[Objective] Animal sera have the potential to induce predatory organ formation in nematode-trapping fungi, while the specific mechanism remains unclear. This study systematically compared the inductive effects of different animal sera on predatory organ formation in nematode-trapping fungi, determined the optimal serum type and concentration, and identified and validated key synergistic active metabolites, aiming to provide a basis for elucidating the chemical signaling mechanisms underlying predatory organ formation and for applications in agricultural biocontrol. [Methods] D. dactyloides capable of producing constricting rings was used as the model strain. Horse, pig, sheep, and bovine sera at different concentrations were applied in induction cultures to determine the optimal induction conditions. Constricting ring development was monitored over time. Ring inflation was assessed by stimulation with 55 ℃ hot water, and trapping and digestion activities against Caenorhabditis elegans were further evaluated. Untargeted metabolomic profiling was performed for horse, pig, and bovine sera with different inductive effects, followed by differential metabolite screening and clustering analysis. Lyso-platelet-activating factor C-16(lyso-PAF C-16), linoleic acid (LA), and glycochenodeoxycholic acid (GCDCA) were subsequently tested in synergistic induction assays. [Results] All the sera were able to induce constricting ring formation, although their induction efficiencies differed markedly. Horse serum showed the strongest induction activity at concentrations of 0.5%-1%. A small number of constricting rings appeared at 48 h, and ring formation peaked at 72-96 h. Rings formed at 48 h could not be stimulated to inflate, whereas those formed at 96 h exhibited efficient inflation and effective nematode trapping and digestion. Metabolomic analysis revealed clear separation among serum groups and identified several candidate metabolites enriched in horse serum. Functional validation showed that GCDCA significantly increased constricting ring formation when combined with 1% horse serum, producing the strongest effect at 0.04 μmol/L. [Conclusion] This study establishes a robust induction system for constricting ring formation in D. dactyloides, clarifies the optimal induction conditions and time, and identifies GCDCA as a key synergistic factor that promotes constricting ring formation.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |