Review Article | Published:

The advantages and disadvantages of being polyploid

Nature Reviews Genetics volume 6, pages 836846 (2005) | Download Citation

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Abstract

Polyploids — organisms that have multiple sets of chromosomes — are common in certain plant and animal taxa, and can be surprisingly stable. The evidence that has emerged from genome analyses also indicates that many other eukaryotic genomes have a polyploid ancestry, suggesting that both humans and most other eukaryotes have either benefited from or endured polyploidy. Studies of polyploids soon after their formation have revealed genetic and epigenetic interactions between redundant genes. These interactions can be related to the phenotypes and evolutionary fates of polyploids. Here, I consider the advantages and challenges of polyploidy, and its evolutionary potential.

Key points

  • The occurrence and behaviour of polyploids — organisms that inherit multiple complete sets of chromosomes — has been studied for nearly a century. Recently, the footprints of ancestral polyploidy have been detected in many eukaryotic genomes, indicating that polyploidization and diploidization can be cyclical.

  • Understanding the effect of polyploidization on gene diversification and genome evolution requires an understanding of the mechanisms that lead to the formation and establishment of polyploidy. The possible incentives and constraints on polyploid formation are discussed.

  • There are three obvious advantages of becoming polyploid: heterosis, gene redundancy (a result of gene duplication) and asexual reproduction. Heterosis causes polyploids to be more vigorous than their diploid progenitors, whereas gene redundancy shields polyploids from the deleterious effect of mutations. Asexual reproduction, for which the mechanistic connection to polyploidy is unclear, enables polyploids to reproduce in the absence of sexual mates.

  • There are several disadvantages, documented or conjectured, of polyploidy. They include the potentially disrupting effects of nuclear and cell enlargement, the propensity of polyploid mitosis and meiosis to produce aneuploid cells, and the epigenetic instability that results in transgressive (non-additive) gene regulation.

  • The amount of experimental evidence that addresses these problems varies considerably. In particular, recent data on gene regulation in polyploids provide interesting but still incomplete information on the genetic responses that are involved in polyploidy and on the role of epigenetic remodelling.

  • Transcriptional remodelling in polyploids has two causes. The first is the interaction of diverged parental genomes that are reunited in the allopolyploid; this interaction has both genetic and epigenetic effects. The second, less characterized causal mechanism is genome duplication.

  • Triploidy and aneuploidy are unstable states that often lead to or result from the more stable polyploidy states such as tetraploidy. Both conditions can have potentially disruptive effects on genome regulation, some of which might result from meiotically unpaired DNA.

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References

  1. 1.

    et al. The Genomes of Oryza sativa: a history of duplications. PLoS Biol. 3, e38 (2005).

  2. 2.

    Polyploidy, evolutionary opportunity, and crop adaptation. Genetica 123, 191–196 (2005).

  3. 3.

    , & Gene order evolution and paleopolyploidy in hemiascomycete yeasts. Proc. Natl Acad. Sci. USA 99, 9272–9277 (2002).

  4. 4.

    & Widespread paleopolyploidy in model plant species inferred from age distributions of duplicate genes. Plant Cell 16, 1667–1678 (2004).

  5. 5.

    & Evolution by polyploidy and gene regulation in Anura. Genet. Mol. Res. 3, 195–212 (2004).

  6. 6.

    , , , & Extent of gene duplication in the genomes of Drosophila, nematode, and yeast. Mol. Biol. Evol. 19, 256–262 (2002).

  7. 7.

    et al. Fugu genome analysis provides evidence for a whole-genome duplication early during the evolution of ray-finned fishes. Mol. Biol. Evol. 21, 1146–1151 (2004).

  8. 8.

    & in The Evolution of the Genome (ed. Gregory, T. R.) 330–363 (Elsevier, San Diego, 2005).

  9. 9.

    Chromosomal Evolution in Higher Plants (Addison–Wesley, Menlo Park, 1970).

  10. 10.

    et al. Phenotypic instability and rapid gene silencing in newly formed Arabidopsis allotetraploids. Plant Cell 12, 1551–1568 (2000).

  11. 11.

    & High levels of chromosome instability in polyploids of Saccharomyces cerevisiae. Mutat. Res. 231, 177–186 (1990).

  12. 12.

    Plant Cytogenetics (CRC Press, Boca Raton, 2003).

