CENTRORADIALIS interacts with FLOWERING LOCUS T-like genes to control spikelet initiation, floret development and grain number.

CENTRORADIALIS (CEN) is a key regulator of flowering time and inflorescence architecture in plants. Natural variation in the barley homolog HvCEN was important for agricultural range expansion of barley cultivation. However, its effects on shoot and spike architecture and consequently yield have not yet been characterised. We evaluated 23 independent hvcen, also termed mat-c, mutants to determine the pleiotropic effects of HvCEN on developmental timing and shoot and spike morphologies of barley under outdoor and controlled conditions. All hvcen mutants flowered early and showed a reduction in spikelet number per spike, tiller number and yield in the outdoor experiments. Mutations in hvcen accelerated spikelet initiation and reduced axillary bud number in a photoperiod independent manner, but promoted floret development only under long days (LDs). The analysis of an hvcen hvft3 double mutant showed that HvCEN interacts with FLOWERING LOCUS T3 (HvFT3) to control spikelet initiation. Furthermore, hvcen hvelf3 (EARLY FLOWERING 3) double mutants with high HvFT1 expression levels under short days (SDs) suggested that HvCEN interacts with HvFT1 to repress floral development. Global transcriptome profiling in developing shoot apices and inflorescences of mutant and wild-type plants revealed that HvCEN controlled transcripts involved in chromatin remodeling activities, cytokinin and cell cycle regulation and cellular respiration under LDs and SDs, while HvCEN affected floral homeotic genes only under LDs. Understanding the stage and organ specific functions of HvCEN and downstream molecular networks will allow manipulating different shoot and spike traits and thereby yield.