Transcription pattern of a FIM homologue in Impatiens during floral development and reversion.
Flowering and reversion in Impatiens are characterised by gradual transitions of organ identity and constitute a unique system for the molecular and physiological study of floral organogenesis. The authors have isolated an Impatiens homologue of the FIM gene of Antirrhinum (UFO in Arabidopsis), Imp-FIM, and analysed its expression in three states of the terminal meristem: vegetative, floral, and reverted. In floral meristems, Imp-FIM transcription is associated with petal identity, as in Antirrhinum and Arabidopsis, but this is achieved through a novel transcription pattern, characterised by a high level of transcript within petal primordia. This novel transcription pattern could contribute to the more diffuse boundaries between organ types in Impatiens. In vegetative meristems, Imp-FIM is expressed in the axils of leaf primordia which are arranged in a spiral. A similar pattern is observed in reverted meristems in which leaf primordia are initiated in a whorled arrangement. This result indicates that the maintenance of floral phyllotaxis is not associated with a specific pattern of Imp-FIM transcription. Transcription of Imp-FIM in a non-reverting line is no different from that in the reverting line. Therefore, the lack of floral commitment in the reverting line does not seem to be responsible for Imp-FIM transcription within petals. The novel transcription pattern in petals, together with features of Impatiens that are reminiscent of fim and ufo mutant phenotypes suggest an evolutionary divergence for Imp-FIM regulation in this species.
Pouteau
S
S
Plant Science Laboratories, University of Reading, UK. pouteau@versailles.inra.fr
Nicholls
D
D
Tooke
F
F
Coen
E
E
Battey
N
N
D000595:Amino Acid Sequence; D017360:Arabidopsis; D003001:Cloning, Molecular; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics; D063245:Plant Development; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012098:Reproduction / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
C088434:FIM protein, Antirrhinum majus; D010446:Peptide Fragments; D010940:Plant Proteins