Define plant tissue culture. Write its two applications.

Explanation

It is the technique of growing and maintaining plant cells tissues or organs on a suitable nutrient medium under controlled environmental conditions in suitable containers. The part which is cultured is called explant, i.e., any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media. This capacity to generate a whole plant from any cell/explant is called cellular totipotency. In fact, the whole plant can be regenerated from any plant part (referred to as explant) or cells. Gottlieb Haberlandt first attempted in 1902 to cultivate the mechanically isolated plant leaf cells on a simple nutrient medium.
Basic Technique of Plant Tissue Culture. The basic technique of plant tissue culture involves the following steps.
1. Preparation of Suitable Nutrient Medium. Sutable nutrient medium as per objective of culture is prepared and transferred into suitable containers.
2. Selection of Explants. Selection of explants such as shoot tip should be done.

3. Sterilisation of explants. Surface sterilization of the explants by disinfectants (e.g., sodium hypochorite) and then washing the explants with sterile distilled water is essential.
4. Inoculation. Inoculation (transfer) of the explants into the suitable nutrient medium (which is sterilized by filter-sterilized to avoid microbial contamination) in culture vessels under sterile conditions is done.
5. Incubation. Growing the culture in the growth chamber or plant tissue culture room, having the appropriate physical condition (i.e., artificial light, 16 hours of photoperiod), temperature `(26^(@)C)` and relative humidity (50-60%) is required.
6. Regeneration. Regeneration of plants from cultured plant tissues is carried out.
7. Hardening. Hardening is gradual exposure of plantlets to an environmental conditions.
8. Plantlet Transfer. After hardening plantlets transferred to the green house or field conditions following acclimatization (hardening) of regenerated plants.