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Published on: November 5, 2019
Regulatory basis for reproductive flexibility in a meningitis-causing fungal pathogen
Pengjie Hu1, Hao Ding1,2, Huimin Liu1,3
1State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
Abstract:
Pathogenic fungi of the genus Cryptococcus can undergo two sexual cycles, involving either bisexual diploidization (after fusion of haploid cells of different mating type) or unisexual diploidization (by autodiploidization of a single cell). Here, we construct a gene-deletion library for 111 transcription factor genes in Cryptococcus deneoformans, and explore the roles of these regulatory networks in the two reproductive modes. We show that transcription factors crucial for bisexual syngamy induce the expression of known mating determinants as well as other conserved genes of unknown function. Deletion of one of these genes, which we term FMP1, leads to defects in bisexual reproduction in C. deneoformans, its sister species Cryptococcus neoformans, and the ascomycete Neurospora crassa. Furthermore, we show that a recently evolved regulatory cascade mediates pre-meiotic unisexual autodiploidization, supporting that this reproductive process is a recent evolutionary innovation. Our findings indicate that genetic circuits with different evolutionary ages govern hallmark events distinguishing unisexual and bisexual reproduction in Cryptococcus.
Insights
This study explores fungal reproduction, identifying key genes controlling sexual cycles in Cryptococcus. It reveals distinct genetic circuits governing bisexual and unisexual reproduction, with FMP1 crucial for bisexual mating.
Area of Science:
- Mycology
- Genetics
- Evolutionary Biology
Background:
- Cryptococcus fungi exhibit two sexual reproduction modes: bisexual diploidization and unisexual diploidization.
- Understanding the genetic regulation of these distinct reproductive pathways is crucial for fungal biology.
Purpose of the Study:
- To investigate the roles of transcription factor gene networks in the bisexual and unisexual reproductive cycles of Cryptococcus.
- To identify novel genes and regulatory mechanisms governing fungal sexual reproduction.
Main Methods:
- Construction of a gene-deletion library for 111 transcription factor genes in Cryptococcus deneoformans.
- Analysis of gene expression and reproductive phenotypes following gene deletions.
- Comparative analysis across Cryptococcus species and Neurospora crassa.
Main Results:
- Transcription factors essential for bisexual syngamy regulate mating determinants and other conserved genes.
- Deletion of the FMP1 gene impairs bisexual reproduction in Cryptococcus deneoformans, Cryptococcus neoformans, and Neurospora crassa.
- A novel, recently evolved regulatory cascade controls pre-meiotic unisexual autodiploidization.
Conclusions:
- Distinct genetic circuits with varying evolutionary ages govern unisexual and bisexual reproduction in Cryptococcus.
- Unisexual autodiploidization represents a recent evolutionary innovation in fungal reproduction.
- FMP1 is a conserved regulator of bisexual reproduction across different fungal species.
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