A Bacillus ‐based synthetic community: integrated growth promotion and control of fusarium root rot and black shank in tobacco
Delong Kong, Hongtao Shen, Zhengxiong Song, Xile Song, Haibang Du, Yifan Du, Wei Zheng, Yebin Kang, Pu Miao, Weidong Duan, Jianqiang XuAbstract
BACKGROUND
Soil‐borne diseases such as Fusarium root rot and black shank severely threaten tobacco ( Nicotiana tabacum L.) production.
RESULTS
We assembled a Bacillus ‐based synthetic microbial community (SynCom) from three well‐characterized strains with complementary antagonistic and plant growth‐promoting traits: B. amyloliquefaciens G12 (isolated from the tobacco rhizosphere), and two tobacco endophytic strains, B. pumilus Y4 and B. velezensis X25. Prior studies showed that G12 strongly antagonizes Fusarium oxysporum , whereas Y4 and X25 inhibit Phytophthora nicotianae . The SynCom members showed good compatibility (inhibition rate <25%) and the SynCom exhibited higher indole‐3‐acetic acid production (11.57 ± 0.24 mg·L −1 ) than any single strain. Glasshouse assays showed significant disease suppression (82.9% preventive; 65.3% curative), accompanied by enhanced activities of defense‐related enzymes and improved root traits. Root activity increased by >40%, and root length and surface area were 1.5–2.0‐fold greater than those of the single‐strain treatments. Transcriptome analysis identified 12 475 differentially expressed genes and suggested possible involvement of jasmonic acid ‐related signaling and secondary metabolism pathways in the plant response to SynCom treatment. Field trials confirmed ≤40% disease reduction and a 37.5–41.3% increase in middle‐leaf‐based estimated yield, outperforming a commercial B. subtilis product. Rhizosphere profiling showed no major change in overall community diversity and only minor, nonsignificant shifts in the relative abundance of Bacillus and Fusarium under SynCom treatment.
CONCLUSION
This Bacillus SynCom provides enhanced disease control and growth promotion relative to single‐strain treatments, with limited alteration of the overall rhizosphere community structure, supporting its potential as a sustainable strategy for the management of Fusarium root rot and black shank in tobacco. © 2026 Society of Chemical Industry.