What is Callus?
Plant Tissue Growth
Callus is an unorganized mass of cells that develop on plant tissue in response to stress or wound. It's documented as early as 1902 by the plant physiologist, G. Haberlandt.
Differentiation Potential
Callus contains cells that retain the ability to differentiate into a wide range of plant organs, such as roots, stems, and leaves.
Model System for Research
Callus is an excellent model system for studying the fundamental processes of cell growth and differentiation, as well as the molecular mechanisms that control them.
History of Callus Culture
Early Exploration
The early days of callus culture are filled with serendipitous discoveries. They discovered you could cultivate whole plants from a single callus, which was a major breakthrough in tissue culture.
Refining Techniques
Over the years, scientists have developed numerous techniques for callus culture, including suspension culture, organ culture, and embryo culture.
Commercial Applications
Callus culture has many commercial applications, such as micropropagation of crops, production of secondary metabolites, and genetic transformation of plants.
Callus Culture Techniques
Explants
Explants taken from various plant tissues are cultured on nutrient media containing synthetic or natural growth regulators and other supplements.
Induction
Dividing cells at the cut end of the explant begin to grow into a mass of undifferentiated, disorganized cells referred to as callus.
Sub-culturing
The callus is then transferred to fresh media for further proliferation or differentiation into desired structures or organs.
Applications of Callus Culture
Production of Secondary Metabolites
Secondary metabolites, such as alkaloids, flavonoids, and terpenoids, are synthesized by plants in response to environmental stress and can have pharmaceutical, cosmetic, and nutritional values.
Micropropagation of Crops
Callus culture is an efficient method for producing large numbers of genetically identical plants in a short time, early yield and improved quality control.
Genetic Transformation of Plants
Callus culture is an essential technique for introducing new genes into plant genomes, which is vital for creating genetically modified crops and improving agricultural productivity.
Advantages and Disadvantages of Callus Culture
Advantages
🔹Mass production of plants from a small explant tissue.
🔹In vitro production of more secondary metabolites in reduced time.
🔹Uniform plant batch production.
🔹Genetic improvements of plants.
Disadvantages
🔹Genetic variability among the plant produced, due to somaclonal variation.
🔹High contamination rate during plant growth due to sterilization processes.
🔹Expensive in terms of equipment and maintenance of a sterile environment.
Future Developments in Callus Culture
Bioreactors for Callus Production
Bioreactors can provide better control and facilitate mass production of callus, thereby reducing the cost and time required for biological production.
Integrating Gene Editing Techniques
The fast and efficient CRISPR/Cas9 system could be applied to callus culture for the rapid development of new plant varieties with enhanced traits.
Culturing under Salt Stress
Researchers are developing techniques to culture callus under salt stress, which could have valuable applications in the production of salt-tolerant crops.
