The Role of PERPETUAL FLOWERING 1 in the Regulation of Gibberellins in A. alpina

TILMES, V; MATEOS, J. L.; COUPLAND, G

Foz do Iguazu

Congreso; 11th International Congress of Plant Molecular Biology; 2015

Perennial plants live for many years, while annual plants completely senesce after flowering. In the perennial life cycle of Arabis alpina, seasonal flowering patterns are specified by the MADS-box transcription factor PERPETUAL FLOWERING 1 (PEP1). PEP1 is the ortholog of the floral repressor FLOWERING LOCUS C (FLC) in the annual model Arabidopsis thaliana. FLC represses flowering before winter and FLC transcription is stably repressed by vernalization. In contrast, PEP1 transcription is only temporarily downregulated by vernalization. In order to assess conservation of PEP1 and FLC targets, we performed ChIP-seq and genome-wide expression profiling to identify genes that are bound and regulated by PEP1 in A. alpina or FLC in A. thaliana, respectively. We discovered that the regulation of genes encoding transcription factors that control flowering time is conserved between species, whereas genes affecting many other functions, such as the regulation of gibberellin levels and response, are species specific. Physiological experiments indicate that in A. alpina, gibberellins act during vernalization to promote flowering and PEP1 is involved in the maintenance of gibberellin homeostasis in low temperatures. In summary, this genome-wide comparison of transcription factor targets revealed that only a low fraction of PEP1/FLC targets is conserved and these mainly have a developmental function in the control of flowering. Species-specific targets were predominantly involved in responses to environmental factors.