Genetic engineering techniques like transgenesis allow for direct manipulation of crop genes to develop improved varieties. The process involves isolating a gene of interest, cloning it, designing it for plant transformation, and inserting it into a crop plant using methods like Agrobacterium or particle bombardment. This allows transfer of beneficial traits like pest/disease resistance, abiotic stress tolerance, and higher yields to address challenges like increasing food demand. Genetic diversity is important for crop adaptation to future environments, so conservation efforts are needed to preserve this diversity.

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Application of Genetic Engineering in Crop Improvement Through
Transgenesis
Introduction
Genetic engineering is the direct manipulation of an organism's genes using biotechnology. It is
a set of technologies used to change the genetic makeup of cells, including the transfer of genes
within and across species boundaries to produce improved or novel organisms. New DNA is
obtained by either isolating and copying the genetic material of interest using recombinant DNA
methods or by artificially synthesising the DNA. In the current scenario, the most critical
challenge faced by the human race is to provide food security for a growing population. By 2050,
the human population will reach 10 billion and to feed the world, global food production needs
to increase by 60–100%. Besides the growing population rate, extreme weather, reduced
agricultural land availability, increasing biotic and abiotic stresses are significant constraints for
farming and food production. Development of technologies that can contribute to crop
improvement can increase production to some extent. Genetic manipulation techniques using
physical, chemical and biological (T-DNA insertion/transposons) mutagenesis have contributed
majorly in studying the role of genes and identifying the biological mechanisms for the
improvement of crop species in the past few decades. For the past three decades, transgenic
techniques have been used to understand basic plant biology and also used for crop
improvement. However, the integration of transgenes into the host genome is non-specific,
sometimes unstable and is a matter of public concern when it comes to edible crop species. A
construct is usually created and used to insert this DNA into the host organism. The first
recombinant DNA molecule was made by Paul Berg in 1972 by combining DNA from the
monkey virus SV40 with the lambda virus. As well as inserting genes, the process can be used to
remove, or "knock out", genes. The new DNA can be inserted randomly, or targeted to a specific
part of the genome.Genetic modification for crop improvement. Genetic modification (GM) of
crops involves the transfer of genes for specific traits between distantly related plant species
using recombinant DNA technology known as transgenesis. Although there is a scientific
consensus that currently available food derived from GM crops poses no greater risk to human
health than conventional food, GM food safety is a leading concern with critics. Gene flow,
impact on non-target organisms, control of the food supply and intellectual property rights have
also been raised as potential issues. Even before the creation of transgenics, the alteration of
crops to improve their production was performed through selection. In fact, this selection has
been going on for thousands of years and only in the past few centuries has it become a dedicated
science onto itself. So, why has there been a push to switch from selection to the use of genetic
techniques (transgenics) to improve crops over the recent decades? Simply put, to manipulate
plants through selection takes many generations (i.e. large investments of time) and does not
always work. Through the use of transgenics, one can produce plants with desired traits and even

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increase yields to allow for more crops that last longer and withstand pests and disease. The
Flavr Savr was engineered to have a longer shelf life, but most current GM crops are modified to
increase resistance to insects and herbicides.
What is a Transgenic Crop?
A transgenic crop is a genetically modified organism (GMO). Transgenic indicates that a transfer
of genes has occurred using recombinant DNA technology [1]. Generally a transgenic crop
contains one or more genes that have been inserted artificially either from an unrelated plant or
from different species altogether.
Why do we use Transgenic Crops?
Plants have been modified for many reasons over the years but the most common purpose is to
produce the best products possible. Before recombinant DNA technology, it was possible to
produce some improved products, although it was very difficult to do and many things could not
be improved or changed. An improved product may involve changing the color or the size of a
plant, making it more appealing to the buyer’s eye. Or it may be more practical, allowing
increased tolerance to cold, frost, or drought; all making a crop easier to grow in a constantly
changing environment. Goals like these are unattainable with traditional selection programs and
thus transgenics is now preferred when trying to come up with new products to improve sales.
One of the hottest areas right now is the modification of crops to increase the resistance of plants
to insects and diseases they may carry. Improving resistance to these diseases and insects also
reduces the need for herbicides and pesticides. This makes the plants safer for the consumer and
allows the farmer to save money on chemicals. In conclusion, transgenic crops are an
economically safer method of producing crop products, which makes them appealing and
potentially profitable.
Climate Change and Its Impact on Plant Genetic Resources
The most profound and direct impacts of climate change over previous decade and the next few
decades will surely be on agriculture and food security. The effects of climate change will also
depend on current production conditions. The area where already being obstructed by other
stresses, such as pollution and will likely to have more adverse impact by changing climate.
Food production systems rely on highly selected cultivars under better endowed environments
but it might be increasingly vulnerable to climate change impacts such as pest and disease
spread. If food production levels decreases over the year, there will be huge pressure to cultivate
the crops under marginal lands or implement unsustainable practices that, over the long-term,
degrade lands and resources and adversely impact biodiversity on and near agricultural areas. In
fact, such situations have already been experienced by most of the developing countries. These
changes have been seen to cause a decrease in the variability of those genetic loci (alleles of a
gene) controlling physical and phenotypic responses to changing climate. Therefore, genetic
variation holds the key to the ability of populations and species to persist over evolutionary

