The ability or capacity of the mature living cells when free from the plant body develop into a new organism in controlled condition is known as Totipotency.
(Lotus = entire, potential = power). Haberlandt in 1902(German botanist) has first given the concept of cellular totipotency in plant body.
He stated that ever living cell of the plant body able to regenerate the whole plant body because it is derived from the fertilized egg and contain hereditary information. He tried to grow isolated green cells of leaves but failed to achieve the success. Later in 1950 F.E. Steward got success in proving the cellular totipotency.Cellular totipotency is a property of plant cell because a differentiated plant cell retain its capacity to give rise to a whole plant but in animal cell its losses the capacity of regeneration after differentiation.
Steward et al took the 2mg. slices of phloem tissue of carrot (Daucus carrotd) and grown in a liquid nutrient medium containing coconut water. The part of the plant is taken for tissue culture is known as Explants (Ex. Phloem tissue of Carrot root). The liquid nutrient medium containing explants was allowed some hours for shaking.
Then the culture cell divide continuously to form mass of undifferentiated tissue known as callus. Some of these cell cluster started differentiating the initial of root. When it transfer to semi solid medium then it develop shoot system and give rise new plant. These plant then transfer to pot/soil where they develop in to flowing plant.
Steward experiment shows that in plant even mature (fully differentiated cells) can dedifferentiate, divide, come together re-differentiate and produced a new plant. Plant tissue derived form root, stem, leaf, vegetative bud, floral bud, anther & embryo can exhibit cellular totipotency.
Totipotency character of plant cell has been used in tissue culture as follows:
1. It helps in rapid multiplication of plant with desirable character.
2. Multiplication of rare plants.
3. To pass the seed dormancy.
4. Quick propagation of useful plants.
5. Develop haploid plant.
6. Produce virus free & disease resistant plant.
7. Help in protoplast fusion & somatic hybridization.
8. Produce high yielding varieties crop plants.
9. Help in embryo rescue.