Production of Artificial Clones in Plants (OCR A Level Biology): Revision Note

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

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