How Does Chemical Coordination Occur in Plants?

Chemical coordination in plants occurs with the help of special chemical messengers called Plant Hormones or Phytohormones.

These chemicals are synthesized in one part of the plant (usually the tips of roots or shoots) and simply diffuse to other parts where they are needed to trigger a response.

1. Auxins: Produced at the shoot tip. They help the cells grow longer. They are responsible for phototropism (bending of the plant toward light).
2. Gibberellins: Help in the growth of the stem and seed germination.
3. Cytokinins: Promote rapid cell division. They are present in high concentrations in areas of rapid growth, like fruits and seeds.
4. Abscisic Acid (ABA): This is a growth inhibitor. It stops growth, causes leaves to wilt and fall, and helps the plant survive stress (like severe drought).

When sunlight falls on only one side of a plant, the hormone Auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells on the shady side to grow longer, causing the plant to bend towards the light.