22.2 Artificial Cloning in Plants

Question 1

What is micropropagation?

Answer 1

process of making many clones

from single parent

using tissue culture

Question 2

When is micropropagation used?

Answer 2

when plant with desirable characteristics:

• does not readily produce seeds
• does not respond well to natural cloning
• is very rare
• has been GM or selectively bred with difficulty
• is required to be “pathogen free”

Question 3

Outline the steps by which a plant can be grown by micropropagation:

Answer 3

1. take sample of meristem tissue - this is called the explant
2. Sterilise explant
3. Place explant in sterile culture medium containing plant hormones which stimulate mitosis
   
   1. cells proliferate, forming callus
4. Callus divided & each clump of cells transferred to new culture medium.
   
   1. contains different balance of plant hormones for growing plantlets
5. Plantlets planted into compost

Question 4

What are the advantages & disadvantages of growing plants by micropropagation?

Answer 4

• ADVANTAGES
  
  • rapid production of plants with guaranteed characteristics
  • culturing meristem produces disease-free plants
  • allows cultures to be grown from seedless plants
  • reliable for increasing numbers of endangered plants
• DISADVANTAGES
  
  • produces monoculture >> susceptible to same environmental changes
  • expensive & requires skilled workers
  • explants & plantlets vulnerable to infection
  • if source material infected with disease, then all deriving explants will be diseased
  • large numbers of new plants can be lost in process - can have low yield

Question 5

Name an example of a crop which is commonly made by micropropagation:

Answer 5

bananas

(they have no seeds, ∴ require micropropagation to reproduce)