Fecha de publicación: -- Fuente: PubMed "Tobacco production" mSphere. 2026 Aug 31:e0050126. doi: 10.1128/msphere.00501-26. Online ahead of print.ABSTRACTPhytophthora nicotianae is a persistent and highly destructive soilborne oomycete that causes black shank of tobacco and continues to threaten its production despite integrated management. Although soil microbiomes are increasingly recognized as important components of disease outcomes, little is known about how soil microbial communities vary with P. nicotianae DNA concentrations and black shank pressure under field conditions. We examined relationships among 17 soil physicochemical properties, microbial community features, P. nicotianae DNA levels, and black shank outcomes in three flue-cured tobacco fields sampled repeatedly throughout one growing season. Phytophthora nicotianae DNA concentrations were associated with several soil physicochemical properties. The field with the lowest disease pressure had higher microbial alpha diversity, the simplest bacterial network, and a moderately complex fungal network. In contrast, the field with the highest black shank mortality showed the lowest alpha diversity, the most complex bacterial network, and the least complex fungal network. Over the growing season, microbial alpha diversity declined, and disease outcomes were associated with field-specific shifts in microbial community composition. Trichoderma, Fusarium, and Globodera were most abundant in the high-disease field, whereas multiple bacterial groups within Firmicutes, Proteobacteria, and Actinobacteriota were negatively associated with P. nicotianae in the lower-disease fields. These results indicate that P. nicotianae DNA abundance and black shank pressure are associated with soil physicochemical properties and field-dependent patterns in microbial diversity, community composition, network topology, and several microbial taxa. Our study provides a field-based foundation for future research to experimentally test candidate microbial indicators and microbe-pathogen relationships relevant to black shank risk assessment.IMPORTANCEBlack shank is a persistent soilborne disease that threatens tobacco production and is difficult to manage because the pathogen survives in soil and disease outcomes vary from field to field. This study shows that measuring the pathogen alone may not fully explain disease risk. Across three Virginia tobacco fields, black shank pressure was linked to soil properties and differences in the soil microbial community. Fields with lower disease pressure had higher microbial diversity and different groups of bacteria associated with lower levels of Phytophthora nicotianae, the causal agent of black shank. These findings suggest that future disease-risk assessment may be improved by considering soil conditions and microbial indicators together with pathogen detection. The work provides a foundation for identifying soil and microbial features that could support more targeted and sustainable black shank management strategies.PMID:42671211 | DOI:10.1128/msphere.00501-26