Characterization of the Gene Family in and the Role of in Cold Tolerance

Plant-specific TCP transcription factors play a key role in plant development and stress responses. shows higher cold tolerance than its ornamental polyploid counterpart. However, whether the gene family plays a role in conferring cold tolerance upon remains unknown. Here, we identified 23 genes in , systematically analyzed their phylogenetic relationships and synteny with TCPs from other species, and evaluated their expression profiles at low temperature. Phylogenetic analysis of the protein sequences suggested that CnTCP proteins fall into two classes and three clades, with a typical bHLH domain. However, differences between and Arabidopsis in predicted protein structure and binding sites suggested a unique function of CnTCPs in . Furthermore, expression profiles showed that expression of most were downregulated under cold conditions, suggesting their importance in plant responses to cold stress. Notably, expression of and of its predicted target genes, //, led to fast responses to cold. Overexpression of Arabidopsis led to hypersensitivity to cold, suggesting that might play a negative role in responses to cold stress. Our results provide a foundation for future functional genomic studies on this gene family in chrysanthemum.