Transgenic technology

kettleitchyΒιοτεχνολογία

5 Δεκ 2012 (πριν από 8 χρόνια και 7 μήνες)

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Transgenic technology


Transgenic technology


Breeding method


Crop Improvement

Problems in Agriculture

1.
Quantity

2.
Quality

3.
Stress Environment

4.
Public acceptance

Important Traits


High crop yield


High nutritional quality


Abiotic stress tolerance


Pest resistance


Adaptation to inter
-
cropping


Nitrogen Fixation

Insensitivity to photo
-
period


Elimination of toxic compounds


Biotech goes global

Wide range of crops

57 fruits, vegetables, field crops and other plants


ranging from lab
trials to commercial production

14 Vegetables

Broccoli

Cabbage

Carrot

Cauliflower

Cucumber

Eggplant

Lettuce

Onion

Pea/Bean

Pepper

Potato

Spinach

Squash

Tomato

16 Fruits

Apple

Banana

Cantaloupe

Cherry

Citrus

Coconut

Grape

Kiwi

Mango

Melon

Papaya

Pineapple

Plum

Raspberry

Strawberry

Watermelon

16 Field Crops

Alfalfa

Barley

Canola

Cassava

Clover

Cotton

Flax

Maize

Rice

Safflower

Sorghum

Soybean

Sugar Beet

Sugar Cane

Sunflower

Wheat

11 other crops

Chicory

Cocoa

Coffee

Garlic

Lupins

Mustard

Oil Palm

Oilseed Poppy

Olive

Peanut

Tobacco

Field Crops by Country

FIELD CROPS
by COUNTRY
Soybean
Cotton
Maize
Canola
Sugar beet
Rice
Flax
Wheat
Sugar cane
Barley
Alfalfa
Cassava
Sunflower
Clover
Safflower
Sorghum
Canada
P
A
P
P
A
A
A
F
F
F
F
F
F
United States
P
P
P
P
A
A
A
F
F
F
F
F
Australia
a
P
a
a
a
F
F
F
F
West Europe
(15/15)
a
F
P
a
F
F
F
F
F
F
Argentina
P
P
P
F
F
L
L
F
F
Mexico
A
P
F
F
F
F
F
China
F
P
F
L
L
F
L
L
L
Japan
a
a
a
a
a
F
L
South Africa
P
P
P
F
F
Brazil
P
F
F
F
F
L
South Korea
a
a
Indonesia
F
a
F
L
L
L
Uruguay
P
P
Egypt
A
F
A
F
F
L
East Europe
(7/12)
P
A
F
India
P
F
L
Colombia
P
L
Philippines
P
L
Paraguay
P
Chile
p
p
Honduras
A
Belize
F
F
F
Cuba
L
L
F
Thailand
F
F
L
Venezuela
L
L
F
Zimbabwe
F
F
Bolivia
F
F
Costa Rica
L
F
New Zealand
F
Malaysia
L
Pakistan
L
L
commercial Production
P
Morocco
L
regulatory Approval
A
Bangladesh
L
Field study
F
Kenya
L
Lab / greenhouse
L

Herbicide Resistance


Insect Resistance




Virus Resistance



Delayed Fruit Ripening

The big five successful traits

Hot Issue

1.
Genetically Modified Food

2.
Golden Rice

3.
Molecular Farming

Roundup Ready™ Soybeans

A problem in agriculture is the reduced growth of crops imposed by the
presence of unwanted weeds. Herbicides such as Roundup
TM

and Liberty
Link
TM

are able to kill a wide range of weeds and have the advantage of
breaking down easily. Development of herbicide resistant crops allows the
elimination of surrounding weeds without harm to the crops
.

a)
Glyphosate Resistance


i.

Glyphosate = “Roundup”, “Tumbleweed” = Systemic herbicide

ii.
Marketed under the name Roundup, glyphosate inhibits the enzyme EPSPS
(S
-
enol
p
yruvl
s
hikimate
-
3
p
hosphate


involved in chloroplast amino acid
synthesis)
, makes aromatic amino acids.

iii.
The gene encoding EPSPS has been transferred from glyphosate
-
resistant E.
coli into plants, allowing plants to be resistant.



