Elevated Sporulation Efficiency in Fission Yeast Schizosaccharomyces japonicus Strains Isolated from Drosophila

The fission yeast , comprising var. and var. varieties, has unique characteristics such as striking hyphal growth not seen in other species; however, information on its diversity and evolution, in particular mating and sporulation, remains limited. Here we compared the growth and mating phenotypes of 17 wild strains of , including eight var. strains newly isolated from an insect ( ). Unlike existing wild strains isolated from fruits/plants, the strains isolated from sporulated at high frequency even under nitrogen-abundant conditions. In addition, one of the strains from was stained by iodine vapor, although the type strain of var. is not stained. Sequence analysis further showed that the nucleotide and amino acid sequences of pheromone-related genes have diversified among the eight strains from , suggesting crossing between cells of different genetic backgrounds occurs frequently in this insect. Much of yeast ecology remains unclear, but our findings suggest that insects such as might be a good niche for mating and sporulation, and will provide a basis for the understanding of sporulation mechanisms via signal transduction, as well as the ecology and evolution of yeast.