Plant Biotechnology

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Chapter 6

• Plant Biotechnology

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Plant Structure
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Plant Structure
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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
• Resistant to herbicides
• Pest resistant
• Vaccines

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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 numbers 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

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Methods Used in Plant Transgenesis

• Protoplast Fusion to create plant hybrids
• Degrade cell wall with cellulase
• A cell lacking a cell wall is called a protoplast
• The protoplasts from different species of plants
  can be fused together to create a hybrid
• The fused protoplasts grow in nutrient agar for a
  few weeks
• The colonies are then transferred to media to
  induce root and shoot growth

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Methods Used in Plant Transgenesis

• Ti plasmid found in Agrobacter, a type of soil
  bacteria that infects plants
• Integrates into the DNA of the host cell, making
  it an ideal vehicle for transferring recombinant
  DNA to plant cells

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Methods Used in Plant Transgenesis

• Leaf fragment Technique
• 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

Transgenic Plant Animation
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Methods Used in Plant Transgenesis

• Gene Guns
• Use on Agrobacter-resistant crops
• Blast tiny metal beads coated with DNA into an
  embryonic plant cell
• Aim at the nucleus or a chloroplast
• Shoot in gene of interest and a gene marker
  (reporter)

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Methods Used in Plant Transgenesis

• Chloroplast Engineering
• More genes can be inserted at one time
• Genes are more likely to be expressed
• DNA is separate from the nucleus

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Methods Used in Plant Transgenesis

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

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Methods Used in Plant Transgenesis

• RNA Interference (RNAi)
• Inhibits gene expression by interfering with
  transcription or translation of RNA molecules

RNAi video and animations
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Practical Applications in the Field

• Vaccines for Plants
• Contain dead or weakened strains of plant viruses
  to turn on the plants immune system
• Transgenic plants express viral proteins to
  confer immunity

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Practical Applications in the Field

• Genetic Pesticides
• Bacillus thuringiensis (Bt) produces a protein
  that is toxic to plant pests
• Transgenic plants contain the gene for the Bt
  toxin and have a built-in defense against these
  plant pests

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Practical Applications in the Field

• Herbicide Resistance resistant to glyphosate

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Practical Applications in the Field

• Safe Storage
• avidin-blocks the availability of biotin for
  insects
• Stronger fibers
• Enhanced Nutrition
• Golden rice that is genetically modified to
  produce large amounts of beta carotene

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Practical Applications in the Field

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

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Practical Applications in the Field

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

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Health and Environmental Concerns

• Human Health
• Allergens
• Environment
• Super weeds