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period of time through changing environments . If this persists, neither any organism can predict
its future (and evolutionary theory does not require them to) nor can any of those organisms be
optimally adapted for all environmental conditions. Nonetheless, the current genetic composition
of a crop species influences how well its members will adapt to future physical and biotic
environments.The population can also migrate across the landscape over generations. By
contrast, populations that have a narrow range of genotypes and are more phenotypically uniform
may merely fail to survive and reproduce at all as the conditions become less locally favorable.
Such populations are more likely to become extirpated (locally extinct), and in extreme cases the
entire plant species may end up at risk of extinction. For example, the Florida Yew (Torreya
taxifolia) is currently one of the rarest conifer species in North America. But in the early
Holocene (10,000 years ago), when conditions in southeastern North America were cooler and
wetter than today, the species was probably widespread. The reasons for that are not completely
understood, but T. taxifolia failed to migrate towards the northward as climate changed during
the Holocene. Today, it is restricted to a few locations in the Apalachicola River Basin in
southern Georgia and the Florida panhandle. As the T. taxifolia story illustrates, once plant
species are pushed into marginal habitat at the limitations of their physiological tolerance, they
may enter an extinction vortex, a downward cycle of small populations, and so on. Reduced
genetic variability is a key step in the extinction vortex. Gene banks must be better to respond to
novel and increased demands on germplasm for adapting agriculture to climate change. Gene
banks need to include different characteristics in their screening processes and their collections
need to be comprehensive, including what are now considered minor crops, and that may come
with huge impact on food baskets.
Genetic Engineering for crop improvement
Genetic engineering becomes a powerful technique that applicable for altering the genetic make
up of the crop plants. It is achieved through transgenic or recombinant DNA technology. The
crop plants having so many desired characters but due the presence of one or few unfavourable
characters makes the crop to limit in its area and production. This makes the farmers to
forcefully have to shift to other crops. And also to overcome the malnutritional problems facing a
huge mass of the people of the world, transgenic technology helps in mitigating this problem in
an effective manner. Recombinant technology is also helpful in solving the problems arising due
to biotic and abiotic stresses. To over come all these problems, transgenic technology helps to
transfer desired characters from various sources to required crop plants by identification and
isolating the gene of our interest. The technology of genetic modification trough transgenic
approach is more directed and the inserted genes can be easily followed. In contrast to green
revolution that only emphasis on three main crops (rice, wheat and maize) and produced
ambivalent results, the gene revolution represents a technical and ethical advance and can be use
to improve the characteristics of all targeted plants with significantly enhanced social impacts.
However, genetic engineering is not set to replace conventional plant breeding but is a modern
tool for use of plant breeders to fasten the breeding programme.

