Persistent organic fertilization reinforces soil-borne disease suppressiveness of rhizosphere bacterial community

Background and aims Soil-borne diseases are an increasingly serious threat to agriculture systems. Organic fertilization would improve soil quality and microbial community as well, and thus is appreciated a promising control strategy for soil-borne diseases. Yet, how soil microbial communities mediate disease control under organic fertilization remains largely unknown. Here, we aimed to explore the microbial mechanism of controlling soil-borne diseases by organic fertilization. Methods We investigated the effects of various fertilization regimes on the soil suppressiveness toward pathogenic fungi in the peanut rhizosphere. The fertilization regimes tested were organic fertilizer, chemical fertilizers, and a combination of both. Results Uninterrupted application of organic fertilizer in peanut field plots for seven planting seasons resulted in a control of peanut root rot, with a significantly higher peanut yield. Upon organic fertilization, bacterial microbiome assembly in the rhizosphere played a key role in developing soil suppressiveness against peanut root rot; upon chemical fertilization, the potential fungal pathogens dominated the fungal microbiome assembly in the rhizosphere to boost root rot. Further, structural equation model revealed that the rhizosphere bacterial community contributed to the control of root rot. Furthermore, upon organic fertilization, the rhizosphere bacterial community strongly suppressed mycelial growth and spore germination of Fusarium sp. ACCC 36194. Conclusions Collectively, in a monocropping system, persistent organic fertilization favors the development of a protective microbial shield in the plant rhizosphere, maintaining the rhizosphere health.