Micropropagation (Edexcel IGCSE Biology (Modular)): 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

• Large numbers of genetically identical plants can be produced using micropropagation

• The stages of micropropagation are:

  • Small pieces are cut from the plant to be cloned - these pieces 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

• Advantages of micropropagation include:

  • The production of (many) genetically identical clones of plants with desirable traits

  • Commercial benefits:

    • Can produce plants cheaply and in large quantities per square metre

    • Fast production: plantlets grow into mature plants quicker than from seeds

    • Can be done at any time of year, without any seasonal limitations on growth

    • Ensures plants are disease-free (as they're grown in a sterile lab) and if the original plant has a trait for disease resistance, this trait is preserved in all the cloned plantlets

  • Another advantage is micropropagation is that is can can be used in conservation to preserve 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)