Genome-Wide Identification, Characterization, and Expression Profile Analysis of CONSTANS-like Genes in Woodland Strawberry ( Fragaria vesca ).

() gene is one of the most important regulators in the flowering process of the plant, playing a core role in the photoperiodic flowering induction pathway. In this study, we identified 10 distinct genes () in woodland strawberry (). They were classified into three groups with specific gene structure characteristics or protein domains in each group. The effect of selection pressure on the in the woodland strawberry was tested by Ka/Ks, and it was shown that the evolution rate of was controlled by purification selection factors. Intraspecific synteny analysis of woodland strawberry showed that at least one duplication event existed in the gene family members. Collinearity analysis of woodland strawberry genome with genomes of , rice (), and apple ( × a) showed that genes of and × a owned higher similarity for their similar genomes compared with those of other two species. The showed different tissue-specific expression patterns. Moreover, real-time quantitative PCR results revealed that the expressions of the most followed a 24-h rhythm oscillation under both long-day (LD) and short-day (SD) conditions. Further expression analysis showed that the individual expression changing profile of and was opposite to each other under both LD and SD conditions. Moreover, the expression of and was both negatively correlated with the flowering time variation of the woodland strawberry grown under LD and SD conditions, indicating their potential vital roles in the photoperiodic flowering regulation. Further protein interaction network analysis also showed that most of the candidate interaction proteins of FveCO3 and FveCO5 were predicted to be the flowering regulators. Finally, LUC assay indicated that both FveCO3 and FveCO5 could bind to the promoter of , the key regulator of flowering regulation in the woodland strawberry, and thus activate its expression. Taken together, this study laid a foundation for understanding the exact roles of FveCOs in the reproductive development regulation of the woodland strawberry, especially in the photoperiodic flowering process.