title: Microsatellite and flow cytometry analysis to help understand the origin of Dioscorea alata polyploids.
abstract: OBJECTIVE
  Dioscorea alata is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and tetraploids) limits the efficiency of polyploid breeding. The objective of the present study was to use flow cytometry and microsatellite markers to understand the origin of D. alata polyploids.
  
  
  METHODS
  Different progeny generated by intracytotype crosses (2x × 2x) and intercytotype crosses (2x × 4x and 3x × 2x) were analysed in order to understand endosperm incompatibility phenomena and gamete origins via the heterozygosity rate transmitted to progeny.
  
  
  RESULTS
  This work shows that in a 2x × 2x cross, triploids with viable seeds are obtained only via a phenomenon of diploid female non-gametic reduction. The study of the transmission of heterozygosity made it possible to exclude polyspermy and polyembryony as the mechanisms at the origin of triploids. The fact that no seedlings were obtained by a 3x × 2x cross made it possible to confirm the sterility of triploid females. Flow cytometry analyses carried out on the endosperm of seeds resulting from 2x × 4x crosses revealed endosperm incompatibility phenomena.
  
  
  CONCLUSIONS
  The major conclusion is that the polyploids of D. alata would have appeared through the formation of unreduced gametes. The triploid pool would have been built and diversified through the formation of 2n gametes in diploid females as the result of the non-viability of seeds resulting from the formation of 2n sperm and of the non-viability of intercytotype crosses. The tetraploids would have appeared through bilateral sexual polyploidization via the union of two unreduced gametes due to the sterility of triploids.
authors.affiliation: CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), Station de Roujol, 97170 Petit Bourg, Guadeloupe, France.
authors.forename: A
authors.initials: A
authors.lastname: Nemorin
authors.forename: J
authors.initials: J
authors.lastname: David
authors.forename: E
authors.initials: E
authors.lastname: Maledon
authors.forename: E
authors.initials: E
authors.lastname: Nudol
authors.forename: J
authors.initials: J
authors.lastname: Dalon
authors.forename: G
authors.initials: G
authors.lastname: Arnau
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics*; D003433:Crosses, Genetic; D027742:Dioscorea / Q000235:genetics*; D056625:Endosperm / Q000235:genetics; D005434:Flow Cytometry / Q000379:methods*; D005819:Genetic Markers / Q000235:genetics; D055993:Germ Cells, Plant; D018895:Microsatellite Repeats / Q000235:genetics*; D011123:Polyploidy; D012639:Seeds / Q000235:genetics
chemical_list: D005819:Genetic Markers
keywords: 2n gametes; Dioscorea alata; bilateral sexual polyploidization; endosperm balance; polyploidy; triploid origin
references.citation: J Hered. 2008 Mar-Apr;99(2):177-81
references.pmid: 18209111
references.citation: Genetics. 2007 May;176(1):85-94
references.pmid: 17339217
references.citation: New Phytol. 2010 Apr;186(1):5-17
references.pmid: 20070540
references.citation: Heredity (Edinb). 2007 Mar;98(3):143-50
references.pmid: 17091127
references.citation: Cytometry A. 2005 Apr;64(2):72-9
references.pmid: 15739186
references.citation: Mol Ecol Resour. 2010 Nov;10(6):1106-8
references.pmid: 21565125
references.citation: Theor Appl Genet. 1982 Jun;61(2):161-9
references.pmid: 24270339
references.citation: New Phytol. 1995 Jan;129(1):1-22
references.pmid: 33874422
references.citation: Nature. 2002 Jan 31;415(6871):522-6
references.pmid: 11823859
references.citation: Sex Plant Reprod. 2009 Mar;22(1):45-51
references.pmid: 20033455
references.citation: Heredity (Edinb). 2001 Aug;87(Pt 2):136-45
references.pmid: 11703503
references.citation: Sex Plant Reprod. 2009 Mar;22(1):27-36
references.pmid: 20033453
references.citation: Trends Plant Sci. 2004 Oct;9(10):507-14
references.pmid: 15465686
references.citation: J Exp Bot. 2009;60(5):1465-78
references.pmid: 19213812
references.citation: Ontogenez. 2007 May-Jun;38(3):166-91
references.pmid: 17621974
references.citation: Development. 1998 Sep;125(17):3329-41
references.pmid: 9693137
references.citation: Theor Appl Genet. 2009 May;118(7):1239-49
references.pmid: 19253018
references.citation: Heredity (Edinb). 2001 Nov;87(Pt 5):573-82
references.pmid: 11869348
references.citation: EXS. 1994;69:185-201
references.pmid: 7994106
references.citation: Trends Genet. 2010 Mar;26(3):142-8
references.pmid: 20089326
references.citation: Theor Appl Genet. 1990 Dec;80(6):785-90
references.pmid: 24221109
references.citation: Genetics. 1999 Dec;153(4):1493-9
references.pmid: 10581260