title: A reference genetic linkage map of apomictic Hieracium species based on expressed markers derived from developing ovule transcripts.
abstract: OBJECTIVE
  Apomixis in plants generates clonal progeny with a maternal genotype through asexual seed formation. Hieracium subgenus Pilosella (Asteraceae) contains polyploid, highly heterozygous apomictic and sexual species. Within apomictic Hieracium, dominant genetic loci independently regulate the qualitative developmental components of apomixis. In H. praealtum, LOSS OF APOMEIOSIS (LOA) enables formation of embryo sacs without meiosis and LOSS OF PARTHENOGENESIS (LOP) enables fertilization-independent seed formation. A locus required for fertilization-independent endosperm formation (AutE) has been identified in H. piloselloides. Additional quantitative loci appear to influence the penetrance of the qualitative loci, although the controlling genes remain unknown. This study aimed to develop the first genetic linkage maps for sexual and apomictic Hieracium species using simple sequence repeat (SSR) markers derived from expressed transcripts within the developing ovaries.
  
  
  METHODS
  RNA from microdissected Hieracium ovule cell types and ovaries was sequenced and SSRs were identified. Two different F1 mapping populations were created to overcome difficulties associated with genome complexity and asexual reproduction. SSR markers were analysed within each mapping population to generate draft linkage maps for apomictic and sexual Hieracium species.
  
  
  RESULTS
  A collection of 14 684 Hieracium expressed SSR markers were developed and linkage maps were constructed for Hieracium species using a subset of the SSR markers. Both the LOA and LOP loci were successfully assigned to linkage groups; however, AutE could not be mapped using the current populations. Comparisons with lettuce (Lactuca sativa) revealed partial macrosynteny between the two Asteraceae species.
  
  
  CONCLUSIONS
  A collection of SSR markers and draft linkage maps were developed for two apomictic and one sexual Hieracium species. These maps will support cloning of controlling genes at LOA and LOP loci in Hieracium and should also assist with identification of quantitative loci that affect the expressivity of apomixis. Future work will focus on mapping AutE using alternative populations.
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Kenta
authors.initials: K
authors.lastname: Shirasawa
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Hand
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Henderson
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Susan D
authors.initials: SD
authors.lastname: Johnson
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Taylor
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Spriggs
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Hayley
authors.initials: H
authors.lastname: Siddons
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Hideki
authors.initials: H
authors.lastname: Hirakawa
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Isobe
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.affiliation: Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba 292-0818, Japan and Commonwealth Scientific and Industrial Research Organization (CSIRO), Agriculture Flagship, Waite Campus, Hartley Grove, Urrbrae, South Australia 5064, Australia Anna.Koltunow@csiro.au.
authors.forename: Anna M G
authors.initials: AM
authors.lastname: Koltunow
mesh_terms: D060832:Apomixis; D019659:Asteraceae / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D002874:Chromosome Mapping; D005819:Genetic Markers; D006238:Haploidy; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D056771:Ovule / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011123:Polyploidy; D040641:Quantitative Trait Loci
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins
keywords: Hieracium; LOA; LOP; LOSS OF APOMEIOSIS; LOSS OF PARTHENOGENESIS; Pilosella; SSR; apomixis; apospory; linkage map; molecular markers; parthenogenesis