8.2.4 Producing Tissue Cultures of Explants

Stages of Producing Tissue Cultures

1. Selection of Explants:

• An explant is a small piece of tissue taken from a parent plant, such as a leaf, stem, or root.
• The explant is typically taken from a plant with desirable traits (e.g., disease resistance or high yield).

2. Sterilisation:

• The explant is sterilised using substances like ethanol or sodium hypochlorite to remove microorganisms.

3. Placement in Growth Medium:

• The sterilised explant is placed in a sterile nutrient medium containing:
• Glucose: for energy.
• Agar: as a solid support.
• Minerals: essential nutrients for plant growth.
• Plant hormones (e.g., auxins and cytokinins) to stimulate cell division and differentiation.

4. Callus Formation:

• The explant cells divide by mitosis, forming a callus, which is a mass of undifferentiated cells.

5. Regeneration of Shoots and Roots:

• By altering the concentration of hormones, the callus is encouraged to form:
• Shoots (using cytokinins).
• Roots (using auxins).

6. Transfer to Soil:

• Once small plants (plantlets) have developed, they are transferred to sterile soil or compost in controlled conditions to continue growing.

Applications of Tissue Culture

1. Cloning Plants:

• To produce genetically identical plants with desirable traits such as disease resistance or high yield.

2. Preservation of Rare Species:

• Used to conserve endangered plants by creating large populations.

3. Crop Improvement:

• Allows for rapid multiplication of genetically modified plants.

4. Pathogen-Free Plants:

• Produces plants free from viruses and bacteria for agriculture.

Advantages of Tissue Culture

• Rapid multiplication of plants in a short time.
• Can be carried out all year round, regardless of season.
• Allows for the production of genetically uniform plants.

Disadvantages of Tissue Culture

• Requires specialised equipment and skills, making it costly.
• Risk of contamination, which can lead to loss of cultures.
• Produces genetically identical plants, making them vulnerable to diseases and pests.