The VQ motif-containing proteins VQ18 and VQ26 regulate flowering time in Arabidopsis thaliana

Floral induction in plants represents a critical developmental transition from vegetative growth to the reproductive phase, which is vital for reproductive success. Identifying new genes that control flowering time and understanding their regulatory mechanisms is crucial for improving our knowledge of plant adaptability to the environment. Here, we identify VQ motif-containing proteins VQ18 and VQ26 as novel promoters of flowering that function redundantly to regulate this process in Arabidopsis. The VQ18 and VQ26 proteins promote flowering in Arabidopsis through their interaction with the CONSTANS (CO) protein. This interaction enhances the stability of the CO protein and augments its transcriptional activation of the FLOWERING LOCUS T (FT) gene. Furthermore, VQ18 and VQ26 exhibit binding affinity for the TARGET OF EAT1 (TOE1) and TOE2 proteins, thereby diminishing the binding affinity and inhibitory effects of TOEs on FT, which alleviates the repression of flowering by TOEs. Additionally, VQ18 and VQ26 are implicated in the regulation of flowering timing by competing with TOEs for interaction with CO. Our findings broaden the functions of VQ proteins and reveal new regulatory interactions in the flowering network, providing insights into how plants balance positive and negative signals to regulate flowering time.