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•Transgenic plants are plants that have been genetically modified using genetic engineering techniques. This involves the introduction of new genetic material into the plant’s genome, typically from another plant or organism.

•The genetic modification process can be used to produce plants with desirable traits, such as resistance to pests or disease, improved nutrient content, or increased yield. For example, a transgenic plant might be engineered to produce a toxin that kills insects that would otherwise damage the plant, or to produce a higher concentration of a specific nutrient, such as vitamin A.

•The process of creating transgenic plants typically involves identifying a gene or set of genes that encode the desired trait, isolating those genes, and then inserting them into the genome of the target plant using techniques such as gene gun or Agrobacterium-mediated transformation.

•Transgenic plants have the potential to offer many benefits, such as increased crop yields, reduced use of pesticides and herbicides, and improved nutritional content. However, there are also concerns about the potential risks associated with the release of genetically modified organisms into the environment, as well as concerns about the potential impact of transgenic plants on human health.

★PRODUCTION OF TRANSGENIC PLANTS:-

Transgenic plants are plants that have had their DNA modified by the introduction of genes from another organism. This can be done through a variety of techniques, but the most common method is through genetic engineering.

★The production of transgenic plants involves several steps:

(1-)Identification of the gene of interest:

The first step is to identify the gene of interest that is to be introduced into the plant. This gene can come from any organism, such as bacteria, fungi, or animals.

(2)Isolation of the gene:

Once the gene has been identified, it is isolated from the organism’s DNA and amplified through a process called polymerase chain reaction (PCR).

(3)Construction of the transgene:

The isolated gene is then inserted into a vector, which is a DNA molecule that can be used to transfer the gene into the plant. The vector also contains other DNA sequences that are required for the gene to function properly in the plant.

(4)Transformation of the plant:

The constructed transgene is introduced into the plant through one of several methods, including biolistic transformation (using a gene gun), Agrobacterium-mediated transformation (using a bacteria), or electroporation (using an electric field).

(5)Selection and regeneration of transgenic plants:

After the transgene has been introduced, the plant is grown in a selective medium that only allows the growth of transgenic cells. Once transgenic cells have been identified, they are grown into whole plants through a process called regeneration.

(6)Testing and characterization of transgenic plants:

★Vector mediated Gene transfer:-

The final step is to test and characterize the transgenic plants to ensure that they have the desired characteristics and that the transgene has been properly integrated into the plant’s genome. This includes DNA sequencing, gene expression analysis, and phenotype analysis.

Vector-mediated gene transfer is a technique used to introduce new genetic material into cells by using a vector as a carrier. A vector is usually a virus or a plasmid, which is modified to carry the desired genetic material. The vector is introduced into the target cells, where it delivers the new genetic material.

There are two types of vectors commonly used in gene transfer: viral vectors and non-viral vectors. Viral vectors are derived from viruses, which have the natural ability to infect and deliver their genetic material into host cells. Non-viral vectors, on the other hand, do not rely on viral infection and instead use other mechanisms to enter cells, such as electroporation or lipofection.

Vector-mediated gene transfer has many potential applications, including gene therapy for inherited diseases, genetic engineering of crops, and the creation of transgenic animals for research purposes. However, there are also some risks associated with gene transfer, such as immune reactions and unintended effects on the genome. Therefore, careful consideration and rigorous testing are necessary to ensure the safety and efficacy of vector-mediated gene transfer in various applications.

Plasmids of Agrobacterium, Caulimo virus and Gemini viruses have been used as potential vectors to carry out genetic transformation.

★AGROBACTERIUM MEDIATED GENE TRANSFER:

Agrobacterium-mediated gene transfer is a technique used to introduce foreign DNA into the genome of a plant using a soil bacterium called Agrobacterium tumefaciens. This technique has been widely used for plant genetic engineering and has become a powerful tool for introducing new traits into crops.

Agrobacterium tumefaciens has a natural ability to transfer a segment of its own DNA called T-DNA (Transfer DNA) into plant cells, which causes a tumor-like growth called crown gall disease. Researchers have learned how to manipulate this process by replacing the T-DNA with desired genes of interest.

