Agricultural Biotechnology

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22 Οκτ 2013 (πριν από 3 χρόνια και 11 μήνες)

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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)

From a bacterium that
infects plants

Causes tumors

Used for dicots

Viruses

Specific for plant types

Used for monocots



Ti Plasmid


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

Effects of Treatment with Roundup

Roundup Ready Soybeans

Traditional Soybeans

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

3’
-
TACGGTCGCCTG
-
5’

5’
-
ATGCCAGCGGAC
-
3’

Sense

strand

Original Gene

Template

Antisense construct

5’
-
ATGCCAGCGGAC
-
3’

3’
-
TACGGTCGCCTG
-
5’

AUGCCAGCGGAC

mRNA

UACGGUCGCCUG

Antisense

product

mRNA cannot be translated

5’
-
AUGCCAGCGGAC
-
3’

mRNA

3’
-
UACGGUCGCCUG
-
5’

Antisense

product

Promoter

Promoter

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

Cytokines

Blood Clotting Factors

2.
Transgenic vegetables
as vaccines


Vaccine against
travelers diarrhea in
potatoes

3.
Pharmaceutical
delivery by
Rhizosecretion

Tested with jellyfish
protein

Plant Improvements

Textile, paper and wood products



1.
Changes to facilitate
manufacturing

Gene for biodegradable
plastic introduced into cotton

Bacteria producing blue dye

2.
Introduction of
herbicide resistance

Roundup Ready Cotton

3.
Resistance to pests

Bt cotton, Bt trees

Applying Your Knowledge

A.
Which plant has a gene for an altered amino acid
synthesis EPSPS enzyme?

B.
Which plant makes its own pesticide?

C.
Which plant provides beta
-
carotene, a precursor
to Vitamin A?

1.
Golden Rice

2.
Improved Oil Canola

3.
Roundup Ready Soybeans

4.
Bt corn

5.
Flavr
-
Savr Tomato

What Are the Concerns?