Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

in Journal of the American Society for Horticultural Science

Genome size variation can be used to investigate biodiversity, genome evolution, and taxonomic relationships among related taxa. Plant breeders use genome size variation to identify parents useful for breeding sterile or improved ornamentals. Lilacs (Syringa) are deciduous trees and shrubs valued for their fragrant spring and summer flowers. The genus is divided into six series: Syringa (Vulgares), Pinnatifoliae, Ligustrae, Ligustrina, Pubescentes, and Villosae. Reports conflict on genome evolution, base chromosome number, and polyploidy in lilac. The purpose of this study was to investigate genome size and ploidy variation across a diverse collection. Flow cytometry was used to estimate monoploid (1Cx) and holoploid (2C) genome sizes in series, species, cultivars, and seedlings from parents with three ploidy combinations: 2x x 2x, 2x x 3x, and 3x x 2x. Pollen diameter was measured to investigate the frequency of unreduced gametes in diploid and triploid Syringa vulgaris cultivars. Three triploids of S. vulgaris were observed: ‘Aucubaefolia’, ‘Agincourt Beauty’, and ‘President Grévy’. Across taxa, significant variations in 1Cx genome size were discovered. The smallest and largest values were found in the interspecific hybrids S. ×laciniata (1.32 ± 0.04 pg) and S. ×hyacinthiflora ‘Old Glory’ (1.78 ± 0.05), both of which are in series Syringa. Series Syringa (1.68 ± 0.02 pg) had a significantly larger 1Cx genome size than the other series. No significant differences were found within series Pubescentes (1.47 ± 0.01 pg), Villosae (1.55 ± 0.02 pg), Ligustrina (1.49 ± 0.05 pg), and Pinnatifoliae (1.52 ± 0.02 pg). For S. vulgaris crosses, no significant variation in 2C genome size was discovered in 2x x 2x crosses. Interploid crosses between ‘Blue Skies’ (2x) and ‘President Grévy’ (3x) produced an aneuploid population with variable 2C genome sizes ranging from 3.41 ± 0.03 to 4.35 ± 0.03 pg. Only one viable seedling was recovered from a cross combination between ‘President Grévy’ (3x) and ‘Sensation’ (2x). This seedling had a larger 2C genome size (5.65 ± 0.02 pg) than either parent and the largest 2C genome size currently reported in lilac. ‘Sensation’ produced 8.5% unreduced pollen, which we inferred was responsible for the increased genome size. No unreduced pollen was discovered in the other diploids examined. Increased ploidy may provide a mechanism for recovering progeny from incompatible taxa in lilac breeding.

Contributor Notes

This research was funded in part by the Oregon Department of Agriculture.

We acknowledge the assistance of Mara Friddle, Kim Shearer, and Aleen Haddad in this research.

Graduate Research Assistant.

Corresponding author. E-mail: ryan.contreras@oregonstate.edu.

Article Sections

Article Figures

  • View in gallery

    Stained chromosomes in root tip cells of six accessions of Syringa. Photomicrographs viewed at ×1000 with scale bar at 1 μm: (A) Triploid (2n = 3x = 69) S. vulgaris ‘Aucubaefolia’; (B) diploid (2n = 2x = 46) S. ×hyacinthiflora ‘Maiden’s Blush’; (C) diploid (2n = 2x = 46) S. ×hyacinthiflora ‘Old Glory’; (D) diploid (2n = 2x = 46) S. ×prestoniae ‘Miss Canada’; (E) diploid (2n = 2x = 46) S. reticulata; (F) diploid (2n = 2x = 46) S. pubescens Bloomerang® Purple.

  • View in gallery

    Flow cytometry histogram of three taxa of Syringa vulgaris with an internal standard: (A) ‘Sensation’ (2C relative genome size = 3.33 pg); (B) ‘President Grévy’ (2C relative genome size = 4.85 pg); (C) hybrid (H2013–150–01) ‘President Grévy’ × ‘Sensation’ (2C relative genome size = 5.65 pg); (D) internal standard Pisum sativum ‘Ctirad’ (2C genome size = 8.76 pg).

