What is the plant tissue culture?
Plant tissue culture is a method that is used to grow plant cells, tissues, or organs under sterile, controlled conditions of light, temperature and humidity, in a nutrient culture medium.
History of plant tissue culture
In 1839. Schleiden and Schwann proposed that the cell is the basic unit of life and is capable of autotomy. Therefore each cell in the plant can regenerate into a whole plant.
According to these theories, in 1902 Gottlieb Haberlandt developed the concept of In vitro cell culture(Tissue culture). He is known as the father of tissue culture.
In 1907, Hanning took embryos of Crucifers and grow them to maturity. In 1908, Simon regenerated callus, buds, roots, and poplar stem segments. He established the basis of Callus culture.
During 1950, scientists found that any part of a plant grown in a nutrient medium under sterile conditions can give rise to a whole plant. This property of plant cells to produce new plants is called totipotency. The term totipotency was developed by Steward in 1968.
Techniques of tissue culture
- Preparation of glassware for sterilization
Glasswares are wrapped in foil and tighten caps of bottles must be loosened before the sterilization.
- Preparation of medium.
The nutrient medium contains a carbon source such as sucrose, inorganic salts, vitamins, amino acids, growth regulators such as auxins and cytokinins, and agar as a semisolid supporter. Auxin stimulates root development and cytokinin stimulates shoot development.
- Autoclaving glassware and medium for sterilization.
The glassware top that including the medium is covered with foil and placed in the autoclave. Then set the temperature to 121oC, pressure to 15 psi, and run the autoclave for 15min. This mode is called Slow exhaust mode. This mode prevents the liquid from boiling and out over the flask.
To sterilize the glasswares also use autoclaving method. The wrapped glasswares are placed in the autoclave and set the temperature to 121oC, pressure to 15 psi, and time to 20 min. This mode is called Fast exhaust mode.
- Preparation of explant.
The plant part which is used in tissue culture is known as Explant. Any part of the plant under sterile conditions can be taken as an explant.
To prepare the explant, first of all, we need to cut small parts of a plant. These cuttings should be wrapped in moist paper and store at 40 C before the preparation of the explant.
Tissue culture should be done in aseptic condition inside the laminar airflow hood. Apparatus are sprayed with 70% ethanol before keeping it in the hood.
Then plant parts washing with running tap water and then wash with sterilized distilled water. Forceps, scalpels should be sterilized by washing with 90% ethanol and flaming.
Taking out the stem using a sterilized forceps and cut top and bottom parts to remove bleach affected areas.
- Keep explant in the tubes with the medium.
This explant is placed in the nutrient medium. Then seal the tube by using parafilm.
Then allowed to multiply and form a group of tissue called callus. The callus is an irregular, unorganized and undifferentiated mass of actively dividing cells. This callus is allowed to multiply to form many plantlets.
- Plantlets are transferred to different containers.
Plantlets are transferred into different containers for rapid multiplication. After that, the containers are sealed.
Then store in incubation room. In the incubation room, the temperature is kept as 22 – 28 oC and humidity is kept as 60-70%. Provide the light by using fluorescence tube lights. As well as always make sure that there is fresh air in the incubation room.
Finally, well-developed plantlets are transplanted to the soil for normal growth.
Tissue culture techniques are used to develop a large number of plants in a short time duration. Tissue culture is mostly used for growing banana, pineapple, tomato, sweet potato, date, eggplant, rubber, jojoba, yam, etc. This is also called micropropagation.
These all plants are developed from the same plant part of the parent plant. Therefore these plants are genetically identical.
Tissue culture is used for growing healthy plants from diseased plants. In this term, taking explant from the apical or axillary meristem. Because meristem is highly vascularized. Therefore it is always free from pathogens.
Plants without seed can be multiplied using the tissue culture method. When sexual reproduction is not possible tissue culture techniques are used.
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