  13. 13.

    & Neopolyploidy in flowering plants. Annu. Rev. Ecol. Syst. 33, 589–639 (2002).

  14. 14.

    , , , & Duplication and DNA segmental loss in the rice genome: implications for diploidization. New Phytol. 165, 937–946 (2005).

  15. 15.

    , & Ancient polyploidization predating divergence of the cereals, and its consequences for comparative genomics. Proc. Natl Acad. Sci. USA 101, 9903–9908 (2004).

  16. 16.

    & Polyploidy and genome evolution in plants. Curr. Opin. Plant Biol. 8, 135–141 (2005).

  17. 17.

    & in The Evolution of the Genome (ed. Gregory, T. R.) 289–327 (Elsevier, San Diego, 2005).

  18. 18.

    et al. Modeling gene and genome duplications in eukaryotes. Proc. Natl Acad. Sci. USA 102, 5454–5459 (2005).

  19. 19.

    , , & A simple method for predicting the functional differentiation of duplicate genes and its application to MIKC-type MADS-box genes. Nucleic Acids Res. 33, e12 (2005).

  20. 20.

    , , & Yeast genome duplication was followed by asynchronous differentiation of duplicated genes. Nature 421, 848–852 (2003).

  21. 21.

    & Subfunctionalization of duplicated genes as a transition state to neofunctionalization. BMC Evol. Biol. 5, 28 (2005).

  22. 22.

    & Genomic background predicts the fate of duplicated genes: evidence from the yeast genome. Genetics 166, 1995–1999 (2004).

  23. 23.

    , & Metabolic network analysis of the causes and evolution of enzyme dispensability in yeast. Nature 429, 661–664 (2004).

  24. 24.

    et al. Genomic duplication, fractionation and the origin of regulatory novelty. Genetics 166, 935–945 (2004).

  25. 25.

    & The origins of genome complexity. Science 302, 1401–1404 (2003).

  26. 26.

    & Pathways, mechanisms, and rates of polyploid formation in flowering plants. Annu. Rev. Ecol. Syst. 29, 467–501 (1998).

  27. 27.

    , & in The Evolution of the Genome (ed. Gregory, T. R.) 372–414 (Elsevier, San Diego, 2005).

  28. 28.

    & in The Evolution of the Genome (ed. Gregory, T. R.) 428–501 (Elsevier, San Diego, 2005).

  29. 29.

    et al. Cytogenetic analysis of 750 spontaneous abortions with the direct-preparation method of chorionic villi and its implications for studying genetic causes of pregnancy wastage. Am. J. Hum. Genet. 47, 656–663 (1990).

  30. 30.

    & Gametophytic heterosis for in vitro pollen traits in alfalfa. Crop Sci. 31, 1510–1513 (1991).

  31. 31.

    & Selection–mutation balance in polysomic tetraploids: impact of double reduction and gametophytic selection on the frequency and subchromosomal localization of deleterious mutations. Proc. Natl Acad. Sci. USA. 97, 6608–6613 (2000).

  32. 32.

    & How to make an egg: transcriptional regulation in oocytes. Differentiation 73, 1–17 (2005).

  33. 33.

    , , , & Reproductive biology: delivering spermatozoan RNA to the oocyte. Nature 429, 154 (2004).

  34. 34.

    & Gene expression in spermiogenesis. Cell. Mol. Life Sci. 62, 344–354 (2005).

  35. 35.

    et al. Nonadditive gene expression in diploid and triploid hybrids of maize. Genetics 169, 389–397 (2005).

  36. 36.

    , & In search of the molecular basis of heterosis. Plant Cell 15, 2236–2239 (2003).

  37. 37.

    , , & Relationships among genetic distance, forage yield and heterozygosity in isogenic diploid and tetraploid alfalfa populations. Theor. Appl. Genet. 89, 323–328 (1994).

  38. 38.

    , Complementary gene interactions in alfalfa are greater in autotetraploids than diploids. Crop Sci. 34, 823–829 (1994).

  39. 39.

    & Female gametophyte development. Plant Cell. 16, S133–S141 (2004).

  40. 40.

    Control of male gametophyte development. Plant Cell. 16, S142–S153 (2004).

  41. 41.

    & Masking and purging mutations following EMS treatment in haploid, diploid and tetraploid yeast (Saccharomyces cerevisiae). Genet. Res. 77, 9–26 (2001).

