Interactions Between Auxin and Cytokinin as a Means of Regulating Root and Shoot Growth
- Plants must maintain a balance between root and shoot growth to ensure efficient nutrient uptake, water absorption, and photosynthesis.
- This coordination is regulated by two key phytohormones:
- Auxin (produced in shoot tips, transported to roots)
- Cytokinin (produced in root tips, transported to shoots)
How Auxin and Cytokinin Regulate Growth
Auxin: The Shoot-to-Root Signal
- Produced mainly in the shoot apical meristem (SAM).
- Transported downward to the roots via the phloem and polar auxin transport mechanisms.
- Stimulates root growth, lateral root formation, and cell elongation.
- High auxin concentration in shoots suppresses lateral bud growth, maintaining apical dominance.
Cytokinin: The Root-to-Shoot Signal
- Produced mainly in the root apical meristem (RAM).
- Transported upward to the shoots via the xylem.
- Stimulates shoot growth, promoting cell division in the shoot meristem.
- High cytokinin concentration promotes lateral bud growth, counteracting auxin’s apical dominance effect.
Think of auxin and cytokinin as two friends on a seesaw. When one goes up, the other balances it out, ensuring the seesaw remains stable.
