Divergent pathogenic strategies of Fusarium species in Panax notoginseng and biocontrol by a Bacillus-Serratia consortium

Fusarium-induced root rot severely constrains Panax notoginseng cultivation, yet the differential pathogenicity and ecological interactions among coexisting Fusarium species remain poorly understood. By isolating three pathogenic isolates—Fusarium oxysporum LP1 and F. solani LP2/LP3—we uncovered a distinct ecological trade-off: F. oxysporum exhibits higher niche occupancy, whereas F. solani demonstrates markedly greater virulence. To manage this disease, we engineered the Bacillus subtilis-Serratia marcescens synthetic microbial consortium (BS) comprising antagonistic strains XY-6 and XB-7. BS application significantly enhanced disease suppression (56%) compared with single-strain treatments (21%–25%). Mechanistic evaluations revealed a synergistic triple-mode of action: (i) direct pathogen inhibition via cell-free filtrates (38% reduction); (ii) activation of host systemic resistance, evidenced by substantially increased peroxidase (133%) and superoxide dismutase (173%) activities; and (iii) beneficial restructuring of the rhizosphere fungal community, characterized by Mortierellomycota enrichment, elevated α-diversity, and fortified microbial interaction networks. Collectively, this study illuminates the ecological trade-off between virulence and niche fitness among Fusarium species, and provides a robust, sustainable microbiome-engineering strategy for mitigating soil-borne diseases in medicinal crops.