Plant Tissue Culture Techniques

Study Notes

Plant tissue culture is a technique used to grow plant cells, tissues, organs, seeds, or other plant parts in a sterile environment on a nutrient medium.

1902: The concept of totipotency (the ability of a single plant cell to generate a whole plant) was proposed by Haberlandt.
1937: White successfully established root cultures of tomatoes.
1941: Van Overbeek used coconut milk to promote growth and development of young Datura embryos.
1957: Skoog and Miller identified the role of auxins and cytokinins in shoot and root formation in tobacco tissues.
1962: Murashige and Skoog developed a growth medium for tobacco culture.
1987: Isolation of the Bt gene from Bacillus thuringiensis.

Totipotency: The ability of plant cells to regenerate into a whole new plant.
Plasticity: The ability of plants to adjust their metabolism, growth, and development in response to their environment.

Plant tissue cultures are initiated from multicellular tissue fragments, known as explants, taken from living plants.
Explants can originate from various plant tissues, including leaves, stems, roots, petioles, hypocotyls, cotyledons, embryos, and meristems.
Explants can be either haploid or diploid.
Plant growth can be achieved in two ways:
- Formation of shoots directly on appropriate media.
- Somatic embryogenesis.

All materials used in tissue culture, including vessels, instruments, media, and plant material, must be sterilized to eliminate microbes.
Sterilization methods include:
- Dry heat treatment
- Flame sterilization
- Autoclaving
- Filter sterilization
- Wiping with 70% ethanol
- Surface sterilization

Explants are usually placed on a solid culture medium, but can be placed directly into liquid medium for cell suspension cultures.
Culture media typically consist of inorganic salts, organic nutrients, vitamins, and plant hormones.
As cultures grow, pieces are removed and transferred to new media to aid growth or modify culture morphology.

White's medium - one of the earliest plant tissue culture media.
MS medium - formulated by Murashige and Skoog, widely used for various culture systems.
B5 medium - developed by Gamborg, used for cell suspension and callus cultures, and protoplast culture.
N6 medium - formulated by Chu, used for cereal anther culture.
Nitsch's medium - for anther culture.

Commercial production of plants for potting, landscaping, and floriculture
Conservation of rare or endangered plant species
Screening cells for desirable traits (e.g., herbicide resistance)
Large-scale growth of plant cells in bioreactors for valuable compounds (secondary metabolites, recombinant proteins).
Crossing distantly related species using protoplast fusion
Producing clean plant material from virus-infected stock.
Producing identical sterile hybrid species.