New Delhi, India
February 5, 2008
Source:
Ministry of the Environment
(India)
GM crops have been developed to incorporate various traits such
as insect pest resistance, herbicide tolerance, disease
resistance, altered nutritional profile, enhanced storage life
etc. The benefits of their use include increased crop yields,
reduction in farm costs and thereby increase in farm profit as
well as protection of the environment. Research is focused on a
second generation of GM crops that feature increased nutritional
and/or industrial traits such as easy processability. These
varieties are expected to bring in more direct benefits to
consumer such as correction of dietary deficiencies. The range
of crops being targeted for genetic improvement include several
commercially important crops such as maize, soybean, tomato,
cotton, potato, mustard, rice etc.
The transgenic crop show different traits like pest resistance,
herbicide resistance, cold tolerance, drought tolerance,
increased nutrition and plant pharmaceuticals. Its potential
benefits are mainly in improved farming with cheaper food and
more food. This helps in availability of more crops, better
quality products, improvement in health and reduced use of
chemicals and herbicides.
INSECT RESISTANCE
Insect pest menace is one of the major factors that destabilize
crop productivity. Insects have been known to damage the crops
in the field and during storage. Crop productivity is under
constant threat of pest and disease incidence all over the
globe. Biotechnology has opened up new avenues for natural
protection for plants by providing new biopesticides, such as
microorganisms, that are toxic to targeted crop pests but do not
harm humans, animals, fish, birds or beneficial insects.
One of the best-known examples is that of commonly found soil
bacterium Bacillus thuringiensis. The spores of Bacillus
thuringiensis (Bt) contain a crystalline protein (cry), which
breaks down to release a toxin, known as deltaendotoxin, is
highly toxic to lepidopteran larvae. Different cry genes, which
are known as Bt genes have been identified cloned and
characterized.
HERBICIDE TOLERANCE
Good planting conditions for crops also sustain weeds that can
reduce crop productivity as they compete for the same nutrients
the desired plant needs. To prevent this, herbicides are sprayed
over crops to eliminate the undesirable weeds. As the crop
plants themselves are affected by a high concentration of
herbicides, these herbicides are required to be applied several
times during the growth cycle leading to not only increased
expenditure to the farmers but also harmful effects to the
environment. Further, many effective broad spectrum herbicides
do not distinguish between weeds and crops. Crop plants can be
modified to make them resistant to herbicides, so as to
eliminate weeds more selectively. For example-GM cotton and
soyabean resistant to herbicide Roundup TM have been developed.
Genes that provide resistance to other herbicides such as
sulfonyl ureas, gluphosinates etc. have also been identified and
transferred to produce various GM plants. When the herbicide is
sprayed, it will kill the weeds but have no effect on the crop
plants. Therefore, the herbicide can be applied in a single dose
or a fewer doses of higher concentration. For example,
genetically modified soyabean of Monsanto requires only one
application of weed killer “Roundup” instead of multiple
applications, reducing farming cost and environmental damage.
DISEASE RESISTANCE
Plants are susceptible to viral, bacterial and fungal diseases.
Much progress has been made in evolving GM plants resistant to
viruses. For example, expression of a gene that encodes the coat
protein of tobacco mosaic virus (TMV) in GM tobacco plants has
been shown to enable the plants to resist TMV infection. A
number of other viral resistant plant species have been
developed including squash and potatoes.
PRODUCT QUALITY IMPROVEMENT
There are several areas where GM techniques are being applied to
improve product quality as well as improved nutritional profiles
such as Improved flavour, Increased shelf life, High nutritional
value Greater processability and Changes in composition. One of
the most successful and initial research efforts to change the
characteristics of a plant product was carried out with
tomatoes. Tomatoes need to be picked while still green so that
they are firm enough to withstand mechanical handling and
transport. GM tomatoes have been developed that have normal
color and flavor but they soften more slowly and can be picked
and processed after they are ripe. They also have higher content
of soluble solids and are, therefore, better than normal
tomatoes for further processing.
Improvement in nutritional characteristics includes increasing
the contents of vitamins, minerals and other micronutrients,
modifying fats and oils, altering the starch and sugar content
or protein/amino acid profiles etc. Transgenic lines of potato
with increased levels of starch have been developed by
introducing a gene from bacteria for enhancing starch
biosynthesis.
Rice with enhanced level of beta carotene (the precursor of
vitamin A) and iron are being developed to address the problems
of vitamin A deficiency.
RESISTANCE TO ENVIRONMENTAL STRESSES
Crops plants need to cope up with abiotic stresses such as
drought, cold, heat and soils that are too acidic or saline to
support plant growth. While plant breeders have successfully
incorporated genetic resistance to biotic stresses such as
diseases into many crop plants through cross breeding, their
success at creating crops resistant to abiotic stresses has been
more limited, largely because few crops have close relatives
with genes for resistance to environmental stresses.
Therefore crop biotechnology is being increasingly used to
develop crops that can tolerate difficult growing conditions.
For example, researchers have genetically modified tomato and
canola plants that tolerate salt levels 300 percent greater than
non-genetically modified varieties. Other researchers have
identified many genes involved in cold, heat and drought
tolerances found naturally in some plants and bacteria and are
trying to incorporate them in crops.
PLANT BASED PHARMACEUTICALS
Plants are among the most efficient bioreactors, which produce
quantities of material with sunlight, and soil based nutrients
as inputs. Attempts are being made to replace the traditional
fermentation procedure for the production of biopharmaceuticals
to plant based production. The benefits of using plants are the
ability to increase production at low cost by planting more
acres, rather than building fermentation capacity, lower capital
and operating cost, simplified downstream processing etc.
Therapeutic drugs to treat cancer, infectious diseases,
autoimmune deficiencies, cardiovascular diseases and several
vaccines can potentially be grown in plants. Transgenic
technology is being used to produce a plant that will generate a
seed that expresses a desired therapeutic protein. This seed can
propagate under the right growing conditions to yield plants and
seed stock for producing the desire protein. The desired protein
can be extracted from the seed to make a biopharmaceutical.
Plant based therapeutics are expected to be highly cost
effective.
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