title: Ploidy and domestication are associated with genome size variation in Palms.
abstract: OBJECTIVE
  The genome size of a species (C-value) is associated with growth, development and adaptation to environmental changes. Angiosperm C-values range 1200-fold and frequently vary within species, although little is known about the impacts of domestication on genome size. Genome size variation among related species of palms is of evolutionary significance because changes characterize clades and may be associated with polyploidy, transposon amplifications, deletions, or rearrangements. Further knowledge of genome size will provide crucial information needed for planning of whole genome sequencing and accurate annotations. We studied the genome size of Cocos nucifera and its variation among cultivars, and compared it to values for related palms from the Attaleinae subtribe.
  
  
  METHODS
  Flow cytometric analysis of isolated nuclei from young palm leaves was used to estimate genome sizes of 23 coconut cultivars (Talls, Dwarfs, and hybrids) worldwide and 17 Cocoseae species. Ancestral genome size was reconstructed on a maximum likelihood phylogeny of Attaleinae from seven WRKY loci.
  
  
  RESULTS
  The coconut genome is large-averaging 5.966 pg-and shows intraspecific variation associated with domestication. Variation among Tall coconuts was significantly greater than among Dwarfs. Attaleinae genomes showed moderate size variation across genera, except polyploids Jubaeopsis caffra, Voanioala gerardii, Beccariophoenix alfredii, and Allagoptera caudescens, which had larger genomes.
  
  
  CONCLUSIONS
  Our results contribute to the understanding of the relationship between domestication and genome size in long-lived tree crops and provide a basis for whole-genome sequencing of the coconut and other domesticated plants. Polyploidy evolved independently in two clades within Attaleinae.
authors.affiliation: Research School of Biology, Division of Evolution, Ecology and Genetics, The Australian National University, Acton, ACT 2601, Australia bee.gunn@anu.edu.au.
authors.forename: Bee F
authors.initials: BF
authors.lastname: Gunn
authors.affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Baudouin
authors.affiliation: CIRAD, UMR DIADE, F-34398 Montpellier, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Beulé
authors.affiliation: CIRAD, UMR DIADE, F-34398 Montpellier, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Ilbert
authors.affiliation: Montpellier Rio Imaging, IRB, INSERM U1040, CHU de Montpellier 34295 Montpellier, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Duperray
authors.affiliation: Research School of Biology, Division of Evolution, Ecology and Genetics, The Australian National University, Acton, ACT 2601, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Crisp
authors.affiliation: Station de Recherche Marc Delorme, Port Bouët. 07 BP 13 Abidjan, Côte d'Ivoire.
authors.forename: Auguste
authors.initials: A
authors.lastname: Issali
authors.affiliation: Station de Recherche Marc Delorme, Port Bouët. 07 BP 13 Abidjan, Côte d'Ivoire.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Konan
authors.affiliation: CIRAD, UMR DIADE, F-34398 Montpellier, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Rival
mesh_terms: D028023:Arecaceae / Q000235:genetics*; D005075:Biological Evolution; D003059:Cocos / Q000235:genetics; D059646:Genome Size; D018745:Genome, Plant; D010802:Phylogeny; D000069600:Plant Breeding; D011003:Ploidies; D017422:Sequence Analysis, DNA; D013045:Species Specificity
keywords: Attaleinae; C-value; Cocos nucifera; domestication; evolution; flow cytometry; holoploidy; minimum generation time; nuclear DNA content; polyploidy