Micropropagation (Edexcel IGCSE Biology)
Revision Note
Micropropagation
Tissue culture is a process in which very small ('micro') pieces of plants (‘tissue’) are grown (‘cultured’) using nutrient media
Because they are initially grown in petri dishes on nutrient agar we say they are grown ‘in vitro’ – outside a living organism
The method to propagate plants in vitro is as follows:
Cells are scraped from the parent plant (these cells are known as explants)
The surface of the explants are sterilised using a disinfectant followed by a rinse with sterile water
Sterilised explants are transferred to a sterile petri dish containing sterile nutrient agar
The growth medium encourages the explant cells to grow and divide into small masses of cells (known as a callus)
Each callus is transferred to a fresh growth medium that contains a range of plant growth regulators (hormones). The presence of these hormones causes the callus to develop roots, stems and leaves, forming a plantlet
Plantlets can be transferred to individual potting trays and develop into plants
The steps of micropropagation to reproduce cloned plants
Commercial Use of Micropropagation
Advantages of micropropagation
Clones are genetically identical individuals
The cloning of plants has many important commercial uses
It allows a variety of a plant with desirable characteristics to be produced:
Cheaply
With a greater yield (a large number of plants can be produced per square metre)
Quickly (the plantlets are ready to grow into mature plants)
At any time of the year
Identical to each other (so they retain the desired characteristic)
Disease-free or resistant plants can be bred
It can also ensure diseases prevalent in other areas of the world are not imported and spread by ensuring native varieties of plants are produced in large enough quantities to supply demand in one country without importing plants from abroad
Tissue culture can also be an important process in preserving rare plant species
Disadvantages of micropropagation
There are a number of drawbacks to using micropropagation:
Trained personnel and a sterile laboratory are required
All the plants produced are genetically identical and so will all be vulnerable to the same diseases and pests (the lack of genetic variation makes them less able to adapt to environmental change)
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