Untargeted GC-TOFMS Analysis Reveals Metabolomic Changes in Salvia miltiorrhiza Bunge Leaf and Root in Response to Long-Term Drought Stress

Salvia miltiorrhiza Bunge (Danshen) is an important traditional Chinese medicine herb. This study aimed to investigate the drought-responsive metabolic profiling in S. miltiorrhiza using gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analysis. Fifty day-old S. miltiorrhiza seedlings were treated with two (moderate drought, MD) and four weeks (high drought, HD) of withholding water. The S. miltiorrhiza leaf and root samples were prepared for the GC-TOFMS analysis. Differential metabolites with substantial changes in content in S. miltiorrhiza leaf and root were identified using multivariate and univariate statistics. A total of 178 and 157 annotated metabolites were detected in S. miltiorrhiza leaf and root, respectively. Multivariate analysis showed that significantly discriminant metabolites in S. miltiorrhiza leaf by drought were associated with “galactose metabolism” and “citrate cycle”. In addition, the significantly discriminant metabolites in S. miltiorrhiza root were associated with “starch and sucrose metabolism”. Univariate statistics showed that the content of succinic acid, d-glucose, and oxoglutaric acid in S. miltiorrhiza leaf was increased by drought (fold change, FC > 1.5). Allose, d-xylose, melibiose, mannose, sorbitol, quinic acid, sinigrin, and taurine in S. miltiorrhiza root were decreased by drought (FC < 0.67). There were different metabolic profiles between S. miltiorrhiza leaf and root. However, the influence of drought stress on the pharmacological value and accumulation of bioactive constituents in S. miltiorrhiza should be further investigated.