At the Australian PlantBank, tissue culture techniques are regularly used to maintain cultures of flannel flower and waratah cultivars. Tissue culture is also used to produce material for cryopreservation for those species not suited to seedbanking, such as rainforest seeds.
What is tissue culture?
Tissue culture involves taking very small pieces of plant (bud, shoot tips, or other parts) and growing them on special nutrient media in sterile conditions. This method allows the production of many plants from a single shoot - a great advantage when plants are rare – and for species that do not reproduce by seed.
The plants are grown under sterile conditions on liquid or solid medium that contains nutrients and one or more plant growth regulators. The key to tissue culture is 'totipotency' – this is the ability for a plant to regenerate from a single cell back into a whole plant.
Tissue culture is also known as micropropagation.
Just like you might take a cutting from your garden, dip it in root power and pot it up, small pieces of plant tissue are carefully placed in a jelly-like substance called agar and allowed to grow (initiation). If the plant survives and continues to grow, they can be cut into small pieces again (allowing plants to be multiplied) and regrown or transferred to a potting mix (exflasking).
Each plant comes from one original cutting, so they are all identical (clones) and therefore tissue culture can be used to propagate and multiply thousands of the same plant over and over again. This is great when a plant is highly valued, or when researchers require identical plants of the same age, size and even genetic type!
At PlantBank, our tissue culture plants are grown in plastic or glass containers placed in controlled growth rooms set at about 24 degrees Celsius, under lights (16 hours on and 8 hours off).
Uses of Tissue Culture
- Large-scale micropropagation of plants. Many house and garden plants are mass produced using tissue culture.
- To conserve highly threatened species, particularly when there is a shortage of material available for conservation
- To reproduce plants which don’t produce seed or don’t germinate well
- To conserve plants not suited to seedbanking e.g. rainforest seeds
- To germinate seeds of species which require a mycorrhizal partner in the wild e.g. terrestrial orchids
- To enable the transport of plants to other states or countries without transporting pathogens or pests
- To prepare material for cryopreservation and to recover it after freezing.