title: Floral meristem indeterminacy depends on flower position and is facilitated by acarpellate gynoecium development in Impatiens balsamina.
abstract: * Floral meristems are generally determinate. Termination of their activity varies with species, occurring after carpel or ovule development, depending on the placentation type. In terminal flowering Impatiens balsamina (cv. Dwarf Bush Flowered) some flowers exhibit meristem indeterminacy; they produce organs from the placenta after ovule development. * Here we provide a detailed description of gynoecium development in this line and explore the basis of the indeterminate nature of some of its floral meristems. * We find that the placenta is sometimes established without complete carpel fusion. Proliferative growth derives from meristematic remnants of the placenta and is more common in the terminal inflorescence. RNA in situ hybridization reveals that IbLFY (Impatiens LFY homologue) is expressed in all meristem states, even in proliferating meristems. Expression of IbAG in axillary flowers is as expected in the meristem, stamens and carpels but absent from the proliferating meristem. * We conclude that I. balsamina has cauline placentation. Incomplete suppression of inflorescence identity in flowers of the terminal inflorescence leads to floral meristem proliferation after ovule development in this species.
authors.affiliation: School of Biological Sciences, University of Reading, Whiteknights, Reading, RG6 6AS, UK. t.chiurugwi@reading.ac.uk
authors.forename: Tinashe
authors.initials: T
authors.lastname: Chiurugwi
authors.forename: Sylvie
authors.initials: S
authors.lastname: Pouteau
authors.forename: David
authors.initials: D
authors.lastname: Nicholls
authors.forename: Fiona
authors.initials: F
authors.lastname: Tooke
authors.forename: Matthew
authors.initials: M
authors.lastname: Ordidge
authors.forename: Nick
authors.initials: N
authors.lastname: Battey
mesh_terms: D002454:Cell Differentiation; D049109:Cell Proliferation; D035264:Flowers / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development; D029069:Impatiens / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development*; D018519:Meristem / Q000166:cytology / Q000254:growth & development*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D014157:Transcription Factors