  • View in gallery

    Linear model of lilac 2x × 3x aneuploid progeny with predicted chromosome number based on theoretical chromosome size of 0.061 pg [(4.85 − 3.45 pg)/23 chromosomes]. Parent taxa of aneuploid progeny: diploid female parent Syringa vulgaris ‘Blue Skies’ (2n = 2x = 46) and triploid male parent S. vulgaris ‘President Grévy’ (2n = 3x = 69). Linear model follows the formula: y = 16.224x − 9.7743.

  • View in gallery

    Frequency distribution of viable pollen grain diameters of four cultivars of Syringa vulgaris. Regions to the right of asterisks were measured to be 26% larger than the mean and indicate unreduced gametes: (A) ‘Ludwig Spaeth’ (0% unreduced gametes); (B) ‘Sensation’ (8.5% unreduced gametes) [insert: unreduced (left) and reduced (right) pollen grains stained with 2% acetocarmine and viewed at ×630 magnification (scale bar = 10 μm)]; (C) ‘Miss Ellen Willmott’ (0% unreduced gametes); (D) ‘President Grévy’ (0.6% unreduced gametes).

Article References

  • BaiC.AlversonW.S.FollansbeeA.WallerD.M.2012New reports of nuclear DNA content for 407 vascular plant taxa from the United StatesAnn. Bot.11016231629

    • Search Google Scholar
    • Export Citation
  • BehrendA.GluschakA.PrzybylaA.HoheA.2015Interploid crosses in heather (Calluna vulgaris)Sci. Hort.181162167

  • BennettM.D.LeitchI.J.2011Nuclear DNA amounts in angiosperms: Targets, trends and tomorrowAnn. Bot.107467590

  • BrandhamP.E.1982Inter-embryo competition in the progeny of autotriploid Aloineae (Liliaceae)Genetica592942

  • BurtonT.L.HusbandB.C.2001Fecundity and offspring ploidy in matings among diploid, triploid and tetraploid Chamerion angustifolium (Onagraceae): Consequences for tetraploid establishmentHeredity87573582

    • Search Google Scholar
    • Export Citation
  • CarputoD.1999Post-zygotic gametic selection due to endosperm balance number explains unusual chromosome numbers of 3x × 2x progeny in SolanumSex. Plant Reprod.122731

    • Search Google Scholar
    • Export Citation
  • ChenJ.-T.ZhangZ.-S.HongD.-Y.2009A taxonomic revision of the Syringa pubescens complex (Oleaceae)Ann. Mo. Bot. Gard.96237250

  • ChenZ.J.NiZ.2006Mechanisms of genomic rearrangements and gene expression changes in plant polyploidsBioEssays28240252

  • ContrerasR.N.FriddleM.LattierJ.D.2013Relative fertility and ploidy levels of selected rose-of-sharon cultivarsProc. Southern Nursery Assn. Res. Conf.58232236

    • Search Google Scholar
    • Export Citation
  • ContrerasR.N.RanneyT.G.TalluryS.P.2007Reproductive behavior of diploid and allotetraploid Rhododendron L. ‘Fragrant Affinity’HortScience423134

    • Search Google Scholar
    • Export Citation
  • DarlingtonC.D.WylieA.P.1956Chromosome atlas of flowering plants. Macmillan New York NY

  • DiaoW.-P.BaoS.-Y.JiangB.CuiL.ChenJ.-F.2009Primary trisomics obtained from autotriploid by diploid reciprocal crosses in cucumberSex. Plant Reprod.224551

    • Search Google Scholar
    • Export Citation
  • FarcoG.E.DematteisM.2014Meiotic behavior and pollen fertility in trioploid and tetraploid natural populations of Campuloclinum macrocephalum (Eupatorieae, Asteraceae)Plant Syst. Evol.30018431852

