What is Plant Tissue Culture
Plant tissue culture is a collection of techniques used to maintain and grow plant cells, tissues or organs under sterile conditions on a artificial nutrient culture medium.
Plant tissue culture made it possible to produce a large number of clones of a plant in a short time by manipulating Micropropagation.
Principle of Plant Tissue Culture
- Plant tissue culture is based on the fact that various plant cells have the ability to regenerate a whole plant (called Totipotency).
- Single cells, pieces of leaves, stems or roots can be used to generate a new plant on culture media by providing the required nutrients and plant hormones.
Explant: Any part of the plant which is being cultured is called explant.
Explants can be taken from many different parts of a plant including portions of shoots, roots, stems, leaves, flowers, and single undifferentiated cells.
A good explant should have high rates of growth and regeneration & should be free from microbial contamination.
The choice of explant also determines if the plantlets developed via tissue culture will be haploid or diploid.
Hormones used in Plant Tissue Culture
- Abscisic Acid
Plant hormones play an important role in the growth and differentiation of cultured cells and tissues.
The composition of plant tissue culture medium can vary depending upon the type of plant tissues or cell that is used for culture.
The most widely used nutrient medium is MS medium
(developed by Murashige and Skoog).
A typical nutrient medium consists of:
- inorganic salts (both micro and macro elements),
- a carbon source (usually sucrose),
- vitamins, amino acids,
- and growth regulators (e.g. auxins and cytokinins and gibberellins).
Generally, a gelling agent agar is added to the liquid medium for its solidification. An optimum pH (usually 5.7) is also very important for the proper growth of explant.
Types of Plant Tissue Culture
1. Cell culture:
Cell culture is the culture of isolated individual cells, obtained from an explant tissue or callus. These cultures are carried out in dispersion medium and are referred to as cell suspension cultures.
2. Protoplast culture:
Protoplast is a biological term refers to the cell in which the cell wall has been removed.
In this, isolated protoplasts are cultured on a suitable medium under the aseptic condition.
- The protoplast culture is aimed to develop genetically transformed plant.
- Somatic hybridization of two plant species through protoplast fusion in done by protoplast culture.
3. Callus culture:
Callus is the unorganised and undifferentiated dividing mass of cells.
Callus culture involves the growth of callus from explant by providing appropriate conditions. Darkness and solid medium gelled by agar stimulate callus formation.
4. Organ culture:
In organ Culture, isolated plant organs are used as explant for culturing process. The organ culture may be organized or unorganized.
5. Seed culture:
Seeds may be cultured in-vitro to generate seedlings or plants. It is the best method for raising the sterile seedling.
6. Embryo culture:
Embryo culture is the isolation and growth of mature or immature embryo in-vitro with the aim of obtaining a viable plant.
In some plants, seed dormancy may be due to chemical inhibitors or mechanical resistance etc. Excision of embryos and culturing them in nutrient media help in developing viable seedlings.
7. Meristem Culture:
A Meristem is a localized group of cells, which are actively dividing and undifferentiated & give rise to permanent tissue.
The apical meristem of shoots of is cultured to get the disease-free plants even if the plant is infected.
8. Anther Culture:
Anthers of some plants are cultured on a suitable medium to produce haploid plants, it is called anther culture. Sometimes, pollen grains are separated from anthers and cultured on a
This technique was first used in India to produce haploids of Datura.
Plant Tissue Culture Techniques
This technique is used for developing high- quality clonal plants. This has the potential to provide rapid and large scale propagation of new genotypes.
- Somatic cell genetics:
It is used mostly in terms of haploid production and somatic hybridization.
- Transgenic plants:
It is used for expression of mammalian genes or plant genes for various species. It is helpful to give resistance against insects, virus and other pathogens as well as the herbicide.
General Steps of Plant Tissue Culture
- Preparation of Suitable Nutrient Medium.
- Selection of Explants.
- Sterilisation of Explants:
This is done by disinfectants and then washing the explants with sterile distilled water.
- Inoculation of explant:
transfer of sterile explant on the nutrient medium under aseptic (free from contamination) condition.
Growing the culture in the growth chamber. After the defined period of incubation, an unorganized and undifferentiated (no root and shoot) mass of cells called callus is obtained from each explant.
- Transfer of callus and Regeneration.
gradual exposure of plantlets to environmental conditions.
- Transfer of plantlets to the field.
Applications of Plant Tissue Culture
- A large number of plants having identical features to the parents can be produced by this method.
- To conserve rare or endangered plant species.
- For the production of highly valuable transgenic plants.
- Many plantlets can be produced without seeds.
- Healthy and disease free plants can be propagated by this technique.
- Large-scale production of artificial seeds through somatic embryogenesis.
- Genetic variation present among plant cells of a culture is called soma clonal variation. This variation has been used to develop several useful varieties.
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