Introduction to tissue culture callus

In 1902, G. Haberlandt noticed that the plant cells can be grown in synthetic media. The discovery by Haberlandt that the plant cells have the capacity to grow in a nutrient medium in presence of sufficient light made an impact in plant propagation and crop improvement. This has become possible with the development of techniques to regenerate whole plants from the tissue cultured cells.

The ability of a plant cell to give rise to a whole plant is called totipotency. In this method, instead of taking cuttings from a plant, a cell (or few cells) or a tissue is taken from a plant and cultured in suitable containers in which nutrient medium is present. Through these methods new plants can be obtained from single cells or a clump of cells or a bud or other organ of a plant. The portion of the plant that is taken from the desired plant is referred as Explant. By this method, thousands of plants can be produced from a single desirable parent inone generation. These techniques require maintenance of sterile conditions in the medium. The explant need to be sterilised before it is introduced into the medium. All the elements that are required for the growth of the plant are provided in the medium. In addition, the media will contain one or more growth regulators as supplements, depending on the purpose for which the explant is introduced in to the medium. The medium is kept free from bacteria and fungi. Cells or tissues are grown n culture under aseptic conditions.

Tissue Culture Callus Description

Culture techniques are now available for cells, tissues or organs from the plant. In the tissue culture, the explant often divides to give rise to an unorganised mass of tissue called Callus. Te callus or the explant as such, will undergo differentiation into shoots; roots or embryo like structures (Embryoids). This differentiation is dependent on the concentration and combination of the plant growth substances like auxins, kinetin, gibberellin etc., in the medium. Some times numerous independent shoots (multiple shoots) differentiate from the explant or callus.

Plants raised through tissue culture are routinely used in agriculture, horticulture and forestry. When we use a diploid explant, we get a diploid plant like in any of the vegetative propagation methods. Similarly, if we want to develop a haploid plant, it is possible to obtain it through tissue culture. For this, we need to select a haploid cell in the plant. The best choice of a haploid cell is pollen grain . Development of haploid plants through tissue culture was discovered by Indian Scientists Shipra Guha and Satish Maheswari.

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