Tissue Culture

What is Tissue Culture?

Tissue culture is a method under which fragments of plants and animal tissues are cultured and grown in a laboratory. The organs, many times, are used for tissue culture. Broth and agar are the media used for the growth of the culture. This method is also known as micropropagation. a sterile workplace, a greenhouse, trained manpower, and a nursery are all it requires. It is beneficial for the production of disease-free plants and plants in developing countries. In developing countries, oil palm, banana, plantain, eggplant, pineapple, rubber tree, tomato, sweet potato have been produced by tissue culture. Following are the main categories of cultures:-

  • Primary culture:- These model the natural function of the tissue and are generally mortal. They consist of natural tissues excised from the living organisms by biopsy.

  • Culture of established cell lines:- These are derived from tumor biopsies, or from the primary cells that had undergone mutation and continued to replicate.


Types of Tissue Culture.

Listed below are some type of tissue culture techniques:-

  • Seed Culture:- In seed culture,  explants are obtained from an in-vitro derived plant and hence are introduced into a laboratory where they proliferate. To prevent the plants from tissue damage it should be sterilized.

  • Embryo Culture:- Embryo culture involves the in-vitro development of an embryo. For this process, an embryo is isolated from and living organism, both a mature or an immature embryo can be used. Mature embryos can be obtained from ripe seeds whereas the immature embryos are obtained from the seeds that failed to germinate. The ovule, seed, or fruit has already been sterilized, hence there is no need to sterilize them.

  • Callus Culture:- A callus can be defined as an unorganized, dividing mass of cells. A callus is the explants are cultured in a proper medium good. The growth of callus is followed by organ differentiation. This culture is grown on a gel-like medium composed of agar and specific nutrients which are required for the growth of the cells.

  • Organ Culture:- In organ culture, any organ of the plant such as, shoot, leaf can be used as an explant. Many methods can be used for the organ culture such as, plasma clot method, raft method, grid method and Agar gel method. This method can be used to preserve the structure and functions of an organism.

  • Protoplast Culture:- It can be defined as a cell without a cell wall. The hanging-drop method or micro-culture chambers can be used to culture a protoplast. A number of phases can be observed in protoplast culture, development of cell walls, cell division, regeneration of a whole plant. 

  • Suspension Culture:- suspension culture can be defined as a form of culture in which single cells or small aggregates of cells mul­tiply while suspended in an agitated liquid medium. It can also be called cell culture or cell suspension culture.

  • Meristem Culture:- meristems have the main function of the production of new cells and the synthesis of protoplasm. Shoot meristem consists of a group of certain actively dividing cells that are being protected by the developing leaves.


Animal Cell Culture

Cell culture is the process by which cells are grown in a controlled artificial environment. The cells are taken from the organ of an experimental animal, for animal cell culture.The cells may be removed directly or by mechanical or enzymatic action. Fibroblasts, lymphocytes, cells from cardiac and skeletal tissues, cells from the liver, breast, skin, and kidney and different types of tumor cells, are some examples of the cells used in the culture.


Steps of Tissue Culture

Following are the steps of tissue culture:-


Initiation Phase:-

This is a stage when the tissue is initiated into the culture. To prevent the process from any contamination the tissue of interest is obtained, introduced, and sterilized.


Multiplication Phase:-

In the multiplication stage, The sterilized ex-plant is introduced into the medium which consists of growth regulators and appropriate nutrients, they are responsible for the multiplication of cells. Hence this undifferentiated mass of cells is known as a callus.


Root Formation:-

This is the stage when the root starts forming. To initiate the formation of root plant growth hormones are added.  Consequently,  complete plantlets are obtained.


Shoot Formation:-

For the formation of the shoot, plant growth hormones are added and growth is observed for a week.


Acclimatization:-

When the plant starts to develop,  the plant is transferred to a greenhouse for it to develop under controlled environmental conditions. Thereafter it is finally transferred to the nurseries for its growth under natural environmental conditions. 

FAQ (Frequently Asked Questions)

1. Explain the Importance of Tissue Culture.

Tissue culture is one of the most important cultures in biology, because of its wide range of applications:-

  • Animal and plant tissue, both can be used for culturing. Animal tissue culture, for example, helps to preserve a tissue or an organ whereas plant tissue culture can be used for genetic modification of a plant or in a simpler form, to increase its yield.

  • To produce plants with desired characteristics, its cells can be genetically altered

  • Clones, it is the exact copy of the plant that it produces with its ability to rejuvenate the tissue rapidly.

  • Tissue culture helps in the production of endangered species and hence conserves the plant biodiversity.

  • It can be used as an efficient technique of quickly producing plants without any tubers, bulbs, or seeds.

2. What is an Explant? Mention the Various Types of Explants Used in Plant Tissue Culture?

An explant can be defined as that part of the plant which holds the potential and is effectively capable of giving rise to a whole new plant. Explants can be of various types used in the process of regeneration such as apical meristems, roots, cotyledons, nodal segments, leaf discs, pedicle, petiole, anther, ovary, embryo, etc. A mother plant can be defined as the source of explants which is to be used for further multiplication. The mother plant should be completely devoid of any bacterial/fungal infection before any multiplication happens. To create a clone, the grower cuts a branch from the mother plant and places it in a substrate, where it develops roots of its own, which can be used repeatedly.