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The varieties of maize, tobacco, cotton etc., that are resistance to herbicide were developed by
transformation of plants with glyphosate resistant gene through Agrobacterium mediated
transformation. Transgenic technology yielded genetically modified (GM) crops having novel
genes with favourable characteristics like higher yields, herbicide resistant, insect and disease
resistant, drought resistant, salinity resistant, etc.
Depending upon their preference, there are three methods for transformation of the novel genes
are as follows:
 Biological method
 Mechanical method
 Chemical method
1. Biological method:
This method involves the use of biological systems for transformation of the desired gene or
genes.
 Agrobacterium mediated transformation: Agrobacterium remains on the preferred
mechanism to introduce exogenous genes into plant cells. One of the reasons for this is
the wide spectrum of plants that are susceptible to transformation by this bacterium.
 A modified T-DNA region of the Ti (Tumor inducing) plasmid in which the genes
responsible for tumor formation are removed and inserted the foreign novel gene by
genetic engineering.
 Viruses: Phages (Viruses that infect bacteria) and Tobacco Mosaic virus can be used as
vectors for transformation of genes into plant cells. The technique is still being
developed.
2. Mechanical method:
It includes the use of equipments for transformation of gene is as follows;
•Electrophoration: Is a process whereby electric pulses of high field strength are used to
reversibly permiabilise cell membranes to facilitate uptake of
DNA. Electrophoration has been successfully used for transforming plants in which efficient
regeneration of plants from protoplast is possible.
•Microinjection: In this case needles used for injecting DNA are with a diameter greater than
cell diameter. DNA (0.3 ml) solution is injected with conventional syringe into region of plant
which will develop into floral tillers fourteen days before meiosis.

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•Biolistic or Microprojectile for DNA transfer: This method involves bombardment of particles
carrying DNA or RNA of interest into target cells using high velocity transfer mechanism. This
method can be used for any plant cells, leaves, root sections, embryo seeds and pollens.
3. Chemical method: This method using polyethylene glycol and calcium phosphate for gene
transfer.
How are Transgenic Crops Made?
For many years plant breeding entailed the selection of the finest plants to get the best crops. In
those days, variation occurred through induced mutation or hybridization where two or more
plants were crossed. Selection occurred through nature, using a “selection of the fittest” concept,
where only the seeds best adapted to that environment succeeded. For example, farmers selected
only the biggest seeds with non-shattering seed heads, assuming these to be the best. Today,
scientists can not only select, but also create crops by inserting genes to make a seeds bare any
trait desired.
In order to make a transgenic crop, there are five main steps: extracting DNA, cloning a gene of
interest, designing the gene for plant infiltration, transformation, and finally plant breeding.
Figure: Overview of how transgenic crops are created.
To understand this process, one must first known a bit about DNA (deoxyribonucleic acids).
DNA is the universal programming language of all cells and stores their genetic information. It
contains thousands of genes, which are discrete segments of DNA that encode the information
necessary to produce and assemble specific proteins. All genes require specific regions in order
to be utilized (or expressed) by a cell. These regions include (see Figure 2):
1. A promoter region, which signals where a gene begins and it used to express the gene;

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2. A termination sequence, which signals the end of a gene;
3. And the coding region, which contains the actual gene to be expressed.
All these regions together allow a gene to create a protein. Once a gene is transcribed into a
protein, it can then function as an enzyme to catalyze biochemical reactions or as a structural unit
of a cell, both of which will contribute to the appearance of a particular trait in that organism.
Figure: Gene Regions.
All species are capable of turning DNA into protein through a process known as translation. This
capability makes it possible to artificially put genes from one organism into another-a process
generally termed transgenics. But just isolating random DNA and inserting it into another
organism is not practical. We must first know what particular segments of DNA, and in
particular what genes, to insert. Unfortunately, with reference to producing new crops, not much
is known about which genes are responsible for increased plant yield, tolerance to different
stresses and insects, color, or various other plant characteristics. Much of the research in
transgenics is now focused on how to identify and sequence genes contributing to these
characteristics.
Genes that are determined to contribute to certain traits then need to be obtained in a significant
amount before they can be inserted into another organism. In order to obtain the DNA
comprising a gene, DNA is first extracted from cells and put into a bacterial plasmid. A plasmid
is a molecular biological tool that allows any segment of DNA in be put into a carrier cell
(usually a bacterial cell) and replicated to produce more of it. A bacterial cell (i.e. E. coli) that
contains a plasmid can put aside and used over and over again to produce copies of the gene the
researcher is interested in, a process that is generally referred to as “cloning” the gene. The word
“cloning” referring to how many identical copies of the original gene can now be produced at
will. Plasmids containing this gene can be used to modify the gene in any way the researcher
sees fit, allowing novel effects on the gene trait to be produced .
Once the gene of interest has been amplified, it is time to introduce it into the plant species we
are interested in. The nucleus of the plant cell is the target for the new transgenic DNA. There
are many methods of doing this but the two most common methods include the “Gene Gun” and
Agrobacterium method.
The “Gene Gun” method, also known as the micro-projectile bombardment method, is most
commonly used in species such as corn and rice. As its name implies, this procedure involves

