Plant Hormones

Signal Transduction Pathway

Convert chemical messengers into developmental/environmental responses through receptor perception, intracellular signaling cascades, and transcriptional reprogramming

Chemical Signals

Regulate growth, development, and stress responses with specialized glands

Auxins

Promote elongation of cells in shoots /produced in shoot apical meristem

Apical Dominance

Inhibits growth of lateral buds

Gibberellins

Stem elongation/division/germination; found in apical buds, roots, leaves, embryos + cause leaf & fruit aging

Dormancy

Metabolic activity slows, growth stops, and plants conserve energy to survive unfavorable conditions like winter cold or drought

Cytokinins

Promote cell division in meristems, prevent senescence (plant aging), and promote growth/cell specialization

Senescence

Final, highly regulated stage of development, acting as a controlled aging process that leads to the death of tissues, organs, or the entire plant

Abscisic Acid

Prevent seeds from germinating prematurely/regulate stomata opening; stress response to drought/cold, etc – slows metabolism (produced by tissues with chloroplasts)

Ethylene

Abscission, leaf + flower aging, fruit ripening; responds to stress and influences seed germination

Abscission

Separation of plant parts from the parent body, driven by hormone changes and environmental stress

Brassinosteroids

Similar to animal steroid hormones; cell elongation, xylem development, less leaf drop (helps respond to stress/protect plants from heat/cold/salinity/injury)