    • Search Google Scholar
    • Export Citation
  • FialaJ.L.VrugtmanF.2008Lilac: A gardener’s encyclopedia. 2nd ed. Timber Press Portland OR

  • GalbraithD.W.BennetzenJ.L.KelloggE.A.PiresJ.C.SoltisP.S.2011The genomes of all angiosperms: A call for a coordinated global censusJ. Bot.2011110

    • Search Google Scholar
    • Export Citation
  • GreenP.S.1995Proposal to reject the name Syringa buxifolia Nakai (Oleaceae)Taxon44636

  • GreenP.S.ChangM.C.1995Some taxonomic changes in Syringa L. (Oleaceae), including a revision of series PubescentesNovon5329333

  • GreilhuberJ.1998Intraspecific variation in genome size: A critical reassessmentAnn. Bot.822735

  • GreilhuberJ.DoleželJ.LysákM.A.BennettM.D.2005The origin, evolution and proposed stabilization of the terms ‘genome size’ and ‘C-value’ to describe nuclear DNA contentsAnn. Bot.95255260

    • Search Google Scholar
    • Export Citation
  • GreilhuberJ.TemschE.M.LoureiroJ.C.M.2007Nuclear DNA content measurement p. 67–101. In: J. Doležel J. Greilhuber and J. Suda (eds.). Flow cytometry with plant cells: Analysis of genes chromosomes and genomes. Wiley Weinheim Germany

  • HarderM.L.VerhagenS.WintonL.EinspahrD.W.1976Tetraploid aspen production using unreduced pollen from triploid malesFor. Sci.22329330

  • HarlanJ.R.deWetJ.M.J.1975On Ö. Winge and a prayer: The origins of polyploidyBot. Rev.41361390

  • HayashiM.KatoJ.OhashiH.MiiM.2009Unreduced 3x gamete formation of allotriploid hybrid derived from the cross of Primula denticulata (4x) x P. rosea (2x) as a causal factor for producing pentaploid hybrids in the backcross with pollen of tetraploid P. denticulataEuphytica169123131

    • Search Google Scholar
    • Export Citation
  • HerbenT.TrávníčekP.ChrtekJ.2016Reduced and unreduced gametes combine almost freely in a multiploidy systemPerspect. Plant Ecol. Evol. Syst.181522

    • Search Google Scholar
    • Export Citation
  • IorizzoM.AversanoR.BradeenJ.M.FruscianteL.CarputoD.2012Fertilization fitness and offspring ploidy in 3x × 2x matings in potatoPlant Biosyst.146317321

    • Search Google Scholar
    • Export Citation
  • KatoJ.IshikawaR.MiiM.2001Different genetic combinations in inter-section hybrids obtained from the crosses between Primula sieboldii (section Cortusoides) and P. obconica (section Obconicolisteri) by the embryo rescue techniqueTheor. Appl. Genet.10211291135

    • Search Google Scholar
    • Export Citation
  • KimK.-J.JansenR.K.1998A chloroplast DNA phylogeny of lilacs (Syringa, Oleaceae): Plastome groups show strong correlations with crossing groupsAmer. J. Bot.8513381351

    • Search Google Scholar
    • Export Citation
  • LattierJ.D.ChenH.ContrerasR.N.2017Improved method of enzyme digestion for root tip cytologyHortScience5210291032

  • LattierJ.D.ContrerasR.N.2017Intraspecific, interspecific, and interseries cross-compatibility in lilacJ. Amer. Soc. Hort. Sci.142279288

    • Search Google Scholar
    • Export Citation
  • LattierK.S.2016Inducing and evaluating phenotypic and cytometric variation in landscape plants: Observations from AcerOrnithogalum and Penstemon. Oregon State Univ. Corvallis OR MS Diss

  • LaviaG.I.OrtizA.M.RobledoG.FernándezA.SeijoG.2011Origin of triploid Arachis pintoi (Leguminosae) by autopolyploidy evidenced by FISH and meiotic behaviourAnn. Bot.108103111

