An exocyst component, Sec5, is essential for ascospore formation in .

In this study, we identified Sec5 in , a homologue of Sec5 in and a possible exocyst component of the fungus. To examine how Sec5 affects the life cycle of , we generated null mutant strains of the gene (). The strains showed a strong reduction in hyphal growth and a slight reduction in pathogenicity. In sexual reproduction, they possessed the ability to develop pseudothecia. However, all ascospores were aborted in any of the asci obtained from crosses between and the wild-type. Our cytological study revealed that the abortion was caused by impairments of the post-meiotic stages in ascospore development, where ascospore delimitation and young spore elongation occur.