Rhizobacterial Bacillus enrichment in soil enhances smoke tree resistance to Verticillium wilt

Authors: GUO, RUIFENG - Beijing Forestry University; LI, BIMENG - Beijing Forestry University; ZHAO, YIZE - Beijing Forestry University; TANG, CHEN - Beijing Forestry University; Klosterman, Steven; WANG, YONGLIN - Beijing Forestry University

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2024
Publication Date: 6/19/2024
Citation: Guo, R., Li, B., Zhao, Y., Tang, C., Klosterman, S.J., Wang, Y. 2024. Rhizobacterial Bacillus enrichment in soil enhances smoke tree resistance to Verticillium wilt. Plant Cell and Environment. 47(11):4086-4100. https://doi.org/10.1111/pce.15004.
DOI: https://doi.org/10.1111/pce.15004

Interpretive Summary: The fungus Verticillium dahliae is a broad host range plant pathogen that causes a disease known as Verticillium wilt on numerous important crops and ornamental plants, such as trees. The study of the belowground microbial populations and their associations with plants can provide insight into which microbes are associated with healthy and diseased plants. In this study, the microbial populations in below ground samples of two stands of smoke trees with Verticillium wilt were examined for the enrichment of taxa, revealing that the bacterial genus Bacillus was dominant in soils of the diseased areas. Isolation of bacteria from the soil and inoculation of smoke tree seedlings with V. dahliae and the different Bacillus strains revealed that B. subtilis was suppressive to Verticillium wilt disease. Additionally, application of fungicide propiconazole in combination with the bacterium Bacillus subtilis provided Verticillium wilt control on smoke tree seedlings. This work provides insight into new methods for Verticillium wilt disease control.

Technical Abstract: Verticillium wilt, caused by the soilborne fungus Verticillium dahliae, poses a serious threat to the health of more than 200 plant species worldwide. Although plant rhizosphere-associated microbiota can influence plant resistance to V. dahliae, empirical evidence underlying Verticillium wilt resistance of perennial trees is scarce. In this study, we systemically investigated the effect of the soil microbiota on the resistance of smoke trees (Cotinus coggygria) to Verticillium wilt using field, greenhouse and laboratory experiments. Comparative analysis of the soil microbiota in the two stands of smoke trees suggested that Bacillus represented the most abundant and key microbial genus related to potential disease suppression. Smoke tree seedlings were inoculated with isolated Bacillus strains, which exhibited disease suppressiveness and plant growth-promoting properties. Furthermore, repletion of Bacillus agents to disease conducive soil significantly resulted in reduced incidence of smoke tree wilt and increased resistance of the soil microbiota to V. dahliae. Finally, we explored a more effective combination of Bacillus agents with the fungicide propiconazole to combat Verticillium wilt. The results establish a foundation for the development of an effective control for this disease. Overall, this work provides a direct link between Bacillus enrichment and disease resistance of smoke trees, facilitating the development of green control strategies and measurements of soil-borne diseases.