1. Ethylene and Senescence
Matt Mckechnie

2. Properties Hormone Structure
only gas of the five classic plant hormones
Structure
hydrocarbon

3. Historical facts Ancient Egypt fig gashing Ancient China
burned incense to ripen pears
Neljubow (1901)
coal lamps
Cousins (1910)
oranges
Gane (1934)
natural product
Burg & Thimann (1959)
quantification
McKeon et al. (1995)
biosynthetic pathway

4. Functions Stimulates bromelliad, pineapple flower induction
Induction of femaleness in flowers
Stimulates flower opening
Stimulates fruit 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

5. Senescence
Plants age productively because as tissues senesce they produce enzymes necessary to recycle valuable materials and reroute the subunits to areas for use by active growth in some other place, at some other time or in the next generation

6. Biosynthesis of ethylene
from methionine
from the Yang cycle
to AdoMet
-while consuming 1 ATP
to ACC (limiting step)
via ACC synthase
to ethylene
via ACC oxidase

7. Senescence-mechanism
Hormonal response
Climacteric
Protein synthesis
For limited/controlled hydrolysis
Transport
To seeds, active growth areas or storage

8. Controlling Senescence
cytokinins and gibberellins
seeds, roots
High [CO2]
Limits respiration
Harsh Chemicals (florists)
Antifungal agents-sodium benzoate
Anti-ethylene agents (silver nitrate)

9. Detecting Ethylene Quantitatively Gas chromatography
sensitive down to parts per trillion

10. Detecting Ethylene Qualitatively Bioassays
for best results: triple response in pea seedlings
other bioassays
epinasty of tomato leaves
root hair formation
leaf abscission

11. Associated research
SAGs response vs. different stresses and hormone treatments
ethylene
detached leaves in the dark were most affected
Indicated by older and younger leaves reacting similarly
four new SAGs were isolated