Important progress in the biosynthesis mechanism of blackberry flavonoids

Integrative analysis of the metabolome and transcriptome provides insights into the mechanisms of flavonoid biosynthesis in blackberry

The blackberry is rich in phenols, flavonoids and anthocyanins, which have medicinal values such as antioxidant, blood pressure reduction and immunity improvement. The richness of anthocyanins is one of the most significant features of the mature blackberry fruit, and its content directly affects the nutritional and sensory quality of the fruit, and is also the main indicator to evaluate its medicinal quality. Anthocyanins are the downstream products of flavonoid biosynthesis pathway, and there are few studies on how flavonoids and anthocyanins are synthesized and accumulated in blackberry fruits, and which transcription factors regulate them, which greatly limit the development of blackberry industry. Therefore, screening blackberry varieties with high anthocyanin content and investigating the mechanism of efficient anthocyanin accumulation can clarify the mechanism of anthocyanin biosynthesis from the root and provide a realistic basis for its effective utilization.

In order to investigate the transcriptional and metabolic mechanisms of flavonoid synthesis in blackberry fruits and the regulatory network of key genes, the Blackberry Research and Utilization Project Group of the Fruit Tree Research Center used the immature and mature fruits of blackberry high anthocyanin variety 'Chester' as research materials, established a blackberry mRNA library (containing 17,566 significantly differentially expressed genes) and identified the relevant metabolic genes. The mRNA library (containing 17,566 significantly differentially expressed genes) was established and related metabolites were identified. In blackberry fruits, 1251 transcription factors were identified in 55 different families, with the C2H2 and bHLH transcription factor families being the most abundant. Interestingly, three structural enzyme genes, CHI, LAR and SAT, were found to be highly correlated with MYB and bHLH; the transcription factors were also correlated with each other to different degrees, suggesting that the highly correlated genes or transcription factors may have similar regulatory patterns or potential reciprocal functions. In addition, 8 differential metabolites and 16 differential genes were annotated to the flavonoid biosynthetic pathway, which laid the foundation for further studies on flavonoid biosynthesis and metabolism, and is the focus of future structural gene function studies and differential metabolite accumulation investigations. This study provides a reference value for the future cultivation of blackberry germplasm resources with high flavonoid content and the development of related pharmaceutical industries.