Metabolome and transcriptome analyses reveal quality change in the orange-rooted Salvia miltiorrhiza (Danshen) from cultivated field

Abstract Background The dry root and rhizome of Salvia miltiorrhiza Bunge, or Danshen, is a well-known, traditional Chinese medicine. Tanshinones are active compounds that accumulate in the periderm, resulting in red-colored roots. However, lines with orange roots have been observed in cultivated fields. Here, we performed metabolome and transcriptome analyses to investigate the changes of orange-rooted Danshen. Methods Metabolome analysis was performed by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-Tof–MS) to investigate the metabolites variation between orange Danshen and normal Danshen. RNA sequencing and KEGG enrichment analysis were performed to analyzing the differentially expressed genes between orange-rooted and normal Danshen. Results In total, 40 lipophilic components were detected in metabolome analysis, and seven compounds were significantly decreased in the orange Danshen, including the most abundant active compounds, tanshinone IIA and tanshinone I in normal Danshen. Systematic analysis of transcriptome profiles revealed that the down-regulated genes related to catalytic dehydrogenation was not detected. However, two genes related to stress resistance, and four genes related to endoplasmic reticulum (ER)-associated degradation of proteins were up-regulated in orange Danshen. Conclusions Decreases in the content of dehydrogenated furan ring tanshinones such as tanshinone IIA resulted in phenotypic changes and quality degradation of Danshen. Transcriptome analysis indicated that incorrect folding and ER-associated degradation of corresponding enzymes, which could catalyze C15-C16 dehydrogenase, might be contributed to the decrease in dehydrogenated furan ring tanshinones, rather than lower expression of the relative genes. This limited dehydrogenation of cryptotanshinone and dihydrotanshinone I into tanshinones IIA and I products, respectively, led to a reduced quality of Danshen in cultivated fields.