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high velocity micro-projectiles to deliver DNA into living cells using a gun. It involves sticking
DNA to small micro-projectiles and then firing these into a cell. This technique is clean and safe.
It enables scientists to transform organized tissue of plant species and has a universal delivery
system common to many tissue types from many different species1. It can give rise to un-wanted
side effects, such as the gene of interest being rearranged upon entry or the target cell sustaining
damage upon bombardment. Nevertheless, it has been quite useful for getting transgenes into
organisms when no other options are available.
The Agrobacterium method involves the use of a soil-dwelling bacteria known as Agrobacterium
tumefaciens, which has the ability to infect plant cells with a piece of its DNA. The piece of
DNA that infects a plant is integrated into a plants chromosome through a tumor-inducing
plasmid (Ti plasmid), which can take control of the plant’s cellular machinery and use it to make
many copies of its own bacterial DNA. The Ti plasmid is a large circular DNA particle that
replicates independently of the bacterial chromosome .
Figure : Transfer DNA on a plasmid in Agrobacterium
The importance of this plasmid is that it contains regions of transfer DNA (tDNA), where a
researcher can insert a gene, which can be transferred to a plant cell through a process known as
a floral dip. A floral dip involves dipping flowering plants into a solution of Agrobacterium
carrying the gene of interest, followed by the transgenic seeds being collected directly from the
plant. This process is useful in that it is a natural method of transfer and therefore thought of as a
more acceptable technique. In addition, Agrobacterium is capable of transferring large fragments
of DNA very efficiently without substantial rearrangements, followed by maintaining high
stability of the gene that was transferred . One of the biggest limitations of Agrobacterium is that
not all important food crops can be infected by this bacteria.
Significance of Genetic Conservation of Crop Plants
The growing population pressure and urbanization of agricultural lands and rapid modernization
in every field of our day-to-day activities that create biodiversity are getting too eroded in direct
and indirect way. For instance, land degradation, deforestation, urbanization, coastal
development, and environmental stress are collectively leading to large-scale extinction of plant
species especially agriculturally important food crops. On the other hand, system driven famine
such as, Irish potato famine and Southern corn leaf blight epidemic in USA are the two instances
of food crises caused by large-scale cultivation of genetically homogenous varieties of potato
and corn, respectively. Even after these historical events, the importance of PGR had only got

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popular recognition when the spread of green revolution across cultivated crops threatened the
conservation of land races. Green revolution technologies introduced improved crop varieties
that have higher yields, and it was hoped that they would increase farmers’ income.
Consequently, the Consultative Group of International Agricultural Researches (CIGAR)
initiated gene banks and research centers of domestication for conserving PGR in most of the
stable food crops around the world. Center for domestication: maize (Mexico), wheat and barley
(middle/near East and North Africa), rice (North China), and potatoes (Peru); for further
information see http://www.cigar.org/center/index.html.) The Food and Agriculture Organization
(FAO) supported the International Treaty on Plant Genetic Resources (ITPGR) and UN
supported the Convention on Biological Diversity (CBD) which are the international agreements
that recognize the important role of genetic diversity conservation. Such treaty still plays in
current and future food production as one of the major supremo.
Genetic diversity is the key pillar of biodiversity and diversity within species, between species,
and of ecosystems, which was defined at the Rio de Janeiro Earth Summit. However, the
problem is that modern crop varieties, especially, have been developed primarily for high
yielding potential under well endowed production conditions. Such varieties are often not
suitable for low income farmers in marginal production environments as they are facing highly
variable stress conditions. Land races or traditional varieties have been found to have higher
stability (adaptation over time) in low-input agriculture under marginal environments, thus, their
cultivation may contribute farm level resilience in face of food production shocks. This is
especially true in some part of Ethiopia where agroclimatic conditions are challenging,
technological progress is slow, and market institutions are poorly developed and have no
appropriate infrastructure. The goal of conservation genetics is to maintain genetic diversity at
many levels and to provide tools for population monitoring and assessment that can be used for
conservation planning. Every individual is genetically unique by nature. Conservation efforts and
related research are rarely directed towards individuals but genetic variation is always measured
in individuals and this can only be estimated for collections of individuals in a
population/species. It is possible to identify the genetic variation from phenotypic variation
either by quantitative traits (traits that vary continuous and are governed by many genes, e.g.,
plant height) or discrete traits traits that fall into discrete categories and are governed by one or
few major genes (e.g., white, pink, or red petal color in certain flowers) which are referred to as
qualitative traits. Genetic variation can also be identified by examining variation at the level of
enzymes using the process of protein electrophoresis. Further, genetic variations can also be
examined by the order of nucleotides in the DNA sequence.
Applications of Genetic Engineering in crop improvement
Transgenic breeding enables the transfer of genes across taxonomic boundaries unlike
conventional breeding where it is possible to transfer genes from closely related species only. It

