Life History and Developmental Processes in the BasidiomyceteCoprinus cinereus

Abstract

SUMMARY Coprinus cinereus has two main types of mycelia, the asexual monokaryon and the sexual dikaryon, formed by fusion of compatible monokaryons. Syngamy (plasmogamy) and karyogamy are spatially and temporally separated, which is typical for basidiomycetous fungi. This property of the dikaryon enables an easy exchange of nuclear partners in further dikaryotic-monokaryotic and dikaryotic-dikaryotic mycelial fusions. Fruiting bodies normally develop on the dikaryon, and the cytological process of fruiting-body development has been described in its principles. Within the specialized basidia, present within the gills of the fruiting bodies, karyogamy occurs in a synchronized manner. It is directly followed by meiosis and by the production of the meiotic basidiospores. The synchrony of karyogamy and meiosis has made the fungus a classical object to study meiotic cytology and recombination. Several genes involved in these processes have been identified. Both monokaryons and dikaryons can form multicellular resting bodies (sclerotia) and different types of mitotic spores, the small uninucleate aerial oidia, and, within submerged mycelium, the large thick-walled chlamydospores. The decision about whether a structure will be formed is made on the basis of environmental signals (light, temperature, humidity, and nutrients). Of the intrinsic factors that control development, the products of the two mating type loci are most important. Mutant complementation and PCR approaches identified further genes which possibly link the two mating-type pathways with each other and with nutritional regulation, for example with the cAMP signaling pathway. Among genes specifically expressed within the fruiting body are those for two galectins, β-galactoside binding lectins that probably act in hyphal aggregation. These genes serve as molecular markers to study development in wild-type and mutant strains. The isolation of genes for potential non-DNA methyltransferases, needed for tissue formation within the fruiting body, promises the discovery of new signaling pathways, possibly involving secondary fungal metabolites.

Fruiting body development in Coprinus cinereus: regulated expression of two galectins secreted by a non-classical pathway The GenBank accession number for the sequence reported in this paper is AF130360

“…Under these conditions, fruiting body development initiated with the formation of hyphal knots in the dark period. Upon light induction, these hyphal knots can differentiate into initials and primordia, where all the tissues that comprise the mushroom are present (see reviews by Moore, 1998 ;Ku$ es, 2000) (Fig. 1).…”

“…1). When exposed to light, hyphal knots develop into a compact hyphal mass, termed an initial (reviewed by Moore et al, 1979 ;Ku$ es, 2000) (Fig. 1).…”

“…In particular, such homokaryons can have the ability to form fruiting bodies (Swamy et al, 1984), demonstrating the regulatory function of the matingtype loci in fruiting body development. In the initial stage of fruiting body (basidiocarp) development, hyphae form localized, highly branched structures termed hyphal knots (Matthews & Niederpruem, 1972 ; reviewed by Ku$ es, 2000) (Fig. 1).…”

“…Fruiting body development in the heterothallic basidiomycetous fungus Coprinus cinereus is a process involving various hyphal-hyphal (cell-cell) interactions and occurs as a response of the mycelium to external stimuli such as light, temperature and depletion of nutrients (Matthews & Niederpruem, 1972 ; reviewed by Moore, 1998 ;Ku$ es, 2000). Fruiting bodies form on the dikaryon, a mycelium that is generated through mating of compatible primary mycelia (monokaryons) obtained from germination of the haploid basidiospores produced in the hymenium of fruiting bodies.…”

Diversity, population genetics, and evolution of macrofungi associated with animals

“…These organisms have autodigestive chitinases and digest themselves (Nagy et al 2013). Their basidiospores are black and released within a brown liquid to the dung during which the caps autolyze, typically within a few hours after basidiospores are formed (Kues 2000). Because of the mucous liquid around them, these spores cannot be dispersed by wind and may be scattered to a limited extent by rain.…”