Abscisic acid
Abscisic acid is a plant hormone that coordinates responses to drought and other stresses, promotes seed dormancy, and regulates stomatal closure.
PYR/PYL/RCAR receptors: A family of plant proteins that bind abscisic acid and initiate its core signaling pathway. These receptors detect the hormone and trigger the signaling events behind its effects.
Stomatal closure: The narrowing or closing of a plant stoma as its guard cells lose turgor. This response to abscisic acid limits water loss during drought.
Plant hormone: A signaling molecule produced by plants that regulates growth, development, or physiological responses. Abscisic acid is one member of this diverse signaling system.
Gibberellin: A group of plant hormones that promote processes including stem elongation, seed germination, and flowering. Gibberellin often promotes germination where abscisic acid maintains dormancy.
Frederick Addicott: An American plant physiologist whose research helped establish abscisic acid as a plant growth regulator. His studies of cotton fruit abscission contributed to the hormone’s early history.
Protein phosphatase 2C: A family of enzymes that remove phosphate groups from proteins, including regulators of abscisic acid signaling. Abscisic acid-bound receptors inhibit these enzymes, releasing downstream signaling proteins.
Seed dormancy: A temporary state in which a viable seed does not germinate despite otherwise favorable conditions. Abscisic acid promotes dormancy and helps prevent premature germination.
Stoma: A microscopic pore in a plant epidermis that permits gas exchange and water-vapor loss. Stomata are the structures whose aperture changes during abscisic-acid-mediated water conservation.
Auxin: A class of plant hormones that regulates growth, development, and responses to environmental cues. Auxin chiefly coordinates growth patterns, contrasting with abscisic acid’s prominent stress and dormancy roles.
Abscission: The regulated shedding of plant organs such as leaves, flowers, or fruits. Early research linked a substance later identified as abscisic acid to fruit abscission.