askosporer

Ascospores, or askospores, are the sexual spores produced by fungi in the phylum Ascomycota. They form inside sac-like cells called asci (singular: ascus) and are released to initiate new generations after fertilization. The production of ascospores is a key stage of the fungal life cycle, contributing to genetic diversity within the lineage.

Development typically begins with plasmogamy and subsequent karyogamy within an ascus, followed by meiosis. In many species, the meiotic division is followed by a mitotic division, yielding eight haploid ascospores per ascus. Asci are housed within fruiting bodies known as ascocarps, which can take various forms such as open cups (apothecia), flask-shaped structures (perithecia), or fully enclosed bodies (cleistothecia). The spores are often released when the ascus or ascocarp ruptures or responds to humidity, enabling dispersal by wind, water, or vectors.

Ascospores exhibit considerable diversity in size, shape, ornamentation, and septation, reflecting the wide range of ecological niches occupied by Ascomycota. They contrast with basidiospores produced by basidiomycete fungi. Ascospores play crucial roles in ecology and industry, including roles in decomposition, food production, and some plant diseases. The term derives from Greek roots meaning “sac” and “seed” or “spore.”