Question

Describe the tissue culture technique in plants.

Answer 1

1. Explant culture: A proper explant is excised from the plant, which may be a cell, tissue or a piece of the plant organ. Generally, parenchyma tissue or meristem is used as explants. It is sterilised properly and placed on a solid nutrient medium. The cells from the explant absorb nutrients and start multiplying.
2. Callus formation and its culture: The callus is the unorganised mass of cells produced due to the growth of the explant. Generally, it has thin-walled living parenchyma cells. It develops due to the proliferation of cells from explants. All the cells of callus are identical because they are produced by mitosis only.
3. Organogenesis: Now the growth hormones, like auxins and cytokinins, in proper proportion are provided to the callus to induce the formation of organs. If auxins are more, roots are formed (rhizogenesis), and if the cytokinins are in greater quantity, then the shoot system begins to develop (caulogenesis).
4. Formation of cell or suspension culture: For formation of cell or suspension culture, the callus can be transferred to liquid nutrient medium, and it is agitated. Due to this, the cells from the callus get separated. This cell culture is to be agitated constantly at 100-250 rpm. The agitation serves the purpose of aeration, mixing of medium and prevents the aggregation of cells. By the callus and suspension culture, we can achieve cell biomass production which can be utilized for biochemical isolation, regeneration of new plantlets, the formation of transgenic plants and protoplast culture.