4-Vinyl Guaiacol exists widely in rhizosphere soil of Lanzhou lily (Lilium davidii var. unicolor) and has a strong negative effect on lily planting.

• It was found for the first time that 4-Vinyl guaiacol (4-VG) existed widely in the rhizosphere soil of Lanzhou lily with high relative content. • 4-VG inhibited the growth of F. oxysporum B4 hypha, promoted spore germination, and increased fusaric acid content. • 4-VG significantly inhibited the growth and health of Lanzhou lily. • 4-VG assists the pathogen F. oxysporum B4 in infecting Lanzhou lily. Phenolics from the rhizosphere soil are a key factor that leads to obstacles in the continuous cropping system. While we tested the phenolics in the rhizosphere soil of Lanzhou lily (Lilium davidii var. unicolor), a high relative content 4-Vinyl Guaiacol (4-VG) was firstly detected. Therefore, we attempted to explore the role of 4-VG stress in Lanzhou lily physiology and disease, and the potential enhanced effects of pathogenicity in Fusarium oxysporum B4 (F. oxysporum B4). The effects of different concentrations of 4-VG (0, 0.01, 0.05, 0.1, 0.2, 0.5, 1 mM) on the growth of F. oxysporum B4 and the production of fusaric acid were examined. The result indicated that 4-VG inhibited the growth of F. oxysporum B4 hypha, promoted spore germination, and increased fusaric acid content. Furthermore, transcriptome sequencing of F. oxysporum B4 hypha after stress mediated by 0.5 mM 4-VG was performed to help characterize the response mechanism to 4-VG. Compared with the control group, differentially expressed genes (DEGs) were mainly related to the growth and fusaric acid synthesis of F. oxysporum B4. Except that, the increase of infection area formed after F. oxysporum B4 infected the squama of Lanzhou lily under the high concentration of 4-VG was measured and indicated that 4-VG played a role in the F. oxysporum B4 infection. The exogenous addition of 4-VG significantly inhibited the growth and health of Lanzhou lily. Under the dual stress of F. oxysporum B4 and different concentrations of 4-VG, it significantly enhanced the incidence and disease index of Lanzhou lily. These results suggest the key role of 4-VG from rhizosphere soil in the occurrence of Lanzhou lily Fusarium wilt. [ABSTRACT FROM AUTHOR]