Biotechnology - Unit 4: Plant Biotechnology by Doctor-dr

by Microbiology Doctor-dr

Table Of Content

·         Introduction

·         Conventional Plant Breeding Vs. Molecular Plant Breeding

·         Transgenic Plants

·         Gene-Transfer Methods In Plants

1.Vector-Mediated Or Indirect Gene Transfer

·         Mechanism Of Gene Transfer By Agrobacterium

2. Direct Gene Transfer (Physical Methods Of Gene Transfer)

1.       Microinjection

2.       Chemical-Mediated Gene Transfer

3.       Electroporation

4.       Biolistic Method

5.       Chloroplast Engineering

·         Applications Of Transgenic Technologies In Plants

1. Herbicide Tolerance

2. Insect Resistance

3. Disease Resistance

4. Abiotic Stress Tolerance

5. Delayed-Ripening Fruits And Vegetables

6. Male Sterility

7. Improvement Of Nutrient Qualities Of Plants

8. Transgenic Plants As Bioreactors (Molecular Farming)

9. Biodegradable Plastics

10. Plant Secondary Products

·         Risks Associated With Genetically Modified (Gm) Food

·         Oversight

·         Conclusion

Plant Biotechnology

Introduction

The recent decade has seen extraordinary progress in plant biotechnology, from the study of the science to large-scale commercial applications.

Plant biotechnology applications may be classified into two categories: 

1. those aimed at traditional plant breeding (e.g. better yield, quality, resistance to pests and diseases, tolerance to abiotic stressors) and 
2. those aimed at wholly unique applications (such as the use of plants as bioreactors to generate pharmaceuticals, vaccines or biodegradable plastics).

Conventional plant breeding vs. molecular plant breeding

• Plant breeding is founded on Mendelian genetics principles. 
• In the past, plant breeding was considered an art, with the selection of superior genotypes of a given crop relying heavily on subjective judgements made by the breeder. 
• With increasing knowledge of the genes underlying useful traits, plant breeding has become a more directed and scientific activity
• As a result of the generation of molecular maps of crop genomes, extensive sequencing of expressed sequences (ESTs) and genomic sequences, and the study of genome organisation, repetitive and non-coding sequences, and the ability to identify polymorphisms at specific loci that can be exploited as molecular markers.

Transgenic Plants

Transgenic plants are plants that have foreign DNA added to them. 

There are three basic motivations for generating transgenic plants.

1. First, the inclusion of a gene frequently increases a crop plant's agricultural, horticultural, or decorative value.
2. Second, transgenic plants can function as living bioreactors, producing commercially essential proteins or metabolites at a low cost.
3. Third, plant genetic transformation is an effective tool for researching gene activity during development and other biological processes.

• Over 150 distinct plant species, including many crop and forest species, have been genetically changed in over 50 nations globally to far.
• Plant biotechnology has had a significant influence on plant breeding initiatives.
• because it reduces the 10 to 15 years required to establish a new variety using standard plant-breeding processes.

GENE-TRANSFER METHODS IN PLANTS

• It is now feasible to produce transgenic plants from all main agricultural plant species. 
• A variety of genetic transformation technologies have been established for the creation of transgenic plants.
• These are mostly classified into two categories.

1. Gene transfer through vectors
2. Vector-less gene transfer or direct gene transfer

1. Vector-Mediated or Indirect Gene Transfer

• Agrobacterium-mediated gene transfer is the most efficient method of gene transfer because it is a natural method of genetic engineering. 
• The bacterium Agrobacterium tumefaciens causes certain plants to develop a tumour called a gall, which is most commonly located at the crown of the plant—the junction of root and stem. 
• This "crown gall disease" affects broad-leaf plants including fruit trees, grapes, and ornamental plants.

