FCS-Like Zinc finger 14 (FLZ14) mediates the crosstalk between TORC and SnRK1 in response to sugar availability

Matching resource availability to growth is crucial for plant fitness. We identified that FCS- Like Zinc finger 14 (FLZ14) gauges carbon (C) status to adjust growth by inhibiting the TARGET OF RAPAMYCIN (TOR) activity in short days via REGULATORY- ASSOCIATED PROTEIN OF TARGET OF RAPAMYCIN 1B (RAPTOR1B). Besides being transcriptionally induced by sugars, the amplitude of FLZ14 induction correlates to the diel sugar status, indicating that FLZ14 responses to sugar oscillations in planta. Genetic evidence elucidated that FLZ14 is involved in the crosstalk between TORC and SUCROSE NON-FERMENTING RELATED KINASE 1 (SnRK1). In short photoperiods, FLZ14 and KIN10 genetically interact to set the pace of TORC activity. By contrast, under long day photoperiods, FLZ14 and RAPTOR1B genetically interact, most likely to downregulate SnRK1 signalling. This report highlights the function of a sugar-responsive gene in mediating the crosstalk between TORC and SnRK1 to fine-tune growth.