In this article we will discuss about the meaning of tissue culture.
The growth of cells, tissues and organs, outside the organism in artificial media of salts and nutrients is called tissue culture. Depending on the cell type, the cells may be capable of a limited number of divisions or they may divide indefinitely. Under appropriate conditions, the cultured tissues of some plants can often be made to regenerate new plants.
The technique of plant tissue culture includes growing of plant tissues in a nutrient medium i.e. in vitro. Unorganized tissue or callus is cultured under this technique. These days, the term (plant tissue culture) is used for protoplast, cell, tissue, organ or whole plant culture in a nutrient medium under aseptic conditions.
Under this technique the explants (i.e. cells, tissues or organs of a plant) are carefully separated and grown aseptically on a nutrient medium (Fig. 1) under controlled conditions of light and temperature.
The sterile growth medium or nutrient medium for culturing explants should typically contain sugar (or sugars) as a energy and carbon source, mineral salts and growth substances and is usually solidified with agar.
The technique of plant cell culture is important in several types of researches e.g. study of cell cycle, cell growth and development. It has also given rise to the phenomenon of totipotency of plants cells which means that “all living plant cells have the ability to regenerate a plant when isolated and cultured in a suitable medium”, or “all living plants in a plant body can potentially give rise to whole plants”.
The technique of meristem culture (i.e. shoot apex and root apex) is important in obtaining virus-free materials from many vegetatively propagated crop plants. It is so because the meristems of even virus infected plants are usually virus free.
In technique of micro-propagation, the shoot apices are cultured under such conditions which promote the growth of a mass of proliferating lateral shoots. When about 6-8 weeks old such lateral shoots are cut and again cultured.
By transferring them to a suitable medium, rooting is induced. This technique is useful for the rapid multiplication of new cultivars and pathogen-free plants, e.g. in potatoes, strawberries and several ornamental plants.
The technique of embryo culture is used in rescuing such embryos that might otherwise abort.
The technique of antber culture is used in producing haploid cultures or haploid plantlets. When treated with colchicine, such haploid plantlets or cultures may be developed into diploid plants.
The technique of protoplast culture is used in several experiments of plant genetic manipulation.
Composition of some Common Culture Media: