title: Patterns of MADS-box gene expression mark flower-type development in Gerbera hybrida (Asteraceae).
abstract: BACKGROUND
  The inflorescence of the cut-flower crop Gerbera hybrida (Asteraceae) consists of two principal flower types, ray and disc, which form a tightly packed head, or capitulum. Despite great interest in plant morphological evolution and the tractability of the gerbera system, very little is known regarding genetic mechanisms involved in flower type specification. Here, we provide comparative staging of ray and disc flower development and microarray screening for differentially expressed genes, accomplished via microdissection of hundreds of coordinately developing flower primordia.
  
  
  RESULTS
  Using a 9K gerbera cDNA microarray we identified a number of genes with putative specificity to individual flower types. Intrestingly, several of these encode homologs of MADS-box transcription factors otherwise known to regulate flower organ development. From these and previously obtained data, we hypothesize the functions and protein-protein interactions of several gerbera MADS-box factors.
  
  
  CONCLUSIONS
  Our RNA expression results suggest that flower-type specific MADS protein complexes may play a central role in differential development of ray and disc flowers across the gerbera capitulum, and that some commonality is shared with known protein functions in floral organ determination. These findings support the intriguing conjecture that the gerbera flowering head is more than a mere floral analog at the level of gene regulation.
authors.affiliation: Department of Applied Biology, P.O.Box 27, 00014 University of Helsinki, Finland. paula.elomaa@helsinki.fi
authors.forename: Roosa A E
authors.initials: RA
authors.lastname: Laitinen
authors.forename: Suvi
authors.initials: S
authors.lastname: Broholm
authors.forename: Victor A
authors.initials: VA
authors.lastname: Albert
authors.forename: Teemu H
authors.initials: TH
authors.lastname: Teeri
authors.forename: Paula
authors.initials: P
authors.lastname: Elomaa
mesh_terms: D019659:Asteraceae / Q000145:classification / Q000235:genetics* / Q000254:growth & development*; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D026161:MADS Domain Proteins / Q000235:genetics*; D046228:Microarray Analysis; D008954:Models, Biological; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D026161:MADS Domain Proteins; D014157:Transcription Factors