Describe the tissue culture technique and what are the advantages of tissue culture over conventional method of plant breeding in crop improvement programmes?

The technique of growing culturing of plants in in vitro process is called tissue culture. It involves the following steps.
i) Preparation of nutrient medium :
* For the growth of normal plant water & minerals and CO_{2 ,}Oxygen all are require.
* They derive all these nutrients from nature (soil & atmosphere).
* In tissue culture preparation of nutrient culture medium is essential.
* Nutrient culture medium is a mixture of essential nutrients which are mixed in distilled water.
ii) Sterilisation of nutrient medium :
* The nutrient medium is rich in nutrients and therefore attracts the growth of micro organisms.
* The culture medium is autoclaved for 15 min, at 121°C for 15 pounds of pressure.
iii) Preparation of explant :
* Any living part of the plant taken out and grown in special nutrient is called explant.
* After collecting explant sterilization of explant with Sodium hypochlorite and distilled water.
iv) Inoculation of explant :
* The plant cell which is used as seedling material in tissue culture is called explant.
* The transfer of explants on to the sterilized nutrient medium is called inoculation.
v) Incubation for Growth :
* The culture tubes with explant are incubated in a culture room under controlled conditions for 3 to 4 weeks. Then the cells of explant divide & re-divide and produce a mass of cells called callus.
* When growth regulator are supplied to this callus it produces shoots and roots and is called organogenesis.
* Some times embryo like structures (embryoids) called somatic embryos are formed from the callus.
vi) Acclimatization of plantlets and transfer to pots :
* The plants produced through tissue culture are planted in pots kept in glass house for 1-2 weeks. Finally they are transferred to field.
Advantages :
* Through tissue culture it is possible to produce large number of plants with in short period of time with in the short space is called micropropagation.
* Plants thus produced are genetically identical to the original plants and hence they are called somaclones.
* It is useful to produce many economically important plants like tomato, banana, apple, teak, eucalyptus, bamboo etc.....
* Virus free plant can be produced by meristem culture.
FLOW CHART OF PLANT TISSUE CULTURE