1. Signal Transduction of Plant Hormone Ethylene
Dr. Hongwei Guo
Peking University
June 22, 2006

2. Plant Growth and Development
Highly plastic ----plants cannot run!
Perception of environmental signals involves multiple plant hormones
environmental signals:
light
gravity
temperature
water
nutrients
touch
Pathogens, etc

3. The simplest molecule on the earth that has a biological function
Plant hormones
Classical Five:
Auxins
Gibberellins (GAs)
Cytokinins
Abscisic acid (ABA)
Ethylene C H
Ethylene (C2H4)
Newly defined:
Brassinosteroids
Jasmonic acid (JA)
Salicylic acid (SA)
Nitric oxide (NO)
The simplest molecule on the earth that has a biological function

5. Ethylene can do more… senescence abscission pathogen defense
--Germination
--Senescence
--Abscission
--Nodulation
--Stress tolerance
--Pathogen defense
senescence
abscission
pathogen defense

6. A simple genetic system Arabidopsis seedling
Shortened root and hypocotyl
Swollen hypocotyl
Exaggerated apical hook
…triple response…
-C2H4
+C2H4

7. Ethylene Response Mutants
ein
wild type
ctr
10 ein
(ethylene insensitive)
5 ctr
(constitutive triple response)
+ C2H4
- C2H4

8. A genetic model of ethylene signaling pathwayER
EIL1
nucleus
cytoplasm

9. A SCF complex degrades EIN3 protein
proteasome
SCFEBF1/2
EIN3
ethylene
response
(degraded)
EIN3 Ub
EBF1/2 E2
ASK1
Rbx
Cullin1
(Guo and Ecker, Cell 2003)

10. A working model on the ethylene signaling pathway in Arabidopsis
Signals and Stress
(SCFEBF1/2 E3 ligase)
ASK
Cul1
Rbx
C2H4
Receptors
(ETR1/2
ERS1/2
EIN4)
CTR1
EIN2
EBF1/2
EIN6?
EIN5
EIL1
EIN3
EBF1/2 mRNA
Target genes
(Guo and Ecker, 2004)
EBS

11. ACS JA SCFEBF EIN3/EIL1 Glucose SCFCOI1 EIL2-5? Primary ethylene ERF1
environmental stimuli
cytokinin
auxin
deveopmental signals
SAM
ACS
ACC
ACO
C2H4
Receptors/
CTR1
(RNAi)
EIN5 JA
SCFCOI1
EIN2
SCFEBF
EIN3/EIL1
EIL2-5?
Glucose
Primary ethylene
response genes
others
TFs
EDFs
ERFs
ERF1
others
Expansins
HLS1
Light
PRs
Other types of
ethylene responses
Cell growth
(elongation/
expansion)
Differential growth
(hook formation)
Defense
response

12. Acknowledgments Peking University Fengying An Hongjiang Li Xiaorui Guo
Qiuchen Xing
Salk Institute, USA
Dr. Joseph Ecker
UCLA, USA
Dr. Chentao Lin
IBMP, France
Dr. Pascal Genschik