Comparative analysis of carotenoid accumulation during the flowering period in three <i>Coreopsis tinctoria</i> cultivars with different petal colors

<i>Coreopsis tinctoria</i> Nutt., known for its vibrant flower colors, possesses significant ornamental and medicinal value, making it a highly promising medicinal flower variety. It is widely favored by consumers as a health tea, with flower color being a crucial quality factor. The growth indicators and pigment content during the flow-ering period were determined in three <i>C. tinctoria</i> cultivars exhibiting different petal colors: 'JS' (entirely golden yellow), 'LS' (golden yellow tops with reddish-brown bases), and 'MS' (entirely reddish-brown). Additionally, a comparative metabolomic analysis of carotenoid metabolites was conducted. The results showed that the three <i>C. tinctoria</i> cultivars exhibited distinct differences in flower phenotypes and growth characteristics. For example, plant height and stem diameter significantly differed among 'JS', 'LS', and 'MS' at various flowering stages. The total carotenoid content of 'JS', 'LS', and 'MS' was mainly concentrated in the early flowering stage (S2), full flowering stage (S3) and late flowering stage (S4), with significant differences observed. 'LS' and 'JS' reached their highest total carotenoid content in stages S3 and S4, respectively. Analysis revealed 58 carotenoid metabolites (seven carotenes and 51 xanthophylls) with abundances that varied significantly by flower color and developmental stage. Of these, 12 metabolites (two carotenes and 10 xanthophylls) were significantly enriched in the carotenoid pathway and exhibited notably high accumulation during the S2 and S3 stages, suggesting their important role in petal coloration variation. This study provides a theoretical basis for understanding the flower color mechanism of <i>C. tinctoria</i> and lays a foundation for the extraction and utilization of its active components.