A common set of genes responding to florigenic and photoperiodic induction at the shoot apical meristem of rice
Flowering of rice is triggered by transcriptional reprogramming at the shoot apical meristem (SAM) mediated by florigenic proteins produced in leaves in response to changes in the photoperiod. Florigens are more rapidly expressed under short day (SD) and include the HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T1 (RFT1) Phosphatidyl Ethanolamine Binding Proteins (PEBP). Hd3a and RFT1 are largely redundant at converting the SAM into an inflorescence, but whether they activate the same target genes and convey all photoperiodic information that modifies gene expression at the SAM is currently unclear.  We uncoupled the contribution of Hd3a, RFT1 and SD to transcriptome reprogramming at the SAM, by RNA-sequencing of dex-inducible over-expressors of single florigens and wild type plants exposed to photoperiodic induction. Fifteen highly differentially expressed genes common to Hd3a, RFT1 and SD were retrieved, ten of which still uncharacterized. Detailed functional studies on some candidates revealed a role for LOC_Os04g13150 in determining tiller angle and bract development and the gene was renamed BROADER TILLER ANGLE 1 (BRT1). We identified a core set of genes common to florigenic and photoperiodic induction and defined the function of a novel florigen target controlling tiller angle. Overall design: RNA-seq on naturally induced plants and florigen overexpressing plants