Antifungal activity of Ligusticum chuanxiong essential oil and its active composition butylidenephthalide against Sclerotium rolfsii

Abstract BACKGROUND Peanut stem rot caused by Sclerotium rolfsii is an epidemic disastrous soil‐borne disease. Recently, natural products tend to be safe alternative antifungal agents to combat pathogens. RESULTS This work determined the preliminary antifungal activity of 29 essential oils against S. rolfsii and found that Ligusticum chuanxiong essential oil (LCEO) showed the best antifungal activity, with an EC 50 value of 81.79 mg L −1 . Sixteen components (98.78%) were identified in LCEO by gas chromatography‐mass spectrometry analysis, the majority by volume comprising five phthalides (93.14%). Among these five phthalides, butylidenephthalide was the most effective compound against S. rolfsii . Butylidenephthalide not only exhibited favorable in vitro antifungal activity against the mycelial growth, sclerotia production and germination of S. rolfsi , but also presented efficient in vivo efficacy in the control of peanut stem rot. Seven days after application in the glasshouse, the protective and curative efficacy of butylidenephthalide at 300 mg L −1 (52.02%, 44.88%) and LCEO at 1000 mg L −1 (49.60%, 44.29%) against S. rolfsii were similar to that of the reference fungicide polyoxin at 300 mg L −1 (54.61%, 48.28%). Butylidenephthalide also significantly decreased the oxalic acid and polygalacturonase content of S. rolfsii , suggesting a decreased infection ability on plants. Results of biochemical actions indicated that butylidenephthalide did not have any effect on the cell membrane integrity and permeability but significantly decreased nutrient contents, disrupted the mitochondrial membrane, inhibited energy metabolism and induced reactive oxygen species (ROS) accumulation of S. rolfsii . CONCLUSION Our results could provide an important reference for understanding the application potential and mechanisms of butylidenephthalide in the control of S. rolfsii . © 2023 Society of Chemical Industry.