Complex transcriptome network regulates the anthocyanin accumulation of four Panax ginseng cultivars in fruit

Background

Panax ginseng fruit tissue is one of the richest sources of valuable constituents such as ginsenosides and anthocyanins. Although anthocyanins extracted from the fruit tissue of P. ginseng are utilized, it is uncertain how anthocyanin accumulation is regulated and which anthocyanin varieties are synthesized.

Methods

Fruits of four P. ginseng cultivars were collected for total RNA extraction and RNA-Seq analysis using the Illumina HiSeq X platform. Anthocyanins were extracted and analyzed by UPLC-DAD-QToF/MS to identify and quantify individual derivatives. Differentially expressed genes (DEGs) were identified, followed by functional annotation and network analysis to evaluate gene expression patterns.

Results

Comparative transcriptome analysis of four differently colored P. ginseng cultivars revealed that flavonoid biosynthetic genes associated with the karrikin response and jasmonate-responsive genes were upregulated in anthocyanin-rich fruits. Network analysis further revealed a putative regulatory complex consists of karrikin- and jasmonate-responsive genes along with flavonoid biosynthetic genes. Analyzing the UPLC-DAD extracts of the fruit of cv. Chunpoong found that the fruit tissue of P. ginseng is rich in pelargonidin.

Conclusion

Our research provides how anthocyanin is accumulated and which type is accumulated in fruit tissue of P. ginseng, including the original compound, pelargonidin 3-O-(2″-O-glucosyl)galactoside. We expect that our research will lead to improved breeding efficiency for the development of cultivars containing more flavonoid species that are beneficial to humans.