• Microbiologists Mary-Dell Chilton, Eugene W. Nester, and Milton P. Gordon were the first to demonstrate in the late 1970s that crown gall tumours were caused by DNA from an Agrobacterium plasmid that was transported and integrated into plant DNA.
• Ti plasmid was the term given to the plasmid that caused the tumour.
• The plasmid is made up of a set of genes (T-DNA) that were cut from the plasmid and put into the plant genome.
• The host plant then keeps that foreign genetic material alive by duplicating it alongside the plant's own genes, which are eventually translated to generate proteins.
• These proteins are in charge of the manufacture of plant hormones, which promote unregulated cell division and the creation of tumours.
• T-DNA also contains genes for the manufacture of metabolites required for the development and replication of Agrobacterium in plant tissue.
• T-DNA boundaries are designated by particular DNA sequences that may be identified by the enzyme system that cleaves T-DNA and inserts it into plant chromosomes, resulting in the creation of the crown gall tumour.
• This natural occurrence of plant genetic engineering is significant in biology because it shows that DNA may be transported between biological kingdoms.
• Apart from transferring genes across plants, this understanding is currently used to transmit new desirable features from other creatures such as bacteria and animals to plants.
• As a result, Agrobacterium has emerged as the primary vehicle for plant genetic modification.

Mechanism of Gene Transfer by Agrobacterium

• Ti plasmids (tumor-inducing plasmids) can be deactivated by deleting the T-DNA components while leaving the boundaries intact.
• Cloning genes of interest in lieu of T-DNA allows Agrobacterium to introduce foreign DNA into plant genes, mistaking it for T-DNA.
• The overall method would thus be to create a'recombinant' plasmid bearing the relevant gene that codes for the desired feature to be transmitted to the plant.
• The gene might be for herbicide resistance or the capacity to produce a particular protein of economic importance, such as an antibody or hormone.
• The recombinant plasmid is then introduced into the Agrobacterium.
• Finally, bacteria bearing these modified Ti plasmids (without T-DNA) are introduced into the host plant, where plasmid DNA fragments are inserted into the host plant genome.

A: Agrobacterium tumefaciens 

B: Agrobacterium genome 

C: Ti Plasmid : 

    a: T-DNA 

    b: Vir genes 

    c: Replication origin 

    d: Opines catabolism genes 

D: Plant cell 

E: Mitochondria 

F: Chloroplast 

G: Nucleus

• The 'Flavor-Savr' tomato was the first genetically altered food, thanks to Agrobacterium gene transfer.
• Plant tissue, such as terminal meristems or leaf discs, or cultured plant cells, are cocultured with A. tumefaciens containing recombinant plasmids, allowing the bacteria to infect the tissue or cells.
• The converted tissues are now put to a shoot-inducing mixture containing one or two antibiotics that kill bacteria as well as untransformed plant cells.
• The expression of various reporter genes related with the gene of interest, such as -glucuronidase (gus), luciferase (luc), or green fluorescent protein, can also detect the transformation (gfp).
• It is placed to a root-inducing media after the formation of shoots, where it grows roots.
• After suitable acclimatisation or hardening, fully established transgenic plants can be moved to soil.
• Transgenic plants may be tested for the presence of the foreign gene and its correct expression using various molecular methods like as Southern hybridization, Northern hybridization, PCR, and so on.

2. Direct Gene Transfer (Physical Methods of Gene Transfer)

• One of the key issues in Agrobacterium-mediated gene transfer is host specificity, as well as the difficulties in plant regeneration following gene transfer by infection.
• Most monocot plants are resistant to Agrobacterium infection.
• In such circumstances, alternative gene transfer procedures that do not entail infection by any creature have been devised.

Direct Gene Transfer

Following are some of the direct gene transfer methods developed for the genetic engineering of specific plants:

1. Microinjection

2. Chemical-mediated Gene Transfer

3. Electroporation

4. Biolistic Method

5. Chloroplast Engineering

1. Microinjection:

• Micro-injection is performed utilising automated equipment (robotics) and a micro-needle.
• The desired gene is delivered directly into the plant protoplast as a plasmid or alone.
• The DNA might be transported straight into the nucleus or into the cytoplasm.
• Injections into the nucleus are more effective than injections into the cytoplasm.
• However, micro-injection has only resulted in a few transgenic plants.
• The approach is time-consuming, technically complex, and restricted in terms of the amount of cells injected.

