The productivity of plants is effected before visible damage

Ground Level Ozone WorkshopSaturday March 7, 2009Stony Brook University

No visible symptoms Moderate damage Severe damage

Alistair Rogers

Vandermeiren et al (2005)

New York State NOx emissions (tons mile-2)

0 – 55 – 1010 - 2000www.airnow.gov

www.airnow.gov

0 - 64

65 - 84

85 - 104

105 - 124

125+

Ozone concentration

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

IPCC (2001, 2007)

2000 2020 2040 2060 2080 210040

60

80

Ozo

ne (

ppb

)

Year

Seasonal average of daily peak ozone (ppb)

0 40 80 120

Pe

rce

nt

yie

ld n

o o

zon

e

40

60

80

100

Soybean

Wheat

Sorghum

Corn

(USDA)

Mean crop responses to ozone

Feng & Kobayashi (2009)

Current impact of background ozone on crop yield

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

O3guard cell

cuticle

mesophyll

epidermis

stoma

chloroplast

O3damagingoxidants

vitamin C

signaling

ethylene jasmonate aspirin

Reduced photosynthesisAccelerated senescenceImproved defense against O3

nucleus

Repair & protection pathways

signaling

O3damagingoxidants

vitamin C

O3damagingoxidants

vitamin C

nucleus

Repair & protection pathways

signalingChanges to the cell wall

sugar & starch

energy

rubisco

chloroplast

CO2

light reactions

dark reactions

protease

O3damagingoxidants

vitamin C

signaling

0

100

0

50

150

% c

ontr

ol

4 8 12 16

Time (h)

light reactions

rubisco activity

dark reactions

Long & Naidu (2002)

Impact of acute ozone exposure on photosynthesis

0

100

50

150

% c

ontr

ol light reactions

rubiscocontent

stomatalconductance

Long & Naidu (2002)

Impact of chronic ozone exposure on photosynthesis in wheat

completion ofleaf expansion

early grain fill

lategrain fill

Impact of chronic ozone exposure on photosynthesis in soybean

Fiscus et al (2005)

O3damagingoxidants

vitamin C

signaling

nucleus

photosynthetic gene transcription

senescence associatedgene transcription

accelerated senescence

Leaf

are

a in

dex

CO2

ControlO3

Demody et al (2006)www.soyface.illinois.eduwww.soyface.illinois.edu

Summary

reducedphotosynthesis +

reduced leaf area =

reducedproductivity

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)