    • Search Google Scholar
    • Export Citation
  • LevanA.1936Different results in reciprocal crosses between diploid and triploid Allium schoenoprasum LNature138508

  • LiJ.AlexanderJ.H.ZhangD.2002Paraphyletic Syringa (Oleaceae): Evidence from sequences of nuclear and ribosomal DNA ITS and ETS regionsSyst. Bot.27592597

    • Search Google Scholar
    • Export Citation
  • LiJ.Goldman-HuertasB.DeYoungJ.AlexanderJ.III2012Phylogenetics and diversification of Syringa inferred from nuclear and plastid DNA sequencesCastanea778288

    • Search Google Scholar
    • Export Citation
  • LimK.-B.RamannaM.S.JacobsenE.van TuylJ.M.2003Evaluation of BC2 progenies derived from 3x − 2x and 3x − 4x crosses of Lilium hybrids: A GISH analysisTheor. Appl. Genet.106568574

    • Search Google Scholar
    • Export Citation
  • LuC.KatoM.2001Fertilization fitness and relation to chromosome number in interspecific progeny between Brassica napus and B. rapa: A comparative study using natural and resynthesized B. napusBreed. Sci.517381

    • Search Google Scholar
    • Export Citation
  • Marasek-CiolakowskaA.XieS.ArensP.van TuylJ.M.2014Ploidy manipulation and introgression breeding in darwin hybrid tulipsEuphytica198389400

    • Search Google Scholar
    • Export Citation
  • MillerG.N.1955The genus Fraxinus, the ashes, in North America, north of MexicoCornell Univ. Agr. Expt. Sta. Memoirs335164

  • MizuochiH.MatsuzakiH.MoueT.OkazakiK.2009Diploid endosperm formation in Tulipa spp. and identification of a 1:1 maternal-to-paternal genome ratio in endosperms of T. gesneriana LSex. Plant Reprod.222736

    • Search Google Scholar
    • Export Citation
  • NesomG.L.2010Fraxinus biltmoreana and Fraxinus smallii (Oleaceae), forest trees of the eastern United StatesPhytoneuron51130

  • OlsenR.T.RanneyT.G.ViloriaZ.2006Reproductive behavior of induced allotetraploid ×Chitalpa and in vitro embryo culture of polyploid progenyJ. Amer. Soc. Hort. Sci.131716724

    • Search Google Scholar
    • Export Citation
  • OlszewskaM.J.OsieckaR.1984Relationship between 2C DNA content, systematic position and level of DNA endoreplication during differentiation of root parenchyma in dicot shrubs and trees. Comparison with herbaceous speciesBiochem. Physiol. Pflanz.179641657

    • Search Google Scholar
    • Export Citation
  • OsujiJ.O.VuylstekeD.OrtizR.1997Ploidy variation in hybrids from interploid 3x x 2x crosses in MusaTropicultura153739

  • PalmerI.E.RanneyT.G.LynchN.P.BirR.E.2009Crossability, cytogenetics, and reproductive pathways in Rudbeckia subgenus RudbeckiaHortScience444448

    • Search Google Scholar
    • Export Citation
  • ParrisJ.K.RanneyT.G.KnapH.T.BairdW.V.2010Ploidy levels, relative genome sizes, and base pair composition in MagnoliaJ. Amer. Soc. Hort. Sci.135533547

    • Search Google Scholar
    • Export Citation
  • PhillipsW.D.RanneyT.G.TouchellD.H.EakerT.A.2016Fertility and reproductive pathways of triploid flowering pears (Pyrus sp.)HortScience51968971

    • Search Google Scholar
    • Export Citation
  • PringleJ.S.1981A review of attempted and reported interseries and intergeneric hybridization in Syringa (Oleaceae)Baileya204991

  • Purdue University Cytometry Laboratories2014Cytospec Version 7. 12 July 2017. <http://www.cyto.purdue.edu/Purdue_software>

