8.2 Transgenic plants and crops
4 min read•august 7, 2024
Transgenic plants and crops are a game-changer in agriculture. Scientists can now add specific genes to plants, giving them cool new traits like pest resistance or better nutrition. It's like upgrading plants to have superpowers!
This tech has huge potential but also sparks debate. Some people love the idea of crops that need fewer pesticides or can fight hunger. Others worry about safety and environmental impacts. It's a hot topic in biotech!
Transgenic Plant Production Methods
Agrobacterium-mediated Transformation
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Top images from around the web for Agrobacterium-mediated Transformation
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- Uses the soil bacterium to insert desired genes into plant cells
- Agrobacterium naturally infects plant cells and transfers a portion of its DNA () into the plant genome
- Scientists replace the tumor-inducing genes in the T-DNA with the desired genes for the transgenic plant
- The modified Agrobacterium is then used to infect plant cells, which integrate the T-DNA containing the desired genes into their genome
- Transformed plant cells are then regenerated into whole transgenic plants using tissue culture techniques
- Widely used method for creating transgenic dicotyledonous plants (tobacco, tomato, potato)
Particle Bombardment and Other Methods
- () involves coating microscopic gold or tungsten particles with the desired DNA and firing them into plant cells at high velocity
- The DNA-coated particles penetrate the cell wall and membrane, delivering the DNA into the cell
- Some of the delivered DNA is integrated into the plant genome, creating transgenic cells
- Particle bombardment is useful for transforming monocotyledonous plants (corn, wheat, rice) that are not susceptible to Agrobacterium infection
- Other methods for creating transgenic plants include electroporation, microinjection, and viral vectors
- , such as antibiotic resistance genes, are often co-transformed with the desired genes to allow for the selection of successfully transformed cells
Ti Plasmid and Selectable Markers
- The Ti (tumor-inducing) plasmid is a circular DNA molecule found in Agrobacterium that is responsible for its ability to transfer DNA into plant cells
- The T-DNA region of the , which is transferred to the plant genome, is modified to carry the desired genes for the transgenic plant
- The vir (virulence) genes on the Ti plasmid are responsible for the transfer of the T-DNA into the plant cell
- Selectable markers are genes that confer resistance to antibiotics (kanamycin, hygromycin) or herbicides () and are used to select for successfully transformed plant cells
- Only plant cells that have integrated the selectable marker gene along with the desired transgene will survive and grow in the presence of the corresponding antibiotic or herbicide
Transgenic Crop Applications
Insect Resistance and Herbicide Tolerance
- Bt crops are engineered to express insecticidal proteins from the bacterium (Bt)
- Bt proteins are toxic to specific groups of insects (lepidopteran larvae, coleopteran larvae) but are safe for humans and other animals
- Examples of Bt crops include , which is resistant to bollworm, and , which is resistant to European corn borer and corn rootworm
- Herbicide-resistant crops are engineered to tolerate specific herbicides (glyphosate, glufosinate), allowing for more effective weed control
- Examples include and canola, which are resistant to the herbicide glyphosate
- Herbicide-resistant crops allow farmers to spray herbicides over the entire field without damaging the crop, reducing the need for tillage and improving weed management
Nutritional Enhancement and Other Traits
- is a transgenic rice variety engineered to produce , a precursor to vitamin A, in its endosperm
- Developed to address vitamin A deficiency, which is a major public health problem in developing countries
- Other examples of nutritionally enhanced crops include high-oleic soybeans (increased healthy monounsaturated fats) and high-lysine corn (improved protein quality)
- Gene silencing techniques, such as (RNAi), can be used to down-regulate specific genes in transgenic plants
- Examples include the FlavrSavr tomato, which has reduced expression of a gene involved in fruit softening, leading to longer shelf life
- Other applications of gene silencing in transgenic crops include reducing allergens, toxins, or anti-nutritional factors
Transgenic Plant Regulation and Controversy
Biosafety Regulations and Risk Assessment
- Transgenic plants are subject to strict to ensure their safety for human consumption and the environment
- Regulatory agencies (, , in the US) assess the potential risks of transgenic crops before approving their commercialization
- considers the potential for allergenicity, toxicity, and unintended effects on non-target organisms and the ecosystem
- are conducted under controlled conditions to evaluate the performance and safety of transgenic crops before their widespread release
- Biosafety regulations also address issues related to gene flow, such as the potential for transgenes to spread to wild relatives or non-transgenic crops
Public Perception and Controversy
- The development and commercialization of transgenic crops have been accompanied by public controversy and concerns about their safety and environmental impact
- Some concerns include the potential for allergenicity or toxicity of transgenic proteins, the development of or insecticide-resistant pests, and the unintended effects on non-target organisms
- Ethical concerns have been raised about the patenting of living organisms and the control of the food supply by large corporations
- Labeling of genetically modified (GM) foods is mandatory in some countries (European Union) but voluntary in others (United States), leading to debates about consumer choice and the right to know
- Public acceptance of transgenic crops varies widely across countries and regions, with higher acceptance in the Americas and Asia and lower acceptance in Europe and Africa
- Effective science communication and public engagement are crucial for addressing concerns and fostering informed decision-making about the use of transgenic crops in agriculture
Key Terms to Review (27)
Agrobacterium tumefaciens: Agrobacterium tumefaciens is a soil bacterium known for its ability to transfer genetic material to plants, leading to the formation of tumors. This natural ability makes it a crucial tool in biotechnology for creating transgenic plants, where desired genes are inserted into plant genomes to produce specific traits, such as disease resistance or increased yield.
