Ground Level Ozone Workshop
Saturday March 7, 2009
Stony Brook University
The productivity of plants is
effected before visible damage
Alistair Rogers
No visible symptoms
Moderate damage
Severe damage
Vandermeiren et al (2005)
New York State NOx emissions (tons mile-2)
www.airnow.gov
0–5
5 – 10
10 - 2000
Ozone concentration
0 - 64
65 - 84
85 - 104
105 - 124
125+
www.airnow.gov
Ozone concentration has risen by 36% since
the industrial revolution and is predicted to
increase at a rate of 0.5 to 2.5% per annum
Ozone (ppb)
80
60
40
2000 2020 2040 2060 2080 2100
Year
IPCC (2001, 2007)
Mean crop responses to ozone
Percent yield no ozone
100
Sorghum
80
Corn
60
Wheat
Soybean
40
0
40
80
120
Seasonal average of daily peak ozone (ppb)
(USDA)
Current impact of background ozone on crop yield
Feng & Kobayashi (2009)
Impact of background ozone on crop yield in 2030
Feng & Kobayashi (2009)
Acute v Chronic Ozone Exposure
• Acute
– Exposure to high concentrations (>120 ppb) for
several hours
– Uncontrolled cell & tissue death
• Chronic
– Exposure to an elevated background concentration
(daily peaks 40 - 120 ppb)
– Often no visible symptoms
– Decreased photosynthesis, accelerated senescence
stoma
cuticle
epidermis
mesophyll
O3
guard cell
chloroplast
damaging
oxidants
O3
vitamin C
signaling
ethylene
jasmonate
aspirin
Reduced photosynthesis
Accelerated senescence
Improved defense against O3
damaging
oxidants
signaling
Repair &
protection
pathways
nucleus
O3
vitamin C
damaging
oxidants
O3
vitamin C
Changes to the cell wall
signaling
Repair &
protection
pathways
nucleus
damaging
oxidants
O3
vitamin C
rubisco
signaling
CO2
dark reactions
sugar &
starch
energy
protease
light reactions
chloroplast
Impact of acute ozone exposure on photosynthesis
% control
150
light reactions
100
dark reactions
50
rubisco activity
0
0
4
8
12
16
Time (h)
Long & Naidu (2002)
Impact of chronic ozone exposure on photosynthesis
in wheat
% control
150
100
50
0
light reactions
rubisco
content
completion of
leaf expansion
early
grain fill
stomatal
conductance
late
grain fill
Long & Naidu (2002)
Impact of chronic ozone exposure on photosynthesis
in soybean
Fiscus et al (2005)
damaging
oxidants
O3
vitamin C
signaling
photosynthetic gene
transcription
senescence associated
gene transcription
nucleus
accelerated
senescence
Leaf area index
CO2
Control
O3
www.soyface.illinois.edu
Demody et al (2006)
Summary
reduced
reduced
reduced
=
+
photosynthesis
leaf area
productivity
How can plants better adapt to ozone?
• Control ozone entry into the leaf
– reduced stress v reduced productivity
• Alter the signal transduction pathway
– Reduced sensitivity v decreased resistance to
pests & pathogens
• Improve detoxification
• Reproductive tissue is still vulnerable
Ainsworth et al (2008)