  42. 42.

    Chromosome number and the mutation rate in Avena and Triticum. Proc. Natl Acad. Sci. USA 15, 876–881 (1929).

  43. 43.

    & The evolutionary dynamics of plant duplicate genes. Curr. Opin. Plant Biol. 8, 122–128 (2005).

  44. 44.

    & Splitting pairs: the diverging fates of duplicated genes. Nature Rev. Genet. 3, 827–837 (2002).

  45. 45.

    & Polyploidy and the evolution of gender dimorphism in plants. Science 289, 2335–2338 (2000).

  46. 46.

    , , & Arabidopsis species hybrids in the study of species differences and evolution of amphiploidy in plants. Plant Physiol. 124, 1605–1614 (2000).

  47. 47.

    et al. Relationship between polyploidy and pollen self-incompatibility phenotype in Petunia hybrida Vilm. Biosci. Biotechnol. Biochem. 63, 1882–1888 (1999).

  48. 48.

    Nucleotype and cell size in vertebrates: a review. Basic Appl. Histochem. 27, 227–256 (1983).

  49. 49.

    , & Relationship between endopolyploidy and cell size in epidermal tissue of Arabidopsis. Plant Cell 5, 1661–1668 (1993).

  50. 50.

    , , , & Interphase chromosomes in Arabidopsis are organized as well defined chromocenters from which euchromatin loops emanate. Proc. Natl Acad. Sci. USA. 99, 14584–14589 (2002).

  51. 51.

    et al. Histone modifications in Arabidopsis — high methylation of H3 lysine 9 is dispensable for constitutive heterochromatin. Plant J. 33, 471–480 (2003).

  52. 52.

    , , & The positioning of rye homologous chromosomes added to wheat through the cell cycle in somatic cells untreated and treated with colchicine. Cytogenet. Genome Res. 109, 112–119 (2005).

  53. 53.

    , , , & The nuclear lamina comes of age. Nature Rev. Mol. Cell Biol. 6, 21–31 (2005).

  54. 54.

    , , & Position-effect variegation and the genetic dissection of chromatin regulation in Drosophila. Semin. Cell Dev. Biol. 14, 67–75 (2003).

  55. 55.

    et al. Expanding the phenotype of LMNA mutations in dilated cardiomyopathy and functional consequences of these mutations. J. Med. Genet. 40, 560–567 (2003).

  56. 56.

    , & Biochemical and immunological characterization of pea nuclear intermediate filament proteins. Planta 218, 965–975 (2004).

  57. 57.

    et al. Genome-wide identification of Arabidopsis coiled-coil proteins and establishment of the ARABI-COIL database. Plant Physiol. 134, 927–939 (2004).

  58. 58.

    Nuclear volume control by nucleoskeletal DNA, selection for cell volume and cell growth rate, and the solution of the DNA C-value paradox. J. Cell Sci. 34, 247–278 (1978).

  59. 59.

    , & Analysis of cell size and DNA content in exponentially growing and stationary-phase batch cultures of Escherichia coli. J. Bacteriol. 177, 6791–6797 (1995). This analysis of ploidy and growth conditions in E. coli addresses the question of why certain cells become endopolypoid; it goes a long way towards demonstrating the generality of the connection between metabolic activity and DNA content.

  60. 60.

    , , & Gigantism in a bacterium, Epulopiscium fishelsoni, correlates with complex patterns in arrangement, quantity, and segregation of DNA. J. Bacteriol. 180, 5601–5611 (1998).

  61. 61.

    , & Plant cell-size control: growing by ploidy? Curr. Opin. Plant Biol. 3, 488–492 (2000).

  62. 62.

    & “Big it up”: endoreduplication and cell-size control in plants. Curr. Opin. Plant Biol. 6, 544–553 (2003).

  63. 63.

    & Evidence of direct polyploidization in the mitotic parthenogenetic Meloidogyne microcephala through doubling of its somatic chromosome number. Fundam. Appl. Nematol. 20, 385–391 (1997).

  64. 64.

    , , , & Somatic polyploidization and cellular proliferation drive body size evolution in nematodes. Proc. Natl Acad. Sci. USA 97, 5285–5290 (2000).

  65. 65.

    Maintenance of normal structure in heteroploid salamander larvae, through compensation of changes in cell size by adjustment of cell number and cell shape. J. Exp. Zool. 100, 445–455 (1945).

