Somaclone

Variation in tissue culture regenerated plants from somatic cells can be employed in the generation of crops with novel features, making somaclonal variation a vital tool in plant breeding. 

Plants regenerated from callus have a lot of somaclonal variety, which isn’t limited to them. 

The differences might be genotypic or phenotypic, with the latter being genetic or epigenetic in nature. Changes in chromosome numbers (polyploidy and aneuploidy), chromosome structure (translocations, deletions, insertions, and duplications), and DNA sequencing are all examples of genetic modifications (base mutations). Gene methylation is an example of an epigenetics-related occurrence.

In Vitro Mutation Induction and Somaclonal Variation

• In sugarcane, banana, and potato, somaclonal variation and in vitro mutation induction have been employed to improve specific features, including disease resistance and other flaws that limit the use of some major commercial cultivars

• Sugarcane was the first crop and the one that yielded the most significant effects

• A full selection system was created, and it was proved that genuine mutants for the key quantitative features could be selected after only three vegetative multiplications in the field

• Sixteen somaclones were obtained, and five of them were approved for further development and commercialization as commercial varieties

• The selection procedure lasted between 5 and 7 years in total, and the results indicated the efficacy of in vitro mutation in comparison to traditional character improvement

Somaclonal Variation, Genetic Variation, or Chimeral Variation

• The variance exhibited in plants grown via plant tissue culture is known as somaclonal variation

• This diversity is largely due to chromosomal rearrangements. Plants regenerated from callus have a lot of somaclonal variety, which isn’t limited to them

• Changes in chromosome numbers (polyploidy and aneuploidy), chromosome structure (translocations, deletions, insertions, and duplications), and DNA sequence (base mutations) are all examples of genetic modifications

• Gene amplification and gene methylation are two common epigenetic processes. Other plant screening approaches must be used if no visual morphogenetic changes are seen

Variation in Somaclonal Structure

• Somaclonal variation occurs when in vitro grown cells undergo genetic variation, and plants generated from such cells are referred to as “somaclones” 

• Long-term callus, cell suspension culture, and plants regenerated from such cultures have all been discovered to have somaclonal variation, which is always related with chromosomal variants

• This form of genetic variation can be used in a variety of ways, including crop enhancement and the creation of mutants and variants (e.g., disease resistance in potato)

• Plant variations generated from tissue cultures of somatic tissues were dubbed “somaclones” by Larkin and Scowcroft. Similarly, “gametoclonal” variation is defined as somatic tissue-derived variants with a gametophytic origin, such as pollen or egg cell

Advantages of Somaclonal Variation 

• When compared to recombinant DNA technology, the methodology for introducing somaclonal variations is simpler and easier

• This method adds more genetic diversity to the equation

• Suitable for higher plant breeding

• A large number of populations are screened at the same time, such as tens of thousands of cell lines

• Cryopreservation can be used to preserve a stable cell line

• Somaclonal variation may affect gene expression, resulting in increased secondary metabolite synthesis

• This protoplast-based approach is widely used in agricultural science (crop improvement) for the development and production of plants with disease resistance (e.g., rice, wheat, apple, tomato), abiotic stress resistance (e.g., aluminium tolerance in carrot, salt tolerance in tobacco and maize), herbicide resistance (e.g., tobacco resistant to sulfonylurea), and improved seed quality (e.g., tobacco resistant to sulfonylurea) (e.g., a new variety of Lathyrus sativus seeds with low content of neurotoxin).

Somaclonal Variation’s Drawbacks 

• This technique is only applicable to plants that have the ability to regenerate into entire plants

• Somaclones can be unstable and non-heritable in rare cases

• Somaclones are more likely to have unfavourable characteristics such as decreased fertility, growth rate, and overall plant performance

• The plant cell line’s stability must be confirmed through repeated selection

Plant Genetic Engineering

Plant genetic engineering is something feasible and has a lot of experience with. Although global crop yields have increased in recent years, plant diseases, pests, and diverse abiotic stresses such as salt, drought, cold, and heavy metal pollution continue to affect crop growth in many locations.

Plant genetic engineering, also known as plant genetic modification or manipulation, is the key to adding desirable features into crops, resulting in plants that use fewer pesticides, fungicides, or fertilisers and are more resistant to stress.

Plant genetic engineering techniques allow for the direct transfer of one or a few genes of interest between closely related or distantly related species in order to gain desired agronomic features. 

Plants can be transformed by knocking out, knocking down, or overexpressing their own genes, in addition to acquiring genes from other species.

Plant disease genetics

• Plants that have been regenerated from culture (calluses, single cells, or protoplasts) generally have a lot of diversity (somaclonal variation), much of which is useless or harmful

• Plants with valuable features, on the other hand, may emerge. Plants regenerated from leaf protoplasts of a potato variety susceptible to both Phytophthora infestans and Alternaria solani

Conclusion

Variation in tissue culture regenerated plants from somatic cells can be employed in the generation of crops with novel features, making somaclonal variation a vital tool in plant breeding. 

Plants regenerated from callus have a lot of somaclonal variety, which isn’t limited to them. The differences might be genotypic or phenotypic, with the latter being genetic or epigenetic in nature.