Characterization and function study of circadian rhythm gene CtPRR1 in Carthamus tinctorius L / 药学实践杂志

ABSTRACT

Objective To explore the effect of circadian rhythm genes on flavonoids biosynthesis in safflower and its molecular mechanism. Methods Based on the transcriptome and metabolomic database of safflower corolla, we screened the circadian rhythm genes that correlate with biosynthesis of flavonoids in safflower. qPCR was used to quantify the expressions of circadian rhythm genes in different flowering stages at different time points in a single day. LC-MS was performed to determine the accumulation of flavonoids. The correlation between them was analyzed as well. Yeast Two-Hybrid experiment was used to verify the interactive proteins of these genes. Results Seven circadian rhythm genes PRR1, PRR2, ELF3, FT, PHYB, GI and ZTL were obtained. PRR1 gene was positively correlated with flavonoids accumulation (r≥0.7). The full length of PRR1 is 3 201 bp, encoding 421 amino acids, which is highly homologous with rice OsPRR73 gene and named as CtPRR1 (GenBank accession number MW492035). CtPRR1 was mainly expressed in flowers, and the expression level increased in the daytime and declined in the evening gradually. Correspondingly, the content of flavonoids showed an opposite variation. Both of them displayed a circadian rhythm with a negative correlation (r≥−0.7). In addition, 2 heat shock proteins along with 3 AP2 transcription factors interacting with CtPRR1 protein were obtained via Yeast Two-Hybrid experiment. Conclusion CtPRR1 negatively regulated the safflower flavonoids accumulation in a circadian rhythm way, which may be affected by these interacting proteins.