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MOLECULAR
FARMING
INTRODUCTION
Biotechnology in agriculture has two categories:
1. “Improvements” to existing livestock and
crops, and
2. Development of entirely new uses for both
animals and plants (biopharming).
“Improvements", include ‘input traits’ such as crops
with extra resistance to insect attack, improved
weed control, increase the plants tolerance to
cold, drought and other environmental factor.
Ex "Roundup ready" soya, "Starlite" corn, or "Frosttolerant" tomatoes.
MOLECULAR FARMING
• Molecular farming is a method used
to integrate a foreign gene into
plants.
• Molecular farming is the term for
new use plants only (not animals ) and
is different in that this does not
affect and has nothing to do with
Food.
• There are two types of Molecular
Farming: Medical and non-Medical.
Medical Molecular Farming
• The first synthesis of a
pharmaceutically-relevant protein,
human growth hormone, was described
in transgenic tobacco plants in 1986.
• Now, molecular farming has become
commercially interesting as a method
for the production of recombinant
pharmaceutical proteins, in particular
antibodies.
Non-Medical Molecular Farming
Non-Medical Molecular Farming includes
Industrial Enzymes and Polymers.
• Industrial enzymes: for example laccase
in transgenic maize,
• Technical proteins for research
purposes: for example avidin, which is
also produced in maize,
• Milk proteins such as human beta casein,
which is produced in transgenic
tomatoes,
• Protein polymers: collagens, which are
used for medical as well as industrial
purposes.
Next…
• Potentially the biggest development in
this field could be the development of
plants growing biodegradable plastics.
• Other uses could be as Industrial oils
such as hydraulic oil or highg yielding
biodiesels, new solid Biofuels, new
Fibres and Papers, and as agents for
Bioremediation and Phytoremediation,
environmentally cleaning up
contamination.
Types of Molecular Farming
WHY PLANTS?
• Plants are also very flexible and can
produce a wide variety of proteins.
• Crop plants can synthesize a wide
variety of proteins that are free of
mammalian toxins and pathogens.
• Crop plants produce large amounts of
biomass at low cost and require limited
facilities.
• Crops are therefore well suited for the
production of safe low-cost therapeutic
proteins.
Table Comparison of Expression Systems
Expressions
System
Yeast
Bacteria
Plant viruses
Transgenic
Plants
Animal Cell
Cultures
Transgenic
Animals
Cost of
maintaining
inexpensive
inexpensive
inexpensive
inexpensive
expensive
expensive
-2.0°C
-2.0°C
-2.0°C
RT*
N2**
N/A
Gene size
(protein)
restriction
Unknown
Unknown
Limited
Not limited
Limited
Limited
Production
cost
Medium
Medium
Low
Low
High
High
Protein yield
High
Medium
Very high
High
Medium to
high
High
Therapeutic
risk
Unknown
yes
Unknown
Unknown
yes
yes
Type of
storage
* RT – room temperature.
** N2 – culture must be maintained under nitrogen gas.
HOW IS IT DONE?
• Genetic enhancement is used to
introduce and express genes coding
for the high value proteins.
PRODUCTION OF BRYODIN IN
TOBACCO PLANT
• Tobacco plants that are able to produce
bryodin.
• This protein, which is produced in the
roots of bryonia, deactivates ribosomes
and is being tested for its effect
against HIV infection.
Plant Transformation
1.
2.
The plant leaf disc is dipped in
a solution of bacteria. The
bacterial "Trojan Horse"
infects the edges of the leaf
disc and in the process
integrates the pharmaceutical
protein gone into the plant
genome (pict 1).
After infection the discs are
placed on selection media that
a flows only plant cells that
carry the protein gene to
survive and regenerate into
plantlets. After about six
weeks on selection media, a
large number of plantlets that
carry the pharmaceutical
protein gene are visible at the
edges of the original leaf disc
(pict 2 & 3).
3. The plantlets are
removed from the
leaf disc and placed
in clear plastic boxes
that contain media
that allows them to
form roots (pict 4).
4. The rooted plantlets
are placed in pots
and plants are
allowed to grow and
produce seed. This
seed can then be
used for large scale
production of the
pharmaceutical
protein (pict 5).
Protein Trafficking
Following translation
of the molecular
ring gene, the
protein will move
through the
endoplasmic
reticulum and Golgi
apparatus for
processing, folding
and glycosylation.
Field Production
Low alkaloid plants
expressing the
pharmaceutical
protein gone can
then be produced in
the field. Following
harvest the tissue,
the protein
extracted for later
use.
PRODUCTION OF SPIDER
SILK PROTEINS IN PLANTS
Production of transgenic plants
Spider silk protein
Expression of spidroin-ELP-fusion
proteins in the ER of transgenic plants
Purification of spider silk-ELP
fusion proteins
From transgenic
plants SpidroinELP-fusions could
be purified by
addition of salt
and by heat to
95% purity.
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