RNA-Seq assay identifies potential regulon and downstream targets of Msd1 under mating-inducing and -repressing conditions in a global basidiomycete pathogen

Here, we identified a novel transcription factor, Msd1, that plays a crucial role in activating meiosis in C. neoformans. Deletion of MSD1 abolished pre-meiotic diploidization, basidial differentiation, meiosis and the subsequent sporulation. Conversely, overexpression of MSD1 is sufficient to drive meiosis and the formation of meiotic spores in the absence of the external mating-inducing cues or the internal genetic factors of the mating pathway.

Consistently, multiple evolutionarily conserved meiosis-specific genes are transcriptionally regulated by Msd1. Furthermore, Msd1 targets two downstream RNA binding proteins, Csa1 and Csa2, to ensure successful meiosis and sporulation in this species. Collectively, our findings establish this novel transcription factor as the master regulator of meiotic entry in this basidiomycete fungus.