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Bonus #2 is due F 3/21 Today: Water Stress and Genetically Modifying Plants

Bonus #2 is due F 3/21 Today: Water Stress and Genetically Modifying Plants. CB 36.13. Water moves from the ground through roots into the shoot and out stomata in the leaves. What happened to this root?. CB 39.28. Flooding, constant submersion… Why would the plant respond like this?.

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Bonus #2 is due F 3/21 Today: Water Stress and Genetically Modifying Plants

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  1. Bonus #2 is due F 3/21 • Today: • Water Stress • and • Genetically Modifying Plants

  2. CB 36.13 Water moves from the ground through roots into the shoot and out stomata in the leaves.

  3. What happened to this root? CB 39.28

  4. Flooding, constant submersion… Why would the plant respond like this? CB 39.28

  5. CB 36.7 Much of plant support comes from turgor pressure. http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html (wilting)

  6. CB 36.13 Water moves from the ground through roots into the shoot and out stomata in the leaves.

  7. Stomata control entry of CO2 and exit of H2O from plant leaves CB 36.12 Stomata

  8. What about when water is scarce?

  9. Oleander Structural adaptations of a plant that grows in an arid environment CB 36.16

  10. Oleander • Structural adaptations of a plant that grows in an arid environment: • Thick cuticle • Thick epidermis • Recessed stomata CB 36.16

  11. Stomata density can change depending on the environment. Typically ~200-300/mm2

  12. 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

  13. Individual plants can change stomata number to adjust for changes in the environment. New leaves develop with fewer stomata Only mature leaves exposed to high CO2 JA Lake et al (10 May 2001) Nature 411, 154

  14. Stomata aperture is affected by many stimuli: light, water, temperature, sugar content, circadian rhythm, CO2 levels… CB 36.14

  15. Photosynthesis is only efficient over certain temperature range. Transpiration cools plants.

  16. Stomata aperture is affected by many stimuli: light, water, temperature, sugar content, circadian rhythm, CO2 levels… CB 36.14

  17. CB 36.15 Plants must integrate these various signals to determine an appropriate response

  18. Human resource production and use Worldwide Grain Production per Person http://www.earth-policy.org/Indicators/Grain/2006.htm

  19. World Grain Stocks as Days of Consumption http://www.earth-policy.org/Indicators/Grain/2006.htm

  20. ~60 percent of the world grain harvest is consumed as food, ~36 percent as feed, and ~3 percent as fuel. While the use of grain for food and feed grows by roughly 1 percent per year, that used for fuel is growing by over 20 percent per year. http://www.earth-policy.org/Indicators/Grain/2006.htm

  21. from Teosinte Maize By artificial selection that began ~10,000 years ago.

  22. Agricultural Hunter- Gatherer Industrial

  23. Genetic Engineering: Direct manipulation of DNA CB 20.2

  24. We can now insert new genes or modify existing genes of plants CB 20.2

  25. Global area planted with GM crops Texas =70 ha Millions of Hectares http://www.gmo-compass.org/eng/agri_biotechnology/gmo_planting/257.global_gm_planting_2006.html

  26. Why Change a Plant’s DNA? • Can change plant so that it has new or different characteristics • Drought or other stress resistance • Produce needed protein • Insect resistance (Bt toxin) • Herbicide resistance (Round-up) • Chemical remediation

  27. Change is ever present… precipitation changes

  28. Irrigating crops eventually leads to increased soil salinity

  29. 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

  30. Why Change a Plant’s DNA? • Can change plant so that it has new or different characteristics • Produce needed protein • Insect resistance (Bt toxin) • Herbicide resistance (Round-up) • Drought or other stress resistance • Chemical remediation

  31. Common GM Crops in the U.S. % of Total US Acres http://blog.wired.com/wiredscience/2007/09/monsanto-is-hap.html

  32. Types of Genetically Modified Crops Herbicide Tolerance; Insect Resistance; Viral Resistance

  33. Is genetically engineering plants a good idea? Texas =70 ha Millions of Hectares http://www.gmo-compass.org/eng/agri_biotechnology/gmo_planting/257.global_gm_planting_2006.html

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