Virus free plants can be obtained by

Options

A. Antibiotic treatment
B. Bordeaux mixture
C. Root tip culute
D. Shoot tip culture.

Answer

To obtain virus-free plants, the best method is through shoot tip culture. Here’s a step-by-step breakdown of the process:

### Step-by-Step Solution:

1. **Selection of Explant**: The first step is to select the shoot tip of the plant. The shoot tip contains meristematic tissue, which is crucial for the regeneration of the plant.

2. **Sterilization of Tools**: Use a sterilized knife to cut the shoot tip. This is important to prevent contamination from pathogens, including viruses.

3. **Surface Sterilization of Explant**: After cutting the shoot tip, the surface of the explant must be sterilized. This typically involves treating the explant with a disinfectant solution, such as sodium hypochlorite or alcohol, to eliminate any surface contaminants.

4. **Preparation of Culture Media**: The sterilized explant is then placed on a culture medium. This medium is enriched with nutrients and growth hormones necessary for plant growth.

5. **Induction of Callus Formation**: In the culture medium, the explant will initially form a callus, which is an undifferentiated mass of cells. This is a crucial step for further development.

6. **Hormonal Treatment**: The callus is then transferred to a medium with a low concentration of cytokinin and auxins. Auxins promote root development, while cytokinins promote shoot development.

7. **Regeneration of Plantlets**: Over time, the explant will develop into shoots and roots, leading to the formation of complete plantlets.

8. **Acclimatization**: Finally, the plantlets are gradually acclimatized to the external environment before being transferred to soil.

### Conclusion:
The method of shoot tip culture is effective for obtaining virus-free plants due to the presence of meristematic cells that are less likely to carry viral infections.