A Cross-Domain Framework for the Dual Nature of Geotrichum and Magnusiomyces Across Plant, Food, and Clinical Systems.

The arthroconidial yeast genera Geotrichum and Magnusiomyces exhibit a striking dual nature, simultaneously acting as destructive postharvest pathogens, essential agents in dairy fermentation, and life-threatening opportunistic pathogens in immunocompromised hosts. Despite extensive domain-specific research, the mechanistic basis of this functional divergence remains poorly integrated across taxonomy, plant pathology, food microbiology, and clinical mycology. This review proposes a cross-domain framework that integrates taxonomic uncertainty, conserved molecular mechanisms, ecological plasticity, and exposure dynamics to explain this functional divergence. Here, "cross-domain" is used in a non-taxonomic sense and refers to integration across disciplinary and ecological/application contexts-plant pathology, food and dairy microbiology, and clinical mycology-rather than to the formal biological taxonomic rank Domain. The functional versatility of these yeasts can be partly interpreted through the context-dependent deployment of broadly conserved fungal mechanisms-including cell wall-degrading enzymes, CYP51-mediated sterol metabolism, secreted proteins/effectors, and stress-response pathways-operating under contrasting ecological and selective pressures, rather than by fundamentally distinct biological systems. Critically, this framework distinguishes unidirectional exposure pathways linking agricultural, food, and clinical environments from bidirectional feedback systems that may contribute to the emergence and circulation of adaptive traits. Within this perspective, we identify three cross-domain connections: a putative antifungal resistance cycle driven by converging agricultural and clinical azole selection, a dairy-clinical interface shaped by host-associated transmission and strain recombination, and a diagnostic blind spot linked to cross-reactivity in fungal detection systems. These insights are translated into testable hypotheses on genome-based species delimitation, resistance evolution, and domestication stability, providing a structured research agenda for coordinated risk assessment and resistance management within a One Health framework.