Agrobacterium-mediated transformation: Agrobacterium-mediated transformation is a process that utilizes the bacterium Agrobacterium tumefaciens to introduce foreign DNA into the genome of plant cells. This method takes advantage of the natural ability of Agrobacterium to transfer a segment of its DNA, known as T-DNA, into the plant's cells, facilitating the creation of transgenic plants with desired traits.
Bacillus thuringiensis: Bacillus thuringiensis, often abbreviated as Bt, is a soil-dwelling bacterium known for its insecticidal properties. This bacterium produces crystal proteins that are toxic to various insect pests, making it a key player in the development of biopesticides and transgenic crops designed to resist pest damage. Its use in agriculture promotes sustainable practices by reducing reliance on chemical pesticides, leading to positive impacts in both environmental health and food production.
Beta-carotene: Beta-carotene is a pigment found in various plants that gives them a yellow, orange, or red color and serves as a precursor to vitamin A in the human body. In the context of transgenic plants and crops, beta-carotene is significant because it has been genetically engineered into certain crops to enhance their nutritional value, especially in areas where vitamin A deficiency is prevalent. This biotechnology application helps improve public health by addressing nutrient deficiencies through biofortification.
Biolistics: Biolistics is a technique used to deliver genetic material into target cells using high-velocity microprojectiles, often referred to as 'gene guns'. This method allows for the direct introduction of DNA or RNA into plant cells, making it a crucial tool in creating transgenic plants and enhancing crop traits through genetic modification. By utilizing this approach, scientists can effectively bypass some of the limitations found in traditional transformation methods.
Biosafety regulations: Biosafety regulations are a set of guidelines and practices designed to ensure the safe handling, containment, and use of biological materials, particularly those that involve genetically modified organisms (GMOs). These regulations are crucial in managing risks associated with biotechnology, especially in the development and use of transgenic plants and crops, where modified traits can impact the environment and human health. They serve as a framework to minimize potential hazards while promoting innovation in biotechnology.
Biotechnology ethics: Biotechnology ethics refers to the moral principles and guidelines that govern the application of biotechnological advancements, including issues related to genetic manipulation, environmental impact, and the rights of living organisms. It encompasses a range of concerns about how biotechnological tools are used in agriculture, medicine, and research, emphasizing the need for responsible practices that consider both human and ecological well-being.
Bt corn: Bt corn is a genetically modified organism (GMO) derived from the bacterium Bacillus thuringiensis, designed to express a protein that is toxic to specific insect pests. This modification improves crop resilience and yields while reducing reliance on chemical pesticides, showcasing the applications and impact of biotechnology in agriculture, food production, and sustainability.
Bt cotton: Bt cotton is a genetically modified organism (GMO) that has been engineered to express a protein from the bacterium Bacillus thuringiensis (Bt), which provides resistance to certain pests, particularly the cotton bollworm. This modification enhances cotton crop yields and reduces the need for chemical insecticides, making it an important advancement in agricultural biotechnology.
EPA: The Environmental Protection Agency (EPA) is an independent agency of the United States federal government responsible for protecting human health and the environment by enforcing regulations based on laws passed by Congress. It plays a critical role in assessing the environmental impacts of various products, including biotechnology products such as transgenic plants and crops, ensuring they meet safety and environmental standards before they can be commercially released.
FDA: The FDA, or Food and Drug Administration, is a federal agency of the United States Department of Health and Human Services responsible for protecting public health by ensuring the safety and efficacy of food, drugs, cosmetics, and medical devices. The agency plays a crucial role in the approval and regulation of biotechnology products, including transgenic plants, pharmaceuticals, and various biotechnological innovations. By establishing guidelines and regulations, the FDA ensures that these products meet safety standards before they can be marketed to the public.
Field Trials: Field trials are controlled experiments conducted in real-world agricultural settings to evaluate the performance, safety, and efficacy of transgenic plants and crops. These trials are essential for assessing how genetically modified organisms (GMOs) interact with their environment, including their effects on ecosystems, pest resistance, and overall agricultural productivity. By providing data from actual growing conditions, field trials help regulators and researchers understand the potential impacts of transgenic crops on farming practices and the environment.
