Transcript Agricultural Biotechnology

Agricultural Biotechnology
Altering Genes in Plants to
Fight Pests and Improve Nutrition
Unique Methods for Plants
Entire plants can be cultivated from
a single non-reproductive cell
Add gene
cell with
new gene
mass of
cells
(callus)
new plant
Unique Methods
for Plants
Rhizosecretion
 Transgenic plant
grown in water
 Expression of
gene in root cells
 Secretion of gene
product into
surrounding
medium
Tools of Agricultural
Biotechnology
Vectors
Ti plasmid
(tumor inducing)
Viruses
From a bacterium that
infects plants
Causes tumors
Used for dicots
Specific for plant types
Used for monocots
Ti Plasmid
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Tumor-inducing plasmid
from bacteria that integrates
into plant DNA
Tumor-inducing genes
removed
Insertion genes retained
Foreign genes positioned
after bacterial promoter
Antibiotic resistance gene
as marker
Clarification Pause
• With a partner, identify differences
in biotechnological methods used
for plants and animals
– items to consider
• gene delivery
• transgenic organisms
• gene expression
• collection of the gene product
Plant Improvements
Resistance
to Pests
Bt Corn: Produces
its own Pesticide
Insect
pests
Gene for Bt toxin inserted into plants
Bt = Bacillus thuringiensis
Bt toxin = crystals that dissolve
connections between cells in insect gut
Plant Improvements
Resistance to Pests
Viruses •Ti plasmid carrying genes for viral
capsid proteins into tomato and
tobacco plants
•Mechanism of protection against
viruses is unclear
•Possibilities:
•viral protein blocks replication
•viral proteins bind cellular
receptors
Plant Improvements
Resistance to Herbicides
Glyphosate
(Roundup)
Insert gene for mutant EPSPS
enzyme that is less sensitive to
Roundup
EPSPS = enzyme needed to
synthesize amino acids essential
for growth
Use of Ti plasmid to transfer
gene
Roundup Ready Soybeans
Traditional Soybeans
Effects of Treatment with Roundup
Plant Improvements
Improved Food Quality
Improved
Handling and
Storage
Flavr-Savr Tomato
Potato that Resists Bruising
Flavr-Savr Tomato
softens more slowly
after ripening
Plant Improvements
Improved Food Quality
Flavr- Savr
Tomato
•Interference with the production of the enzyme
polygalacturonase (polyGal) by antisense
technology
•antisense sequence to polyGal mRNA is
produced
•antisense sequence binds to polyGal mRNA
and blocks production of the enzyme
•Vector also contains antibiotic resistance to
kanamycin as marker
Antisense Technology
Blocks the expression of a gene by producing
a product that combines with mRNA from the gene
Promoter
Original Gene
Sense
strand
mRNA
Promoter
Template
Antisense construct
3’-TACGGTCGCCTG-5’
5’-ATGCCAGCGGAC-3’
5’-ATGCCAGCGGAC-3’
3’-TACGGTCGCCTG-5’
5’-AUGCCAGCGGAC-3’
3’-UACGGUCGCCUG-5’
mRNA
AUGCCAGCGGAC
UACGGUCGCCUG
mRNA cannot be translated
Antisense
product
Antisense
product
Plant Improvements
Improved Food Quality
Nutrient
Enhanced
Foods
Rice with beta-carotene and extra
iron
Improved Protein Corn
Improved Oil Canola
“Golden” rice
Plant Improvements
Pharmaceutical Production in Plants
1. Soy and Corn seeds
for production and
storage of protein
products
2. Transgenic vegetables
as vaccines
Cytokines
Blood Clotting Factors
3. Pharmaceutical
delivery by
Rhizosecretion
Tested with jellyfish
protein
Vaccine against
travelers diarrhea in
potatoes
Plant Improvements
Textile, paper and wood products
1. Changes to facilitate Gene for biodegradable
plastic introduced into cotton
manufacturing
Bacteria producing blue dye
Roundup Ready Cotton
2. Introduction of
herbicide resistance
3. Resistance to pests Bt cotton, Bt trees
Applying Your Knowledge
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B.
C.
Golden Rice
Improved Oil Canola
Roundup Ready Soybeans
Bt corn
Flavr-Savr Tomato
Which plant has a gene for an altered amino acid
synthesis EPSPS enzyme?
Which plant makes its own pesticide?
Which plant provides beta-carotene, a precursor
to Vitamin A?
What Are the Concerns?