  66. 66.

    , & Tetraploidy in mice, embryonic cell number, and the grain of the developmental map. Dev. Biol. 152, 233–241 (1992).

  67. 67.

    , , & Tetraploid state induces p53-dependent arrest of nontransformed mammalian cells in G1. Mol. Biol. Cell 12, 1315–1328 (2001).

  68. 68.

    , , & Multiple centrosomes arise from tetraploidy checkpoint failure and mitotic centrosome clusters in p53 and RB pocket protein-compromised cells. Proc. Natl Acad. Sci. USA 99, 9819–9924 (2002). This article shows that polyploidy can cause a mitotic crisis.

  69. 69.

    & Mitotically unstable polyploids in the yeast Pichia guilliermondii. J. Basic Microbiol. 32, 331–338 (1992).

  70. 70.

    et al. Polyploids require Bik1 for kinetochore-microtubule attachment. J. Cell Biol. 155, 1173–1184. (2001).

  71. 71.

    , , & Localization of the microtubule end binding protein EB1 reveals alternative pathways of spindle development in Arabidopsis suspension cells. Plant Cell 17, 1737–1748 (2005).

  72. 72.

    Acentrosomal microtubule nucleation in higher plants. Int. Rev. Cytol. 220, 257–289 (2002).

  73. 73.

    , & Multiple spindles and cellularization during microsporogenesis in an artificially induced tetraploid accession of Brachiaria ruziziensis (Gramineae). Plant Cell Rep. 23, 522–527 (2005).

  74. 74.

    et al. Partial diploidization of meiosis in autotetraploid Arabidopsis thaliana. Genetics 165, 1533–1540 (2003).

  75. 75.

    & Chromosomal rearrangement in autotetraploid plants of Arabidopsis thaliana. Hereditas 133, 255–261 (2000).

  76. 76.

    , & Chromosome behavior in early and advanced generation of tetraploid maize. Caryologia 35, 463–470 (1982).

  77. 77.

    Aneuploidy and inbreeding depression in random mating and self-fertilizing autotetraploid populations. Theor. Appl. Genet. 72, 799–806 (1986).

  78. 78.

    Cytogenetics of tetraploid maize. J. Agric. Res. 50, 591–605 (1935).

  79. 79.

    Cytogenetic properties and practical value of tetraploid rye. Hereditas 37, 17–84 (1951).

  80. 80.

    Discussions in Cytogenetics (Burgess, Minneapolis, 1962).

  81. 81.

    Genetic control of chromosome pairing in wheat. Annu. Rev. Genet. 10, 31–51 (1976).

  82. 82.

    , & Homologue recognition during meiosis is associated with a change in chromatin conformation. Nature Cell Biol. 6, 906–908 (2004).

  83. 83.

    et al. PrBn, a major gene controlling homeologous pairing in oilseed rape (Brassica napus) haploids. Genetics 164, 645–653 (2003).

  84. 84.

    et al. Aneuploidy and genetic variation in the Arabidopsis thaliana triploid response. Genetics 170, 1979–1988 (2005). This paper shows that ploidy can “segregate as a trait” in a cross; it also highlights the relationship between polyploidy, triploidy and aneuploidy, and the effect of genetic background.

  85. 85.

    et al. Structural instability of a transgene locus in tobacco is associated with aneuploidy. Plant J. 10, 469–478 (1996).

  86. 86.

    , , & Does the intrinsic instability of aneuploid genomes have a causal role in cancer? Trends Genet. 19, 253–256 (2003).

  87. 87.

    , , & Dosage balance in gene regulation: biological implications. Trends Genet. 21, 219–226 (2005).

  88. 88.

    , & Dosage effects on gene expression in a maize ploidy series. Genetics 142, 1349–1355 (1996).

  89. 89.

    & Genotypic control of chromosome behaviour in rye. XI. The influence of B chromosomes on meiosis. Heredity 22, 333–347 (1967).

  90. 90.

    in The Evolution of the Genome (ed. Gregory, T. R.) 223–286 (Elsevier, San Diego, 2005).

  91. 91.

    , , , & Ploidy regulation of gene expression. Science 285, 251–254 (1999). A microarray analysis of the transcriptome in a yeast ploidy series.

