MICRO PROPAGATION

MICRO PROPAGATION

29.      MICROPROPAGATION

Micropropagation is the tissue culture techniques used for rapid vegetative multiplication of ornamental plants and fruit trees by using small-sized explants. Because of the minute size of the propagules in the culture, the propagation technique is named as micropropagation.
The in vivo clonal propagation of plant is tedious expensive. In vitro, clonal propagation through tissue culture is referred to as micropropagation.
Use of tissue culture for micropropagation was first started by morel for the propagation of orchids.
Plants produced will be genetically identical.
The micro propagation is also known as somaclones propagation since the genetically identical plants produced by PTC are called somaclones.
There are 4 steps of micro propagation
1)    Initiation of culture from on explant like shoot tip on a suitable nutrient medium.
2)    Shoot formation multiple shoots formation from the cultured explant.
3)    Rooting of shoots rooting of in vitro deu shoots.
4)    Transplantation - the hardening of tissue culture raised plants and subsequent trans  plantation to the field.
Protoplast culture and somatic Hybridization
When a hybrid is produced by fusion of somatic cells of two varieties or species, it is known as a somatic hybrid. The process  of producing somatic hybrids is called somatic Hybridization.
Somatic hybridization mainly involve :-
i.    Fusion of protoplast
ii.    Selection of Hybrid cell
iii.    Identification of hybrid plants
First, the cell wall of the plant cells is removed by digestion with a combination of pectinase and cellulase. The plant cells without a cell wall are called protoplast.
The protoplast of the two plants are brought together and made to fuse in a solution of Polyethylene glycol (PEG) or sodium nitrate. The fusion of proto plants with the help of chemicals is called chemofusion.
The fusion of protoplast not only involves the fusion of their cytoplasm but also their nuclei. The fused protoplasts are allowed to grow on the culture medium. Soon they develop their own wall when they are called somatic hybrid cells.
Pomato is  somatic hybrid between potato and Tomato while Bomato is the somatic hybrid between brinjal and Tomato.
Selection of hybrid cell can be done by using certain types of methods like :-
i.    Biochemical Method
ii.    Visual method
iii.    Cytometric method

Somatic Hybridization (A) Production of protoplast using a combination of pectinase and cellulase. (B) Protoplast fusion induced by PEG ultimately yields somatic Hybrid cells.


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