title: Specific expression of LATERAL SUPPRESSOR is controlled by an evolutionarily conserved 3' enhancer.
abstract: Aerial plant architecture is largely based on the activity of axillary meristems (AMs), initiated in the axils of leaves. The Arabidopsis gene LATERAL SUPPRESSOR (LAS), which is expressed in well-defined domains at the adaxial boundary of leaf primordia, is a key regulator of AM formation. The precise definition of organ boundaries is an essential step for the formation of new organs in general and for meristem initiation; however, mechanisms leading to these specific patterns are not well understood. To increase understanding of how the highly specific transcript accumulation in organ boundary regions is established, we investigated the LAS promoter. Analysis of deletion constructs revealed that an essential enhancer necessary for complementation is situated about 3.2 kb downstream of the LAS open reading frame. This enhancer is sufficient to confer promoter specificity as upstream sequences in LAS could be replaced by non-specific promoters, such as the 35S minimal promoter. Further promoter swapping experiments using the PISTILLATA or the full 35S promoter demonstrated that the LAS 3' enhancer also has suppressor functions, largely overwriting the activity of different 5' promoters. Phylogenetic analyses suggest that LAS function and regulation are evolutionarily highly conserved. Homologous elements in downstream regulatory sequences were found in all LAS orthologs, including grasses. Transcomplementation experiments demonstrated the functional conservation of non-coding sequences between Solanum lycopersicum (tomato) and Arabidopsis. In summary, our results show that a highly conserved enhancer/suppressor element is the main regulatory module conferring the boundary-specific expression of LAS.
authors: Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany.
authors: Bodo
authors: B
authors: Raatz
authors: Andrea
authors: A
authors: Eicker
authors: Gregor
authors: G
authors: Schmitz
authors: Elisabeth
authors: E
authors: Fuss
authors: Dörte
authors: D
authors: Müller
authors: Susanne
authors: S
authors: Rossmann
authors: Klaus
authors: K
authors: Theres
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000254:growth & development*; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D029681:Arabidopsis Proteins; C474737:LAS protein, Arabidopsis