Comprehensive evaluation of the novel purple-fleshed tomato germplasm black 'pearl' and analysis of anthocyanin synthesis mechanisms and components.

Anthocyanins endow tomatoes with richer nutritional characteristics. This study provides a comprehensive evaluation of the anthocyanin-rich tomato germplasm black 'Pearl,' which features an appealing purple flesh. The high levels of anthocyanins, antioxidant enzymes, vitamin C, and vitamin E confer a strong total antioxidant capacity. The organic acid and soluble sugar content in flesh are slightly lower, and it has a mild bitterness, with storage characteristics inferior to red-fleshed tomatoes. The correlation analysis between transcriptomics and metabolomics indicates that multiple structural genes and transcription factors in the anthocyanin biosynthetic pathway actively regulate the synthesis of anthocyanins. UPLC-ESI-MS/MS analysis of mature fruits identified a total of 43 types of anthocyanins, including six novel anthocyanins such as petunidin-3-O-rutinoside-5-O-rhamnoside and petunidin-3-O-feruloyl-xyloside-rutinoside. This study enriches our understanding of anthocyanin synthesis and metabolites in tomatoes, while the unique anthocyanins present in black 'Pearl' provide important genetic resources for the future development of high-quality, anthocyanin-rich tomato varieties.