title: Sexual and apomictic reproduction in Hieracium subgenus pilosella are closely interrelated developmental pathways.
abstract: Seed formation in flowering plants requires meiosis of the megaspore mother cell (MMC) inside the ovule, selection of a megaspore that undergoes mitosis to form an embryo sac, and double fertilization to initiate embryo and endosperm formation. During apomixis, or asexual seed formation, in Hieracium ovules, a somatic aposporous initial (AI) cell divides to form a structurally variable aposporous embryo sac and embryo. This entire process, including endosperm development, is fertilization independent. Introduction of reproductive tissue marker genes into sexual and apomictic Hieracium showed that AI cells do not express a MMC marker. Spatial and temporal gene expression patterns of other introduced genes were conserved commencing with the first nuclear division of the AI cell in apomicts and the mitotic initiation of embryo sac formation in sexual plants. Conservation in expression patterns also occurred during embryo and endosperm development, indicating that sexuality and apomixis are interrelated pathways that share regulatory components. The induction of a modified sexual reproduction program in AI cells may enable the manifestation of apomixis in HIERACIUM:
authors.affiliation: Department of Plant Science, Waite Campus, Adelaide University, Glen Osmond, South Australia 5064, Australia.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Tucker
authors.forename: Ana-Claudia G
authors.initials: AC
authors.lastname: Araujo
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Paech
authors.forename: Valerie
authors.initials: V
authors.lastname: Hecht
authors.forename: Ed D L
authors.initials: ED
authors.lastname: Schmidt
authors.forename: Jan-Bart
authors.initials: JB
authors.lastname: Rossell
authors.forename: Sacco C
authors.initials: SC
authors.lastname: De Vries
authors.forename: Anna M G
authors.initials: AM
authors.lastname: Koltunow
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019659:Asteraceae / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D035264:Flowers / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D008540:Meiosis / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C118816:FIE protein, Arabidopsis; C117389:FIS2 protein, Arabidopsis; C111712:MEA protein, Arabidopsis; D009687:Nuclear Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C416221:SPL protein, Arabidopsis; D014157:Transcription Factors; D011494:Protein Kinases; C106294:SERK protein, plant; C440035:SERK1 protein, Arabidopsis; D005966:Glucuronidase