Applications of Ag Biotech - mcvsd

exultantmynabirdBiotechnology

Dec 14, 2012 (4 years and 4 months ago)

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Applications of Ag Biotech



Ag Biotech is applied to help
combat the problems that the
agricultural industry faces,
including but not limited to:



pathogen damage



insect damage



competition with weeds



increased need for
growing population



climate constraints



nutritional value

Plant Pathogens



Humans have dealt with crop
diseases (various pathogens) for
hundreds of years



Example: potato famine (mid
-
1800s in Ireland)



Disease called
potato blight

caused by
Phyophthora infestans

(fungus) almost wiped out all of
Ireland’s potato crop (sole food
source)



Over 1 million people starved to
death and over 2 million
emigrated

Disease
-
Resistance



Introducing genes from other
plants or bacteria encoding
enzymes like
chitinase

or
glucanase
, which break down
chitin or glucan (essential
components of fungal cell walls)



Introducing plant genes to
enhance innate plant defense
mechanisms



Invoking the hypersensitive
reaction (similar to allergic
reaction)

Hypersensitive Reaction



Plants varieties that are
naturally

resistant to specific
types of fungal diseases are often
programmed to have individual
cells quickly die at the site of
fungal infection



This response, known as the
hypersensitive reaction
,
effectively stops an infection in
its tracks



Thus, genetic engineering can
help plant cells 'know’ when a
fungus is attacking

Viral Infections



Viruses cause many
economically important plant
diseases



Beet necrotic yellow vein
virus

(BNYVV) causes sugar
beets to have smaller, hairier
roots, reducing yields by up to
50 percent



The spread of most viruses is
very difficult to control



Once infection sets in, no
chemical treatment methods
are available

Disease
-
Resistance



Insert a gene into several
crops to give plants resistance
to viral infections which
causes protein coating on
outside of virus



Example: tobacco mosaic
virus (TMV) and tobacco
plants (works like a vaccine
-

stimulating the plant’s natural
defenses against disease)




Plant vaccines to protect against reduced growth rate, poor
crop yield, and low crop quality



Disease
-
resistant papayas in Hawaii (Papaya Ringspot Virus)

Insect Pests



It is estimated that about
40%

of world’s food supply is lost to
pests, diseases, & spoilage



An effective way of controlling
insects is to interrupt their life
cycle (reproduction)



Male insects treated with
radiation to make them sterile



Release them over infected area,
so mating occurs but no offspring



Boll weevils eradicated from
South this way

Pesticides



Pesticides are usually the
answer to insect problems



Major problem with those
using chemical pesticides,
besides expense, is getting
chemicals to where insect pest is
invading plant



Topical application only
protects most leaves (not roots
& stem)



Certain pesticides called
systemics

are taken into the
plant

Systemic Pesticides



Expensive



May not take up enough to be
effective



May leave residue in edible
portions of plant



Increased
withdrawal
period

(time from application
of pesticide to harvest required
to render produce safe to eat)

European corn borer



Causing damage to corn
crops



Larvae burrow into
cornstalks and cause severe
damage to the plant



Topical sprays cannot reach
insect since it is hidden and
protected by being inside



Biotech has helped create
corn plants with Bt gene that
are toxic to borer (protecting
plant)

Insect
-
Resistance



Bacillus thuringiensis

(Bt) is a
soil
-
borne bacterial species
discovered in 1911 that acts as a
natural pesticide



It produces a toxin that kills
harmful insects & larvae by
disrupting their digestive
process



Nontoxic to mammals & birds

Uses of Bt



Spread bacterial
spores across field in
order to protect without
using chemicals



Now plants can have
Bt gene built in
(tobacco, tomato, corn,
& cotton)



Widespread use of Bt
gene is success and
controversy

Benefits of Bt Crops



Saves millions of
dollars in pesticides



Cleaner
environment



Reduced labor costs



Reduced fuel
expenses



Reduced machinery
operating costs

Benefits of Bt Crops



Reduction of
mycotoxins

(poisons
produced by fungi that
grow on crops)



Less insect damage
causes less access for
fungi to plant



Bt toxins kill fungus
that produces
mycotoxins

Drawbacks of Bt Crops



Currently, there are
millions of acres of Bt
crops, but many large
obstacles still stand in the
way



Consumer acceptance



Bt toxin harmful to
monarch butterflies
(although in reality, few
butterflies are exposed to
enough pollen to cause
harm)

Weeds



Weeds compete with crops for
nutrients, space, & sunlight
causing slowed growth &
production



Weeds may also harbor insects &
disease organisms that can spread
to crops (control of insects &
disease is more difficult)



Weeds cause impurities in agricultural products (can be
poisonous to livestock, difficult to sort out, cotton picked
amongst weeds will have lint
-

decreased profit)

Herbicides



Herbicides developed that were
effective against killing weeds, but
some crop plants also killed



Nonselective herbicides

kill all
plants they are applied to & most
often used where all vegetation is to
be killed



Selective herbicides

only kill
certain types of plants (ex
-

broadleaf
plants, grasses, etc…)



Any application of herbicides can
be expensive (machinery, fuel, labor
costs)

Herbicide Resistance



Crops can be genetically
engineered to be resistant
to common herbicides
such as
glyphosate

(works by blocking
enzyme required for
photosynthesis)



Transgenic crops produce alternate enzyme not affected by
glyphosate (successful in soybeans)



Farmers with herbicide
-
resistant crops control weeds with
milder chemicals (more friendly to environment)

Roundup



Roundup

is a nonselective
herbicide effective at killing a wide
variety of unwanted vegetation,
relatively inexpensive,
environmentally safe



Roundup uses glyphosate, which
works by stopping the action of an
enzyme that serves a vital role in
the production of essential amino
acids to plants

Roundup



Scientists have genetically
engineered corn, cotton, canola,
and soybeans tolerant of Roundup
and like herbicides



Inserted genetic material that
allows other means of producing
essential amino acids (alternate
pathway)



Animals are not affected by
glyphosate



EPA rated Roundup as
“essentially nontoxic”