Pin1-independent leaf initiation in Arabidopsis.
Phyllotaxis, the regular arrangement of leaves and flowers around the stem, is a key feature of plant architecture. Current models propose that the spatiotemporal regulation of organ initiation is controlled by a positive feedback loop between the plant hormone auxin and its efflux carrier PIN-FORMED1 (PIN1). Consequently, pin1 mutants give rise to naked inflorescence stalks with few or no flowers, indicating that PIN1 plays a crucial role in organ initiation. However, pin1 mutants do produce leaves. In order to understand the regulatory mechanisms controlling leaf initiation in Arabidopsis (Arabidopsis thaliana) rosettes, we have characterized the vegetative pin1 phenotype in detail. We show that although the timing of leaf initiation in vegetative pin1 mutants is variable and divergence angles clearly deviate from the canonical 137° value, leaves are not positioned at random during early developmental stages. Our data further indicate that other PIN proteins are unlikely to explain the persistence of leaf initiation and positioning during pin1 vegetative development. Thus, phyllotaxis appears to be more complex than suggested by current mechanistic models.
Institute of Plant Sciences, University of Bern, CH-3013 Bern, Switzerland.
Bernadette
B
Guenot
Emmanuelle
E
Bayer
Daniel
D
Kierzkowski
Richard S
RS
Smith
Therese
T
Mandel
Petra
P
Žádníková
Eva
E
Benková
Cris
C
Kuhlemeier
D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D018519:Meristem / Q000378:metabolism / Q000648:ultrastructure; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins