Plant tissue culture is a biotechnological technique in which small pieces of plant tissue (called explants) are grown in a sterile, nutrient-rich medium under controlled environmental conditions to produce new plants. It is based on the principle of totipotency, which means that every plant cell has the potential to develop into a complete plant.
This method is one of the most widely used tools in plant biotechnology for research, conservation, and large-scale propagation.
Here’s a detailed explanation of what it is and how it is used:
1. Definition
Plant tissue culture is the in vitro (in glass/laboratory) cultivation of plant cells, tissues, or organs on a nutrient medium containing essential minerals, sugars, vitamins, and plant hormones. The process takes place in a sterile environment to prevent contamination.
2. Basic Steps Involved
- Selection of Explant:
A small part of the plant such as a leaf, stem, root, or meristem is chosen as the starting material. - Sterilization:
The explant and tools are sterilized to remove microorganisms. - Culture Initiation:
The explant is placed on a nutrient medium (like Murashige and Skoog medium) containing plant hormones (auxins and cytokinins). - Callus Formation:
Under suitable conditions, the explant cells divide and form a mass of undifferentiated cells called a callus. - Organogenesis or Embryogenesis:
The callus can be induced to form shoots and roots (organogenesis) or embryos (somatic embryogenesis) by altering hormone concentrations. - Plant Regeneration:
The regenerated plantlets are transferred to soil after acclimatization, where they grow into mature plants.
3. Applications of Plant Tissue Culture in Biotechnology
- Micropropagation (Clonal Propagation):
- Produces large numbers of genetically identical plants (clones) in a short time.
- Commonly used for banana, sugarcane, orchids, and ornamental plants.
- Ensures disease-free and uniform plant production.
- Production of Disease-Free Plants:
- Using meristem culture, plants infected with viruses can be regenerated as healthy, virus-free plants.
- Widely used for crops like potato, strawberry, and sugarcane.
- Germplasm Conservation:
- Plant tissue culture helps conserve rare, endangered, or valuable plant species through cryopreservation (storage in liquid nitrogen) or in vitro storage.
- Ensures the preservation of genetic diversity.
- Somaclonal Variation:
- Variations that arise during tissue culture can lead to the development of new plant varieties with desirable traits such as disease resistance or stress tolerance.
- Somatic Embryogenesis and Artificial Seeds:
- Somatic embryos produced in vitro can be encapsulated to form artificial seeds, which can be stored or transported easily for propagation.
- Genetic Engineering and Transformation:
- Tissue culture provides the platform for introducing new genes into plant cells.
- After gene transfer, tissue culture helps regenerate whole transgenic plants from single transformed cells.
- Secondary Metabolite Production:
- Plant cells cultured in bioreactors can produce valuable compounds such as alkaloids, flavonoids, and essential oils used in medicines and cosmetics.
- Example: Production of anticancer drugs like taxol from cultured cells of Taxus brevifolia.
- Embryo Rescue and Hybrid Development:
- Tissue culture helps save embryos from incompatible crosses in breeding programs, enabling the development of hybrid plants that would otherwise fail to mature naturally.
4. Advantages of Plant Tissue Culture
- Rapid and large-scale plant production.
- Year-round propagation irrespective of season.
- Production of uniform, disease-free plants.
- Conservation of valuable plant species.
- Foundation for genetic modification and crop improvement.
In summary:
Plant tissue culture is a cornerstone of plant biotechnology that allows scientists to grow and manipulate plants under controlled conditions. It is essential for mass propagation, genetic engineering, germplasm preservation, and production of valuable compounds, making it a key technology in modern agriculture, medicine, and environmental conservation.