Which of the following plant organs is NOT a potential explant for tissue culture?
1. Seed
2. Flower
3. Root
4. Shoot tip

Introduction to Plant Tissue Culture

Plant tissue culture is a widely used technique in biotechnology that allows the growth of new plants from small tissue fragments, known as explants, under sterile laboratory conditions. Explants can be derived from various plant organs such as roots, stems, leaves, and shoot tips. However, not all plant organs are suitable for tissue culture due to differences in cellular totipotency and regeneration capacity. In this article, we will explore which plant organ is NOT a potential explant for tissue culture and understand the science behind plant tissue regeneration.

Key Phrase: Plant Tissue Culture Explants

✅ Question and Answer

Question:
Which of the following plant organs is NOT a potential explant for tissue culture?

Options:

1. Seed
2. Flower
3. Root
4. Shoot tip

Correct Answer:
✔️ Option 2: Flower

What is a Plant Explant in Tissue Culture?

An explant is a part of the plant (such as a leaf, stem, root, or shoot tip) used for initiating a tissue culture. Under sterile conditions and the right combination of plant growth hormones, explants can regenerate into whole plants through the process of organogenesis or somatic embryogenesis.

Commonly Used Explants in Plant Tissue Culture:

Root – Used for root initiation and secondary metabolite production.
Shoot Tip – Used for rapid multiplication through shoot elongation.
Leaf – Used for somatic embryogenesis and shoot regeneration.
Cotyledon – Used for early-stage embryo development.

Why Flowers Are Not Suitable as Explants

1. Limited Cellular Totipotency

• Unlike roots and shoot tips, flowers have limited ability to regenerate new plantlets due to their specialized nature for reproduction.
• Most floral tissues are highly differentiated, which reduces their ability to revert to a totipotent state.

2. High Level of Lignification

• Floral tissues often have high levels of lignin, which creates a physical barrier to cellular division and growth.

3. Poor Response to Growth Hormones

• Floral tissues generally have low sensitivity to plant growth regulators (e.g., auxins and cytokinins) essential for inducing cell division and differentiation.

How Plant Tissue Culture Works

1. Explant Selection

• Suitable explants are selected based on the species and tissue type.
• Common choices include root tips, shoot apices, and leaf segments.

2. Sterilization

• Explants are sterilized using chemicals like ethanol or sodium hypochlorite to prevent microbial contamination.

3. Culture Medium Preparation

• Explants are placed in a culture medium containing:
  • Macronutrients and micronutrients – Essential for plant growth.
  • Sucrose – As a carbon source.
  • Plant growth regulators – Auxins and cytokinins for cell division and differentiation.

4. Incubation and Growth

• Explants are incubated under controlled conditions of light, temperature, and humidity.
• After a few weeks, callus formation and organogenesis are observed.

Significance of Explant Selection in Tissue Culture

1. Genetic Stability – Proper explant selection minimizes genetic variations in regenerated plants.
2. High Regeneration Efficiency – Shoot tips and roots offer the highest regeneration success rates.
3. Disease-Free Propagation – Shoot tips and meristem tissues are often free from systemic infections, making them ideal for developing virus-free plants.

Why Flowers Are Unsuitable for Tissue Culture

Techniques Used in Plant Tissue Culture

1. Callus Culture

• Explants are induced to form an undifferentiated mass of cells (callus).
• Callus can be induced to form shoots and roots under the right hormonal balance.

2. Organogenesis

• Direct induction of shoots or roots from explants.
• Commonly used for micropropagation.

3. Somatic Embryogenesis

• Formation of embryo-like structures from somatic cells.
• Often used for large-scale clonal propagation.

Importance of Tissue Culture in Agriculture and Biotechnology

Crop Improvement – Tissue culture is used for producing genetically identical, disease-free plants.
Mass Propagation – Rapid multiplication of elite plant varieties.
Genetic Modification – Transgenic plants can be created using tissue culture techniques.
Pharmaceuticals – Production of secondary metabolites with medicinal properties.

Why Option 2 (Flower) is the Correct Answer

• Flowers are reproductive structures rather than vegetative tissues.
• They lack meristematic tissue essential for regeneration.
• Therefore, flowers are NOT suitable as explants for tissue culture.

Relevance for Competitive Exams

A solid understanding of tissue culture and explants is essential for competitive exams like:
DBT BET JRF
CSIR NET Life Science
IIT JAM
GATE Biotechnology

Conclusion

The correct answer to the question is Option 2 – Flower. Flowers are not suitable for tissue culture because they are specialized for reproduction, not regeneration. Understanding plant tissue culture and explant selection is fundamental for agricultural biotechnology, plant propagation, and genetic improvement. For detailed guidance and structured preparation for DBT BET JRF, CSIR NET Life Science, IIT JAM, and GATE Biotechnology, join Let’s Talk Academy — the leading institute for life science exam preparation.