LectureTopic26-PlantHormones

Hormones

Chemical signals that modify or control physiological processes within a plant.

Etiolation

Morphological adaptations for growing in darkness, where plants show characteristics like elongated stems.

De-etiolation

Changes that occur after exposure to light, allowing shoots and roots to grow normally.

Signal transduction pathways

Link signal reception to plant response through processes of reception, transduction, and response.

Auxin

A plant hormone that promotes elongation of coleoptiles, specifically referring to indoleacetic acid (IAA).

Tropism

Any response resulting in curvature of plant organs toward or away from a stimulus, such as phototropism or gravitropism.

Cytokinins

Plant hormones that stimulate cell division (cytokinesis) and work with auxins to control growth.

Gibberellins

Plant hormones that promote stem elongation, fruit growth, and trigger seed germination.

Abscisic Acid

A hormone that plays a role in seed dormancy and helps plants withstand drought by causing stomata to close rapidly.

Ethylene

A plant hormone produced in response to stressors, affecting processes like fruit ripening, leaf abscission, and senescence.

Triple response

A response to mechanical stress in which a growing shoot slows its elongation, thickens, and grows horizontally.

Expansins

Enzymes activated by lower pH in the cell wall that loosen the fabric, allowing cells to expand.

Phyllotaxy

The arrangement of leaves on the stem, influenced by auxin transport.

Adventitious roots

Roots that grow from places other than the root system, stimulated by auxin (IBA).

Apical dominance

The mechanism where a terminal bud suppresses the growth of axillary buds, controlled by auxins.

Dormancy

A state in which seeds do not germinate until conditions are favorable, influenced by abscisic acid.