A small tissue excised from any part of the plant is called explants. It is grown in an aseptic environment. The aseptic environment comprises of nutrient medium of inorganic salts, organic nutrients like sucrose, vitamins, minerals, growth regulators –auxins, gibberellins and cytokinins. Growth factors like Light and Temperature are regulated by using artificial conditions. These explants will develop roots, stems, and leaves. Then they are planted in the outdoor conditions. This type of micro propagation of plants is known as Tissue Culture.
The aseptic environment should be free from contamination of Microorganisms. The glassware, explants, medium, and any other instruments used should be free from microorganisms like bacteria, fungi etc. All the materials involved should be sterilized well before culturing.
The Components of Tissue culture medium contains both micro and macro nutrients. The Micronutrients are the minerals like Iron, Molybdenum, Zinc, Copper, Boron, and Manganese. The Macronutrients are Nitrogen, Calcium, Magnesium, Sulphur and Phosphorus. The energy source of the medium is the sugar--- sucrose or Fructose. Vitamins like Thiamin, Nicotinic acid, Pyridoxine, Panthothenic acid etc, are added to the medium to bring in optimum growth as they are helpful in carbohydrate metabolism. In addition to this amino acids are also added to stimulate the growth of cells.
This type of culturing plants produces clones of plants that do not involve pollination, fertilization or seeds. The plants produced are genetically identical. Growing the plants in the artificial medium implies that each cell of the plant has the potential to regenerate into a complete plant. Care should be taken to select healthy plants for tissue culture. Several complex organic compounds like Casein hydrolysate are added to produce desired growth.
The four major growth hormones used are auxins, cytokinin, gibberellins and abscissic acid. Their addition is a must to the culture medium. Auxins induce cell division, cell elongation and adventitious root formation. Cytokinins promote cell division and stimulate growth of shoots. Gibberellins are used for merristem growth.
The solidifying agent used for keeping the explants in the nutrient media is preferably Agar. It provides right contact with the nutrient medium and it provides aeration to the explants. Agar is a high molecular weight polysaccharide derived from the sea weeds. It is preferred because it does not react with the nutrient media nor it is digested by the plant enzymes. An optimum pH level of the medium should be maintained for the various components present in the nutrient medium.
The modes of Tissue culture are: Callus culture, Cell suspension culture, Single cell culture, Root culture, Anther culture, closed and open culture.
The technique of Tissue Culture has the following advantages:
· Plants can be rapidly multiplied from a mother plant of known desirable characters.
· Selected and screened plants can be maintained free from serious diseases and pests.
· 98% survival of the plants is certain under field conditions and the plants grow faster.
· Flowering of the plants is uniform. They have short harvesting period.
· Yield is increased by 20% as compared to conventional methods.
· Plants that are difficult to grow under normal conditions can be propagated by this method.
· Tissue culture Method is useful for the cultivation of medicinal plants and spices.
· This method of propagation is very useful in reviving the endangered species of plants.
· Draught resistant and high quality nutritive varieties can be cultivated.
· Several copies of genetically identical plants can be produced from single explants.
· Tissue culture method is economical in time and space.
· By tissue culture methods we can propagate new varieties of plants.
· The entire process is very quick. In short time plants can be grown and maximum yield can be achieved.
· High nutritive and good quality plants can be grown and cultivated by this method by adding suitable vitamins and minerals in the culture medium.
· Since plants are grown in the controlled temperature in the laboratory, season and climate change will not affect the growing crops.
· Tissue culture can be practiced anywhere including arid, semi-arid or desert countries under controlled laboratory environment.
World is facing several geographical problems in the form of climate change due to global warming. We see lot of changes in the climate throughout the world. Season and whether patterns have undergone critical changes. So agriculture is facing a setback. Food has become insufficient for an ever growing population. The problem of hunger and malnutrition are common amongst children all over the world. Children are dying due to hunger, and malnutrition. So, food being one of the essential needs of humanity it should be secured and conserved.
We should promote Tissue Culture practices in agriculture to ensure food security, to remove world hunger and malnutrition. Hence, Tissue culture is a solution to revive agriculture all over the world.
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