1. What is Genetic Transformation?

Genetic transformation refers to the introduction of foreign DNA into plant cells to express new traits or study gene functions.

Tissue culture is key to this process because:

• Plant cells must be totipotent and regenerable

• The environment must be controlled and sterile

• Antibiotic/herbicide selection requires isolated cells or callus

📌 Plant Transformation Techniques

2. Gene Delivery Methods

Each method has trade-offs in efficiency, species compatibility, and technical complexity.

3. Selectable and Reporter Genes

After transformation, not all cells are successful. To identify and isolate transformed cells, scientists use:

Selectable markers:

• nptII – Confers resistance to kanamycin

• bar – Confers resistance to herbicides like Basta or glufosinate

Reporter genes:

• GUS – Produces blue color when stained

• GFP – Green fluorescence under UV light

• LUC – Emits visible light (luciferase)

These help monitor transformation efficiency and expression levels.

4. The Role of Tissue Culture in Transformation

After transformation:

1. Cells are plated on selection media

2. Surviving cells regenerate into shoots and roots

3. Whole plants are transferred to soil and analyzed

4. Molecular screening confirms gene integration

Without regeneration from single cells or callus, transformation would not be feasible.

5. Applications in Real-World Agriculture

Transgenic plants created through tissue culture have revolutionized agriculture:

• Bt crops – Resistant to pests (e.g., Bt cotton, corn)

• Golden rice – Engineered to produce vitamin A

• Herbicide-tolerant crops – Reduce need for tillage

• Papaya ringspot virus–resistant papaya – Saved the Hawaiian papaya industry

• Pharmaceutical plants – Produce vaccines and enzymes

📌 Case Study: Golden Rice