Food Sovereignty: Food sovereignty is the right of people to healthy and culturally appropriate food produced through ecologically sound and sustainable methods. It emphasizes the importance of local food systems and communities having control over their own food production, distribution, and consumption, contrasting with the globalized model of food production that often prioritizes profit over people’s needs.
Glyphosate: Glyphosate is a broad-spectrum systemic herbicide widely used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. As a key component in the development of transgenic plants, glyphosate is often used in conjunction with genetically modified organisms (GMOs) designed to withstand its effects, allowing for more efficient agricultural practices.
Golden Rice: Golden Rice is a genetically modified variety of rice that has been engineered to produce beta-carotene, a precursor to vitamin A. This innovation aims to address vitamin A deficiency, particularly in regions where rice is a staple food, thereby improving the health and nutrition of populations at risk.
Herbicide tolerance: Herbicide tolerance refers to the ability of a plant to survive and thrive despite the application of specific herbicides that would normally inhibit its growth or kill it. This characteristic is particularly important in agriculture, where herbicides are commonly used to control unwanted weeds without harming the crop itself. By incorporating herbicide tolerance into transgenic plants, farmers can achieve better weed management and increased crop yields while minimizing the need for mechanical weeding.
Herbicide-resistant weeds: Herbicide-resistant weeds are plant species that have developed the ability to survive applications of herbicides that are intended to kill them. This phenomenon often arises due to the widespread use of certain herbicides, especially those associated with genetically modified (GM) crops designed to withstand these chemicals. As a result, farmers face significant challenges in managing these weeds, leading to increased agricultural costs and a need for alternative weed control strategies.
Insect resistance: Insect resistance refers to the ability of plants or crops to naturally repel or withstand insect pests, reducing the damage they cause. This trait is increasingly important in agriculture as it allows for reduced pesticide use, lowers production costs, and can enhance crop yields. Insect resistance is often achieved through genetic modification or the selection of specific traits in breeding programs.
Particle bombardment: Particle bombardment is a technique used to introduce foreign DNA into plant cells by physically propelling microscopic particles coated with the DNA into the target cells. This method, also known as biolistics or gene gun technology, allows for stable transformation of plant tissues, making it a vital tool in the development of transgenic plants and crops with improved traits.
Public perception: Public perception refers to the collective beliefs, opinions, and attitudes of the general population toward a particular issue, technology, or innovation. This concept plays a crucial role in shaping the acceptance or rejection of biotechnological advancements, as people's views can influence policy decisions, funding, and overall progress in various fields, including agriculture and medicine.
Risk assessment: Risk assessment is the process of identifying, evaluating, and prioritizing risks associated with a particular activity or product, particularly in biotechnology. This process involves analyzing potential hazards, determining the likelihood of adverse outcomes, and assessing the consequences of those outcomes to ensure safety and effectiveness. It plays a crucial role in the development and commercialization of biotechnological innovations, especially when dealing with genetically modified organisms and their potential environmental and health impacts.
RNA interference: RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression or translation, effectively silencing specific genes. This mechanism plays a crucial role in regulating gene activity and protecting cells from viruses, making it an important tool in biotechnology, especially in the development of transgenic plants and crops.
Roundup Ready Soybeans: Roundup Ready soybeans are genetically modified soybean varieties that have been engineered to be resistant to glyphosate, the active ingredient in the herbicide Roundup. This genetic modification allows farmers to apply glyphosate for weed control without harming the soybean plants, leading to easier and more effective management of weeds in soybean crops.
Selectable Markers: Selectable markers are genes that are introduced into an organism to allow for the identification and selection of cells that have successfully incorporated a desired genetic modification. These markers enable researchers to distinguish between transformed and non-transformed cells, ensuring that only those with the desired traits are propagated and studied further.
T-DNA: T-DNA, or Transfer DNA, is a segment of DNA from the Agrobacterium tumefaciens bacterium that is transferred into the plant genome during the process of transformation. This segment is crucial for creating transgenic plants, as it carries genes that can confer desirable traits such as disease resistance or improved nutritional value. Understanding T-DNA's role helps in the development of genetically modified crops with enhanced features.
Ti plasmid: A ti plasmid, or tumor-inducing plasmid, is a specific type of plasmid found in the bacterium Agrobacterium tumefaciens that has the ability to transfer genetic material into plant cells. This process leads to the formation of tumors in plants, but researchers have harnessed this capability for genetic engineering, allowing for the development of transgenic plants with desired traits, such as pest resistance or improved nutritional content.
USDA: The USDA, or United States Department of Agriculture, is a federal agency responsible for overseeing various aspects of farming, forestry, and food production in the United States. This includes ensuring food safety, regulating agricultural practices, and promoting sustainable agriculture. Its role is particularly significant in the context of biotechnology, as it plays a crucial part in the regulatory process for genetically modified organisms (GMOs), including transgenic plants and crops.