OCR A Level Biology

Revision Notes

6.4.3 Production of Artificial Clones in Plants

Production of Artificial Clones in Plants

Cultivars

  • Gardeners and horticulturalists can harness the natural processes of vegetative reproduction to form the basis of artificial cloning
  • Techniques such as cuttings, layering, grafting, division and budding have been used
  • This creates cultivars, strains of genetically identical plants that can endure as foodstuffs or commercial blooms for many years
  • All methods rely on the formation of meristematic tissue from which plant organs can differentiate

Micropropagation and tissue culture

  • Many plant cells are totipotent, unlike animal cells, and therefore an entire plant can be reproduced from any of these cells
  • Creating clones of cauliflowers is used to demonstrate totipotency through the production of tissue culture
  • Cauliflower is used because it is comprised mostly of actively dividing cells and can withstand being handled
  • A small piece of the plant is cut, this is called an explant, which is then grown into a new clone of the original plant
  • Care must be taken to disinfect the explant and to use aseptic techniques to avoid fungi from colonising the growth medium and causing the micropropagation to fail
  • This technique is used by scientists to reproduce endangered species of plants where relatively little source material exists

Apparatus

  • Eye protection
  • Disinfectant (usually a bleach solution)
  • Sterilising solution
  • Scalpel
  • Gloves
  • Forceps
  • Cauliflower
  • Agar growth medium containing sterilant
  • Container
  • Marker pen

Method

  • Wear eye protection at all times
  • Wipe all surfaces with disinfectant and soak all apparatus in sterilant
    • It is important to ensure a sterile environment so that no fungi contaminate the experiment, which would result in seeing a fungal growth rather than an explant growth
  • Break off a small floret of cauliflower from the plant then using a scalpel, cut a thin section of the floret (about 5-10mm long)
    • This thin section is the explant
  • Sterilise the explant by soaking it in sterilising solution for 15 minutes, swirling the explant around within the solution every 5 minutes
    • This ensures that the explant is sterile and therefore only cauliflower cells are present
  • Take out the explant using sterilised forceps and add it to a container of agar growth medium
    • The growth medium contains all the nutrients that the plant needs for growth and also contains a sterilant to ensure no contamination occurs throughout the experiment
  • Leave the container holding the agar growth medium and the explant on a sunny windowsill for 3 weeks

Steps of micropropagation of cauliflower from an explant 1, downloadable AS Level & A Level Biology revision notes Steps of micropropagation of cauliflower from an explant 2, downloadable AS Level & A Level Biology revision notes Steps of micropropagation of cauliflower from an explant 3, downloadable AS Level & A Level Biology revision notes Steps of micropropagation of cauliflower from an explant 4, downloadable AS Level & A Level Biology revision notes
The steps of micropropagation of a cauliflower from an explant

Results

  • The result of this experiment is to grow a complete cauliflower clone from an explant
  • This shows that the cells in the explant have the capability to produce all the different cell types that make up a full cauliflower plant, hence they are totipotent
  • The complete cauliflower plant can then be distributed to commercial growers/garden centres in large numbers
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