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Development 129, 2519-2527 (2002)
© 2002 The Company of Biologists Limited

Interaction of LEAFY, AGAMOUS and TERMINAL FLOWER1 in maintaining floral meristem identity in Arabidopsis

François Parcy1,2,*, Kirsten Bomblies1,*,{dagger} and Detlef Weigel1,3,{ddagger}

1 Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
2 Institut des Sciences du Végétal, CNRS, 91198 Gif-sur-Yvette Cedex, France
3 Department of Molecular Biology, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany
* These authors contributed equally to this work
{dagger} Present address: Department of Genetics, University of Wisconsin, Madison, WI, USA

{ddagger}Author for correspondence (e-mail: weigel{at}weigelworld.org)

Accepted 22 February 2002

The Arabidopsis transcription factor LEAFY acts upstream of homeotic genes such as AGAMOUS to confer floral identity on meristems that arise after the transition to reproductive development. Compared to the genetic circuitry regulating the establishment of floral meristem identity, little is known about its maintenance. Previous experiments with leafy heterozygous plants and agamous mutants grown in conditions that reduce the floral inductive stimulus have shown that both genes are required to prevent reversion of floral to inflorescence meristems. Here, we present evidence that LEAFY maintains floral meristem identity independently of AGAMOUS, and that the primary role of LEAFY is either direct repression of shoot identity genes or repression of an intermediate factor that activates shoot identity genes. The latter conclusions were deduced from the phenotypes conferred by a gain-of-function transgene, LEAFY:VP16, that appears to act as a dominant negative, or antimorphic, allele during maintenance of floral meristem identity. These observations contrast with previous findings that LEAFY acts as a direct activator of floral homeotic genes, supporting the hypothesis that the transcriptional activity of LEAFY is dependent on specific co-regulators.

Key words: Arabidopsis thaliana, Flower development, Meristem identity, LEAFY, Floral reversion






© The Company of Biologists Ltd 2002