plant cloning

• Rhizomes 


  These are stem structures that grow horizontally underground away from the parent plant. They have 'nodes' from which new shoots and roots can develop. An example of a plant that uses rhizomes is bamboo.
• stolons or runners 


  they grow above the ground, on the surface of the soil. New shoots and roots can either develop from nodes (like in rhizomes) or form at the end of the stolon. An example of a plant that uses stolons is the strawberry
• suckers 


  shoots that grow from sucker buds (undeveloped shoots) present on the shallow roots of a parent plant. An example of a plant that uses suckers is the elm tree.
• tubers 


  large underground plant structures that act as a food store for the plant. They're covered in 'eyes'. Each eye is able to sprout and form a new plant. An example of a plant that uses tubers is the potato.
• Bulbs 


  underground food stores used by some plants. New bulbs are able to develop from the original bulb and form new individual plants. An example of a plant that uses bulbs is the onion.
• Horticulturists (plant growers) and farmers can exploit a plant's natural ability to produce clones. By manipulating the way in which a plant grows, they can induce vegetative propagation, so they get natural clones of the parent plant.
• methods of inducing vegetative propagation

  • take cuttings
  • use grafting - joining the shoot of one plant to the growing stem and root of another plant
  • layering - bending a stem of a growing plant downwards so it enters the soil and grows into a new plant
• Producing clones from cuttings

  1. Use a scalpel or sharp secateurs to take a cutting, between 5 cm and 10 cm long, from the end of a stem of your parent plant

  2. Remove the leaves from the lower end of your cutting (if there are any), leaving just one at the tip

  3. Dip the lower end of the cutting in rooting powder, which contains hormones that induce root formation

  4. Plant your cutting in a pot containing a suitable growth medium (e.g. well-drained compost)

  5. Provide your cutting with a warm and moist environment by either covering the whole pot with a plastic bag or by putting it in a propagator (a specialised piece of kit that provides these conditions)

  6. When your cutting has formed its own roots and is strong enough, you can plant it elsewhere to continue growing
• Tissue culture


  The process of growing cells, tissues or organs from a plant in a controlled environment
• Tissue culture process


  1. Cells taken from original plant

  2. Cells from stem and root tips used as they are stem cells

  3. Cells sterilised to kill microorganisms

  4. Cells grown on culture medium with organic nutrients and plant hormones

  5. Cells divide to produce mass of undifferentiated cells

  6. Mass subdivided to produce many plants quickly

  7. Small plants taken from medium and planted in soil
• The plants grown through tissue culture are genetically identical to the original plant
• Tissue culture is used to clone plants that don't readily reproduce or are endangered or rare.
• • in micropropagation cells are taken from developing cloned plants and subcultured (grown on another fresh culture medium)
  • repeating this process creates large numbers of clones
  • This technique is used extensively in horticulture and agriculture, e.g. to produce fields full of a crop that has been genetically engineered to be pest-resistant.
• micropropagation 


  when tissue culture is used to produce lots of cloned plants very quickly
• arguments for artificial plant cloning

  Desirable genetic characteristics (e.g. high fruit production) are always passed on to clones. This doesn't always happen when plants reproduce sexually.

  Tissue culture allows plants to be reproduced in any season because the environment is controlled.

  Less space is required by tissue culture than would be needed to produce the same number of plants by conventional growing methods.

  It produces lots of plants quickly compared to the time it would take to grow them from seeds.
• arguments against artificial plant cloning

  • Undesirable genetic characteristics (e.g. producing fruit with lots of seeds) are always passed on to clones.
  • Cloned plant populations have no genetic variability, so a single disease could kill them all.
  • Production costs of tissue culture are very high due to high energy use and the training of skilled workers, so it's unsuitable for small scale production.
  • Contamination by microorganisms during tissue culture can be disastrous and result in complete loss of the plants being cultured.