Definition:
Somatic hybridization is a biotechnological technique in which two different somatic cells (non-reproductive cells) from different species or varieties are fused to form a hybrid cell. This process allows the combination of genetic material from two distinct sources to create a novel hybrid organism.
How It Works:
Somatic hybridization is achieved through protoplast fusion, where the cell wall is removed, and only the protoplasts (cell contents enclosed by the plasma membrane) are fused.
Steps Involved in Somatic Hybridization:
Isolation of Protoplasts:
- Plant cells are treated with enzymes like cellulase and pectinase to remove the cell wall.
Fusion of Protoplasts:
- Fusion is induced using chemicals (e.g., polyethylene glycol - PEG) or electrical stimulation (electrofusion).
Selection of Hybrid Cells:
- Only fused cells are selected based on their growth on selective media.
Regeneration into Plants:
- The hybrid protoplasts are cultured to regenerate a complete plant using tissue culture techniques.
Applications of Somatic Hybridization:
Overcoming Sexual Incompatibility:
- Hybridization between species or genera that cannot crossbreed naturally.
- Example: Fusion of Potato and Tomato protoplasts to create "Pomato."
Crop Improvement:
- Developing plants with desirable traits like disease resistance, drought tolerance, and higher yield.
Transfer of Cytoplasmic Traits:
- Useful for incorporating cytoplasmic male sterility or herbicide resistance.
Genetic Variation:
- Creation of novel hybrids with unique genetic combinations.
Advantages:
- Bypasses the limitations of traditional breeding methods.
- Facilitates the transfer of traits from wild or distant species to cultivated crops.
- Useful for introducing polygenic traits.
Limitations:
- High technical expertise is required.
- Somatic hybrids may have undesirable traits.
- Regeneration of plants from hybrids is challenging in some cases.
Conclusion:
Somatic hybridization is a powerful tool in modern biotechnology, enabling the development of plants with improved characteristics. While there are challenges, advancements in tissue culture and protoplast fusion techniques continue to enhance its potential for agricultural and industrial applications.