Plant Hormones

Photo and information found at
http://www.plant-hormones.info/auxins.htm

Auxins - essential for plant body development

• stimulates cell elongation in stem
• stimulates cell division in cambium
• Stimulates differentiation of phloem and xylem
• Stimulates root initiation on stem cuttings and lateral root development in tissue culture 
• Mediates the tropistic response of bending in response to gravity and light 
• The auxin supply from the apical bud suppresses growth of lateral buds 
• Delays leaf senescence 
• Can inhibit or promote (via ethylene stimulation) leaf and fruit abscission 
• Can induce fruit setting and growth in some plants 
• Involved in assimilate movement toward auxin possibly by an effect on phloem transport 
• Delays fruit ripening 
• Promotes flowering in Bromeliads 
• Stimulates growth of flower parts 
• Promotes (via ethylene production) femaleness in dioecious flowers 

Photo and information found at
http://www.plant-hormones.info/abscisicacid.htm

Abscisic Acid - single compound; functions in plant development process

• Stimulates the closure of stomata (water stress brings about an increase in ABA synthesis). 
• Inhibits shoot growth but will not have as much affect on roots or may even promote growth of roots. 
• Induces seeds to synthesize storage proteins. 
• Inhibits the affect of gibberellins on stimulating de novo synthesis of a-amylase. 
• Has some effect on induction and maintenance of dormancy
• Induces gene transcription especially for proteinase inhibitors in response to wounding which may explain an apparent role in pathogen defense. 

Photo: http://biology.kenyon.edu/edwards/project/wendy/ethylene.htm
Info: http://www.plant-hormones.info/ethylene.htm

Ethylene - gaseous hormone; used in plant ripening

• Stimulates the release of dormancy. 
• Stimulates shoot and root growth and differentiation (triple response) 
• May have a role in adventitious root formation. 
• Stimulates leaf and fruit abscission. 
• Stimulates Bromiliad flower induction. 
• Induction of femaleness in dioecious flowers. 
• Stimulates flower opening. 
• Stimulates flower and leaf senescence. 
• Stimulates fruit ripening.