Tissue Culture

Introduction

Tissue culture is already prevalent among scientists globally. It is the unique process by which they can grow the entire plant just from specific cells of it. This helps them make disease-resistant varieties of plants. To continue with the cultural techniques, you need a nursery or  a greenhouse and trained people. The technique is quite costly; therefore, economically important plants are preferred to be developed by this process. 

The technique involves complete control over the temperature, pH, and other necessary conditions for the growth of the tissue. It needs the training to perform the culture. 

Media for Tissue Culture

Preparing a medium is a critical process for the culture to happen. If the culture medium is not appropriate, the process will not proceed. The medium has inorganic elements, organic compounds, and a support matrix. 

Agar, a polysaccharide, is used in making culture mediums. They do not react with the media constituents and are not digestible by plants.

The culture medium varies upon the species under observation. The medium should be of optimum pH to support the process. 

Steps of Tissue Culture

Tissue culture is a very delicate process. Therefore, special care is necessary for the process to occur. Persons with special skills can only perform this technique. 

The basic steps of tissue culture are as follows:

Step 1- Inoculation of Explant

Several precautions are necessary during the transfer of explant to the culture medium. During the transfer, dust particles can cause a hurdle in the proper culturing. Therefore, the sterilisation of equipment is necessary before using it. The inoculation chamber, where the explant is kept, is also sterilised. Sterilisation of headgear and clothes is necessary to prevent the entry of any unwanted particle in the medium. 

Clean your hands and transfer area with 95% alcohol. Avoid any talking in the chamber during the process. The instruments should be flamed before use. The explants should not touch the edges of the culture vessel. Close the vessel with a plug once the explant is carefully kept in the vessel. 

Step 2- Incubation

 After successful vaccination, the incubation of the explant is the next step. The incubation can be through the incubation chambers. Different cultures require varying temperature ranges for incubation. However, the average temperature may be slightly below or above 25 °C.  

The explant requires alternate periods of light and darkness. Some of them may require more light than others. The light source is kept 18 inches above the culture racks. Proper humidity is also necessary for the growth of the explant. However, low humidity can cause desiccation of it. The explant under culture must receive proper air to survive. Shakers are present in incubation chambers to ensure this. 

Step 3- Sub-Culturing

The culture is carefully examined and observed. The explant is transferred to a new fresh culture medium with proper care. During the transfer, the same precautions are necessary. By delaying this transfer, the tissue may not grow properly. 

Step 4- Transplantation of the Cultured Plant

Now, the final step arrives, a plantation of the plant. The plant is transferred to the pot. It is a critical phase for the plant as it becomes habitual with the real environmental condition. Therefore, special care of a plant is necessary until it adapts to the environment. 

Types of Tissue Culture

• Seed Culture- Seed culture is prevalent in plants like orchids. In seed culture, the plant material is directly used. Sterilisation is necessary for preventing any contamination
• Embryo Culture- The culture dealing with in-vitro development of the embryo is the embryo culture. The embryo can be both mature and immature. Mature embryos are from ripe fruits, and immature embryos are from seeds that failed in germination
• Callus Culture- The unorganised mass of cells or callus is now the explant for culture. This culture requires a gel-like medium as Agar. The callus is then differentiated into organs
• Organ Culture– As the name suggests, organ culture requires the entire organ of a plant, such as its leaf. The methods of organ culture are the plasma clot method, raft method, the grid method, and the Agar gel method
• Protoplast Culture- This culture has a cell without its cell wall. The method prevalent in protoplasm culture is a hanging-drop method or micro-culture chambers. The phases in this culture are the development of cell walls, cell division, and regeneration of a whole plant

Significance of Tissue Culture

The tissue culture has immense importance in developing different and better crops. Some of their significance are as follows:

• It produces the copies of plants with better inflorescence, fruits, and other desirable traits
• It reduces the time for the maturation of plants
• It makes it possible to grow plants even in the absence of seeds and pollinating agents
• They can process the genetic modifications of plants as per the requirement
• The plants are in sterile conditions, which reduces the chances of transmission of diseases and pathogens
• Some plants are difficult to grow with seeds, and culture enables easy cultivation
• Disease-resistant plants are made under special techniques

Conclusion

Tissue culture is a very important practice in the modern world. It provides an opportunity of developing better plant varieties with high yields. Certain special traits are added or subtracted as per the requirement. The process is very delicate and requires specialists to perform. Sterilisation of every piece of equipment is necessary before starting the process.