Polyploidy refers to cells or organisms that contain more than two copies of each of their chromosomes. Where an organism is normally diploid, some spontaneous aberrations may occur which are usually caused by a hampered cell division. Polyploid types are termed corresponding to the number of chromosome sets in the nucleus: triploid (three sets; 3n), tetraploid (four sets; 4n), pentaploid (five sets; 5n), hexaploid (six sets; 6n) and so on. A haploid (n) only has one set of chromosomes. Haploidy may also occur as a normal stage in an organism's life cycle as in ferns and fungi. In some instances not all the chromosomes are duplicated and the condition is called aneuploidy. Cells in culture, stained for keratin (red) and DNA (green). ... In biology and ecology, an organism (in Greek organon = instrument) is a complex adaptive system of organs that influence each other in such a way that they function as a more or less stable whole and have properties of life. ... Figure 1: Chromosome. ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... Cell division is the process by which a cell (called the parent cell) divides into two cells (called daughter cells). ... Nucleus usually refers to the center of something, but can mean: In science: Atomic nucleus, the collection of protons and neutrons in the center of an atom that carries the bulk of the atoms mass and positive charge Cell nucleus, the membrane-bound subcellular organelle found in eukaryotes, visible... Aneuploidy is a chromosomal state in which abnormal numbers of specific chromosomes or chromosome sets exist within the nucleus. ...

Examples

Polyploidy occurs in some animals, such as goldfish, but is especially common among ferns and flowering plants, including both wild and cultivated species. Wheat, for example, after millennia of hybridization and modification by humans, has strains that are diploid (two sets of chromosomes), tetraploid (four sets of chromosomes) with the common name of durum or macaroni wheat, and hexaploid (six sets of chromosomes) with the common name of bread wheat. Many agriculturally important plants of the genus Brassica are also tetraploids; their relationship is described by the Triangle of U. Binomial name Aptenodytes forsteri Gray, 1844 For other uses, see Animal (disambiguation). ... {{Taxobox + - | color = pink - | name = Goldfish - | status = Conservation status: Secure - | image = Goldfish. ... Classes Marattiopsida Osmundopsida Gleicheniopsida Pteridopsida A fern, or pteridophyte, is any one of a group of about 20,000 species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. ... Divisions Green algae Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum... In biology, a species is the basic unit of biodiversity. ... Species T. boeoticum T. compactum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum References:   ITIS 42236 2002-09-22 Wheat (Triticum spp. ... In genetics, hybridisation is the process of mixing different species or varieties of organisms. ... Durum wheat (Triticum turgidum durum) is the only tetraploid species of wheat widely cultivated today. ... Close-up photo of a handfull of macaroni noodles. ... Species See text Brassica is a genus of plants in the mustard family (Brassicaceae). ... The Triangle of U is a theory which describes the evolution and relationships between members of the plant genus Brassica. ...

Examples in animals are more common in the ‘lower’ forms such as flatworms, leeches, and brine shrimp. Reproduction is often by parthenogenesis since polyploid animals are often sterile. Polyploid salamanders and lizards are also quite common and parthenogenetic. Rare instances of polyploid mammals are known, but most often result in prenatal death. Kaguya is one success from 460 attempts at growing embryos. ...

Polyploidy can be induced in cell culture by some chemicals: the best known is colchicine, which can result in chromosome doubling, though its use may have other less obvious consequences as well. Colchicine is a highly poisonous alkaloid, originally extracted from plants of the genus Colchicum (Autumn crocus, also known as the Meadow saffron). Originally used to treat rheumatic complaints and especially gout, it was also prescribed for its cathartic and emetic effects. ...

In plant breeding, the induction of polyploids is a common technique to overcome the sterility of a hybrid species. Triticale is the hybrid of wheat (Triticum turgidum) and rye (Secale cereale). It combines sought-after characteristics of the parents, but the initial hybrids are sterile. After polyploidization, the hybrid becomes fertile and can thus be further propagated to become triticale. Triticale Triticale (X Triticosecale) is an artificial hybrid of rye and wheat first bred in laboratories during the late 19th century, but only recently developed into a viable crop. ... Species T. boeoticum T. compactum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum References:   ITIS 42236 2002-09-22 Wheat (Triticum spp. ... Binomial name Secale cereale M.Bieb. ...

Salsify is another example of polyploidy resulting in new species. Species about 45, including: Tragopogon coloratus Tragopogon crocifolius Tragopogon cupani Tragopogon dubius Tragopogon floccosus Tragopogon gracilis Tragopogon hispanica Tragopogon mirabilis Tragopogon mirus Tragopogon miscellus Tragopogon porrifolius Tragopogon pratensis Tragopogon X crantzii Tragopogon X neohybridus The Goatsbeards or Salsifies are the genus Tragopogon of flowering plants within the family Asteraceae. ...

