The genetic modification of plants (also known as plant genetic engineering) involves several well-defined steps to introduce new traits—such as pest resistance, drought tolerance, or enhanced nutrition—into a plant’s genome.
Here’s a clear and simple explanation of the key steps involved:
1. Identification of the Desired Gene
The first step is to find and isolate a gene that controls a useful trait.
- Scientists identify a gene from another plant, bacterium, or organism that produces a desired characteristic.
- For example, the Bt gene from the bacterium Bacillus thuringiensis is used to make insect-resistant plants.
2. Isolation of the Gene
The desired gene is then extracted and purified from the source organism using molecular biology techniques such as restriction enzymes that cut DNA at specific points.
3. Insertion of the Gene into a Vector
The isolated gene is inserted into a vector, which acts as a carrier to deliver the gene into the plant cell.
- Common vectors include plasmids (especially from Agrobacterium tumefaciens) or viral vectors.
- The vector also carries marker genes (for antibiotic or herbicide resistance) to identify successful transformations.
4. Transfer of the Gene into Plant Cells
The vector carrying the desired gene is introduced into plant cells using one of the following methods:
- Agrobacterium-mediated transformation: Uses the natural DNA transfer ability of Agrobacterium tumefaciens.
- Gene gun (biolistics): DNA-coated microscopic particles are shot into plant tissues.
- Electroporation or microinjection: Physical methods to introduce DNA into cells.
- PEG-mediated transformation: DNA uptake by protoplasts (plant cells without cell walls).
5. Selection of Transformed Cells
Not all plant cells take up the foreign gene, so selection markers are used to identify successful ones.
- For example, only cells with the new gene will survive on a medium containing a specific antibiotic or herbicide.
6. Regeneration of Transgenic Plants
The selected transformed cells are grown in a nutrient-rich tissue culture medium containing plant hormones.
- These cells regenerate into complete plants through plant tissue culture techniques.
- Each regenerated plant contains the new gene in all its cells.
7. Confirmation of Gene Integration and Expression
Molecular tests are performed to verify that the new gene has been properly inserted and is functioning:
- PCR (Polymerase Chain Reaction) confirms the presence of the gene.
- Southern blotting checks DNA integration.
- Protein assays confirm that the introduced gene is producing the expected protein or trait.
8. Field Testing and Evaluation
The genetically modified plants are tested in controlled environments and field trials to ensure that:
- The new trait is stable and heritable.
- There are no negative effects on growth, yield, or environment.
9. Regulatory Approval and Commercial Release
Before commercial cultivation, GM plants undergo biosafety evaluations to assess their environmental and health safety.
Once approved, the genetically modified crop can be grown and distributed to farmers.
In summary:
The key steps in plant genetic modification are:
- Identifying and isolating the desired gene
- Inserting the gene into a vector
- Transferring the gene into plant cells
- Selecting transformed cells
- Regenerating complete plants
- Confirming gene integration
- Testing and approving for safe use
Through these steps, scientists create transgenic plants that express beneficial traits for agriculture, nutrition, and sustainability.