SUMMARY Many Sordariomycete fungi produce flask-shaped perithecia that encapsulate meiotic cells and facilitate dispersion of sexual spores. Perithecial development represents a striking example of complex multicellularity in fungi, requiring coordinated gene regulation through transcriptional, chromatin-based, and post-transcriptional mechanisms. This review summarizes recent work to dissect sexual development in several well-studied fungi: Neurospora crassa , Sordaria macrospora , Podospora anserina , and Fusarium graminearum . Studies with these fungi have uncovered interconnected regulatory mechanisms that coordinate fruiting body development. Transcription factor networks control differentiation of perithecial tissues and cell types. Chromatin regulators, such as histone chaperones, ATP-dependent chromatin remodelers, acetyltransferases, and Polycomb Repressive Complex 2, impact major developmental transitions. In addition, post-transcriptional mechanisms that operate during sexual development play critical regulatory roles. Recoding of the transcriptome by A-to-I mRNA editing is specific to perithecia and is essential for sexual development of N. crassa and F. graminearum . Finally, sex-specific genome defense pathways protect genome integrity and are essential for the completion of meiosis in some species. We summarize recent advances and highlight the remarkable regulatory complexity underlying fruiting body development in Sordariomycete fungi. In addition, we identify key open questions for future research.
SUMMARY Reproductive control exerted by endosymbionts over their hosts is an adaptation for maintaining host-symbiont associations across generations. This strategy is particularly well-characterized in endosymbiotic bacteria (EB) associated with arthropods, in which EB of disparate species have independently evolved diverse mechanisms to manipulate host reproduction, thereby ensuring their reliable transmission across host generations. Like arthropods, fungi in the phylum Mucoromycota commonly harbor ancient and highly coevolved EB that significantly affect fungal life histories, including reproduction. In particular, the symbiosis between the mucoromycete Rhizopus microsporus and its Mycetohabitans spp. endosymbionts is significantly contingent on reproductive addiction, as removal of the symbiont results in the loss or severe impairment of host asexual and sexual reproduction. Here, we synthesize the current knowledge on sexual reproduction in mucoromycete fungi and the Rhizopus microsporus–Mycetohabitans symbiosis. We highlight current gaps in the knowledge of mucoromycete reproduction as well as present novel hypotheses for studying these interactions based on the understanding of reproductive manipulation in arthropods.
SUMMARY Species of several mushroom genera, among them Psilocybe and Inocybe , biosynthesize psilocybin, the prodrug to the powerful psychotropic and perception-altering analog, psilocin. While “magic” mushrooms are popular as recreational drugs, advanced clinical trials have shown that psilocybin is a valuable future (and, in some countries, available) medication against depression and anxiety. In this review article, we focus on the metabolic processes leading to psilocybin in the fungal cell and present the biosynthetic enzymes, their structures, and the reactions catalyzed. Remarkably, mushrooms have evolved psilocybin biosynthesis twice independently, involving genes and enzymes that are only distantly related or unrelated altogether. We also present routes on how this iconic natural product can be made biocatalytically in vitro or in heterologous hosts in vivo . Despite substantial progress in psilocybin research over the past decade, we present unsolved questions that remain for the current and the next generation of researchers.
