Signal Transduction and Plant Responses Overview

Signal Transduction

Process of converting environmental stimuli into cellular responses.

Receptor Proteins

Proteins that sense environmental stimuli in plants.

Phosphorylation Cascades

Chemical signal relays activated by receptor proteins.

Second Messengers

Internal chemical signals like Ca²⁺ in cells.

Gene Expression Changes

Alterations in gene activity leading to hormone production.

Phototropism

Plant growth response toward light sources.

Phototropin

Blue light receptor triggering phototropism.

Auxin (IAA)

Hormone that promotes cell elongation in plants.

Gravitropism

Plant growth response to gravitational pull.

Positive Gravitropism

Roots grow toward gravity direction.

Negative Gravitropism

Shoots grow opposite to gravity direction.

Thigmotropism

Directional growth response to touch stimuli.

Phytochrome

Light receptor for red and far-red light.

Active Phytochrome (Pfr)

Form activated by red light, promotes growth.

Inactive Phytochrome (Pr)

Form activated by far-red light, inhibits growth.

Etiolation

Tall, spindly growth in low light conditions.

Night Length Detection

Plants measure darkness to determine flowering time.

Florigen

Hormone triggering flowering under specific light conditions.

Thigmonasty

Non-directional touch response in plants.

Calcium Ions in Thigmonasty

Signal for rapid movement in touch-sensitive plants.

Major Plant Hormones

Chemical signals regulating growth and development.

Auxins Functions

Regulate growth, prevent leaf drop, promote rooting.

Cytokinins Functions

Stimulate cell division and elongation.

Gibberellins Functions

Promote stem elongation and seed germination.

Abscisic Acid Functions

Stress response hormone, inhibits germination.

Ethylene Functions

Gas hormone that ripens fruit and promotes drop.

Brassinosteroids Functions

Enhance growth in stems and leaves.