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also offers new avenues of plant improvement in shorter period compared to conventional
breeding and new possibility of incorporating new genes without problems incompatibility.
1. Herbicide resistant: herbicides normally affect processes like photosynthesis or
biosynthesis of essential amino acids. Transformation of cereal cropswith Glyphosate
resistant gene (Glyphosate = herbicide). Herbicide tolerant (HT) soybean and canola are
released for commercial cultivation.
2. Insect resistant: the genes which responsible for the production of delta-endotoxine in
Bacillus thuringiensis is used as biological insecticide. Thetransgene Cry 1AC has been
transferred to many crops for example looper resistance in soybean, pod borer resistance in
groundnut, head borer resistance in sunflower, semi-looper resistance in castor etc. snowdrop
lectin gene from snow drop (Galanthus nivalis) was transferred to brassica and safflower for
aphid resistant.
3. Resistance against viral infection: coat protein gene from Tobacco Mosaic Virus (TMV)
was transferred to develop resistant varieties of crop plants.The resistant varieties developed
in crop plants like soybean for resistant to yellow mosaic virus, groundnut for resistant to
bud and stem necrosis, clump and stripe virus resistance, whereas in sunflower, resistance
developed for bud necrosis.
4. Resistance against bacterial and fungal pathogens: Chitinase genes was transferred to
crops like Brassica, Soybean, Sunflower, Sesame etc foralternaria leaf spot disease, where
Figure: Applications of Genetic Engineering in crop
improvement

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as in case of groundnut which was introduced against leaf spot and alternaria blight and in
castor for Botrytis resistance. Acetyl transferase gene was transferred for wildfire disease of
tobacco caused by pseudomonas syringae.
5. Improvement of the nutritional qualities in crop plants: The carotene gene has been
transferred from daphoddils to rice grains (Golden Rice) forincreasing Beta-carotene
content in grains and for solving the blindness in childerns. Antisense Fae 1 gene transferred
to Brassica napus and Brassica juncea for low erucic acid content and also for low linolenic
acid content in case of linseed. Antisense ricin gene transferred to castor for reduction of
ricin content and RCA endosperm in castor seeds. Antisense sterol desaturase/ + ac1
inserted into sunflower for developing high oleic acid containing types.
6. Improvement of crop plants against abiotic stresses: transcription factor genes, structural
genes, regulatory genes were introduced into the groundnut,soybean, Brassica juncea, B. napus
to develop drought and salinity tolerant types.
7. Development of transgenic male sterile lines: transgenic male sterile lines of safflower
Brassica juncea were developed through the transfer of
Barnase gene from Bacteria (Bacillus amyloliquefaciens).
8. A long term goal in agriculture is to introduce the genes (Nif genes) for nitrogen fixation in
crop plants.
There is a need to establish reliable protocols for genetic engineering of crop plants so that these
crops also could be brought under the umbrella of crops amenable for genetic engineering. This
technology also increased our capacity to reduce disease susceptible varieties and enhance the
efficiency of production. The greatest challenge in agriculture is to improve food grain
production and eradication of malnutritional problem in the developing countries and hopefully
this technique will be applied to the regions where food shortage is greatest. By knowing the
present problems of farmers and also health point of view, developing safe and efficient
transgenic plants is needed. For achieving these, there is need of intensifying research at national
and international levels to ensure that biotechnology leads to second revolution in agriculture,
which both productive and sustainable. Synergy between GM breeding and traditional plant
breeding needs to be further strengthened.
Presentstatus of transgenic crops
The first transgenic plant product marketed commercially was the well‐ known ‘Flavr Savr’
tomato which had been modified to contain reduced levels of the cell wall softening enzyme
polygalacturonase. Tomato purée with a similar type of modification has been on the market in
the UK since February 1996. Since that time, however, there has been a massive expansion in the

