Transcriptomic and metabolomic analyses for the mechanism underlying anthocyanin synthesis during the growth and development of purple eggplant (Solanum melongena L)

Ting Yang¹Wanping Lv²Runjie Zhuang²Shiyu Wang²Shuqi Fan²Yongxian Wen^1,2,3*

• ¹Fujian Agriculture and Forestry University, Fuzhou, China
• ²College of Computer and information Science, Fujian Agriculture and Forestry University, Fuzhou, China
• ³Institute of Statistics and Applications, Fujian Agriculture and Forestry University, Fuzhou, China

Purple eggplant (Solanum melongena L) is recognized for its high anthocyanin content. However, the regulatory mechanisms underlying anthocyanin biosynthesis during fruit development remain to be elucidated. To explore this, we investigated anthocyanin accumulation dynamics across three developmental stages (S1: white, S2: light purple, and S3: dark purple) using integrated metabolomic and transcriptomic analyses. As the fruit peel color deepened, there was a significant increase in total anthocyanin content. Metabolomic analysis identified 11 distinct anthocyanins types. Transcriptomic analysis revealed significant enrichment of 8 structural genes and 11 MYB transcription factors (TFs) within the anthocyanin biosynthetic pathway. Further studies demonstrated that transient overexpression of SmMYB32 and SmMYB67 markedly enhanced the expression of key biosynthetic genes involved in anthocyanin production. These results suggest that upregulation of anthocyanin biosynthesis genes during fruit development facilitates anthocyanin accumulation, providing useful insights for breeding cultivars with higher anthocyanin content.Anthocyanins, which belong to flavonoids, play a crucial role in determining fruit color due to their distinctive molecular structures and high solubility in water. They can be classified into six groups based on variations in their molecular structures: malvidin, petunidin, pelargonidin, peonidin, delphinidin, and cyanidin. Their synthesis is regulated by various structural genes and regulatory genes through the flavonoid pathway (He and Giusti, 2010; Wei et al., 2011). Key structural genes involved in this process include chalcone synthase (CHS), chalcone isomerase (CHI), flavonol 3′hydroxylase (F3′H), dihydroflavonol-4-reductase (DFR), uridine diphosphate (UDP)-glucose: flavonoid 3-O-glycosyltransferase (UFGT), and glutathione S-transferase (GST) (Jiang et al., 2016).Additionally, other TFs such as MYB (Dubos et al., 2010), WRKY (Li et al., 2020), NAC (Li et al., 2020), bZIP (An et al., 2017), and MADS (Jaakola et al., 2010), have also been proven to participate in regulating anthocyanin biosynthesis.