1. The plant hormone ethylene
What does ethylene do?
Is ethylene important?
How can we study ethylene and use that knowledge to benefit humans?
Ethylene is a GAS!!!
What’s a hormone?

2. Plants synthesize ethylene in response to stress
Wounding
Flooding
Drought stress
Biotic stress
Heat stress
Cold stress
Osmotic stress
Mechanical stress
UV stress
Pathogen attack
Ethylene has it’s hands in everything

3. ETHYLENE is also a pollutant in the environment

4. Ethylene responses Developmental processes
Fruit ripening - ethylene is essential
Promotion of seed germination
Root initiation
Bud dormancy release
Inhibition/promotion of flowering
Sex shifts in flowers
Senescence of leaves, flowers
Responses to abiotic and biotic stress Abscission of leaves, flowers, fruits
Epinasty of leaves
Inhibition/promotion of cell division/elongation
Altered geotropism in roots, stems
Induction of phytoalexins/disease resistance
Aerenchyma formation

5. Historical background
Ethylene has been used (unwittingly) throughout history
Wood burning fires promote synchronous flowering in pineapple
Gashing promotes ripening in figs (4 days later)

6. Historical background
1800s Illuminating gas caused detrimental effects
Plants around the beltway

7. Wounding induces ethylene production
Ethylene causes senescence
Can block ethylene response using silver thiosulfate

8. Apple slices inducing ripening of persimmons
8 days in bag with apple slices
Controls, 8 days outside of bag

9. Ethylene has far-reaching consequences for agriculture and horticulture
Transport and storage of fruits and vegetables requires ethylene control
Flood-tolerant rice created by expression of ethylene response factor genes
“One bad apple spoils the whole bunch…”
Therefore, we would like to manipulate the biosynthesis and/or responses to ethylene

10. Removal of external ethylene

11. Ethylene hormone signaling
What is “signaling”?
How is signaling studied?
How to get the genes that nature did not already manipulate so that we can manipulate them?

12. Signal transduction
Response
Signal
plant cell ?

13. Plant growth, development, and survival depend on appropriate responses to a diverse array of constantly fluctuating external and internal signals

14. Example of signaling pathway activated by an extracellular signal
Signal transduction - the process by which a cell converts one kind of signal or stimulus into another.
Signal transduction processes typically involve a sequence of biochemical reactions or other responses within the cell, resulting in a signal transduction pathway