Up till now we have looked at propagation via Cuttings, Air-layering [that was fantastically covered by guest writer Duncan Colville] and Grafting. For todays entry we will focus on Micropropagation via Tissue Culture.
Cloning plants through the use of plant tissue culture techniques is a method of asexual reproduction. This allows for exact duplicates from a plant specimen to be created. Good properties of plants may be propagated to further generations. Plant tissue culture techniques involves the use of micropropagation and plant cell culture.
In plant breeding, tissue culture is used as a very efficient tool to propagate better improved crops.
Using this method involves plant cells or tissues to be maintained and grown in vitro under aseptic conditions in an artificial medium that provides the necessary nutrients for growth.
During the 1950s, scientists discovered that any part of a plant grown in nutrient rich media under sterile conditions can produce a whole new plant. In culture, the plant part used is called an explant. The ability of plant cells to give rise to a whole new plant is called totipotency.
Tissue culture requires a nutrient dense medium that contains inorganic salts, vitamins, proteins, sucrose, and of course growth regulators.
Plant Tissue Culture Techniques:
The first step of tissue culture has to be excising or cutting. One would start with a small part of plant tissue like the leaf, root or shoot.
This cut out part or explant is then placed in a nutrient medium containing a carbon source such as sucrose, inorganic salts, vitamins, amino acids and growth regulators like auxins and cytokinins.
The Explants are then allowed to multiply and form a group of tissues called callus. Callus is an unorganized, irregular, and undifferentiated mass of actively dividing cells. This callous tissue is allowed to multiply to form many plantlets, which are then transferred to a different container for rapid multiplication.
Following this, the developed plantlets are transplanted to the final media for normal growth and hardening off. Tissue culture is performed using a small part of a plant to develop a large number of plants in a short duration. It is thus also known as micropropagation. As all these plants are developed from the same part of the parent plant, they are genetically identical and called somaclones. Micropropagation is extensively used in floriculture and horticulture and is used in the large scale production of banana, tomato, potato, apple and many more.
This technique can also successfully be used to propagate high yielding varieties with excellent disease resistance in a short time span. Even when a plant is diseased, tissue culture can be used for recovering healthy plants from diseased plant donors. This is possible by taking an explant of the apical or axillary meristem in order to ‘get ahead’ of the disease. This is done because the meristem is always free from pathogens due to lack of vascular supply.
The process of using the meristem for propagation is known as meristem culture. Culturing of meristems has been successfully carried out on many cultivars we know in our markets today.
Some of the many advantages of tissue culture are listed below:
- A large number of plants can be grown in a short period of time.
- Healthy plants can be grown from diseased plants.
- Plants without seeds can be multiplied.
- It is useful where sexual reproduction is not possible.
At the end of the day, tissue culture as a hobby seems daunting and tricky to apply, BUT it is exceptionally rewarding and full of possibilities once you mask up and dive deeper.
When you think you and your workspace is a clean as you can get it, think again.
About the Author
Christoff Boltman is the Seeds for Africa / H2GRO Hydroponic specialist. Christoff has been growing hydroponically for the last 15 years and welcomes the opportunity to share his experience and knowledge with our customers. Feel free to pop in at our showroom and Christoff will be delighted to show you around and advise you on what would best suit your needs.