  92. 92.

    et al. Autopolyploidy in cabbage (Brassica oleracea L.) does not alter significantly the proteomes of green tissues. Proteomics 5, 2131–2139 (2005).

  93. 93.

    & Novel patterns of gene expression in polyploid plants. Trends Genet. 21, 539–543 (2005).

  94. 94.

    , & Formation of stable epialleles and their paramutation-like interaction in tetraploid Arabidopsis thaliana. Nature Genet. 34, 450–454 (2003).

  95. 95.

    , , , & A change of ploidy can modify epigenetic silencing. Proc. Natl Acad. Sci. USA 93, 7114–7119 (1996). A compelling demonstration of epigenetic remodelling that is associated with autopolyploidization.

  96. 96.

    & RIGS (repeat-induced gene silencing) in Arabidopsis is transcriptional and alters chromatin configuration. Proc. Natl Acad. Sci. USA 93, 10881–10886 (1996).

  97. 97.

    et al. Stochastic and epigenetic changes of gene expression in Arabidopsis polyploids. Genetics 167, 1961–1973 (2004). A good example of the epigenetic instability found in neoallopolyploids.

  98. 98.

    et al. Genomic changes in synthetic Arabidopsis polyploids. Plant J. 41, 221–230 (2005).

  99. 99.

    et al. Chromosomal locus rearrangements are a rapid response to formation of the allotetraploid Arabidopsis suecica genome. Proc. Natl Acad. Sci. USA 101, 18240–18245 (2004).

  100. 100.

    , , , & Sequence elimination and cytosine methylation are rapid and reproducible responses of the genome to wide hybridization and allopolyploidy in wheat. Plant Cell 13, 1749–1759 (2001).

  101. 101.

    et al. Remodeling of DNA methylation and phenotypic and transcriptional changes in synthetic Arabidopsis allotetraploids. Plant Physiol. 129, 733–746 (2002). This paper reports on the activation of some transposable elements in neopolyploids of the Arabidopsis genus.

  102. 102.

    , & Gene loss, silencing and activation in a newly synthesized wheat allotetraploid. Genetics 160, 1651–1169 (2002).

  103. 103.

    , , & Allopolyploidy alters gene expression in the highly stable hexaploid wheat. Plant Mol. Biol. 52, 401–414 (2003).

  104. 104.

    , & Transcriptional activation of retrotransposons alters the expression of adjacent genes in wheat. Nature Genet. 33, 102–106 (2003). This report connects the regulation of repeated elements to that of genes in newly formed allopolyploids.

  105. 105.

    , & Genetic and epigenetic consequences of recent hybridization and polyploidy in Spartina (Poaceae). Mol. Ecol. 14, 1163–1175 (2005).

  106. 106.

    et al. Genome-wide non-additive gene regulation in Arabidopsis allotetraploids. Genetics. The first microarray-based comparison of newly formed allopolyploids and their parents.

  107. 107.

    , & Meiotic pairing and imprinted X chromatin assembly in Caenorhabditis elegans. Nature Genet. 36, 100–105 (2004).

  108. 108.

    et al. Silencing of unpaired chromatin and histone H2A ubiquitination in mammalian meiosis. Mol. Cell. Biol. 25, 1041–1053 (2005).

  109. 109.

    et al. Silencing of unsynapsed meiotic chromosomes in the mouse. Nature Genet. 37, 41–47 (2005).

  110. 110.

    , , & Meiotic silencing by unpaired DNA. Cell 107, 905–916 (2001).

  111. 111.

    et al. Polyploidy in arctic plants. Biol. J. Linn. Soc. 82, 521–536 (2004).

  112. 112.

    & Parasite infectivity to hybridising host species: a link between hybrid resistance and allopolyploid speciation? Int. J. Parasitol. 33, 137–144 (2003).

  113. 113.

    , , & Chloroplast DNA indicates a single origin of the allotetraploid Arabidopsis suecica. J. Evol. Biol. 16, 1019–1029 (2003).

  114. 114.

    , & Organ-specific silencing of duplicated genes in a newly synthesized cotton allotetraploid. Genetics 168, 2217–2226 (2004).

  115. 115.

    Paralogs in polyploids: one for all and all for one? Plant Cell 17, 4–11 (2005).

  116. 116.

    & Understanding apomixis: recent advances and remaining conundrums. Plant Cell 16, S228–S245 (2004).

