Examining carotenoid metabolism regulation and its role in flower color variation in Brassica rapa L.

Abstract Carotenoids are crucial pigments that determine the color of flowers, roots, and fruits in plants, imparting them yellow, orange, and red hues. This study comprehensively analyses the Brassica rapas mutant “YB1,” which exhibits altered flower and root colors. Combining physiological and biochemical assessments, transcriptome profiling, and quantitative metabolomics, this study investigated carotenoid accumulation in different tissues of YB1 throughout its growth and development. The results revealed that carotenoid continued to accumulate in the roots and stems of YBI, especially in its cortex, whereas the carotenoid levels in the petals decreased upon flowering. A total of 54 carotenoid compounds, with 30 being unique metabolites, were identified across various tissues. Their levels correlated with the expression pattern of 22 differentially expressed genes related to carotenoid biosynthesis and degradation. Specific genes, including CCD8 and NCED in flowers and ZEP in the roots and stems, were identified as key regulators of color variations in different plant parts. Additionally, we identified genes in the seeds that regulated the conversion of carotenoids to abscisic acid. In conclusion, his study offers valuable insights into the regulation of carotenoid metabolism in B. rapas, which can guide the selection and breeding of carotenoid-rich varieties with diverse colors in the future.