The Genome and Development-Dependent Transcriptomes of Pyronema confluens: A Window into Fungal Evolution
Non-pigmented, regularly septated mycelium germinates from haploid ascospores after a few hours. First orange structures of sexual organs can be observed after two days, they consists of ascogonia (enlarged, cytoplasm-rich female structures) and antheridia (male organs). Cytoplasmic fusion and transfer of nuclei are realized by a trichogyne that grows from an ascogonium towards an antheridium; the formation of dikaryotic ascogenous hyphae begins after plasmogamy and is followed by karyogamy and meiosis (not shown). After the fourth day of incubation, young pigmented apothecia can be observed; these contain many thin paraphyses, but no mature asci yet. By the sixth to seventh day, apothecia are mature and contain numerous asci (shown in top and side view to the left and right, the middle panel shows a flattened apothecium to visualize the ascus rosette). Each ascus contains eight hyaline ascospores. With the exception of the ascogenous hyphae in which karyogamy occurs leading to a diploid nucleus (which directly undergoes meiosis to yield haploid ascospores), all hyphae, both in vegetative or sexual structures, contain haploid nuclei.