2. Chemical-Mediated Gene Transfer

• When treated with membrane-active chemicals such as polyethylene glycol (PEG) and dextran sulphate, protoplasts (plant cells without cell walls) will take in pure DNA.
• The DNA gets integrated into the genome once inside the cell, and the foreign gene begins to express.
• This method is heavily reliant on the development of protoplast systems that can regenerate whole plants.

3. Electroporation

• This is a physical way for delivering DNA into plant protoplasts across membranes using a quick pulse of high voltage direct current.
• When a high-voltage electric pulse is administered in the presence of protoplasts, it creates a huge number of temporary holes in the cell membrane.
• These transient holes aid in the absorption of DNA by protoplasts.
• The DNA is integrated once inside the cell, and the foreign gene begins to express.

• All three techniques—chemical-mediated DNA absorption, micro injection, and electroporation—are heavily reliant on the creation of protoplast systems that can regenerate whole plants.
• These techniques, particularly electroporation, have resulted in transgenic maize, rice, and soybeans.
• However, success rates are modest, and the procedures are not always replicable.

4. Biolistic Method (Microprojectile or Particle-gun Method)

• This is a novel technology that includes employing an electrostatic pulse, air pressure, or gunpowder percussion to propel extremely small particles of tungsten or gold coated with DNA into cells.
• The targeted gene's DNA molecules are coated on minuscule gold or tungsten particles.
• The DNA dissolves and becomes free to integrate into the plant-cell genome as the particles transit through the cell.
• This unlikely procedure really works fairly well and, along with electroporation, has become one of the preferred techniques.
• The benefit of biolistics is that it may be used to entire cells in suspension as well as whole or sliced plant tissues. Plant meristems or tissues capable of regeneration, for example, can be directly targeted.
• This approach, unlike electroporation and microinjection, does not need protoplasts or even single-cell separation.
• Transgenic maize and soybean plants have been created using biolistics.
• This is a highly mechanical or robotically mediated method as well.
• Particle bombardment is often used to create transgenic cereals, and its application has declined as Agrobacterium transformation now works for cereals such as rice and barley. It is still commonly employed in maize and wheat transformation.

5. Chloroplast Engineering

• Chloroplasts include genes that encode a variety of critical and distinct tasks. 
• Some chloroplast proteins are encoded in nuclear DNA, produced in the cell's cytoplasm, and then transported into the proper organelle via a specific method.
• As a result, there are two methods for a specific foreign protein to enter the chloroplast.

1. In one method, a fusion gene encoding the foreign protein and extra amino acids that drive protein transport to the organelle may be introduced into nuclear chromosomal DNA, and the recombinant protein can then be transported into chloroplast following synthesis.
2. To change chloroplast function or manufacture foreign proteins, stable genetic transformation of chloroplasts needs insertion of the foreign DNA into the chloroplast genome rather than the much larger chromosomal DNA.

APPLICATIONS OF TRANSGENIC TECHNOLOGIES IN PLANTS

• The introduction of transgenic technologies in plant biotechnology has the potential to outperform past "revolutions" in production agriculture in terms of technical gains.
• In 1999, 52 percent of soybeans, 30 percent of maize, and 9 percent of cotton and canola in North America were transgenic.
• Other transgenic crops being grown include rice, wheat, barley, sorghum, sugar cane, sugar beet, tomato, potato, sunflower, peanut, papaya, tree species, and horticulture crops.
• Herbicide tolerance (71%) and insect resistance (28%), with just 1% for the other characteristics, dominated the commercially cultivated transgenic traits.