The basic steps in Agrobacterium-mediated gene transfer are:

(i)Preparation of the plant tissue:

Plant tissue, such as leaf, stem or embryo is excised and placed in a culture medium containing nutrients and hormones that promote cell division.

(ii)Transformation of Agrobacterium:

The Agrobacterium strain containing the desired gene is grown in culture media, and the bacteria are harvested and suspended in a solution.

(iv)Co-cultivation of plant tissue with Agrobacterium:

The plant tissue and Agrobacterium are mixed and incubated together for a period of time, allowing the bacteria to infect the plant cells.

(v)Selection of transformed plant cells:

After co-cultivation, the plant cells are washed to remove the Agrobacterium and then placed on a selection medium containing antibiotics or herbicides that kill the non-transformed cells.

(vi)Regeneration of whole plants from transformed cells:

The transformed cells that survive selection are then grown in culture, and whole plants are regenerated from them.This technique has been used to introduce desirable traits into crops, such as resistance to pests and diseases, tolerance to herbicides, and improved nutritional quality. It has also been used to develop genetically modified organisms (GMOs) that are used in agriculture and biotechnology

This technique has been used to introduce desirable traits into crops, such as resistance to pests and diseases, tolerance to herbicides, and improved nutritional quality. It has also been used to develop genetically modified organisms (GMOs) that are used in agriculture and biotechnology.

★There are three approaches to produce TRANSGENIC PLANTS: —

(i)Leaf disc transformation procedure:

Leaf disc transformation is a widely used method to introduce foreign DNA into plant cells. •The procedure involves the following steps:

★Preparation of plant material:Collect healthy leaves from a suitable plant species, typically one that is easy to regenerate from tissue culture. Cut the leaves into small discs (approximately 0.5 to 1 cm in diameter).

★Preparation of transformation solution: Prepare a solution containing the DNA construct to be introduced, along with suitable chemicals such as plant hormones and antibiotics to promote cell division and suppress bacterial growth.

★Incubation of leaf discs in the transformation solution: Place the leaf discs into the transformation solution, and incubate them in the dark at room temperature for several hours. The transformation solution is typically agitated gently to ensure even distribution of the DNA construct.

★Regeneration of transformed plants:After the incubation period, transfer the leaf discs onto a suitable growth medium containing plant hormones and antibiotics. The plant hormones promote the regeneration of plant cells from the leaf discs, while the antibiotics kill any bacterial cells that may be present.

★Selection of transformed plants: After several weeks, the regenerated plants will grow from the leaf discs. Select for transformed plants by screening for the presence of the foreign DNA using methods such as PCR or Southern blotting.

★Confirmation of transgene expression: Finally, confirm the expression of the foreign gene in the transformed plants using techniques such as RT-PCR or western blotting.

Leaf disc transformation is a powerful tool for introducing foreign genes into plants and can be used to generate transgenic plants for research or agricultural purposes.

(ii) Co-cultivated Procedure with Protoplast:

Protoplasts are cells that have had their cell walls removed, leaving behind a naked cell membrane. They can be used in various procedures such as cell fusion, gene transfer, and cell transformation. •Coordinating a procedure with protoplasts involves several steps:

★Isolate protoplast:Protoplasts can be isolated from plant or fungal cells using enzymatic digestion. The enzymes used for digestion vary depending on the cell type and protocol used.

★Prepare the fusion mixture:The fusion mixture typically contains protoplasts from two different cell types, along with polyethylene glycol (PEG) or other fusogens. The fusogen helps the protoplasts to fuse together and form hybrid cells.

★Perform the fusion:The fusion mixture is incubated for a specific amount of time, during which the protoplasts fuse together. The resulting hybrid cells can be cultured and screened for desired traits.

(iii) Wounded -Plant Infection Procedure: This procedure results in plant -regeneration from single transformed cells (protoplast) so providing a genetically uniform collection of transgenic plants.

