Integrated metabarcoding and culturomics reveal the rot-suppressive rhizoplane mycobiome of cassava across contrasting agroecological habitats.

Introduction: Cassava stem and root rot caused by Methods: Rhizoplane fungal communities from healthy and diseased plants in endemic wetlands and non-endemic uplands were profiled using Internal Transcribed Spacer amplicon sequencing, complemented by culture-dependent isolation and soil physicochemical analyses. Core taxa were identified through microbiome modeling and validated by ITS sequencing of isolates. Antagonistic activity against Results: Quality filtering retained 847,760, 1,037,834, and 539,722 high-quality paired-end reads from the upland, wetland diseased, and wetland healthy rhizoplane samples, respectively. Healthy wetland rhizoplanes exhibited higher diversity and stability than diseased counterparts (Shannon +20%; inverse Simpson +60%). Disease was associated with diversity collapse and enrichment of opportunistic taxa, whereas upland communities remained distinct and stable. A conserved core mycobiome dominated by the members of Discussion: Disease emergence coincided with loss of rhizoplane diversity and depletion of key antagonists, indicating failure of microbial resistance under edaphic stress. The consistent identification and validation of