Integrated Metabolomic and Transcriptomic Analyses of Anthocyanin Synthesis During Fruit Development in Lycium...

Lycium ruthenicum Murr. is a highly nutritional cash crop due to its fruit-abundant anthocyanins. With the development of the fruit, the color changes from green to dark purple and the anthocyanin content gradually increases. But the molecular mechanism of the anthocyanin biosynthesis process in L. ruthenicum fruit is still unclear. Five stages of L. ruthenicum fruit based on the color of the pericarp and flesh (BS1-BS5) were used for metabolomics and transcriptomics analyses to investigate the underlying mechanisms of the pigmentation. At the BS3 stage, the anthocyanin content was significantly increased and reached the highest level at the BS5 stage. A total of 25 DAMs related to flavonoids were identified by metabolomics, presenting a gradual increase with fruit development. Delphinidin-3-O-rutinoside and petunidin-3-O-rutinoside were identified as the main anthocyanins. Transcriptome sequencing and DEG analysis identified the key structural genes and transcription factors related to anthocyanin biosynthesis. Anthocyanin accumulation was driven mainly by the upregulation of six structural genes (F3'5'H, DFR, ANS, and UFGT) and eight key transcription factors from the HB, NAC, WRKY, Tify, AP2/ERF, and bHLH families that were significantly correlated with anthocyanin content in L. ruthenicum fruit. This study reveals key candidate genes in the anthocyanin biosynthetic pathway, providing new insights for improving fruit quality.