★GEMINI VIRUSES★

Gemini viruses are a type of plant virus that infects a wide range of crops, including vegetables, fruits, and ornamental plants. They are named for the twinned appearance of their viral particles when viewed under an electron microscope, which resemble the astrological symbol for the constellation Gemini.

Gemini viruses have a circular, single-stranded DNA genome that is encapsulated within a protein coat. They are transmitted between plants by insect vectors, such as whiteflies and leafhoppers. Once a plant is infected, the virus can cause a range of symptoms, including stunted growth, yellowing of leaves, and reduced crop yield.

There are several different species of Gemini viruses, each of which can infect different host plants. Some of the most economically important species include Tomato yellow leaf curl virus, which affects tomato and other solanaceous crops, and African cassava mosaic virus, which infects cassava plants and can cause significant damage to food security in Sub-Saharan Africa.

Management of Gemini viruses is typically focused on controlling their insect vectors through the use of insecticides and cultural practices such as crop rotation and sanitation. Plant breeding efforts to develop resistant varieties are also underway, but progress has been slow due to the complexity of the virus-host interactions involved.

★DIRECT DNA UPTAKE:-

Direct DNA uptake refers to a process by which a cell takes up DNA from its environment without the use of a vector, such as a virus or plasmid. This can occur naturally in some organisms, such as bacteria, or can be induced through laboratory techniques such as electroporation or transformation.

In natural transformation, bacteria take up DNA fragments from their environment and integrate them into their own genome. This process is important for the exchange of genetic material between bacteria and can lead to the acquisition of new traits such as antibiotic resistance.

In the laboratory, direct DNA uptake can be used to introduce foreign DNA into cells for genetic engineering purposes. Electroporation involves the use of an electric field to create temporary pores in the cell membrane, through which DNA can pass. Transformation involves the use of chemical treatments to make the cell membrane more permeable to DNA.

Overall, direct DNA uptake is a valuable tool for genetic engineering and the study of microbial genetics.

★EXAMPLE OF TRANSGENIC PLANTS:-

Transgenic plants are genetically modified plants that have been altered by the insertion of one or more genes from another organism. Here are some examples of transgenic plants:

★BT cotton: This is a type of cotton that has been genetically modified to produce a toxin called Bacillus thuringiensis (Bt) that is toxic to cotton bollworms and other pests.

★Roundup Ready soyabeans: These soybeans have been genetically modified to be resistant to the herbicide glyphosate, which allows farmers to control weeds more easily.

★Golden Rice: This is a type of rice that has been genetically modified to produce beta-carotene, which the body can convert into vitamin A. This is intended to help combat vitamin A deficiency in developing countries.

★Flavr Savr tomatoes: These tomatoes were the first genetically modified food to be sold commercially. They were modified to stay ripe longer and resist rotting.

★Arctic Apples:These apples have been genetically modified to resist browning when sliced or bruised, which helps to reduce food waste.

★Rainbow papaya:This is a type of papaya that has been genetically modified to be resistant to the papaya ringspot virus, which threatened to wipe out the Hawaiian papaya industry.

(1)Viral diseases resistance in plants:

Plants have developed mechanisms to defend themselves against viral diseases.

Some of these mechanisms include:

(i)Physical barriers:

Plants have a tough outer layer that can prevent viruses from entering the plant tissues. For example, the waxy cuticle on leaves acts as a physical barrier to viruses.

(ii)Recognition and response:

(iii)RNA interference:

Plants have an innate immune system that can recognize viral pathogens and trigger a response to prevent the virus from spreading. This response involves the production of antimicrobial compounds and the activation of various defense pathways.

RNA interference (RNAi) is a natural defense mechanism that can be triggered by the presence of viral RNA. This mechanism involves the production of small interfering RNAs (siRNAs) that can specifically target and destroy viral RNA.

(iv)Resistance genes:

Some plant species have resistance genes that provide them with specific resistance against certain viral pathogens. These genes can recognize specific viral proteins and trigger a response to prevent the virus from replicating and spreading.