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growth of transgenic field crops, particularly maize, soybean, oilseed rape, and cotton, such that
in North America transgenic varieties now represent the majority of the acreage of these crops.
For example, it is now estimated that 70% of the Canadian oilseed rape crop in 1999 will be
genetically modified. Most of the varieties grown to date have been modified with genes for
herbicide or insect resistance, both of which provide a significant economic benefit for the
farmer. Material from these modified crops, particularly soybean and maize, is now imported
into the European Union in large quantities. However, in several European countries there is now
considerable consumer resistance to food products containing such GM constituents, either in the
native form or as processed derivatives (e.g. soya lecithin).
In the UK this resistance seems to be based primarily on a mistrust of the government regulatory
process, allied to a strong desire for choice (to date the commodity GM products have not been
segregated from their non‐ GM equivalent). These concerns have led to many retailers removing
GM soya and maize products from sale, though enzymes and vitamins from GM microbes
remain as common components of many foods and drinks. Pending the outcome of ‘farm scale’
trials designed to monitor the environmental impact of GM crops, there has been an associated
delay in the granting of permits for the growth of such crops for sale.
Figure : Present status of transgenic crops

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Advantages of Transgenic Plant:
1.Food supplies become predictable.
When crop yields become predictable, then the food supply becomes predictable at the same
time. This gives us the ability to reduce the presence of food deserts around the world, providing
a greater population with a well-rounded nutritional opportunity that may not have existed in the
past.
2. Nutritional content can be improved.
Genetic modifications do more than add pest resistance or weather resistance to GMO crops. The
nutritional content of the crops can be altered as well, providing a denser nutritional profile than
what previous generations were able to enjoy. This means people in the future could gain the
same nutrition from lower levels of food consumption. The UN Food and Agricultural
Organization notes that rice, genetically modified to produce high levels of Vitamin A, have
helped to reduce global vitamin deficiencies.
3. Genetically modified foods can have a longer shelf life.
Instead of relying on preservatives to maintain food freshness while it sits on a shelf, genetically
modified foods make it possible to extend food life by enhancing the natural qualities of the food
itself. According to Environmental Nutrition, certain preservatives are associated with a higher
carcinogen, heart disease, and allergy risk.
4. We receive medical benefits from GMO crops.
Through a process called “pharming,” it is possible to produce certain proteins and vaccines,
along with other pharmaceutical goods, thanks to the use of genetic modifications. This practice
offers cheaper methods of improving personal health and could change how certain medications
are provided to patients in the future. Imagine being able to eat your dinner to get a tetanus
booster instead of receiving a shot in the arm – that’s the future of this technology.
5. It creates foods that are more appealing to eat.
Colors can be changed or improved with genetically modified foods so they become more

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pleasing to eat. Spoon University reports that deeper colors in foods changes how the brain
perceives what is being eaten. Deeper red colors make food seem to be sweeter, even if it is not.
Brighter foods are associated with better nutrition and improved flavors.
6. Genetically modified foods are easierto transport.
Because GMO crops have a prolonged shelf life, it is easier to transport them greater distances.
This improvement makes it possible to take excess food products from one community and
deliver it to another that may be experiencing a food shortage. GMO foods give us the
opportunity to limit food waste, especially in the developing world, so that hunger can be
reduced and potentially eliminated.
7. Herbicides and pesticides are used less often.
Herbicides and pesticides create certain hazards on croplands that can eventually make the soil
unusable. Farmers growing genetically modified foods do not need to use these products as often
as farmers using traditional growing methods, allowing the soil to recover its nutrient base over
time. Because of the genetic resistance being in the plant itself, the farmer still achieves a
predictable yield at the same time.
DisadvantagesofTransgenic Plant
1.GMO crops may cause antibiotic resistance.
Iowa State University research shows that when crops are modified to include antibiotics and
other items that kill germs and pests, it reduces the effectiveness of an antibiotic or other
medication when it is needed in the traditional sense. Because the foods contain trace amounts of
the antibiotic when consumed, any organisms that would be affected by a prescription antibiotic
have built an immunity to it, which can cause an illness to be more difficult to cure.
2. Farmers growing genetically modified foods have a greater legal liability.
Crops that are genetically modified will create seeds that are genetically modified. Cross-
pollination is possible between GMO crops and non-GMO crops as well, even when specified
farming practices are followed. Because many of the crops and seeds that produce GMO crops
are patented, farmers that aren’t even involved in growing these foods are subjected to a higher

