Forward and reverse genetic dissection of morphogenesis identifies filament-competent Candida auris strains

Candida auris is an emerging healthcare-associated pathogen of global concern. Recent reports have identified C. auris isolates that grow in cellular aggregates or filaments, often without a clear genetic explanation. To investigate the regulation of C. auris morphogenesis, we applied an Agrobacterium-mediated transformation system to all four C. auris clades. We identified aggregating mutants associated with disruption of chitin regulation, while disruption of ELM1 produced a polarized, filamentous growth morphology. We developed a transiently expressed Cas9 and sgRNA system for C. auris that significantly increased targeted transformation efficiency across the four C. auris clades. Using this system, we confirmed the roles of C. auris morphogenesis regulators. Morphogenic mutants showed dysregulated chitinase expression, attenuated virulence, and altered antifungal susceptibility. Our findings provide insights into the genetic regulation of aggregating and filamentous morphogenesis in C. auris. Furthermore, the genetic tools described here will allow for efficient manipulation of the C. auris genome.