Selenium (Se) is not only an essential trace element critical for the proper functioning of an organism, but it is also an abiotic stressor that affects an organism’s growth and metabolite profile. In this study, Epichloë sp. from Festuca sinensis was exposed to increasing concentrations of Na₂SeO₃ (0, 0.1, and 0.2 mmol/L) in a liquid media for eight weeks. The mycelia and fermentation broth of Epichloë sp. were collected from four to eight weeks of cultivation. The mycelial biomass decreased in response to increased Se concentrations, and biomass accumulation peaked at week five. Using gas chromatography-mass spectrometry (GC-MS), approximately 157 and 197 metabolites were determined in the fermentation broth and mycelia, respectively. Diverse changes in extracellular and intracellular metabolites were observed in Epichloë sp. throughout the cultivation period in Se conditions. Some metabolites accumulated in the fermentation broth, while others decreased after different times of Se exposure compared to the control media. However, some metabolites were present at lower concentrations in the mycelia when cultivated with Se. The changes in metabolites under Se conditions were dynamic over the experimental period and were involved in amino acids, carbohydrates, organic acids, fatty acids, and nucleotides. Based on these results, we conclude that selenite concentrations and culture time influence the growth, extracellular and intracellular metabolite profiles of Epichloë sp. from F. sinensis.

Phlomoides rotata, a traditional medicinal plant, is commonly found on the Tibetan Plateau at altitudes of 3100–5200 m. Its primary active medicinal compounds, flavonoids and phenylethanol glycosides (PhGs), exhibit various pharmacological effects, including hemostatic, anti-inflammatory, antitumor, immunomodulatory, and antioxidant activities. This study analyzed flavonoid and PhG metabolites in the roots of P. rotata collected from Henan County (HN), Guoluo County (GL), Yushu County (YS), and Chengduo County (CD) in Qinghai Province. A total of differentially abundant metabolites (DAMs) including 38 flavonoids and 21 PhGs were identified. Six genes (UFGT1, CHS1, COMT2, C4H3, C4H8, and C4H5) and four enzymes (4CL, C4H, PPO, and ALDH) were found to play key roles in regulating flavonoid and PhG biosynthesis in P. rotata roots. With increasing altitude, the relative content of 15 metabolites, the expression of seven genes, and the activity of four enzymes associated with flavonoid and PhG metabolism increased. These findings enhance our understanding of the regulatory mechanisms of flavonoid and PhG metabolism in P. rotata and provide insights into the potential pharmaceutical applications of its bioactive compounds.