Transgenic plants and animals

The development of transgenic plants and animals represents a significant advancement in biotechnology, enabling the introduction of desirable genes from one species into another to enhance or introduce specific traits. These genetically modified organisms (GMOs) have broad applications in agriculture, medicine, and industry, offering solutions to problems such as food security, disease resistance, and the production of valuable biological substances.

Background and Concept

Transgenesis refers to the process of inserting a foreign gene, known as a transgene, into the genome of an organism so that the new gene is stably inherited by its progeny. This technology is achieved through recombinant DNA techniques that allow scientists to manipulate genetic material in ways not possible through traditional breeding methods.
In plants, transgenesis typically involves the transfer of genes to confer traits like pest resistance, herbicide tolerance, or improved nutritional quality. In animals, transgenesis is used for producing models of human diseases, improving livestock production, and manufacturing pharmaceutical proteins.
The recombinant DNA is introduced using vectors such as Agrobacterium tumefaciens (for plants) or microinjection (for animals). Once incorporated, the transgene expresses itself, leading to the desired phenotype.

Techniques for Creating Transgenic Plants

Several advanced techniques are employed to produce transgenic plants:

• Agrobacterium-mediated transformation: The bacterium Agrobacterium tumefaciens naturally transfers a portion of its DNA (the T-DNA) into the plant genome. Scientists modify this mechanism to introduce specific genes into plant cells.
• Gene gun (biolistics): DNA-coated metal particles are shot into plant tissues, where the DNA integrates into the plant genome.
• Electroporation and microinjection: These methods involve the physical insertion of DNA into cells through electrical pulses or fine needles.

Transgenic plants have been engineered for various beneficial traits, such as:

• Pest resistance – e.g., Bt cotton containing genes from Bacillus thuringiensis produces insecticidal proteins.
• Herbicide tolerance – e.g., Roundup Ready soybean resistant to glyphosate.
• Improved nutritional quality – e.g., Golden Rice enriched with provitamin A.
• Stress tolerance – enhanced resistance to drought, salinity, or frost.

Techniques for Creating Transgenic Animals

The creation of transgenic animals involves the stable incorporation of a foreign gene into the germ line of the organism so that the trait is heritable. Common techniques include:

• Microinjection: Direct injection of recombinant DNA into the pronucleus of a fertilised egg, which is then implanted into a surrogate mother.
• Retroviral vectors: Modified viruses are used to deliver the desired gene into the host genome.
• Embryonic stem cell-mediated gene transfer: Target genes are inserted into embryonic stem cells that are subsequently integrated into embryos to produce chimeric animals.
• CRISPR-Cas9 technology: A modern genome-editing tool allowing precise insertion or modification of genes.

Examples of transgenic animals include:

• Transgenic mice for studying human diseases like cancer and diabetes.
• AquaAdvantage salmon, which grows faster than normal salmon due to the insertion of a growth hormone gene.
• Transgenic goats producing human antithrombin III in milk for pharmaceutical use.

Applications and Advantages

Transgenic plants and animals have wide-ranging applications:
Agriculture:

• Enhanced crop yield and quality.
• Resistance to pests, diseases, and adverse environmental conditions.
• Reduced use of chemical pesticides and herbicides.

Medicine:

• Production of recombinant proteins such as insulin, vaccines, and antibodies.
• Development of animal models for human genetic and infectious diseases.
• Gene therapy research and pharmaceutical production through “biopharming”.

Industry:

• Production of enzymes and biodegradable materials.
• Improvement of nutritional and storage qualities in food products.

The advantages of transgenesis include improved productivity, reduced agricultural losses, and opportunities for sustainable farming. It also contributes to scientific understanding of gene function and regulation.

Ethical and Environmental Concerns

Despite the potential benefits, transgenic organisms raise several ethical, ecological, and socio-economic issues. Critics argue that altering genetic material across species boundaries may have unpredictable consequences. Major concerns include:

• Biodiversity loss due to gene flow from transgenic to wild species.
• Development of resistant pests and weeds leading to ecological imbalance.
• Ethical issues concerning animal welfare and the manipulation of life forms.
• Human health concerns, particularly allergenicity or toxicity in genetically modified foods.
• Intellectual property rights, as transgenic technology often benefits large corporations more than small farmers.

Regulatory bodies such as the Genetic Engineering Appraisal Committee (GEAC) in India, the USDA and FDA in the United States, and the European Food Safety Authority (EFSA) in Europe evaluate and approve GMOs for safety and environmental impact before their commercial release.

Future Prospects

The future of transgenic research lies in precision biotechnology. Advances in genome editing tools like CRISPR-Cas systems, TALENs, and ZFNs are allowing scientists to create targeted genetic modifications without introducing foreign DNA, thereby reducing ethical concerns. Transgenic approaches are also contributing to climate-resilient agriculture, improved nutritional security, and biomedical innovations.