1. ETHYLENE C2H4

2. Plant Hormone
Regulatory functions in
growth and development
Stimulators or inhibitors

3. Physiological Effects of Ethylene
Normal growth and development
Stress response
biotic and abiotic

4. Ethylene in organisms Animal Production: not normal Effect:
82+ % as anesthetic in 15 second
ignition at humidity lower than 56 %

5. Ethylene in organisms Bacteria Bacterial rot of cauliflower Fungi
Pennicilium digitatum
Aspergillus flavus
Alternaria solani

6. Ethylene in organisms Neljubov (1901): Gaseous hydrocarbon olefin
Triple response in etiolated pea seedlings
Cousins (1910):
Orange and banana in the same shipment

7. Gane (1934):
Ethylene as a natural plant product

8. Ethylene Diffusibility
Easily released from tissues
Diffuse through the gas phase
intercellular and outside
Rapid and sensitive response system
Active concentration: 10 ppb

9. Ethylene
Biosynthetic
Pathway
(1979)

10. Alternative pathway
Peroxidation of
long chain fatty acids
eg. Linolenic acid

11. Met SAM ACC Ethylene
N-Malonyl ACC
(Nonvolatile compound)

12. Synthesized in most tissues of
almost all higher plants
Easily isolated and quantified
Also found in gymnosperms
lower plants
bacteria

13. Ethylene Production Environmental effect * O2 O2 C2H4 (except rice)
* Temperature
apple T P
peanut / plum T P
* CO2
apple P
sweet potato P
bean no effect

14. Ethylene Production Other hormones Auxin: activate production: 10x
GA: activate in bean citrus blueberry
inhibit in soybean seedling
CK: activate in bean blueberry sorghum
ABA: activate in leaf and fruit
inhibit in seed and soybean seedling

15. Enzymes in Ethylene Biosynthetic Pathway

16. Rate-limiting step of pathway
ACC Synthase or ACCS
Rate-limiting step of pathway
SAM to ACC
ACCS level
Hormone levels
Growth environment
Physiological environment
Developmental environment

17. ACC Synthase or ACCS Amino acid sequences of
tomato, apple, squash and zucchini
Share 40% identity and 80% similarity
Contain 7 highly conserved regions

18. ACC Synthase or ACCS
Different isoforms
Encoded by a multigene family

19. ACC oxidase or ACCO Require aerobic conditions ACC to Ethylene
ACCO level:
environmental stresses

20. ACC oxidase or ACCO Ethylene-forming enzyme : EFE
A ripening-induced cDNA
confers yeast an oxidase activity

21. ACC-N-Malonyl transferase
ACCM
Autoregulation to prevent
ethylene overproduction
Storage / inactive form of ACC

22. Ethylene transport
Diffusion (short distance)
ACC (long distance)

23. Glucose conjugates of ethylene glycol
Ethylene metabolism
oxidation and hydrolysis
Ethylene oxide
ethylene glycol
Glucose conjugates of ethylene glycol
CO2

24. Ethylene Action CS2 a potent inhibitor of ethylene oxidation
No effect on ethylene responses
Action of ethylene ……..?

25. *Ethylene effects
not general for all plants
*A signal of environmental changes
or physiological changes

26. *Manifold effects mediated by
induction of new proteins
*regulator or
modulator or
coordinator of processes

27. Perception by receptors
Ethylene
Perception by receptors
Signal transduction
Responses

28. Reversibly binding to a receptor through a transition metal
Ethylene binding
Ethylene receptors
Hypothesis
Reversibly binding to a receptor
through a transition metal

29. Ethylene-binding components
Membrane bound
Solubility
Chromatographic behaviors
Sensitive to heat
protease
sulfhydryl agent
Nature of protein

30. Ethylene-binding proteins (EBP):
Various tissues and plants
tobacco, bean, Arabidopsis
Specific
High affinity
Saturable
Characteristics of receptor
binding moiety facing the apoplast

31. Ethylene binding protein EBP of Phaseolus vulgaris
Heterotrimer or
Heterotetramer
Subunits of ca. 12 to 14 kDa
Integral membrane protein
จีโนไทป์ เหมือน ฟีโนไทป์ เหมือน และ ต่าง
จีโนไทป์ ต่าง ฟีโนไทป์ เหมือน และ ต่าง
สิ่งแวดล้อมมีอิทธิพลต่อการแสดงออกของยีน

32. Receptor found in Arabidopsis
ETR
Receptor found in Arabidopsis
Dimer
Subunits of 79 to 83 kDa
3 transmembrane segments

33. Classes of ethylene-binding proteins
- High rate constant of
association/dissociation
- Very low rate constant of

34. Classes of ethylene-binding proteins
rice tomato
pea Arabidopsis
Class 2:
bean (Phaseolus)
mungbean

35. Ethylene-insensitive mutant
Arabidopsis
Decreased ethylene binding
Low concentrations of
ethylene binding protein

36. Antibody against Phaseolus EBP
Recognize homologous proteins
from pea
rice
Arabidopsis

37. Signal transduction pathway
Signaling pathway
A two-component system
bacteria
common / well-characterized
key mechanism
protein phosphorylation

38. 2-component signaling pathway
Histidine kinase for
sensing / transducing
extracellular signals

39. 2-component signaling pathway
Phosphotransfer between
two types of signal transducers
Sensory kinase
(input & kinase domains)
Response regulator
(receiver & output domains)

40. Ethylene signal transduction pathway
Genetic and biochemical studies
Similar to a bacterial two-component system
Conserved residues for kinase activity in EBP
Phosphorylation of EBP upon binding of ethylene

41. Ethylene kinase P ATP Model for regulation of ethylene action Response
regulator
Model for regulation
of ethylene action

42. Ethylene binding
Autophosphorylation of kinase
Phosphate transfer to a response regulator
Release of an activated ligand or
activation of soluble factor
Derepression of genes involved in
ethylene responses

43. Model of ethylene signal transductionCu
ETR1 ETR2 EIN4
ERS1 ERS2
Air
CTR1
EIN2
EIN3
OFF

44. Model of ethylene signal transductionCu
ETR1 ETR2 EIN4
ERS1 ERS2
C2H4
CTR1
EIN2 ON
EIN3

45. Model of ethylene signal transduction

46. Regulation of ethylene synthesis and activity
Activated by
high auxin
fruit ripening
flower senescence
wounding
chilling injury
drought
ACCS

47. Regulation of ethylene synthesis and activity
Inhibited by
ABA
ethylene
AVG
AOA
ACCS

48. Regulation of ethylene synthesis and activity
Activated by
ripening
senescence
ethylene
ACCO

49. Regulation of ethylene synthesis and activity
Inhibited by
anaerobiosis
Co2+
high temp (35+)
ACCO

50. Regulation of ethylene synthesis and activity
Ethylene level : Metabolism / Environment
Silver ion
CO2 (high conc at 3 to 5%)
NBD (2,5-norbornadiene)
DACP (diazo-cyclopentadiene)
Cyclic olefins
Cis butene
Ethylene binding

51. Commercial uses of ethylene
- Ethylene - Acetylene - ACC
- Ethylene-releasing compounds
Ethephon / Ethrel
*******************************************
- Ventilation with hypobaric pressure
- Silver - AVG / AOA - KMnO4

52. Ethylene / cell expansion / triple response
thicker and shorter Root/hypocotyl
reorientation of cell expansion