Infection by dsRNA viruses is associated with enhanced sporulation efficiency in Saccharomyces cerevisiae

Abstract

Upon starvation diploid cells of the facultative sexual yeast Saccharomyces cerevisiae undergo sporulation, forming four metabolically quiescent and robust haploid spores encased in a degradable ascus. All endosymbionts, whether they provide net benefits or costs, utilize host resources; in yeast, this should induce an earlier onset of sporulation. Here, we tested whether the presence of endosymbiotic dsRNA viruses (M satellite and L‐A helper) correspond with higher sporulation rate of their host, S. cerevisiae. We find that S. cerevisiae hosting both the M and L‐A viruses (so‐called “killer yeasts”) have significantly higher sporulation efficiency than those without. We also found that the removal of the M virus did not reduce sporulation frequency, possibly because the L‐A virus still utilizes host resources with and without the M virus. Our findings indicate that either virulent resource use by endosymbionts induces sporulation, or that viruses are spread more frequently to sporulating strains. Further exploration is required to distinguish cause from effect.

Astrovirology: how viruses enhance our understanding of life in the Universe

“…Throughout extreme environmental conditions, viruses can also extend protection to their hosts. For instance, viruses can confer host heat tolerance ( Márquez et al, 2007 ), and carry genes for sporulation that may drive their host to form an inactive spore, that is robust to unfavourable conditions ( Trubl et al, 2018 ; Van Goethem et al, 2019 ; Pelusi et al, 2021 ; Travers et al, 2022 ). In another instance, viruses allow photosynthesis in cyanobacteria under desiccating conditions ( Azua-Bustos et al, 2012 ).…”