Abstract: In this study, non-targeted metabolomics based on liquid chromatography-mass spectrometry (LC-MS) was used to investigate the changes in the types and contents of metabolites in HN191 purple hot pepper and Erjingtiao at the immature (30 days after anthesis) and mature (60 days after anthesis) stages. The results showed that the four pepper groups were clearly separated without any non-overlapping from one another by principal component analysis (PCA), indicating significant differences in metabolite composition between varieties and mature stages. Taking variable importance in the projection (VIP) > 1, |fold change| > 2 and P < 0.05 as thresholds, 1 065, 1 010 and 1 487 differential metabolites were identified between HN191 and Erjingtiao fruits at 30 day after anthesis, between HN191 and Erjingtiao fruits at 60 days after anthesis, and between HN191 fruits at 30 and 60 days after anthesis, respectively, which were all enriched to flavonoid-related pathways. In the flavonoid biosynthesis and isoflavone biosynthesis pathways, most of the differential flavonoid metabolites were more abundant in HN191 than in Erjingtiao. In addition, in the anthocyanin biosynthesis pathway, seven delphinidin, cyanidin, and pelargonidin derivatives, including delphinidin, delphinidin-3-(P-coumaroyl)-rutinoside-5-glucoside, delphinidin 3-glucoside 5-caffeoyl-glucoside, cyanidin 3-O-rutinoside 5-O-β-D-glucoside, cyanidin 3-O-β-D-sambubioside, pelargonidin 3-glucoside 5-caffeoyl glucoside and pelargonidin 3-O-β-D-sambubioside, were found to be significantly accumulated in immature HN191 fruit, which may be key metabolites related to anthocyanin biosynthesis in HN191.

Key words: hot pepper; metabolomics; fruit color; flavonoids; anthocyanins