Glufosinate Resistance

i.

Glufosinate (the active ingredient being phosphinothricin) mimics the structure
of the amino acid glutamine, which blocks the enzyme glutamate synthase.

ii.
Plants receive a gene from the bacterium Streptomyces that produce a protein
that inactivates the herbicide
.

Herbicide Resistance

c)
Bromoxynil Resistance


i.
A gene encoding the enzyme bromoxynil nitrilase (BXN) is
transferred from
Klebsiella pneumoniae

bacteria to plants.

ii.
Nitrilase inactivates the Bromoxynil before it kills the plant.

d) Sulfonylurea
.


i.
Kills plants by blocking an enzyme needed for synthesis of the
amino acids valine, leucine, and isoleucine.

ii.
Resistance generated by mutating a gene in tobacco plants,
and transferring the mutated gene into crop plants.


Herbicide Resistance

Insect Resistance

Corn hybrid with a
Bt

gene


Corn hybrid susceptible to European
corn borer

Various insect resistant crops have been produced. Most of
these make use of the Cry gene in the bacteria
Bacillus
thuringiensis (Bt)
; this gene directs the production of a protein
that causes paralysis and death to many insects
.



Insect resistance


Anti
-
Insect Strategy
-

Insecticides

a) Toxic crystal protein from
Bacillus thuringensis


Toxic crystals found during sporulation


Alkaline protein degrades gut wall of lepidopteran larvae


Corn borer catepillars


Cotton bollworm catepillars


Tobacco hornworm catepillars



Gypsy moth larvae


Sprayed onto plants


but will wash off


The Bt toxin isolated from
Bacillus thuringiensis

has been
used in plants. The gene has been placed in corn, cotton,
and potato, and has been marketed.

b) Plant protease inhibitors have been explored since the
1990s:

i.
Naturally produced by plants, are produced in response
to wounding.

ii.
They inhibit insect digestive enzymes after insects
ingest them, causing starvation.

iii.
Tobacco, potato, and peas have been engineered to
resist insects such as weevils that damage crops while
they are in storage

iv.
Results have not been as promising as with Bt toxin,
because it is believed that insects evolved resistance to
protease inhibitors.

Insect resistance


Papaya infected with the papaya
ringspot virus

Virus resistance gene
introduced

Virus Resistant Crops

The Freedom II squash has a
modified coat protein that confer
resistance to zucchini yellows
mosaic virus and watermelon
mosaic virus II.

Scientists are now trying to develop
crops with as many as five virus
resistance genes

a)
Chemicals are used to control the insect vectors of viruses, but
controlling the disease itself is difficult because the disease spreads
quickly.

b)
Plants may be engineered with genes for resistance to viruses,
bacteria, and fungi.

c)
Virus
-
resistant plants have a viral protein coat gene that is
overproduced, preventing the virus from reproducing in the host
cell, because the plant shuts off the virus’ protein coat gene in
response to the overproduction.

d)
Coat protein genes are involved in resistance to diseases such as
cucumber mosaic virus, tobacco rattle virus, and potato virus X.

Virus resistance


e)
Resistance genes for diseases such as fungal rust disease and
tobacco mosaic virus have been isolated from plants and may be
transferred to crop plants.


f)
Yellow Squash and Zucchini



Seeds are available that are resistant to watermelon mottle virus,
zucchini yellow mosaic virus, and cucumber mosaic virus.

g) Potato
.


a)

Monsanto developed potatoes resistant to potato leaf roll virus and potato virus X,
which also contained a Bt toxin gene as a pesticide.

b)

hain restaurants do not use genetically engineered potatoes due to public pressures.

h) Papaya


Varieties resistant to papaya ring spot virus have been developed.

