Molecular cloning and functional characterization of CmSOC1 gene and its promoter region from Chrysanthemum morifolium

Flowering in plants is initiated by a convergence of various external and internal signals. These sensed signals activate distinct pathways that individually promote flowering. The integration of multiple pathways involves several integrators, which play a crucial role in harmonizing the signals to induce the expression of floral identity genes and facilitate the process of flower formation. Various flowering factors and mechanisms have been characterized in the long-day flowering in Arabidopsis. However, flowering mechanisms of the short -day flowering plants is still unknown. The proposed research aimed to investigate the flowering mechanisms of the representative short -day flowering plant, Chrysanthemum morifolium cv. Jimba by characterizing one member of MADS (MCM1, AGAMOUS, DEFICIENS, SRF)-box family, which integrates signals including flowering, SUPPRESSOR OF OVEREXPRESSION OF CONSTANTS1 (SOC1). We isolated 8663 bp of CmSOC1 genomic DNA fragment containing 651 bp coding region and 2064 bp promoter region. Phylogenetic and sequence alignment analysis revealed that the CmSOC1 protein contains conserved K -box, MADS-box, and SOC1 motifs, which are shared with SOC1 orthologous proteins. Bioinformatics analyses of the CmSOC1 promoter region revealed that CmSOC1 promoter includes light and hormone responsive cis -acting regulatory elements and the MADS protein biding CArG-motif. Transgenic Arabidopsis heterologously and chrysanthemum overexpressing CmSOC1 gene to analyze the function of CmSOC1. Overexpression of CmSOC1 led to early flowering of Arabidopsis, especially under short -day conditions and increased expression of floral identity genes LEAFY and APETALA1. Ectopic expression of CmSOC1 in chrysanthemum also induced early flowering. These results highlight the importance of CmSOC1 in the flowering process of short -day flowering plants and provide insights into the molecular mechanisms of flowering in short -day flowering plants. In this study, we suggest that CmSOC1 could serve as a key target for flowering process control in chrysanthemum and long-day flowering plants.