Cloning in plants and animals

1. Cloning in plants and animals F215 control, genomes and environment Module 2 – Biotechnology and gene technologies

2. Learning Outcomes • Describe the production of natural clones in plants using the example of vegetative propagation in elm trees. • Describe the production of artificial clones of plants from tissue culture. • Discuss the advantages and disadvantages of plant cloning in agriculture.

3. Cloning • Cloning is the production of genetically identical organisms • In plants cloning can occur naturally by asexual reproduction. • All cells are produced by mitosis from cells that were originally part of the parent plant • All plants are genetically identical to the parent plant and each other.

4. Advantages Quick All offspring have the genetic information to enable them to survive in the environment Disadvantages No genetic variety Does not allow for natural selection Unable to adapt to environmental conditions. Asexual reproduction

5. Vegetative propagation • Asexual reproduction in plants is known as vegetative propagation • Examples • Strawberry plants produce runners • Potatoes form underground tubers • Daffodils produce bulbs • English Elm produces root suckers (basal sprouts)

6. Vegetative propagation in potatoes

7. English Elm • The English Elm only reproduces by suckering • The growth of new trees from the roots or meristem tissue in the trunks • As all English Elms are genetically identical they are all susceptible to the fungus, Dutch elm disease

8. Artificial Vegetative propagation • It is possible to artificially propagate valuable plants • Taking cuttings – cut a section of stem between nodes, then treat with plant hormones to encourage root growth • Grafting – a shoot section of a woody stem is joined to a root stock • Tissue culture

9. Grafting

10. Tissue Culture • Tissue culture allows for the production of huge numbers of genetically identical plants from a small amount of plant material. • All stages in tissue culture must be carried out in sterile conditions to prevent fungal infection

11. Stages in Plant Tissue Culture • A group of cells are removed from the parent plant called the explant. • Explant is placed on a nutrient growth medium • Cells divide to form a mass of undifferentiated cells called a callus • Single cells removed from callus and placed on a growth medium to stimulate shoot growth • The shoots are placed on a growth medium to stimulate root growth • Growing plants transferred to a greenhouse before planting outside

12. Plant Cloning in Agriculture • Desirable parent plant can be chosen and cloned • Plants mature at same time • In UK, Annual crops are propagated by seed • After years of inbreeding all crops are now genetically uniform • Even though seeds require sexual reproduction, all seeds and plants produced are genetically uniform

13. Plant Cloning in Agriculture • In perennial plants, the high cost of vegetative propagation is offset by • the long periods for which the plants stay in the ground • Relatively high value of the product • Examples • Lavender • Apple trees

14. Disadvantages of plant cloning • Susceptible to disease • Unable to adapt to climate change • Loss of genetic variation

15. Learning Outcomes • Outline the differences between reproductive and non-reproductive cloning.

16. Reproductive cloning Cloning to produce a whole organism Examples Embryo transplantation Dolly the sheep Non-reproductive cloning Using cloning to produce cells Examples Stem cell research Production of cells, tissues or organs Cloning in Animals

17. Non-reproductive cloning in animals • Non-reproductive cloning involves the production of genetically identical cells • 1951 – HeLa cells • Cancerous cells which divide repeatedly in culture solution • Used in medical research • Stem cells • Totipotent or pluripotent • Undifferentiated cells that are able to differentiate into specialised cells • Embryonic stem cells – ethical arguments

18. Possibilities of non-reproductive cloning • Potential future uses include • Regeneration of heart tissue following a heart attack • Repair of nervous tissue • Repairing the spinal cord • Stem cells taken from the patient to produce the tissues mean that tissue rejection by the immune system is less likely

19. Learning Outcomes • Describe how artificial clones of animals can be produced. • Discuss the advantages and disadvantages of cloning animals.

20. Reproductive cloning in animals • Two methods of artificially cloning animals • Splitting embryos for embryo transplantation • All offspring are identical to each other but not to the surrogate mothers • Nuclear transfer using enucleated eggs • Nucleus is taken from a differentiated cell in an adult, and placed into a enucleated egg cell

21. Dolly the sheep is believed to have suffered from a serious health problem which developed at a relatively early age Dolly the Sheep

22. Advantages High value animals Rare animals can be cloned Quickly reproduced Disadvantages Animal welfare Genetic uniformity, loss of genetic variation Uncertainties of health of cloned animals Artificial Cloning in animals • Moral and ethical Arguments • Is it right to clone an aging pet? • Is it right to clone an animal which leads to a cure for human diseases?