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Sequential DNA affinity purification sequencing (seq-DAP-seq) data of MADS SEP3-AG tetramerization mutants.

ABSTRACT: The MADS genes encode transcription factors (TF) that act as master regulators of plant reproduction and flower development. The SEPALLATA (SEP) MADS subfamily is not only absolutely required for the development of floral organs, but also plays roles in inflorescence architecture and determinacy of the floral meristem. The SEPs act as organizers of MADS complexes and are able to form both heterodimers and heterotetramers in vitro. To date, the MADS TF complexes characterized in angiosperm floral organ development contain at least one SEP TF. Whether DNA-binding by SEP-containing dimeric MADS complexes are sufficient for launching floral organ identity programs, however, is not clear as only defects in floral meristem determinacy were observed in tetramerization impaired SEP mutants. Here we used a combination of genome-wide binding studies, high resolution structural studies of the SEP3-AGAMOUS tetramerisation domain, structure-based mutagenesis and complementation experiments in sep1 sep2 sep3 and sep1 sep2 sep3 ag-4 plants transformed with versions of SEP3 encoding tetramerization mutants. We demonstrate that while SEP3 heterodimers are able to bind DNA both in vitro and in vivo and recognize the majority of SEP3 wild type binding sites genome-wide, tetramerisation is not only required for floral meristem determinacy, but also absolutely required for floral organ identity in the second, third and fourth whorls.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE227012 | GEO | 2024/04/30

REPOSITORIES: GEO

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Project description:The molecular mechanisms by which floral homeotic genes act as major developmental switches to specify the identity of floral organs, are still largely unknown. Floral homeotic genes encode transcription factors of the MADS-box family, which are supposed to assemble in a combinatorial fashion into organ-specific multimeric protein complexes. Major mediators of protein interactions are MADS-domain proteins of the SEPALLATA subfamily, which play a crucial role in the development of all types of floral organs. In order to characterize the roles of the SEPALLATA3 transcription factor complexes at the molecular level, we analyzed genome-wide the direct targets of SEPALLATA3. We used chromatin immunoprecipitation followed by ultrahigh-throughput sequencing or hybridization to whole-genome tiling arrays to obtain genome-wide DNA-binding patterns of SEPALLATA3. The results demonstrate that SEPALLATA3 binds to thousands of sites in the genome. Most potential target sites that were strongly bound in wild-type inflorescences, are also bound in the floral homeotic agamous mutant, which displays only the perianth organs, sepals and petals. Characterization of the target genes shows that SEPALLATA3 integrates and modulates different growth-related and hormonal pathways in a combinatorial fashion with other MADS-box proteins and possibly with non-MADS transcription factors. In particular, the results suggest multiple links between SEPALLATA3 and auxin signaling pathways. Our gene expression analyses link the genomic binding site data with the phenotype of plants expressing a dominant repressor version of SEPALLATA3, suggesting that it modulates auxin response to facilitate floral organ outgrowth and morphogenesis. Furthermore, the binding of the SEPALLATA3 protein to cis-regulatory elements of other MADS-box genes and expression analyses reveal that this protein is a key component in the regulatory transcriptional network underlying the formation of floral organs. ChIP experiments were performed on Arabidopsis wildtype and agamous mutant inflorescences using an antibody raised against a C-terminal peptide of SEP3. As control, ChIP experiments were performed on the sep3 mutant.

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Sequential DNA affinity purification sequencing (seq-DAP-seq) data of MADS SEP3-AG tetramerization mutants.

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