Virus resistance


First biotech plant product


Flav’r Sav’r
tomato


“Rot
-
Resistant Tomato”


Anti
-
sense gene


complementary to polygalacturonase (PG)


PG = pectinase


accelerates plant decay/rotting


a)
Allow for crops, such as tomatoes, to have a higher shelf life.

b)
Tomatoes generally ripen and become soft during shipment to a
store.

c)
Tomatoes are usually picked and sprayed with the plant hormone
ethylene to induce ripening, although this does not improve taste

d)
Tomatoes have been engineered to produce less ethylene so
they can develop more taste before ripening, and shipment to
markets.


Delayed Fruit Ripening


Plant Biotechnology Revolution:


Genetically Engineered Foods
.



Foods that contain an added gene sequence


Foods that have a deleted gene sequence


Animal products from animals fed GM feed


Products produced by GM organisms




1.
More than 60% of processed foods in the United States contain
ingredients from genetically engineered organisms.

2.
12 different genetically engineered plants have been approved in the
United States, with many variations of each plant, some approved
and some not.

3.
Soybeans.

a)
Soybean has been modified to be resistant to broad
-
spectrum
herbicides.

b)
Scientists in 2003 removed an antigen from soybean called P34
that can cause a severe allergic response.

4.
Corn

a)
Bt insect resistance is the most common use of engineered corn,
but herbicide resistance is also a desired trait.

Plant Biotechnology Revolution:


Genetically Engineered Foods
.


4.
Corn

a)
Bt insect resistance is the most common use of engineered corn, but herbicide resistance
is also a desired trait.

b)
Products include corn oil, corn syrup, corn flour, baking powder, and alcohol.


c)
By 2002 about 32% of field corn in the United States was engineered.

5.
Canola.

a)
More than 60% of the crop in 2002 was genetically engineered; it is found in many
processed foods, and is also a common cooking oil.

6.
Cotton.

a)
More than 71% of the cotton crop in 2002 was engineered.

b)
Engineered cottonseed oil is found in pastries, snack foods, fried foods, and peanut
butter.

7.
Other Crops



Other engineered plants include papaya, rice, tomato, sugar beet, and red heart
chicory.

Plant Biotechnology Revolution:


Genetically Engineered Foods


Normal rice

“Golden” rice

Golden Rice

Transgenic technology produced a type of rice that accumulates
beta
-
carotene in rice grains. Once inside the body, beta
-
carotene is
converted to vitamin A.

“Normal” rice

Golden Rice

1.
More than one third of the world’s population relies on rice as a food
staple, so rice is an attractive target for enhancement.

2.
Golden Rice was genetically engineered to produce high levels of
beta
-
carotene, which is a precursor to vitamin A. Vitamin A is needed
for proper eyesight.

3.
Biotechnology company Syngenta, who owns the rights to Golden
Rice, is exploring commercial opportunities in the United States and
Japan. Monsanto will provide licenses to Golden Rice technology
royalty
-
free.

4.
Other enhanced crops include iron
-
enriched rice and tomatoes with
three times the normal amount of beta
-
carotene

Plant Biotechnology Revolution:

Nutritionally Enhanced Plants


Pharmaceutical Production in Plants

Genetically

modified

plants

have

been

used

as

“bioreactors”

to

produce

therapeutic

proteins

for

more

than

a

decade
.

A

recent

contribution

by

transgenic

plants

is

the

generation

of

edible

vaccines
.



Edible

vaccines

are

vaccines

produced

in

plants

that

can

be

administered

directly

through

the

ingestion

of

plant

materials

containing

the

vaccine
.

Eating

the

plant

would

then

confer

immunity

against

diseases
.

Edible

vaccines

produced

by

transgenic

plants

are

attractive

for

many

reasons
.

The

cost

associated

with

the

production

of

the

vaccine

is

low,

especially

since

the

vaccine

can

be

ingested

directly,

and

vaccine

production

can

be

rapidly

up

scaled

should

the

need

arises
.

Edible

vaccine

is

likely

to

reach

more

individuals

in

developing

countries
.


The

first

human

clinical

trial

took

place

in

1997
.

Vaccine

against

the

toxin

from

the

bacteria

E
.
coli

was

produced

in

potato
.