  • RamseyJ.SchemskeD.W.1998Pathways, mechanisms, and rates of polyploid formation in flowering plantsAnnu. Rev. Ecol. Syst.29467501

  • RanneyT.G.2006Polyploidy: From evolution to new plant developmentProc. Intl. Plant Propagators Soc.56604607

  • RoseJ.B.KubbaJ.TobuttK.R.2000Chromosome doubling in sterile Syringa vulgaris × S. pinnatifolia hybrids by in vitro culture of nodal explantsPlant Cell Tissue Organ Cult.63127132

    • Search Google Scholar
    • Export Citation
  • RothleutnerJ.J.2014Development of autopolyploid Syringa reticulata subsp. pekinensis for breedingActa Hort.1055213217

  • RounsavilleT.J.RanneyT.G.2010Ploidy levels and genome sizes of Berberis L. and Mahonia Nutt. species, hybrids, and cultivarsHortScience4510291033

    • Search Google Scholar
    • Export Citation
  • RounsavilleT.J.TouchellD.H.RanneyT.G.2011Fertility and reproductive pathways in diploid and triploid Miscanthus sinensisHortScience4613531357

    • Search Google Scholar
    • Export Citation
  • SantamourF.S.Jr1962The relation between polyploidy and morphology in white and biltmore ashesBull. Torrey Bot. Club89228232

  • SantamourF.S.Jr1971A tripoid elm (Ulmus pumila × U. rubra) and its aneuploid progenyBull. Torrey Bot. Club98310314

  • SaxK.1930Chromosome number and behavior in the genus SyringaJ. Arnold Arbor.11714

  • ShearerK.RanneyT.G.2013Ploidy levels and relative genome size of species, hybrids, and cultivars of dogwood (Cornus spp.)HortScience48825830

    • Search Google Scholar
    • Export Citation
  • SheidaiM.ParsianH.Vaezi-JozeS.NoormohammadiZ.2008Chromosome pairing and chiasma formation in some olive (Olea europaea L.) cultivars from IranCytologia73269274

    • Search Google Scholar
    • Export Citation
  • Siljak-YakovlevS.PustahijaF.ŠolićE.M.BogunićF.MuratovićE.BašićN.CatriceO.BrownS.C.2010Towards a genome size and chromosome number database of Balkan flora: C-values in 343 taxa with novel values for 242Adv. Sci. Lett.3190213

    • Search Google Scholar
    • Export Citation
  • SoltisP.S.SoltisD.E.2012Polyploidy and genome evolution. Springer-Verlag Berlin Germany

  • StebbinsJr. G.L.1940The significance of polyploidy in plant evolutionAm. Nat.745466

  • TaylorH.1945Cyto-taxonomy and phylogeny of the OleaceaeBrittonia5337367

  • VorsaN.BallingtonJ.R.1991Fertility of triploid highbush blueberryJ. Amer. Soc. Hort. Sci.116336341

  • WallanderE.AlbertV.A.2000Phylogeny and classification of Oleaceae based on rps16 and trnL-F sequence dataAmer. J. Bot.8718271841

  • WangJ.KangX.ZhuQ.2010Variation in pollen formation and its cytological mechanism in an allotriploid white poplarTree Genet. Genomes6281290

    • Search Google Scholar
    • Export Citation
  • ZonneveldB.J.M.DuncanG.D.2010Genome sizes of Eucomis L’Hér. (Hyacinthaceae) and a description of the new species Eucomis grimshawii G.D. Duncan & ZonneveldPlant Syst. Evol.28499109

    • Search Google Scholar
    • Export Citation
  • ZonneveldB.J.M.LeitchI.J.BennettM.D.2005First nuclear DNA amounts in more than 300 angiospermsAnn. Bot.96229244

Article Information

Google Scholar

Related Content

Article Metrics

All Time Past Year Past 30 Days
Abstract Views 78 78 7
Full Text Views 58 58 0
PDF Downloads 7 7 0