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level of legal liability. Farmers that do grow GMO crops could also face liabilities for letting
seeds go to other fields or allowing cross-pollination to occur.
3. Genes go into different plant species.
Crops share fields with other plants, including weeds. Genetic migrations are known to occur.
What happens when the genes from an herbicide-resistant crop get into the weeds it is designed
to kill? Interactions at the cellular level could create unforeseen complications to future crop
growth where even the benefits of genetically modified foods may not outweigh the problems
that they cause. One example: dozens of weed species are already resistant to atrazine.
4. Independent research is not allowed.
6 companies control most of the genetically modified foods market at the core level. Because
most GMO foods are made from corn, wheat, or soybeans, even food manufacturers that use
these crops are at the mercy of the manufacturer’s preferences. Over 50% of the seed producers
that have created the GMO foods market prohibit any independent research on the final crops as
an effort to protect their profits.
5. Some genetically modified foods may present a carcinogen exposure risk.
A paper that has been twice-published, but retracted once as well, showed that crops tolerant to
commercial pesticides greatly increased the risk of cancer development in rats. The information
from this research study, though limited, has been widely circulated and creates the impression
that all GMO foods are potentially hazardous.
The advantages and disadvantages of genetically modified foods can spark a bitter debate. There
is an advantage in providing the world with better food access, but more food should not come at
the expense of personal health. GMO foods must be labeled in Europe and petitions in the US are
seeking the same thing. We deserve to know what we’re eating and how that food is grown.
Knowing more about genetically modified foods allows us to do just that.
The future of CRISPR technologiesin agriculture
Conventional plant breeding is unlikely to meet increasing food demands and other
environmental challenges. By contrast, CRISPR technology is erasing barriers to genome editing
and could revolutionize plant breeding. However, to fully benefit from the CRISPR revolution,
we should focus on resolving its technical and regulatory uncertainties.Genetic diversity is a key
source for trait improvement in plants. Creating variations in the gene pool is the foremost

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requirement for developing novel plant varieties. Once the desired alterations are achieved,
transgenes can be crossed out from the improved variety. Crop improvement has been done for
years via traditional plant breeding techniques or through various physical, chemical (e.g.,
gamma radiation, ethyl methanesulfonate) and biological methods (e.g., T-DNA, transposon
insertion) leading to point mutations, deletions, rearrangements, and gene duplications. The
advent of site-specific nucleases (SSNs) highlighted the importance of site directed mutagenesis
over random mutagenesis (Osakabe et al., 2010; Sikora et al., 2011). Random mutagenesis has
also its own list of shortcomings too. It produces multiple undesirable rearrangements and
mutations, which are expensive and very complex to screen. Gene editing uses engineered SSNs
to delete, insert or replace a DNA sequence. Development of the engineered
endonucleases/mega-nucleases, zinc finger nucleases (ZFNs), transcription activator-like effector
nucleases (TALENs) and type II clustered regularly interspaced short palindromic repeat
(CRISPR)/CRISPR-associated protein 9 (Cas9) paved the way for single nucleotide excision
mechanism for crop improvement. These genome-editing technologies use programmable
nucleases to increase the specificity of the target locus. Genome editing modifies a specific
genome in precise and predictable manner. There could be varieties of genes, which could be
altered in different cell types and organisms with the aid of nucleases that offer targeted
alterations. ZFNs is one of the oldest gene editing technologies, developed in the 1990s and
owned by Sangamo BioSciences. ZFNs are premeditated restriction enzymes having sequence
specific DNA binding zinc finger motifs and non-specific cleavage domain of Fok1
endonuclease. The emergence of CRISPR technology supersedes ZFNs and TALENs and used
widely as a novel approach from “methods of the year” in 2011 to “breakthrough of the year” in
2015 for their captivated genome editing. This prokaryotic system is promptly accepted for
genome editing in eukaryotic host cells. CRISPR has an added advantage of gene knockout over
RNAi, which is a well-known technique for gene knockdown. CRISPR targets the endogenous
genes that are impossible to specifically target using RNAi technology with more precision and
simplicity. The CRISPR edited tomatoes will be expected to have enhanced flavor, sugar content
and aroma as compared to modern commercial varieties; corn is made resistant to drought with
high yield per hectare; wheat is edited against powdery mildew disease, and mushrooms are
targeted to reduce the melanin content. These genome-editing technologies use programmable
nucleases to increase the specificity of the target locus. Genome editing modifies a specific
genome in precise and predictable manner.