Ingestion

of

this

transgenic

potato

resulted

in

satisfactory

vaccinations

and

no

adverse

effects
.

1.
A new field where plants and animals are genetically
engineered to produce important pharmaceuticals, vaccines,
and other valuable compounds.


2.
Plants may possibly be used as bioreactors to mass
-
produce
chemicals that can accumulate within the cells until they are
harvested.

3.
Soybeans have been used to produce monoclonal antibodies
with therapeutic value for the treatment of colon cancer. Drugs
can also be produced in rice, corn, and tobacco plants

4.
Plants have been engineered to produce human antibodies
against HIV and Epicyte Pharmaceuticals has begun clinical
trials with herpes antibodies produced in plants.

Plant Biotechnology Revolution:

Molecular Farming


5. Edible Vaccines


a)
People in developing countries have limited access to many
vaccines.

b)
Making plants that produce vaccines may be useful for
places where refrigeration is limited.

c)
Potatoes have been studied using a portion of the
E. coli

enterotoxin in mice and humans.

d)
Other candidates for edible vaccines include banana and
tomato, and alfalfa, corn, and wheat are possible
candidates for use in livestock.

e)
Edible vaccines may lead to the eradication of diseases
such as hepatitis B and polio.

Plant Biotechnology Revolution:

Molecular Farming


One

focus

of

current

vaccine

effort

is

on

hepatitis

B,

a

virus

responsible

for

causing

chromic

liver

disease
.

Transgenic

tobacco

and

potatoes

were

engineered

to

express

hepatitis

B

virus

vaccine
.

During

the

past

two

years,

vaccines

against

a

E
.
coli

toxin,

the

respiratory

syncytial

virus,

measles

virus,

and

the

Norwalk

virus

have

been

successfully

expressed

in

plants

and

delivered

orally
.

These

studies

have

supported

the

potential

of

edible

vaccines

as

preventive

agents

of

many

diseases
.


Edible Vaccines

There

is

hope

to

produce

edible

vaccines

in

bananas,

which

are

grown

extensively

throughout

the

developing

world
.


a)
Plant seeds may be a potential source for plastics that could be
produced and easily extracted.

b)
A type of PHA (polyhydroxylalkanoate) polymer called “poly
-
beta
-
hydroxybutyrate”, or PHB, is produced in Arabidopsis, or
mustard plant.

c)

PHB can be made in canola seeds by the transfer of three
genes from the bacterium Alicaligenes eutrophus, which codes
for enzymes in the PHB synthesis pathway.

d)
Monsanto produces a polymer called PHBV through Alicaligenes
fermentation, which is sold under the name Biopol.

Plant Biotechnology Revolution:

Biopolymers and Plants

Areas of ongoing debate


Environment


Human Health


Food security


Socio
-
economic concerns

Environment


Loss of biodiversity


Cross
-
pollination


Emergence of superweeds
and superbugs


Potential increase in use
of herbicides


Need to increase yields to
feed growing population


Possibility of reducing
need for pesticides,
fertilizers


Grow more food on same
amount of land

Anti
-
GM

Pro
-
GM

*Opinions are generalized, and not all opponents or
proponents may hold all of these views.

Human Health


Fear of unknown allergens


Spread of anti
-
biotic
resistance


Inadequate regulation of
new products


Greater regulations than
other foods


Potential benefits to
nutrition


golden rice


enhanced protein content
in corn


soybean oil with less
saturated fat

Anti
-
GM

Pro
-
GM

Food Security


Need redistribution, not
just more


Farmers will not be able to
afford expensive seed


Developing countries
should not have to eat the
food others reject


Modified seeds will allow
farmers to grow more to
feed their family and to
sell, reducing the need for
food aid


Public
-
private cooperation
can transfer technology

Pro
-
GM

Anti
-
GM

Socio
-
economic concerns


Corporations benefit, not
those in need


Products needed in
developing countries are
not being developed
because the market is not
profitable


It is wrong to patent life


Patents needed because
new strains are intellectual
property


Publicly funded research
can benefit the public good