Download Plant Biotechnology

Chapter 6
Plant Biotechnology
Plant Structure
Plant Structure
CO2 + H2O →C6H12O6 + O2
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
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
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
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
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
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)
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
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
Methods Used in Plant
Transgenesis
RNA Interference (RNAi)
• Inhibits gene expression by
interfering with transcription
or translation of RNA
molecules
RNAi video and animations
Practical Applications in the Field
Vaccines for Plants
• Contain dead or weakened
strains of plant viruses to turn
on the plant’s immune system
• Transgenic plants express viral
proteins to confer immunity
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
Practical Applications in the Field
Herbicide Resistance –resistant to glyphosate
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
Practical Applications in the Field
The Future: From Pharmaceuticals to Fuel
• Plant-based petroleum for fuels, alternatives
to rubber, nicotine-free tobacco, etc
Practical Applications in the Field
Metabolic Engineering
• Manipulation of plant biochemistry to produce
nonprotein products or to alter cellular
properties
Health and Environmental
Concerns
Human Health
• Allergens
Environment
• Super weeds