1. PLANTS UBER ALLES (Plants as control freaks)
PLANT HORMONE
PLANTS UBER ALLES
(Plants as control freaks)

2. OUTLINE History and Scientists involved
Control Systems in plants and animals
Differences between plant and animal hormones
Hormone action
Plant Hormone and effects
Experimental Evidence

3. Scientists and History of Plant Hormones
Charles and Francis Darwin – initial proposition-1880
Boysen- Jensen – 1910
Went-1930
Skoog-1950
Kurosawa-1920
Addicott-US,Wareing-England
Various fruit growers – 1960’s
Australian Scientists

4. CONTROL SYSTEMS Necessary for response to stimuli
Nervous system in animals
Tropic response systems in plants and some invertebrates
Hormonal systems in both plants and animals
Endocrine
Exocrine
Hormonal mimics

5. Differences between Plant and animal Hormones
Animal hormones produced by specific glands and/or cells.
Plant hormones are produced by specific regions – ie. Meristems, cambriums ets.
Most animal hormones are transported in some way via blood or by ducts
Plant hormones generally must diffuse into adjacent cells or are carried by phloem

6. Hormonal Action
Most hormones act by way of the second messenger theory. This states that the hormone binds with a receptor in the cell membrane which then triggers an induction of chemical reactions causing specific protein to form

7. HORMONAL ACTION
Once induction has occurred, this frequently sets up a cascade effect which triggers other responses. Ie. Giberillins initiate water uptake in seeds which then causes a multitude of other responses such as production of amylase
These effects are slow to act but long lasting in permanent changes.

8. Plant Hormones Auxins Cytokinins Giberillins Abscissic Acid Ethylene
Florigen
Artificial mimics
Strigolactones

9. Auxins Growth of apical meristem and supression of lateral meristem
Cellular eleongation in grass and herbs
Differentiation of Vascular Tissue
Fruit Development and parthenocarpy
Wound repair and development of adventitious roots
Calcium release – promotes activation of calmodulin – control of calcium receptors

10. Cytokinins Stimulate cell division
Organogenesis in connection with auxins
High cytokinin/auxin rations favor stem and leaf development
Low rations favor root development
Senescence and programmed death of cells –longer shelf life of vegetable in grocery stores

11. Giberillins Rapid , Extensive growth of intact plants
Seed germination and removal of inhibitions
Juvenile characteristics
Increase of fruit size in seedless varieties
Foolish seedling disease

12. Ethylene Fruit Ripening –one rotten apple spoils the bushel
Flowering inhibited in most plants – exception Bromeliads
Sex expression in diecious plants – holly
Abscission – initiates break down of middle lamella at leaf /stem juncture

13. Abscissic Acid Closes stoma in drought conditions
Creates dormancy in seeds and buds
Formation of abscissic layer in leaves causing death and drop of leaf
Counteracts stimulatory effects of other hormones

14. Florigen Stimulates flowering
Has been proven to exist but has never been isolated
Experiments with long day and short day plants

15. Strigolactones Stimulates mycorrhizial fungal attachment to roots
Stimulates formation of lateral buds(Fibionacci numbers)
Helps seeds break dormancy after fire (Australian Fire Ecology)