In the present study, the inhibitory potential of 14 Trichoderma strains (isolated from Asarum rhizosphere) was investigated against Sclerotinia asari using the plate dilution method. The activity of antioxidant enzymes viz; catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and malondialdehyde (MDA) in S. asari treated with the two Trichoderma strains was also evaluated. Untargeted metabolomic analysis by using LC/MS analysis was carried out to determine differential metabolites in T. hamatum (A26) and T. koningiopsis (B30) groups. Moreover, transcriptome analysis of S. asari during the inhibition of S. asari by B30, and A26 compared with the control (CK) was performed. Results indicated that inhibition rates of T. koningiopsis B30, and T. hamatum A26 were highest compared to other strains. Similarly, non-volatile metabolites extracted from the B30 strain showed a 100% inhibition of S. asari. The activity of CAT, SOD, and POD decreased after treatment with A26 and B30 strains while increasing MDA content of S. asari. Antifungal activity of differential metabolites like abamectin, eplerenone, behenic acid, lauric acid, josamycin, erythromycin, and minocycline exhibited the highest inhibition of S. asari. Transcriptome analysis showed that differentially expressed genes were involved in many metabolic pathways which subsequently contributed toward antifungal activity of Trichoderma. These findings suggested that both Trichoderma strains (B30 and A26) could be effectively used as biocontrol agents against Sclerotinia disease of Asarum.

Background:Asarum heterotropoides and Asarum sieboldii are commonly used in traditional Chinese medicine. However, little is known about how they differ in terms of essential oil (EO) and ethanol extract (EE) content and composition. Moreover, the effect of various geographical locations on the essential oil (EO), ethanol extract (EE), and asarinin content of different Asarum samples remains unknown. We tested four root-drying methods, i.e., soil removal and shade drying (P1), water washing and shade drying (P2), and water washing and drying at 30 °C (P3) and 40 °C (P4). We used LC-MS and GC-MS to investigate these differences. We also investigated the pharmacodynamic effects of EO and EE. Results: Overall, the EO, EE and asarinin contents of the analysed samples were 19.21–51.53 μL.g⁻¹, 20.00–45.00 μL.g⁻¹, and 1.268–2.591 mg.g⁻¹, respectively. P1 treatment yielded the lowest volatile oil content compared to the other three treatments. GC-MS analysis revealed 78 EO components. Among the six major EO components, eucarvone, 3,5-dimethoxytoluene, and methyl eugenol were higher in A. heterotropoides than in A. sieboldii. However, the latter had a higher myristicin content. LC-MS analysis identified 888 EE components in roots and leaves of A. heterotropoides and A. sieboldii; 317 differentially accumulated metabolites were identified. EO and EE showed a dose-dependent reduction in the degree of swelling and an increase in the inhibition rate of drug concentration on acetic acid writhing in mice. Asarum EO proved to be more effective than EE in the pharmacodynamic study. Conclusions: We conclude that Asarum species show inter- and intra-specific differences in EO and EE content and composition, which may influence the pharmacodynamics of Asarum root extracts.

Asarum heterotropoides Fr. var. mandshuricum (Maxim.) is a perennial herb native to China. Its essential oil components and asarinin are health-promoting compounds. However, cultivation under natural light can affect the growth and secondary metabolite yield of this sciophyte. Adjustment of light irradiance may be beneficial in this respect. Here, we applied six types of filtered solar irradiance by using filter films of red (I), yellow (II), blue (III), green (IV), purple (V) and 50% sunlight (VI). We measured net photosynthetic rate (APn), activity of phenylpropanoid biosynthetic enzymes, asarinin content, and essential oil content and composition. Light quality treatments V and VI resulted in increased APn, enzyme activities, asarinin content and essential oil content. Samples harvested in September 2020 had relatively higher contents and enzyme activities compared to those harvested in July 2020. Elemicin, 2,5-dimethoxytoluene and methyleugenol accumulated at higher levels in response to light quality V. Light qualities III and IV showed promising results for several compounds. Overall, we conclude that controlling the light conditions in growing environments promotes the amount of asarinin and essential oil by regulating photosynthesis and the activities of phenylpropanoid biosynthetic enzymes.