Autopolyploidy
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- Autopolyploidy refers to polyploids arising from duplication of the chromosomes sets of a single species.
- Generation of Autopolyploids
- Union of two diploid ( unreduced ) gametes - Tetraploid
- Somatic doubling ( tetraploid )
- Union of a haploid and a diploid gamete ( triploid )
- A cross between a tetraploid and a diploid parent ( triploid )
- Fertilization of an egg by two sperms ( triploid )
- Autoployploidy can also be induced artificilly with colchicine or similar drugs.
- All autopolyploids with odd number of sets of chromosomes ( 3n, 5n, 7n ) are sterile due to abnormal meiosis.
- Organisms with even numbered sets of abnormalities (4n, 6n etc) can have equal distribution of chromosomes during meiosis and may form some normal gametes.
- There are a few examples of polyploidy in animals. It is rare probably because it interferes with sex-determination.
- Examples are found in flatworms, leeches, and brine shrimps. In these animals, reproduction is by parthenogenesis.
- Polyploidy is much more common in plants.
- Examples are wheat ( 6x ), alfalfa ( 4x ), coffee ( 4x ), peanuts ( 4x ), strawberries (8x), and cotton ( 4x ). Ornamentals such as roses, chrysanthemums, and tulips are also polyploid.
- Some of the examples of autotriploids are seedless watermelon, blue berries, grapes, banana etc.
- Potato is a natural auto tetrapolyploid ( 4n ).
- Polyploid plants are often larger and have larger component parts than their diploid relatives.
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Last modified: Thursday, 22 December 2011, 7:05 PM
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