  117. 117.

    & Apomixis: a developmental perspective. Annu. Rev. Plant Biol. 54, 547–574 (2003).

  118. 118.

    Apomixis in flowering plants: an overview. Philos. Trans. R. Soc. Lond. B 358, 1085–1093 (2003).

  119. 119.

    & Evolution of triploidy in Apios americana (Leguminosae) revealed by genealogical analysis of the histone H3-Dgene. Evolution 58, 284–295 (2004).

  120. 120.

    & Formation of unreduced megaspores (diplospory) in apomictic dandelions (Taraxacum officinale, s. l.) is controlled by a sex-specific dominant locus. Genetics 166, 483–492 (2004). This is a good example of studies that have shown linkage between a dominant apomictic gene and a heterochromatic B chromosome.

  121. 121.

    , , & Triploid bridge and role of parthenogenesis in the evolution of autopolyploidy. Am. Nat. 164, 101–112 (2004).

  122. 122.

    , & The role of tetraploids in the sexual-asexual cycle in dandelions (Taraxacum). Heredity 93, 390–398 (2004).

  123. 123.

    , , , & Biogeographic distribution of polyploidy and B chromosomes in the apomictic Boechera holboellii complex. Cytogenet. Genome Res. 109, 283–292 (2005).

  124. 124.

    , & Origin of polyploidy in parthenogenetic weevils. J. Theor. Biol. 163, 449–456 (1993).

  125. 125.

    , , , & A rise of ploidy level induces the expression of apomixis in Paspalum notatum. Sex. Plant Reprod. 13, 243–249 (2001).

  126. 126.

    Genetics of apospory in Ranunculus auricomus. V. Conclusions. Bot. Helv. 94, 411–422 (1984).

  127. 127.

    & Two independent loci control agamospermy (apomixis) in the triploid flowering plant Erigeron annuus. Genetics 155, 379–390 (2000).

  128. 128.

    et al. Non-Mendelian transmission of apomixis in maize–Tripsacum hybrids caused by a transmission ratio distortion. Heredity 80, 40–47 (1998).

  129. 129.

    & Asexual reproduction, polyploidy and optimal mutation rates. J. Theor. Biol. 118, 485–589 (1986).

  130. 130.

    , & Is supernumerary chromatin involved in gametophytic apomixis of polyploid plants? Sex. Plant Reprod. 13, 343–349 (2001).

  131. 131.

    , & The centromere paradox: stable inheritance with rapidly evolving DNA. Science 293, 1098–1102 (2001).

  132. 132.

    & A novel meiotic drive locus almost completely distorts segregation in mimulus (monkeyflower) hybrids. Genetics 169, 347–353 (2005).

  133. 133.

    & Recurrent polyploid origins and chloroplast phylogeography in the Arabis holboellii complex (Brassicaceae). Heredity 87, 59–68 (2001).

  134. 134.

    et al. Investigating the hows and whys of DNA endoreduplication. J. Exp. Bot. 52, 183–192 (2001).

  135. 135.

    et al. Polytene chromosomes: 70 years of genetic research. Int. Rev. Cytol. 241, 203–275 (2004).

  136. 136.

    & Molecular cytogenetic analysis of polyploidization in the anther tapetum of diploid and autotetraploid Arabidopsis thaliana plants. Ann. Bot. 87, 729–735 (2001).

  137. 137.

    , & FISH analysis of meiosis in Arabidopsis allopolyploids. Chromosome Res. 11, 217–226 (2003).

  138. 138.

    , , , & Replication of heterochromatin and structure of polytene chromosomes. Mol. Cell. Biol. 20, 6308–6316 (2000).

  139. 139.

    et al. The Drosophila suppressor of underreplication protein binds to late-replicating regions of polytene chromosomes. Genetics 160, 1023–1134 (2002).

  140. 140.

    & Chromosome behavior in triploids of Datura stramonium. I. The male gametophyte. Am. J. Bot. 24, 519–621 (1938).

  141. 141.

    & Chromosome behavior in triploid Datura. II. The female gametophyte. Am. J. Bot. 24, 621–627 (1938).

  142. 142.

    , & Chromosome behavior in triploid Datura. III. The seed. Am. J. Bot. 24, 595–602 (1938).

  143. 143.

    & The effects of polyploidy on sex expression in the spinach. J. Heredity 46, 151–156 (1955).

