Today: Water Stress and Genetically Modifying Plants.
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Transcript of Today: Water Stress and Genetically Modifying Plants.
Today:
Water Stress
and
Genetically Modifying Plants
Fig 37.11
Water moves from the ground through roots into the shoot and out stomata in the leaves.
What happened to this root?
Flooding, constant submersion… Why would the plant respond like this?
Stomata control entry of CO2 and exit of H2O from plant leaves
Stomata
Fig 30.10
What about when water is scarce?
Fig 37.16
Structural adaptations of a plant that grows in an arid environment
Oleander
Structural adaptations of a plant that grows in an arid environment:
•Thick cuticle
•Thick epidermis
•Recessed stomata
Oleander
Fig 37.16
Stomata density can change depending on the environment. Typically ~200-300/mm2
Individual plants can change stomata number to adjust for changes in the environment.
Only mature leaves exposed to high CO2
New leaves develop with fewer stomata
JA Lake et al (10 May 2001) Nature 411, 154
Measurements of herbarium samples and present day samples have shown a 40% decrease in stomata over the last 200 years.
F. I. Woodward (18 June 1987) Nature 327, 617 - 618
Changes in precipitation 1900-2000
Irrigating crops eventually leads to increased soil salinity
Freshwater is not pure water. It contains many salts, such as: sodium 6mg/L; chloride 7mg/L; calcium 15mg/L; sulfate 11mg/L; silica 7mg/L; magnesium 4mg/L; and potassium 3mg/L
http://science.jrank.org/pages/2857/Freshwater.html
Human resource production and use
http://www.earth-policy.org/Indicators/Grain/2006.htm
Worldwide Grain Production per Person
http://www.earth-policy.org/Indicators/Grain/2006.htm
Land use in USA, 1997
from Teosinte MaizeBy artificial selection that began ~10,000 years ago.
Hunter-Gatherer
Agricultural
Industrial
Genetic Engineering: Direct manipulation of DNA
We can now insert new genes or modify existing genes of plants
Agrobacterium infect plants, inserting some of their DNA into the plants genome. Fig 19.17
Fig 19.17
Agrobacterium infect plants, inserting some of their DNA into the plants genome.
Fig 19.17After inserting a gene into the Agrobacteria, they will insert that gene into the plant's DNA.
Mil
lion
s of
Hec
tare
s
Texas =70 ha
Global area planted with GM crops
http://www.gmo-compass.org/eng/agri_biotechnology/gmo_planting/257.global_gm_planting_2006.html
The agricultural release of genetically modified organisms is the largest scale
experiment that has ever been performed.
Why Change a Plant’s DNA?
•Can change plant so that it has new or different characteristics
–Insect resistance (Bt toxin)
–Herbicide resistance (Round-up)
–Drought or other stress resistance
Tbl 19.5
% o
f T
otal
US
Acr
esCommon GM Crops in the U.S.
http://blog.wired.com/
wiredscience/2007/09/
monsanto-is-hap.html
Are Genetically Modifying Plants Safe?
Human impacts:
Dead zone in Gulf of
Mexico from
Mississippi River
http://blog.nola.com/times-picayune/2007/06/despite_promises_to_fix_it_the.html
Pollen is easily transferred from plant to plant, and to related species.
GM crops illegal
GM crops found in Oaxaca and other MX states
Genetic information moves.
GM crops illegal
GM crops found in Oaxaca and other MX states
Genetic information moves, and is self-replicating.
Monsanto's is one of the largest sellers of GMO's
Monsanto Stock price
http://research.scottrade.com/public/stocks/snapshot/snapshot.asp
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Animals