Plant Hormones Flashcards
Plant growth regulator
plant hormone used to manipulate plant growth (height, flowering)
Auxins
the group of hormones that help plants make roots, essential for plant growth, division, and expansion
-Induces formation of xylem and phloem
-Induces tissue regeneration after wound
-Stimulates root growth
-Required for fruit growth
-Delays senescence
-Inhibits abscission
Rooting hormones
IAA, IBA, WAA (too much will inhibit growth! Always tap off)
Cytokinin
-promotes cell division in roots and shoots
-involved in cell differentiation
-regulates development of roots and leaves
-Synthesized in roots, cambium and other dividing tissue
-Travels up from roots to shoots
-Signals lateral bud growth
-Delays leaf senescence
-Involved in seeds breaking dormancy
-Stimulates leaf expansion
High auxin and low cytokinin
roots form
Equal auxin and cytokinin
maintain
Low auxin and high cytokinin
shoots form
Apical dominance
auxin from the apical bud diffuses down, inhibits growth of lateral buds
Removing the apical bud
removes inhibition on lateral buds
Ethylene
gas that naturally occurs in plants and promotes abscission
-Influences tissue growth
-Fruit ripening
-Fruit and leaf abscission
-Senescence
-Rapid stem growth (helping seedlings emerge into the sun
Abscisic Acid
once through to effect abscission
-Stimulates production of seed storage proteins
-Prevents premature germination
-In drought, roots synthesize and release this acid to reduce transpiration
Gibberellins
present throughout plant, highest concentration in immature seeds
-Stem and leaf elongation
-Breaking seed dormancy (can be a substitute for cold or light requirements)
What hormones promote abscission?
Ethylene and auxin