LATE ELONGATED HYPOCOTYL is a core component of far-red light-induced flowering in chrysanthemum

Abstract

Flowering is one of the critical biological traits that reflects the reproductive capacity of plants. Chrysanthemums are economically valuable horticultural crops, with the majority being short-day varieties that bloom in autumn, although long-day (LD) varieties have also evolved. Far-red (FR) light has been shown to promote flowering in chrysanthemums, yet the underlying molecular mechanisms remain poorly understood. Here, we identify CmLHY, a core component of the circadian clock oscillator, as a key regulator that responds to FR light signals to induce flowering under LD conditions in chrysanthemum. Transcriptome sequencing of CmLHY-RNAi and WT plants identified CmLATE as a downstream target gene of CmLHY. Yeast one-hybrid, electrophoretic mobility shift assay and dual-luciferase reporter assays demonstrated that CmLHY directly binds to the promoter of CmLATE and activates its expression, thereby upregulating the downstream flowering integrator CmFTL3 to regulate chrysanthemum flowering.In summary, our findings reveal the molecular mechanism by which the CmLHY-CmLATE module in circadian clock responds to FR light, regulating flowering under LD conditions in chrysanthemums. This study provides new insights into the molecular network of plants integrating external light signals to regulate flowering.