Polyploid crops

Polyploid plants in general are more robust and more sturdy than diploids. In the breeding of crops, those plants that are stronger and tougher are selected. Thus many crops have unintentionally been bred to a higher level of ploidy:

• Triploid crops: banana, apple
• Tetraploid crops: durum or macaroni wheat, maize, cotton, potato, cabbage, leek, tobacco, peanut, Pelargonium
• Hexaploid crops: chrysanthemum, bread wheat, triticale, oat
• Octaploid crops: strawberry, dahlia, pansies, sugar cane

Some crops are found in a variety of ploidy. Apples, tulips and lilies for example are commonly found as both diploid and triploid. For other meanings, see banana (disambiguation) Species Hybrid origin; see text A banana plant is a herb in the genus, Musa, which because of its size and structure, is often mistaken for a tree. ... This article is about the tree and its fruit. ... Durum wheat (Triticum turgidum durum) is the only tetraploid species of wheat widely cultivated today. ... Close-up photo of a handfull of macaroni noodles. ... Binomial name Zea mays L. Maize (Zea mays ssp. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... Binomial name Solanum tuberosum L. The potato (plural form: potatoes) (Solanum tuberosum) is a perennial plant of the Solanaceae, or nightshade, family, grown for its starchy tuber. ... Cultivar Group Brassica oleraceaCapitata Group The cabbage (Brassica oleracea Capitata Group) is a plant of the Family Brassicaceae (or Cruciferae). ... Leek is a placename in more than one country: Netherlands: Leek, Netherlands United Kingdom: Leek, Staffordshire Leek is also a vegetable: Leek (vegetable) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Species N. glauca N. longiflora N. rustica N. sylvestris N. tabacum Ref: ITIS 30562 as of August 26, 2005 Tobacco (, L.) refers to a genus of broad-leafed plants of the nightshade family indigenous to North and South America, or to the dried and cured leaves of such plants. ... Binomial name Arachis hypogaea L. The peanut or groundnut (Arachis hypogaea) is a species in the pea family Fabaceae native to South America. ... Species About 200: Pelargonium radens Pelargonium scabrum Pelargonium triste et al. ... Species - tricolor daisy - pyrethrum - pyrethum daisy - crown daisy - marguerite - daisy - florists           chrysanthemum C. segetum - corndaisy Ref: ITIS 35791 See also Daisy (disambiguation) The chrysanthemum, also known as the mum, is a flowering perennial plant of the genus Chrysanthemum in the daisy family (Asteraceae). ... Triticale Triticale (X Triticosecale) is an artificial hybrid of rye and wheat first bred in laboratories during the late 19th century, but only recently developed into a viable crop. ... Binomial name Avena sativa Carolus Linnaeus (1753) The Oat (Avena sativa) is a species of cereal grain, and the seeds of this plant. ... Species 20+ species; see text The strawberry (Fragaria) is a genus of plants in the family Rosaceae, and the fruit of these plants. ... Species 30 species, 20,000 cultivars Dahlia is a genus of bushy, summer- and autumn-flowering, tuberous perennials that are originally from Mexico, where they are the national flower. ... Binomial name Viola tricolor hortensis Viola * wittrockiana The Pansy or Pansy Violet is a cultivated garden flower. ... Species Ref: ITIS 42058 as of 2004-05-05 Sugarcane is one of six species of a tall tropical southeast Asian grass (Family Poaceae) having stout fibrous jointed stalks whose sap at one time was the primary source of sugar. ... This article is about the tree and its fruit. ... Species See text. ... lily is the best name in the whole wide world. ...

Terminology

Autopolyploidy

Autopolyploids are polyploids with chromosomes derived from a single species. Autopolyploids can arise from a naturally occurring spontaneous genome doubling (for example potato). In general, autopolyploids are sterile. Bananas and apples can be found as triploid autopolyploids. For other meanings, see banana (disambiguation) Species Hybrid origin; see text A banana plant is a herb in the genus, Musa, which because of its size and structure, is often mistaken for a tree. ... This article is about the tree and its fruit. ...

Allopolyploidy

Allopolyploids are polyploids with chromosomes derived from different species. Allopolyploids are fertile. Triticale is an example of an allopolyploid, having six chromosome sets, four from wheat (Triticum turgidum) and two from rye (Secale cereale). Cabbage is a very interesting example of a fertile allotetraploid crop (see Triangle of U). Amphidiploidy is another word for an allopolyploid. Triticale Triticale (X Triticosecale) is an artificial hybrid of rye and wheat first bred in laboratories during the late 19th century, but only recently developed into a viable crop. ... The Triangle of U is a theory which describes the evolution and relationships between members of the plant genus Brassica. ...

