title: When sexual meets apomict: genome size, ploidy level and reproductive mode variation of Sorbus aria s.l. and S. austriaca (Rosaceae) in Bosnia and Herzegovina.
abstract: OBJECTIVE
  Allopolyploidy and intraspecific heteroploid crosses are associated, in certain groups, with changes in the mating system. The genus Sorbus represents an appropriate model to study the relationships between ploidy and reproductive mode variations. Diploid S. aria and tetraploid apomictic S. austriaca were screened for ploidy and mating system variations within pure and sympatric populations in order to gain insights into their putative causalities.
  
  
  METHODS
  Flow cytometry was used to assess genome size and ploidy level among 380 S. aria s.l. and S. austriaca individuals from Bosnia and Herzegovina, with 303 single-seed flow cytometric seed screenings being performed to identify their mating system. Pollen viability and seed set were also determined.
  
  
  RESULTS
  Flow cytometry confirmed the presence of di-, tri- and tetraploid cytotype mixtures in mixed-ploidy populations of S. aria and S. austriaca. No ploidy variation was detected in single-species populations. Diploid S. aria mother plants always produced sexually originated seeds, whereas tetraploid S. austriaca as well as triploid S. aria were obligate apomicts. Tetraploid S. aria preserved sexuality in a low portion of plants. A tendency towards a balanced 2m : 1p parental genome contribution to the endosperm was shared by diploids and tetraploids, regardless of their sexual or asexual origin. In contrast, most triploids apparently tolerated endosperm imbalance.
  
  
  CONCLUSIONS
  Coexistence of apomictic tetraploids and sexual diploids drives the production of novel polyploid cytotypes with predominantly apomictic reproductive modes. The data suggest that processes governing cytotype diversity and mating system variation in Sorbus from Bosnia and Herzegovina are probably parallel to those in other diversity hotspots of this genus. The results represent a solid contribution to knowledge of the reproduction of Sorbus and will inform future investigations of the molecular and genetic mechanisms involved in triggering and regulating cytotype diversity and alteration of reproductive modes.
authors.affiliation: Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina.
authors.forename: Alma
authors.initials: A
authors.lastname: Hajrudinović
authors.affiliation: CNRS, Université Paris-Sud, AgroParisTech, UMR 8079, Ecologie, Systématique, Evolution, Bât. 360, 91450 Orsay, France and.
authors.forename: Sonja
authors.initials: S
authors.lastname: Siljak-Yakovlev
authors.affiliation: Pôle de Biologie Cellulaire, Imagif, Centre de Recherche de Gif (FRC3115), CNRS, Saclay Plant Sciences, 91198, Gif-sur-Yvette Cedex, France.
authors.forename: Spencer C
authors.initials: SC
authors.lastname: Brown
authors.affiliation: Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina.
authors.forename: Fatima
authors.initials: F
authors.lastname: Pustahija
authors.affiliation: Pôle de Biologie Cellulaire, Imagif, Centre de Recherche de Gif (FRC3115), CNRS, Saclay Plant Sciences, 91198, Gif-sur-Yvette Cedex, France.
authors.forename: Mickael
authors.initials: M
authors.lastname: Bourge
authors.affiliation: Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina.
authors.forename: Dalibor
authors.initials: D
authors.lastname: Ballian
authors.affiliation: Faculty of Forestry, University of Sarajevo, Zagrebačka 20, 71000 Sarajevo, Bosnia and Herzegovina, faruk.bogunic@gmail.com.
authors.forename: Faruk
authors.initials: F
authors.lastname: Bogunić
mesh_terms: D060832:Apomixis / Q000235:genetics*; D017522:Bosnia and Herzegovina; D002467:Cell Nucleus / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D056625:Endosperm / Q000235:genetics; D005434:Flow Cytometry; D059646:Genome Size; D005843:Geography; D011003:Ploidies; D011058:Pollen / Q000502:physiology; D012098:Reproduction / Q000235:genetics; D012639:Seeds / Q000502:physiology; D031994:Sorbus / Q000235:genetics* / Q000502:physiology*
chemical_list: D018744:DNA, Plant
keywords: Apomixis; Rosaceae.; Sorbus aria; Sorbus austriaca; cytotypes; genome size; polyploidy; reproduction mode; sexuality