16. 16
Different plasmids with specific Cas9 activity:
Crop Plasmid Gene/insert
name
Promoter Selectable
Marker
Cas
9
type
Significance Reference
sgRNA
expressio
n
Cas9
expression
Oryza sativa pRGEB3
2
PTG1/Cas9 U3
snoRNA
Rice
ubiquitin
Hygromycin Cut Enhanced
multiplex
editing
capability via
endogenous
tRNA
processing
system
Xie et al.,
2015
Zea mays pHSE401 gRNA
scaffold
AtU6-26 35S Hygromycin Cut Improved
designingof
CRISPR/Cas9
binary vector.
Easy method
for one or
more gRNA
assembly in
expression
cassette, high
efficiency
mutant
generation
Xinget al.,
2014
Arabidopsis
thaliana
pKI 1.1R Human codon
optimized
spCas9
U6-26p CaMV35S
, WOX2,
RPS5A
Hygromycin Cut pKIR vector
harboring
RPS5A
maintains
high
constitutive
expression
andheritable
muatations at
all
developmenta
l stages
Tsutsui and
Higashiyama
, 2017
Arabidopsis,
Nicotiana
benthamiana
, Oryza
sativa
pYPQ159 hSpCas9D10
A (human
codon
optimized)
AtU6-26 2× 35S Spectinomyci
n
Nick This toolbox
provides
reagents to
efficiently
assemble
DNA
constructs for
monocots and
dicots using
Golden Gate
Lowder et
al., 2015

17. 17
Should We Use Transgenic Crops?
In the end, the perceived advantages and disadvantages of transgenic crops must be married to
each other to provide a crop that is environmentally sound and non-hazardous. Producers of
transgenic crops and the agencies that study their effects are aware of this point. However, to
date, there has been little evidence to support either case. More research is required in this field
to determine the true safety of these plants and to decide whether they are safe for both the
environment and for those who consume these products over the ages. At the least, most would
agree that the potential advantage of producing crops that provide the human population with
more and cheaper food makes transgenic technology a useful invention.
Conclusion
The primary advantage of genetically modified foods is that crop yields become more consistent
and productive, allowing more people to be fed. According to Oxfam, the world currently
produced about 20% more food calories than what is required for every human being to be
healthy. GMOs are not without disadvantages. Although there are no conclusive links, Brown
University concluded that changes to foods on a genetic level combine proteins that humans are
not used to consuming. This may increase the chances of an allergic reaction occurring. Since
1999, the rates of food allergies in children has increased from 3.4% to 5.1%.
References
1. Stephens J., Barakate A. (2017). “Gene editing technologies – ZFNs, TALENs, and
CRISPR/Cas9,” in Encyclopedia of Applied Plant Sciences 2 Edn eds Thomas B., Murray B.
G., Murphyp D. J., editors. (Cambridge, MA: Academic Press; ) 157–161. 10.1016/B978-0-12-
394807-6.00242-2
2. Ma X, Zhu Q, Chen Y, Liu YG,Mol Plant. 2016 Jul 6; 9(7):961-74.
3.Chawla HS. 2000. Introduction to Plant Biotechnology. Enfield, NH, USA: Science Publishers
Inc.
4. Crawley MJ, Brown SL, Hails RS, Kohn DD, Rees M. 2001. Transgenic crops in natural
habitats. Nature 409: 682-3.
5. Ferber D. 1999. Risks and benefits: GM crops in the cross hairs. Science 286: 1662-6.

18. 18
6. Gasser CS, Fraley RT. 1989. Genetically engineered plants for crop improvement. Science
244(4910): 1293-9.
7. Losey JE, Rayor LS, Carter ME. 1999. Transgenic pollen harms monarch larvae. Nature
399(6733): 214.
Additional Reading and Texts Consulted
1. Colorado State University. 2002. Transgenic Crops: An introduction and resource guide.
2. Animation of the process of cloning genes
3. Animation of how a gene gun works
4. Buchanan B. 2001. Genetic engineering and the allergy issue. Plant Physiology 126:5-7.
Web link :
 faostat3.fao.org
 vittana.org