Cultivated strawberry (Fragaria × ananassa) is highly sensitive to temperature fluctuations, which influence floral induction, fruit ripening, and quality formation. CONSTANS-LIKE (COL) transcription factors are central regulators of photoperiod-dependent flowering and stress responses; however, their roles in temperature-mediated fruit quality regulation in octoploid strawberry remain unclear. In this study, 63 FaCOL genes were identified in the octoploid strawberry genome and systematically characterized through phylogenetic analysis, gene structure, conserved motifs, cis-element composition, and synteny relationships. Transcriptome profiling of fruits exposed to low (6 °C) and high (26 °C) temperatures revealed distinct temperature-responsive expression patterns among FaCOL members. Notably, FaCOL57 and FaCOL59 exhibited antagonistic responses: FaCOL57 was induced by cold but repressed by heat, whereas FaCOL59 showed the opposite trend. Tissue-specific expression analysis indicated preferential accumulation of FaCOL57 transcripts in floral tissues and FaCOL59 in ripening fruits. Functional analyses demonstrated that virus-induced gene silencing of either gene significantly reduced anthocyanin and soluble sugar contents, while transient overexpression enhanced the accumulation of anthocyanin, sucrose, glucose, and fructose. Promoter analysis of key metabolic genes identified multiple canonical COL-binding elements, suggesting potential transcriptional regulation. These findings demonstrate that FaCOL57 and FaCOL59 function as positive regulators of anthocyanin and soluble sugar accumulation in cultivated strawberry and exhibit contrasting temperature-responsive expression patterns. Our results expand the functional diversity of the FaCOL gene family in octoploid strawberry and FaCOL57 and FaCOL59 may function as transcriptional nodes capable of integrating cold cues with metabolic outputs. This study establishes a foundation for further mechanistic dissection of FaCOL-mediated environmental signal integration and offers potential molecular targets for improving fruit quality stability under variable temperature conditions.
Sheng et al. (Thu,) studied this question.