- 1) Definition
- 2) Gottlieb Haberlandt
- 3) Experiment of F. C Steward
- 4) Micropropagation
- 5) Protocol of Tissue Culture
- 6) Types of Tissue Cultures
- 7) Procedure and Importance
- 8) Cell Suspension Culture
- 9) Importance of Cell suspension culture
Tissue culture is the growth of tissue that may be of plants, animals, or any other organism in an artificial liquid culture medium.
In 1902, German botanist Gottlieb Haberlandt said that plant cells are totipotent i.e., each cell has the full genetic potential of the organism and therefore a single cell could become a complete plant.
Experiment of F. C Steward
In 1958, F. C Steward a botanist of Cornell University grew a complete carrot plant from a tiny piece of phloem. He provided the cells with sugars, minerals, and necessary vitamins. He also added coconut milk.
It was discovered later that coconut milk contains cytokinin – the plant hormone. When the cultured cells began dividing, they produced a callus. A callus is an undifferentiated group of cells. Then the callus differentiated into shoots and roots and developed into a complete plant.
Tissue culture techniques are the gift of modern biotechnology and now led to micropropagation. This is the commercial method of producing thousands, even millions of identical seedlings in a limited amount of space.
Protocol of Tissue Culture
- Because plants are totipotent, it is possible to grow an entire plant from a single cell.
- Enzymes are used to digest the wall of small pieces of tissue; usually mesophyll tissue from a leaf, and the result is naked cells without walls called protoplasts.
- These protoplasts regenerate a new cell wall and start dividing. These clumps of cells can be manipulated to form somatic embryos.
- It is possible to form somatic embryos at a large scale in bioreactors at once. This is done for certain vegetables like tomato, celery, asparagus, and some ornamental plants such as lilies, begonias, African violets, etc.
Types of Tissue Cultures
One of the simplest and easiest methods to accomplish micropropagation or tissue culture is meristem culture. If the correct proportions of auxins and cytokinin are added to a liquid medium, many new shoots will develop from a single shoot tip.
When these developed shoots are removed, more shoots are formed. Since the shoots are genetically identical, the adult plant that will develop from these shoots are called clonal plants and have the same traits.
Advantage of Meristem culture
The advantage of the meristem culture is that unlike other portions of a plant is virus-free, therefore the plants produce are also virus-free. The presence of viruses makes plants weak and less productive.
Anther culture is a technique in which mature anthers are cultured in the medium containing minerals, vitamins, and growth regulators.
Procedure and Importance
- The haploid tube cells within the pollen grains divide, producing pro-embryos consisting of 20 to 40 cells.
- Finally, the pollen grains rupture releasing haploid embryos.
- The experimenter can now generate a haploid plant, or a chemical agent can be added that encourages chromosomal doubling.
- After chromosomal doubling, the resulting plants are diploid but homozygous for all their alleles.
Anther culture is a direct way to produce plants that express recessive alleles. If the recessive allele governs desirable traits, the plants will have these traits.
Cell Suspension Culture
Rapidly growing cultures are cut into small pieces and shaken in a liquid medium so that single cells or small clumps of cells break off and form a suspension.
Importance of Cell suspension culture
- These cells will produce the same chemicals as the entire plant. For example, cell suspension cultures of Cinchona ledgeriana produce quinine and those of Digitalis Ianata produce digitoxin.
- Scientists think and envision that it will be possible to maintain cell suspension cultures in bioreactors for the purpose of producing chemicals used in the production of drugs, agricultural chemicals, cosmetics, etc.
If this is possible, there will no longer need for farming plants for the purpose of acquiring the chemicals they produce.