence releases lateral buds.
OlympIQ exam lens
- ✓Auxin: apical dominance, elongation, rooting and parthenocarpy.
- ✓Coleoptile tip detects light; unequal elongation bends the shoot.
- ✓Auxin can affect leaf abscission differently with age.
In phototropism, the tip perceives light; the elongation zone executes the bend.
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