plant hormones: auxin

Question

Indole-3-acetic acid (IAA) predominantly promotes which process?

RankGuru · Accepted Answer

1. **IAA (Auxin)**: The most common naturally occurring auxin in plants.
2. **Acid Growth Hypothesis**: Auxin stimulates proton pumps in the cell membrane, which pump $H^+$ into the cell wall. The resulting acidity activates enzymes (expansins) that loosen the cellulose fibers.
3. **Result**: Turgor pressure then causes the cell to expand, leading to **cell elongation**, particularly in stems.
4. **Other Effects**: Auxin also promotes apical dominance, root initiation, and prevents premature fruit/leaf drop.

Rank Guru

plant hormones: auxin

Select the correct option: