Soil fungal networks exhibit sparser interactions than bacterial networks in diseased banana plantations.

Soil microorganisms play a crucial role in suppressing soil-borne diseases. Although the composition of microbial communities in healthy versus diseased soils is somewhat understood, the interplay between microbial interactions and disease incidence remains unclear. This study used 16S rRNA and fungal internal transcribed spacer (ITS) sequencing to investigate the bacterial and fungal community composition in three soil types: forest soil (Z), soil from healthy banana plantations (H), and soil from diseased banana plantations (D). Principal coordinate analysis revealed significant differences among the bacterial and fungal community structures of the three soil types. Compared with those in forest soil, bacterial and fungal diversities significantly decreased in diseased banana soil. Key microorganisms, including the bacteria Chloroflexi and Pseudonocardia and the fungi Mortierellomycota and Moesziomyces, were significantly increased in soil from diseased banana plantations. Redundancy analysis revealed that total nitrogen and available phosphorus were the primary drivers of the soil microbial community structure. The neutral community model posited that the bacterial community assembly in banana plantations is predominantly governed by stochastic processes, whereas the fungal community assembly in banana plantations is primarily driven by deterministic processes. Furthermore, co-occurrence network analysis revealed that the proportion of positive edges in the fungal network of soil from diseased banana plantations was 5.92 times lower than that in soil from healthy banana plantations, and its fungal network structure was sparse and simple. In conclusion, reduced interactions within the fungal network were significantly linked to the epidemiology of Fusarium wilt. These findings underscore the critical role of soil fungal communities in modulating pathogens.

Importance: Soil microorganisms are pivotal in mitigating soil-borne diseases. The intricate mechanisms underlying the interactions among microbes and their impact on disease occurrence remain enigmatic. This study underscores that a reduction in fungal network interactions correlates with the incidence of soil-borne Fusarium wilt.