Tissue culture

What is tissue culture?

Tissue culture is a method of vegetative plant propagation in which small pieces of plant tissue are grown under sterile, controlled conditions on a specially prepared nutrient medium. The technique can produce large numbers of plants from a relatively small amount of selected parent material.

When is it useful?

Tissue culture is particularly useful when large numbers of genetically uniform plants are required, when conventional propagation is slow or difficult, or when carefully selected plant material needs to be multiplied efficiently. It is widely used commercially for several crops, including bananas.

Basic process

1. Select healthy plant material from the plant to be propagated.
2. Remove a suitable small piece of tissue, known as an explant.
3. Surface-sterilize the explant and introduce it into a sterile culture environment.
4. Place the tissue on a suitable nutrient medium containing the mineral nutrients, sugars and plant growth regulators required for the particular stage of culture.
5. Maintain controlled conditions that encourage the tissue to produce shoots or other suitable propagules.
6. Transfer developing material to appropriate media as necessary to multiply shoots and induce roots.
7. Once plantlets have developed sufficiently, remove them from the sterile culture environment and gradually acclimatize them to normal humidity, light and growing conditions.
8. After successful acclimatization, transplant the young plants into pots, nursery beds or their final growing location.

Sterile conditions

Tissue culture requires much stricter hygiene than ordinary propagation methods. The nutrient-rich culture medium can also support fungi and bacteria, so contamination can quickly destroy a culture. Work is therefore normally carried out with sterilized material, equipment and media in a controlled environment.

Genetic uniformity

Tissue culture is commonly used for clonal multiplication, producing plants intended to retain the characteristics of selected parent material. However, genetic or developmental variation can sometimes arise during the culture process, particularly after extensive multiplication. Tissue-cultured plants should therefore not automatically be assumed to be perfectly identical in every case.

Acclimatization

Plantlets produced in culture develop under protected conditions with high humidity and a controlled nutrient supply. They cannot normally be moved directly into field conditions. A gradual acclimatization or hardening stage is necessary so that they can adapt to lower humidity, stronger light and normal soil or potting media.

Tissue culture at Yuyo

Tissue culture normally requires specialized laboratory facilities and is therefore different from propagation methods carried out directly at the finca. It is included here because plants arriving at Yuyo may have been commercially propagated by tissue culture and because the propagation history of a species or individual can be relevant to its management.

Important

Culture medium, sterilization procedure, plant growth regulators, temperature, light, multiplication method and acclimatization requirements are highly species-specific. Tissue culture should therefore be based on an established protocol for the plant concerned.