Unveiling genome plasticity as a mechanism of non-antifungal-induced antifungal resistance in Cryptococcus neoformans

<i>Cryptococcus neoformans</i>, a critical priority pathogen designated by the World Health Organization, poses significant therapeutic challenges due to the limited availability of treatment options. The emergence of antifungal resistance, coupled with cross-resistance, further hampers treatment efficacy. Aneuploidy, known for its ability to induce diverse traits, including antifungal resistance, remains poorly understood in <i>C. neoformans</i>. We investigated the impact of tunicamycin, a well-established ER stress inducer, on aneuploidy formation in <i>C. neoformans</i>. Our findings show that both mild and severe ER stress induced by tunicamycin lead to the formation of aneuploid strains in <i>C. neoformans</i>. These aneuploid strains exhibit diverse karyotypes, with some conferring resistance or cross-resistance to antifungal drugs fluconazole and 5-flucytosine. Furthermore, these aneuploid strains display instability, spontaneously losing extra chromosomes in the absence of stress. Transcriptome analysis reveals the simultaneous upregulation of multiple drug resistance-associated genes in aneuploid strains. Our study reveals the genome plasticity of <i>C. neoformans</i> as a major mechanism contributing to non-antifungal-induced antifungal resistance.