APPLICATIONS OF TRANSGENIC TECHNOLOGIES IN PLANTS

Transgenic technologies offer following applications:

1. Herbicide Tolerance

2. Insect Resistance

3. Disease Resistance

4. Abiotic Stress Tolerance

5. Delayed-Ripening Fruits and Vegetables

6. Male Sterility

7. Improvement of Nutrient Qualities of plants

8. Transgenic Plants as Bioreactors (Molecular Farming)

9. Biodegradable Plastics

10. Plant Secondary Products

1. Herbicide Tolerance

• Weed growth is one of agriculture's most serious concerns.
• Weeds are undesirable weeds that grow alongside agricultural plants.
• Because these plants compete with agricultural plants for space, light, water, and nutrients, crop yield suffers.
• Herbicides are the most often used method for controlling weeds.
• However, if the crop is not resistant to the herbicide employed, these herbicides might lower agricultural output.
• Furthermore, pesticides pollute the land and water.
• Herbicide tolerance in agricultural plants can be achieved by genetic engineering.
• Herbicide-tolerant crops allow farmers to manage weeds with a specific herbicide while causing no damage to the crop.
• Engineered resistance to glyphosate, glufosinate, bromoxynil, triazines, 2,4-D, and isoxazoles is now available, based on the expression of a herbicide insensitive gene, degradation of the herbicide, or overexpression of the herbicide target gene product.
• The control that transgenic herbicide resistant crops give to farmers has resulted in a 33% reduction in glyphosate usage on Roundup Ready soybeans and a 20% reduction in glufosinate consumption on Liberty Link canola.

2. Insect Resistance

• Plants are always attacked by many sorts of insects and pests since leaves are their food supply.
• These pests have the potential to harm agricultural plants and diminish output.
• The use of insecticides to kill insects and pests is a popular pest control method.
• These substances are potentially hazardous to people and other animals, and they can damage water and the environment.
• Transgenic plants, by developing insect-resistant crops, provide a viable answer for pest management and environmental protection under these conditions.
• Commercially cultivated transgenic cotton, maize, and potato crops express Bacillus thuringiensis (Bt) toxins to give resistance to eating insects.
• B. thuringiensis synthesises S-endotoxin crystalline proteins encoded by Cry genes during sporulation.
• In the alkaline midgut of an insect, prototoxins are cleaved to the active toxin.
• This binds to particular receptors in the stomach epithelial cells, causing holes to develop and, eventually, the insect's death.
• These Bt proteins or bacteria are not dangerous to humans or other creatures such as flies, butterflies, silkworms, and so on.
• The Bt cotton plant is the most recent example of farming an insect-resistant crop. It is resistant to the ballworm (helicoperpa armigera), which causes significant damage to cotton agriculture across the world.
• Aside from cotton, a variety of agricultural plants, including potatoes, rice, maize, wheat, tomatoes, soybeans, wheat, brinjal, cauliflower, cabbage, and others, have been modified with the Bt toxin gene.
• These transgenic crops have been discovered to be highly successful in pest management, considerably increasing yield while reducing chemical pollution in the environment.

3. Disease Resistance

• Plants are susceptible to a wide range of illnesses, including pathogenic and deficient disorders.
• Deficiency illnesses can be controlled by adding the appropriate manures.
• Pathogen-caused illnesses, on the other hand, cause crop devastation and financial loss.
• Fungi, viruses, and bacteria are significant pathogens that cause agricultural yield to decrease or crop damage to occur.
• This problem can be solved using biotechnological techniques.
• There are various disease-resistant crops that have been developed to withstand a viral attack.
• These plants have viral coat proteins built into them.
• This virus-derived resistance has yielded encouraging results in crops such as potatoes, tobacco, tomatoes, and papayas, among others.
• Some nations have commercialised transgenic papayas that are resistant to the ring spot virus.
• Effective resistance to a wide range of viruses, including Cucumber Mosaic Virus (CMV), Tobacco Mosaic Virus (TMV), Papaya Ring Spot Virus (PRSV), and Chrysanthemum Ring Spot Virus (CymRSV), has been developed.
• When a plant is attacked by a bacterium or fungus, it produces substances such as proteins and enzymes that may combat the invading pathogens.
• Pathogenesis-related proteins, or PR proteins, are proteins generated in plants as a result of a pathogenic assault.
• They contain enzymes like chitinase as well as antifungal proteins.
• Phytoalexins are organic chemicals generated in plants as a result of pathogen assault and other damage caused by insect bites.
• A significant range of transgenic crops with improved resistance to different fungal infections have been developed, with genes responsible for manufacturing any of the anti-fungal chemicals listed above.

