Regulatory basis for reproductive flexibility in a meningitis-causing fungal pathogen

Sexual reproduction facilitates infections and adaptations in Cryptococcus pathogens that cause fatal meningoencephalitis and have two distinct sexual cycles (bisexual and unisexual). Here, by constructing a gene-deletion strains library for transcription factor (TF) genes in Cryptococcus deneoformans, we explore spatiotemporal TF networks in sequential stages of mating community development and identified key regulators that determine processes specific to different reproductive modes. We show that the TFs crucial for bisex-specific syngamy coordinately induce the expression of a specific group of genes centered on the ancient mating determinants, which includes FMP1, a previously unidentified component of the conserved fungal mating pathway. Furthermore, we identify that a recently evolved regulatory cascade mediates the pre-meiotic autodiploidization process that defines Cryptococcus unisex, supporting that unisex is a recent evolutionary innovation. Our findings indicate that genetic circuits with different evolutionary ages govern the hallmark events distinguishing unisex and bisex, enabling reproductive flexibility that benefits Cryptococcus pathogenicity. 18 samples contain wildtype, vea2Δ, CQS2OE and pum1Δ at two time points with 3 repeats, 8 samples contain CQS2 ChIP-Seq data with FLAG and mCherry tag with two repeats. For RNA-seq analyses, strains were cultured in YPD liquid medium at 30 °C overnight. The cells were washed with ddH2O and spotted on V8 medium to stimulate unisexual reproduction. The level and integrity of RNA in each sample were evaluated using a Qubit RNA Assay Kit on a Qubit 2.0 Flurometer (Life Technologies, CA, USA) and RNA Nano 6000 Assay Kit with the Bioanalyzer 2100 system (Agilent Technologies, CA, USA), respectively. RNA purity was assessed using a Nano Photometer spectrophotometer (IMPLEN, CA, USA). The transcriptome libraries were generated using the VAHTS mRNA-seq v2 Library Prep Kit (Vazyme Biotech Co., Ltd, Nanjing, China) according to the manufacturer?s instructions.