  144. 144.

    & Fecundity and offspring ploidy in matings among diploid, triploid and tetraploid Chamerion angustifolium (Onagraceae): consequences for tetraploid establishment. Heredity 87, 573–582 (2001).

  145. 145.

    Chromosome studies in Arabidopsis thaliana. Genetics 48, 483–490 (1963).

  146. 146.

    et al. A bisexually reproducing all-triploid vertebrate. Nature Genet. 30, 325–328 (2002). A recently discovered example of fixed sexual triploidy.

  147. 147.

    & Permanent odd polyploidy in a grass (Andropogon ternatus). Genome 29, 340–344 (1987).

  148. 148.

    Polarised segregation in the pollen mother cells of a stable triploid. Heredity 2, 119–129 (1948).

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Acknowledgements

I wish to thank three anonymous reviewers for their suggestions. I also gratefully acknowledge funding by the National Science Foundation Plant Genome Program.

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  1. Department of Biology, Box 355325, University of Washington, Seattle, Washington 98195, USA.  comai@u.washington.edu

    • Luca Comai

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The author declares no competing financial interests.

Glossary

NEOPOLYPLOID

A polyploid that has been produced by artificially inducing chromosome doubling.

DIPLOIDIZATION

Gradual conversion from polyploidy to diploidy through genetic changes that differentiate duplicated loci.

SUBFUNCTIONALIZATION

Retention by duplicated genes of different components of the original common function.

NEOFUNCTIONALIZATION

Acquisition of novel function by a duplicated gene.

EPIGENETIC

A mitotically stable change in gene expression that depends not on a change in DNA sequence, but on covalent modifications of DNA or chromatin proteins such as histones.

HETEROSIS

The increase in performance displayed by hybrids compared with their inbred parents. Because performance can be a subjective trait (for example, age of reproduction), a more precise definition is non-additive inheritance in which a trait in the F1 transgresses both parental values.

DYSGENESIS

Sterility or other deleterious trait of an F1 hybrid that results from incompatibilities between parental genomes.

ALLOPOLYPLOID

A polyploid that is generated through hybridization and thus combines different types of chromosome sets; by contrast, an autopolyploid arises through the multiplication of the same chromosome set.

HOMEOLOGOUS

Duplicated genes or chromosomes that are derived from different parental species and are related by ancestry.

MULTIVALENT

Meiotic association of more than two chromosomes, resulting in synapsis and recombination between partners.

ANEUPLOIDY

The property of having a chromosome number that is not an exact multiple of X.

CENTROSOME

The microtubule-organizing centre that divides to organize the two poles of the mitotic spindle and directs assembly of the cytoskeleton, so controlling cell division, motility and shape.

INBREEDING DEPRESSION

The loss of vigour and fitness that is observed when genome-wide heterozygosity is decreased by inbreeding.

GENOTOXICITY

The action of chemical, physical and biological agents that damage DNA.

ENDOREDUPLICATION

Successive rounds of DNA replication without cytokinesis.

ENDOPOLYPLOIDY

The property of cells in certain developmental stages of an organism of having more chromatid sets or, less frequently, more chromosome sets than the germ line.

APOMICTIC

Species that produce embryos from maternal tissues, bypassing normal meiosis and sexual fusion of egg and sperm.

SEGREGATION DISTORTION

Departure from the expected gametic ratio of alleles that is observed in the progeny of a cross, usually caused by preferential loss of certain chromosomes during gametogenesis (meiotic drive) or by selection on gametes and zygotes.

PLASTICITY

The ability of the same genotype to change and adapt its phenotype in response to different environmental conditions.

EUPLOID

An organism or cell that has a balanced set of chromosomes.

B CHROMOSOMES

Supernumerary chromosomes that differ from the normal complement by being dispensable, often heterochromatic and exhibiting unusual meiotic behaviour.

ACCESSION

A strain of a species, usually classified from the geographical site of isolation. In the Arabidopsis genus it is also known as an ecotype.

HAPLOTYPE

Allelic composition over a contiguous chromosome stretch.

GENOMIC SHOCK

The concomitant and widespread misregulation and activation of suppressed heterochromatic elements, leading to genomic remodelling.

ENDOSPERM

A fertilization-derived, triploid nutritive tissue that is found in the seeds of flowering plants.

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