Factors enforcing the species boundary between the human pathogens Cryptococcus neoformans and Cryptococcus deneoformans

作者：Shelby Priest, Marco A. Coelho, Verónica Mixão, Shelly Applen Clancey, Yitong Xu, Sheng Sun, Toni Gabaldón, Joseph Heitman · 发表于：PLoS Genetics · 年份：2021 · DOI：10.1371/journal.pgen.1008871 · 被引用次数：30 · 研究领域：Fungal Infections and Studies、Plant Disease Resistance and Genetics、Yeasts and Rust Fungi Studies

Hybridization has resulted in the origin and variation in extant species, and hybrids continue to arise despite pre- and post-zygotic barriers that limit their formation and evolutionary success. One important system that maintains species boundaries in prokaryotes and eukaryotes is the mismatch repair pathway, which blocks recombination between divergent DNA sequences. Previous studies illuminated the role of the mismatch repair component Msh2 in blocking genetic recombination between divergent DNA during meiosis. Loss of Msh2 results in increased interspecific genetic recombination in bacterial and yeast models, and increased viability of progeny derived from yeast hybrid crosses. Hybrid isolates of two pathogenic fungal Cryptococcus species, Cryptococcus neoformans and Cryptococcus deneoformans, are isolated regularly from both clinical and environmental sources. In the present study, we sought to determine if loss of Msh2 would relax the species boundary between C. neoformans and C. deneoformans. We found that crosses between these two species in which both parents lack Msh2 produced hybrid progeny with increased viability and high levels of aneuploidy. Whole-genome sequencing revealed few instances of recombination among hybrid progeny and did not identify increased levels of recombination in progeny derived from parents lacking Msh2. Several hybrid progeny produced structures associated with sexual reproduction when incubated alone on nutrient-rich medium in light, a no...