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Plant Biotechnology

Plant Biotechnology. Chapter 6 Fall 2008. CO 2 + H 2 O →C 6 H 12 O 6 + O 2. Agriculture: The Next Revolution. Biggest industry in the world ($1.3 trillion of products per year)

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Plant Biotechnology

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  1. Plant Biotechnology Chapter 6 Fall 2008

  2. CO2 + H2O →C6H12O6 + O2

  3. Agriculture: The Next Revolution • Biggest industry in the world ($1.3 trillion of products per year) • Plant transgenesis allows innovations that are impossible to achieve with conventional hybridization methods (e.g. conventional -> strength of cotton 1.5%; insertion of a single gene > strength 60%!) • Resistant to herbicides • Pest resistant • Vaccines • 74% of all soybean crops are genetically modified • 32% of all corn

  4. Methods Used in Plant Transgenesis • Unique advantages of plants: • The long history of plant breeding provides plant geneticists with a wealth of strains that can be exploited at the molecular level • Plants produce large no.s of progeny; so rare mutations and recombinations can be found more easily • Plants have been regenerative capabilities, even from one cell • Species boundaries and sexual compatibility are no longer an issue

  5. Protoplast Fusion (figure 6.2) • When injured, a mass of cells called a callus may grow over the site • Callus cells have the capability to redifferentiate into shoots and roots • Must remove the cellulose around these cells before DNA can be introduced; produce a protoplast

  6. Leaf Fragment Technique (figures 6.3 & 6.4) • Small discs of leaf incubated with genetically modified Agrobacter Ti plasmid • Treat with hormones to stimulate shoot and root development • Limitation: cannot infect monocotyledonous plants only dicotyledonous such as tomatoes, potatoes, apples and soybeans

  7. Gene Guns • Use on Agrobacter-resistant crops • Blast tiny metal beads coated with DNA into an embryonic plant cell (figure 6.5) • Aim at the nucleus or a chloroplast • Shoot in gene of interest and a gene marker (reporter) • Why is it more advantageous to genetically alter chloroplasts vs the nucleus? • More genes can be inserted at one time, more likely to be expressed, DNA is separate from the nucleus (figure 6.6)

  8. Antisense Technology • Flavr SavrTM tomato introduced in 1994 • Ripe tomatoes normally produce the enzyme, polyglacturonase (PG) which digests pectin • Scientists isolated gene, produced a complementary gene which produces a complementary mRNA that binds to the normal mRNA inactivating the normal mRNA for this enzyme (figure 6.7)

  9. RNA interference • Inhibits gene expression by interfering with transcription or translation of RNA molecules • http://www.pbs.org/wgbh/nova/sciencenow/3210/02.html

  10. Practical Applications in the Field (table 6.1) • Vaccines for Plants (figure 6.8) • Genetic Pesticides • Bacillus thuringiensis (Bt) • Safe Storage (avidin-blocks the availability of biotin for insects) • Herbicide Resistance –resistant to glyphosate (figure 6.10) • Stronger fibers (already mentioned) • Enhanced Nutrition Golden Rice (vit A)

  11. The Future: From Pharmaceuticals to Fuel • Plant-based petroleum for fuels, alternatives to rubber, nicotine-free tobacco, etc

  12. Metabolic Engineering • Manipulation of plant biochemistry to produce nonprotein products or to alter cellular properties

  13. Health and Environmental Concerns • Human Health • Allergens • Environment • Super weeds

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