Gr 12 Micro Propogagation of Plants

Micropropagation of plants using tissues from the shoot apex, nutrient agar gels and growth hormones

Micropropagation is a technique used to produce large numbers of identical plants (clones) from a selected stock plant

• Plants can reproduce asexually from meristems because they are undifferentiated cells capable of indeterminate growth
• When a plant cutting is used to reproduce asexually in the native environment it is called vegetative propagation
• When plant tissues are cultured in the laboratory (in vitro) in order to reproduce asexually it is called micropropagation

The process of micropropagation involves a number of key steps:

• Specific plant tissue (typically the undifferentiated shoot apex) is selected from a stock plant and sterilised
• The tissue sample (called the explant) is grown on a sterile nutrient agar gel
• The explant is treated with growth hormones (e.g. auxins) to stimulate shoot and root development
• The growing shoots can be continuously divided and separated to form new samples (multiplication phase)
• Once the root and shoot are developed, the cloned plant can be transferred to soil

Micropropagation is used to rapidly produce large numbers of cloned plants under controlled conditions:

Rapid Bulking

• Desirable stock plants can be cloned via micropropagation to conserve the fidelity of the selected characteristic
• This process is more reliable that selective breeding because new plants are genetically identical to the stock plant
• This technique is also used to rapidly produce large quantities of plants created via genetic modification

Virus-Free Strains

• Plant viruses have the potential to decimate crops, crippling economies and leading to famine
• Viruses typically spread through infected plants via the vascular tissue – which meristems do not contain
• Propagating plants from the non-infected meristems allows for the rapid reproduction of virus-free plant strains

Propagation of Rare Species

• Micropropagation is commonly used to increase numbers of rare or endangered plant species
• It is also used to increase numbers of species that are difficult to breed sexually (e.g. orchids)
• It may also be used to increase numbers of plant species that are commercially in demand