4. Abiotic Stress Tolerance

• Abiotic stress is another important component that effects plant development and production.
• Plants create metabolites in response to stressors such as excessive temperature, drought, or salt. Among these metabolites are:
• stress-related osmolytes such as sugars
• sugar derivatives such as trahalose, fructans, mannitol, etc.,
• amino acids such as proline, glycine, betaine,
• heat-shock proteins and anti-freeze proteins
• Crop plants have been genetically modified to over-express genes involved in the synthesis of one or more of the metabolites listed above.
• Various research organisations have created salinity-tolerant rice and drought-resistant sugarcane.
  

5. Delayed-Ripening Fruits and Vegetables

• One of the issues affecting agro-industries is the shelf life of fruits and vegetables.
• A variety of major metabolic pathways contribute to fruit development and ripening.
• One of the main molecules involved in fruit ripening is the gaseous hormone ethylene.
• The process of fruit ripening can be sped up by inhibiting ethylene production.
• Commercially available methods for extending shelf life include:
• switching off polygalacturonase genes
• switching off genes in the ethylene biosynthesis pathway or degrading intermediates in that pathway
• and expression of cytokinin genes
• Antisense mRNA technology is employed for this purpose.
• In the instance of anti-sense mRNA technology, a reverse copy of a gene (a complementary gene) is inserted in a plant with all of the required regulatory components present in the regular gene (for example, antisense m-RNA for the ethylene biosynthesis gene).
• Because ethylene production may not occur in such plants, fruit ripening will be exceedingly sluggish under normal conditions.
• This delayed ripening aids in the export of sensitive fruits like tomatoes.

• Flavr Savr tomato is a superb example of antiense technology.
• Flavr Savr tomato debuted in 1994.
• Ripe tomatoes generally release the enzyme polyglacturonase (PG), which digests pectin, weakening the fruit and making it more prone to fungal diseases.
• Scientists extracted the PG gene, which creates a complementary gene that produces a complementary mRNA that binds to the normal mRNA and inactivates the normal mRNA for this enzyme.

6. Male Sterility

• Male sterility is an essential feature in plant breeding because it limits selfpollination and encourages cross-pollination.
• As a result, creating male sterility in agricultural plants is critical in terms of plant breeding.

• Male sterility is introduced into agricultural plants by introducing the gene code for the RNA-hydrolyzing enzyme barnase.
• This enzyme prevents pollen production, rendering the plant male infertile.
• With the aid of the tapetal specific promoter (TA29), this gene is engineered to express solely in the tapetal cells of the anther, limiting enzyme activity to the cells engaged in pollen generation.
• The insertion of another gene, barstar, which inhibits or suppresses the function of barnase, can restore male fertility.

7. Transgenic Plants with Improved Nutrient Qualities

• Crop plants can be genetically engineered for the improvement of nutritive qualities such as:
• the edible parts like grains, fruits, tubers, etc.,
• protein content
• starch qualities, etc. 

a. Golden rice

• Rice is often devoid of vitamin A.
• Golden rice, a genetically altered rice, does produce vitamin A.
• A lack of vitamin A can lead to a disease known as night blindness.
• In third-world nations, this problem is severe.
• The goal is that introducing golden rice would rescue millions of people from the repercussions of vitamin A deficiency in nations where rice is a mainstay of the diet.

b. Protein quality of seeds and tubers

• Nutritionally-enhanced foods will have more nutrients such as proteins, vitamins, and other beneficial compounds.
• Protein molecules rich in essential amino acids can have their genes extracted and transplanted to food crops with the appropriate promoters to express them in the edible section of the plant.
• Other examples of boosting the nutritional content of food materials by genetic engineering include protein-enhanced sweet potatoes, rice, wheat, and maize, high vitamin-A canola oil, and improved antioxidant fruits and vegetables.

