Inhibition of respiration prompts commitment to unisexual reproduction in Cryptococcus deneoformans

In the human fungal pathogen Cryptococcus deneoformans, sexual reproduction facilitates evolution and adaptation. This fungus can undergo two sexual modes: α × a sexual reproduction and unisexual reproduction (without mating partner cooperation), with α-unisexual reproduction predominating. However, the mechanism driving commitment to α-unisexual reproduction has remained elusive. Here, through a multilayered genetic screen of transfer DNA (T-DNA) insertional mutants, we identified several mutants with enhanced unisexual reproduction but impaired α × a heterothallic mating. Genome sequencing of these mutants revealed that the T-DNA insertions are enriched in genes involved in respiration. Consistently, pharmacological inhibition of respiration recapitulated this phenotype. This respiratory-inhibition-prompted selection for unisexual development requires the filamentation activator Znf2, which directly inhibits the cyclin Cln1, resulting in cell-cycle arrest in the G2/M phase, which promotes unisexual development but functionally excludes α × a heterothallic mating. Collectively, our findings uncover a mechanism that commits unisexual reproduction through respiratory inhibition.