Paleopolyploidy

Ancient genome duplications probably characterize all life. Duplication events that occurred long ago in the history of various evolutionary lineages can be difficult to detect because of subsequent diploidization (such that a polyploid starts to behave cytogentically as a diploid over time) as mutations and gene translations gradually make one copy of each chromosome unline its other copy. In many cases, these events can be inferred only through comparing sequenced genomes. Examples of unexpected but recently confirmed ancient genome duplications include the baker's yeast (Saccharomyces cerevisiae), mustard weed/thale cress (Arabidopsis thaliana), rice (Oryza sativa), and an early evolutionary ancestor of the vertebrates (which includes the human lineage) and another near the origin of the teleost fishes. ll angiosperms (flowering plants) may have paleopolyploidy in their ancestry. All eukaryotes probably experienced a polyploidy event at some point in their evolutionary history, as likeliest the first living organisms had only one chromosome. An evolutionary lineage (also called a clade) is composed of species, taxa, or individuals that are related by descent from a common ancestor. ... In genetics and biochemistry, sequencing means to determine the primary structure (or primary sequence) of an unbranched biopolymer. ... Yeasts constitute a group of single-celled (unicellular) fungi, a few species of which are commonly used to leaven bread, ferment alcoholic beverages, and even drive experimental fuel cells. ... Binomial name Saccharomyces cerevisiae Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ... Binomial name Arabidopsis thaliana (L.) Heynh. ... Species Oryza glaberrima Oryza sativa Rice refers to two species (Oryza sativa and Oryza glaberrima) of grass, native to tropical and subtropical southeastern Asia and to Africa, which together provide more than one fifth of the calories consumed by humans. ... Species Oryza barthii Oryza glaberrima Oryza latifolia Oryza longistaminata Oryza punctata Oryza rufipogon Oryza sativa References ITIS 41975 2002-09-22 This article is about the food grain, not the university or Condoleezza Rice; see also rice (disambiguation). ... A speculative phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea, and eukaryotes. ... An ancestor is a parent or (recursively) the parent of an ancestor (i. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu† Homo sapiens sapiens Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin for wise man or thinking man) under the family Hominidae (the great apes). ... Orders See text The Actinopterygii are the ray-finned fish. ... Atlantic herring, Clupea harengus, the most abundant fish species in the world, Photo by Uwe Kils This page is about the animals which live in water. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (also spelled eucaryote) is an organism with complex cells, in which the genetic material is organized into membrane-bound nuclei. ...

References

• Griffiths, A. J. et al. 2000. An introduction to genetic analysis, 7th ed. W. H. Freeman, New York ISBN 0716735202

Further reading

• Arabidopsis Genome Initiative (2000). Analysis of the genome sequence of the flowering plant Arabidopsis thaliana. Nature 408: 796-815.
• Eakin, G.S. & Behringer, R.R. (2003). Tetraploid development in the mouse. Developmental Dynamics 228: 751-766.
• Gregory, T.R. & Mable, B.K. (2005). Polyploidy in animals. In The Evolution of the Genome (edited by T.R. Gregory). Elsevier, San Diego, pp. 427-517.
• Jaillon, O. et al. (2004). Genome duplication in the teleost fish Tetraodon nigroviridis reveals the early vertebrate proto-karyotype. Nature 431: 946-957.
• Paterson, A.H., Bowers, J. E., Van de Peer, Y. & Vandepoele, K. (2005). Ancient duplication of cereal genomes. New Phytologist 165: 658-661.
• Raes, J., Vandepoele, K., Saeys, Y., Simillion, C. & Van de Peer, Y. (2003). Investigating ancient duplication events in the Arabidopsis genome. Journal of Structural and Functional Genomics 3: 117-129.
• Simillion, C., Vandepoele, K., Van Montagu, M., Zabeau, M. & Van de Peer, Y. (2002). The hidden duplication past of Arabidopsis thaliana. Proceedings of the National Academy of Science of the USA 99: 13627-13632.
• Taylor, J.S., Braasch, I., Frickey, T., Meyer, A. & Van de Peer, Y. (2003). Genome duplication, a trait shared by 22,000 species of ray-finned fish. Genome Research 13: 382-390.
• Tate, J.A., Soltis, D.E., & Soltis, P.S. (2005). Polyploidy in plants. In The Evolution of the Genome (edited by T.R. Gregory). Elsevier, San Diego, pp.371-426.
• Van de Peer, Y., Taylor, J.S. & Meyer, A. (2003). Are all fishes ancient polyploids? Journal of Structural and Functional Genomics 3: 65-73.
• Van de Peer, Y. (2004). Tetraodon genome confirms Takifugu findings: most fish are ancient polyploids. Genome Biology 5(12):250.
• Van de Peer, Y. and Meyer, A. (2005). Large-scale gene and ancient genome duplications. In The Evolution of the Genome (edited by T.R. Gregory). Elsevier, San Diego, pp.329-368
• Wolfe, K.H. & Shields, D.C. (1997). Molecular evidence for an ancient duplication of the entire yeast genome. Nature 387: 708-713.
• Wolfe, K.H. (2001). Yesterday's polyploids and the mystery of diploidization. Nature Reviews Genetics 2: 333-341.

// Summary The Evolution of the Genome is a book edited by Dr. T. Ryan Gregory of the University of Guelph, Ontario, Canada, covering a wide range of topics in the study of genome evolution. ... // Summary The Evolution of the Genome is a book edited by Dr. T. Ryan Gregory of the University of Guelph, Ontario, Canada, covering a wide range of topics in the study of genome evolution. ... // Summary The Evolution of the Genome is a book edited by Dr. T. Ryan Gregory of the University of Guelph, Ontario, Canada, covering a wide range of topics in the study of genome evolution. ...

External links

• Polyploidy on Kimball's Biology Pages