8. Transgenic Plants as Bioreactors (Molecular Farming)

• Modern techniques for producing transgenic plants and isolating new genes responsible for the manufacture of numerous industrial proteins, enzymes, and medications for humans and other species have resulted in the creation of a whole new and remarkable technology.

Drugs and animal proteins may be grown on the farm!

• Plants are very cheap, and the raw materials necessary for plant cultivation, harvesting, and product extraction are quite easy and inexpensive.
• If the plants are transformed with the appropriate gene and promoters, they can serve as a bioreactor to create the essential chemicals.
• in adequate amounts, such as proteins (therapeutic proteins), antibodies, vaccinations, enzymes, amino acids, vitamins, medicines, and so on.

Some examples are described below

a. Diagnostic and Therapeutic Proteins

• By using plants as the bioreactor against the use of conventional fermentation.
• techniques, which include costly equipments, upstream and downstream processing,
• the cost of production can be brought down substantially.
• Proteins such as plasma proteins, peptide hormones, interferons, and cytokinins can be produced in specific organs of transgenic plants such as:
• the leaves in the case of tobacco.
• tubers in the case of the potato and.
• the stem in sugarcane.

b. A recombinant form of the natural hormone: rBST (bovine somatotropin) which causes cows to produce milk—can be synthesized through transgenic plants.

• rBST increases milk production by as much as 10 to 15%.
• It is used to treat over 30% of U.S. cows.

c. Food enzymes, including a purer, more stable form of chymosin used to curdle milk in cheese production, are now being synthesized by transgenic plants.

• It is used to make 60% of hard cheeses.
• This can replace the chymosin of rennet from slaughtered calves stomachs.

d. Edible Vaccines

• Transgenic plants can also be utilised as edible vaccinations if the vaccines are expressed directly in the plant's edible components.
• If the plants are transformed with the vaccine-producing gene linked to an organ-specific promoter, it will express, and the raw, edible component may be consumed for immunisation.
• The vaccine molecules in raw food (tuber, fruit, or leaves) will be absorbed by the cell lining of the mouth and food canal as it travels to the stomach.
• This sort of vaccine may be used on both people and animals.
• For example, fodder plants can be genetically modified to generate the protective antigen anthrax bacterium, allowing calves to be automatically immunised against the deadly anthrax.
• Antigenic protein production in edible sections of crops such as tomatoes, bananas, and apples is beneficial for human vaccination.
• Without refrigeration, edible vaccinations are simple to store and carry.
• The delivery technique is also quite straightforward.
• The cost of the product is relatively inexpensive since expensive equipment and downstream processing procedures are not required for industrial fermentation production.
• Vaccination against illnesses such as cholera, hepatitis, small pox, TB, and others will become a reality in the near future.

9. Biodegradable Plastics

• Because plastic is not biodegradable, it causes a slew of environmental issues.
• Some bacteria may generate biodegradable polymers, such as polyhydroxy butyrate (PHB).
• When Arabidopsis plants are genetically altered with the genes responsible for PHB biosynthesis, they may manufacture these PHB globules in the chloroplasts.
• This bioplastic is easily recovered and purified from plant leaves.
• A number of firms are already creating transgenic plants to investigate the feasibility of generating biodegradable polymers on a large scale.

10. Plant Secondary Products

• It is feasible to use metabolic engineering to improve a specific secondary metabolite or to develop a novel chemical by a medicinal plant.
• In general, over-expression of a key enzyme gene in the biosynthetic pathway results in increased synthesis of the desired product.
• For example, metabolic engineering approaches in Taxus buccata tissue cultures have significantly increased the production of the anti-cancer medication taxol.
• Induction of hairy root cultures with Agrobacterium rhizogenes is another in vitro approach for increasing the synthesis of metabolites, particularly those generated in roots.
• Root cultures may provide as a source of root-specific compounds.

