Transcriptomic analysis of the key quality differences between Medicinal Mulberry and White Mulberry

Objective By analyzing the organic acid and flavonoid metabolism of different varieties of mulberries, the molecular mechanisms underlying key quality differences in mulberries are revealed.

Methods Two characteristic mulberries (white mulberry and medicinal mulberry) from Xinjiang were selected as experimental materials. Differential analysis of organic acid and flavonoid content were conducted, and transcriptomics technology were used to screen key differentially expressed genes (DEGs), and then the molecular mechanism of mulberry quality formation was revealed by analyzing the key signaling pathways and genes among different varieties of mulberry.

Results The main organic acid in medicinal mulberry is citric acid 28.99 g/kg, and the content of citric acid, tartaric acid, and total acid in medicinal mulberry are higher than that in white mulberry. The main organic acid in white mulberry is malic acid 3.16 g/kg, and malic acid, succinic acid, and fumaric acid in white mulberry are higher than those in medicinal mulberry. The flavonoid content in medicinal mulberry 1.72 mg/g is significantly higher than that in white mulberry 0.29 mg/g. A total of 22870 DEGs were detected in white mulberry and medicinal mulberry, of which 18188 were up-regulated and 4682 were down-regulated. By analyzing the citric acid metabolism pathway and flavonoid metabolism pathway, the encoding enzymes of malic acid enzyme (ME), malic acid dehydrogenase (MDH), citric acid synthase (CS), ATP citrate lyase (ACL), isocitrate dehydrogenase (IDH) and aconite hydratase (ACO), chalcone synthase (CHS), chalcone isomerase (CHI), and flavonoid 3β-Hydroxylase (F₃H) and other key genes are responsible for the quality differences between the two types of mulberries. Finally, these DEGs were validated through RT-qPCR, ensuring the authenticity and reliability of transcriptome data.

Conclusion There is a significant difference in the content of organic acids and flavonoids between medicinal mulberry and white mulberry. Transcriptome data shows that CS, ACL, IDH, ACO, CHS, CHI, F₃H, FLS, DFR, and ANS play important regulatory roles in the synthesis and metabolism of organic acids and flavonoids, and are key genes that cause key quality differences in mulberry varieties.