Safflower CtFT genes orchestrating flowering time and flavonoid biosynthesis

Safflower thrives in dry environments but faces difficulties with flowering in wet and rainy summers. Flavonoids play a role in flower development and can potentially alleviate these challenges. Furthermore, the FLOWERING LOCUS T (FT) family of phosphatidylethanolamine-binding protein (PEBP) genes play a crucial role in the photoperiodic flowering pathway. However, their direct impact on flowering and flavonoid biosynthesis under different light duration is elusive.

Utilizing the genome sequencing of Safflower (Jihong NO.1), the current study identifies three specific genes (CtFT1, CtFT2, and CtFT3) that exhibit upregulation in response to long-day conditions. The overexpression of CtFT2, displayed an early, whereas CtFT1 and CtFT3 late flowering phenotype in Arabidopsis thaliana. Interestingly, the transient overexpression of CtFT1 in safflower leaves caused early flowering, while overexpressing CtFT2 and CtFT3 led to late flowering. Additionally, overexpressing CtFT3 in Arabidopsis and CtFT1, CtFT2, and CtFT3 in safflower leaves, significantly increased flavonoid synthesis.

These findings showed that overexpression of CtFT genes could affect the flowering time and significantly increase the flavonoid content of safflower. The function of CtFT gene is different in safflower and Arabidopsis. This study provides valuable insights into the role of CtFT genes in flower formation and flavonoid synthesis in safflower, which may help in improving safflower breeding quality and its adaptability to diverse environmental conditions.