Risks Associated with Genetically Modified (GM) Food

• The use of genetically modified plants and animals has become commonplace in today’s society without many people being aware of it
• The lack of consumer consent in the choice to eat genetically modified foods creates an ethical dilemma 
• much as “70 percent” of food prepackaged in a normal grocery store contain genetically modified foods
• Are they all safe?

Flavr Savr tomato 

• genetically modified tomato that rot longer 
• but less resistant to pests and easily caught diseases, which made the crops even more costly to grow and thus higher price for consumers

1. Food Allergies

• The biggest issue regarding GM crops is their proclivity to cause allergic responses.
• The dread of allergic reactions originates from the belief that any protein might cause an allergic response.
• Companies introduce a new protein into an organism when they create a new gene, and it is uncertain whether or not these new proteins may trigger allergic responses.
• Brazil nuts and soybeans are two examples of allergy threats posed by genetically modified foods.
• To make soybeans more nutritious, a protein from Brazil nuts was added, however it was discovered that those who were sensitive to Brazil nuts were also extremely allergic to the GM soybeans.

2. Creation of super-weeds

• Another issue raised by genetic engineering is the development of super-weeds by horizontal gene transfer from GM crops to weed plants.
• Crop hybridization with neighbouring weeds may allow weeds to acquire features we don't want them to have, such as herbicide resistance.
• Similarly, genes for viral disease resistance or insect resistance might benefit weed populations near a crop field.

3. Creation of super bugs

• Antibiotic resistance is combined with new genes while creating GM crops since gene transfer is only effective in a few cells and a marker is required to detect successful transfers.
• The risk of gene transfer stems from the possibility that genes from GM crops would be picked up by harmful bacteria in people' guts.
• If bacteria containing antibiotic resistance genes create illness, doctors may find it difficult to cure.

4. Environmental Impacts

Environmental risks involved with GM crops are numerous

1. Decrease in the biodiversity: 

• They include the capacity of the GMO to escape and perhaps introduce the modified genes into natural populations.
• The most serious issue is the possible loss of biodiversity in crops and their accompanying insects and animals, which might change the forces of natural selection due to direct human interference.

2. GM pesticide-producing crops: are hazardous to non-target species, for example, long-term exposure to pollen from GM insect resistant maize affects the behaviour and survival of America's most famous butterfly, the monarch butterfly.

3. GM crops are toxic to beneficial insects.

• For example, GM Bt crops adversely affect beneficial insects important to controlling maize pests, such as green lacewings.
• The toxin Cry1Ab affects the learning performance of honeybees.

4. GM crops are a threat to soil ecosystems.

• Many Bt crops secrete their toxin from their roots into the soil.
• Residues left in the field contain the active Bt toxin.
• Generally, GM herbicide tolerant (HT) crops are connected with one of two herbicides: glyphosate or glufosinate.
• Both herbicides are problematic.
• Several new research indicate that Roundup is significantly more dangerous than previously considered.
• It is poisonous to aquatic species such as frog larvae, for example.

5. Poisoned Wildlife

• The introduction of alien genes into plants might have catastrophic effects for animals in a variety of situations.
• Engineering crop plants, such as tobacco or rice, to create polymers or medicines, for example, might imperil mice or deer that devour crops or crop waste left in fields after harvesting.

Oversight

• To maintain the balance between the benefits and hazards of genetically modified foods, adequate supervision is required to keep the risks indicated above in mind.
• Many measures are taken while analysing the safety of novel GM foods to determine the safety of the new proteins.
• In the United States, three major entities are active in the regulation of genetically modified foods:

1. the Food and Drug Administration (FDA)
2. the Environmental Protection Agency (EPA) and
3. the United States Department of Agriculture (USDA)

Conclusion

• There are various possible advantages and concerns associated with genetically modified crops.
• Several safety investigations have had both favourable and poor outcomes.
• Long-term research to assess safety and dangers are required.