This study aimed to investigate the effects of the root exudates from Cyperus rotundus, a common weed in Guizhou tabacco fields, on the tobacco bacterial wilt pathogen Ralstonia solanacearum strain AS-1 and the biocontrol agent Bacillus velezensis strain JXF-16. Non-targeted metabolomics (LC-MS) was employed to identify the chemical composition of C. rotundus root exudates and to explore the effects of specific bioactive constituents on the two bacterial strains. Turbidimetric assays were used to measure the impact of the active compounds on bacterial growth, crystal violet staining was applied to quantify biofilm formation, and semi-solid plate culture assays were conducted to assess bacterial motility. Additionally, pot experiments were performed to evaluate the efficacy of the exogenous active compounds in controlling bacterial wilt. Results revealed that a total of 21 types of chemical compounds and 3176 active substances were detected by LC-MS. At the concentration of 50 μmol/L, myristic acid, 4-ethyloctanoic acid, ligustrazine and betaine significantly promoted the growth, biofilm formation and motility of R. solanacearum. However, at higher concentrations, the compounds exhibited inhibitory effects on bacterial growth and biofilm formation. Tetramethylpyrazine (50 μmol/L) and betaine (100 μmol/L) significantly enhanced the growth, biofilm formation and motility of B. velezensis. Conversely, lauric acid and 2-dodecylbenzenesulfonic acid at concentrations above 50 μmol/L significantly inhibited the growth, biofilm formation, and motility of both R. solanacearum and B. velezensis. Pot experiments demonstrated that lauric acid and 2-dodecylbenzenesulfonic acid at 150 μmol/L and 200 μmol/L effectively controlled bacterial wilt, with the relative control efficacies surpassing those of chemical pesticides and biocontrol agents. Notably, 2-dodecylbenzenesulfonic acid at 200 μmol/L achieved a control efficacy of 80.28%. The results would provide important theoretical insights into the role of C. rotundus root exudates within the tobacco field ecosystem and lay an applied foundation for developing novel bioactive compound-based strategies to control tobacco bacterial wilt.
| 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 |