What is Somaclonal variation (plant tissue culture)? Causes, Disadvantages, Advantages, Examples.

Summary

In this video, Dr. Abhishek explores somaclonal variation in plant tissue culture, explaining how genetic and epigenetic changes can arise during in vitro propagation, sometimes resulting in plants that differ from their mother explant. The video covers causes such as stress conditions, hormone imbalances, and oxidative stress, along with the types of genetic and epigenetic alterations observed. While somaclonal variation can hinder clonal fidelity, it also offers a powerful tool for developing improved plant varieties with enhanced yield, disease resistance, stress tolerance, and nutritional quality, without the need for genetic modification. Several practical horticultural examples are highlighted.

Takeaways

• 🌱 Somaclonal variation refers to genetic or epigenetic changes that occur in plants during in vitro propagation, resulting in plants that are no longer identical to the mother plant.
• 🧬 The term 'somaclonal variation' was first introduced by Larkin and Scowcroft in 1981.
• ⚡ Stressful conditions such as harsh sterilization, wounding, hormone imbalance, and light stress increase reactive oxygen species, which are a major cause of somaclonal variation.
• 🔬 Genetic fidelity testing using markers like RAPD, ISSR, and SSRs is essential to determine if propagated plants remain genetically identical.
• 🧪 Somaclonal variation is more likely in protoplast culture, cell suspension culture, and callus culture due to rapid cell division.
• 🧩 Types of changes during somaclonal variation include genetic alterations (mutations, translocations, deletions, insertions, chromosomal changes) and epigenetic modifications (DNA methylation, histone changes).
• ⚠️ Disadvantages include loss of clonal fidelity, production of plants with undesirable traits, and genetic instability over generations.
• 🌟 Advantages include the development of novel plant varieties with improved yield, nutritional quality, disease resistance, and abiotic stress tolerance.
• 💡 Somaclonal variation can produce improved plant varieties without introducing foreign DNA, avoiding regulatory hurdles associated with genetically modified crops.
• 💰 Producing somaclonal variants is cheaper and technologically simpler compared to gene cloning or genetic engineering.
• 🍏 Examples of improved horticultural crops include apple resistant to white root rot, drought-tolerant carrot, thornless blackberry, high-yield garlic, and salinity-tolerant sweet potato.

Q & A

What is somaclonal variation in plant tissue culture?

Somaclonal variation refers to genetic or epigenetic changes that occur during in vitro propagation of plants, resulting in offspring that are not genetically identical to the mother plant.

Who first introduced the term somaclonal variation and when?

The term somaclonal variation was first introduced by Larkin and Scowcroft in 1981.

What are the main causes of somaclonal variation during plant tissue culture?

Somaclonal variation is mainly caused by stressful conditions such as harsh surface sterilization, wounding, hormone imbalances in culture media, light conditions, and oxidative stress from reactive oxygen species.

Which types of plant cultures are more prone to somaclonal variation?

Rapidly dividing undifferentiated cells, such as in protoplast cultures, cell suspension cultures, or callus cultures, are more prone to somaclonal variation due to higher chances of genetic changes.

What kinds of genetic changes can occur in somaclonal variation?

Genetic changes include single base mutations, translocations, deletions, insertions, duplications, activation of transposable elements, and chromosomal gain or loss. Variations can also occur in mitochondrial and chloroplast DNA.

What epigenetic changes are associated with somaclonal variation?

Epigenetic changes may include DNA methylation and histone modifications, which can alter gene expression and affect plant characteristics.

What are the disadvantages of somaclonal variation?

Disadvantages include reduced clonal fidelity, the possibility of producing plants with undesirable traits, and genetic instability across generations.

What are the advantages of somaclonal variation in plant breeding?

Advantages include the rapid development of novel plant varieties with improved traits such as higher yield, disease resistance, stress tolerance, and enhanced nutritional quality. It is also faster, cheaper, and does not require external DNA or regulatory approval like genetic engineering.

Can you provide examples of horticultural crops developed through somaclonal variation?

Examples include apples resistant to white root rot, fusarium-resistant bananas with early flowering, thornless blackberries, drought-resistant carrots, garlic with higher bulb yield, fusarium-resistant peas, high-yield pineapples and potatoes, stevia with high glycoside content, fungal-resistant strawberries, salinity-tolerant sweet potatoes, and Vidania with higher withanolide content.

How is genetic fidelity tested in plants to detect somaclonal variation?

Genetic fidelity is tested using molecular markers such as RAPD, ISSR, and SSR, which can identify whether plants are genetically identical or have accumulated variations.

Why does subculturing increase the chances of somaclonal variation?

Subculturing over multiple generations increases the chances of somaclonal variation because the repeated cell divisions in culture amplify the likelihood of genetic and epigenetic changes.