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In this study, we isolated and sequenced eight non-allelic laccase genes from Coprinopsis cinerea ( Coprinus cinereus) homokaryon AmutBmut. These eight genes represent the largest laccase gene family identified so far in a single haploid fungal genome. We analyzed the phylogenetic relationships between these genes by intron positions, amino acid sequence conservation and similarities in promoter sequences. All deduced protein products have the laccase signature sequences L1-L4, the typical conserved cysteine and the ten histidine residues which are ligands in the two laccase copper-binding centers, T1 and T2/T3. Proteins Lcc2 and Lcc3 of Coprinopsis cinerea are most similar to the acidic, membrane-associated laccase CLAC2 from Coprinellus congregatus implicated in neutralization of acidic medium. All other laccases from the saprophyte Coprinopsis cinerea, including the well described enzyme Lcc1, form a cluster separate from these three enzymes and from various laccases of wood-rotting and plant-pathogenic basidiomycetes.

The cacao-pathogenic Moniliophthora perniciosa C-biotype is a primarily homothallic Agaricomycete of which the genome has recently become available. Searching of the genome sequence with mating type proteins from other basidiomycetes detected one or possibly two potential genes for HD1 homeodomain transcription factors, 7 or possibly 8 genes for potential pheromone receptors and five genes for putative pheromone precursors. Apparently, the fungus possesses gene functions encoded in the tetrapolar basidiomycetes in the A and B mating loci, respectively. In the tetrapolar species, the A and B mating type genes govern formation of clamp cells at hyphal septa of the dikaryon and their fusion with sub-apical cells as well as mushroom production. The C-biotype forms fused clamp cells and also basidiocarps on mycelia germinated from basidiospores and their development might be controlled by the detected genes. It represents the first example of a primarily homothallic basidiomycete where A - and B -mating-type-like genes were found. Various strategies are discussed as how self-compatibility in presence of such genes can evolve. An A -mating-type like gene for an HD2 homeodomain transcription factor is, however, not included in the available sequence representing estimated 69% coverage of the haploid genome but there are non-mating genes for other homeodomain transcription factors of currently unknown function that are conserved in basidiomycetes and also various ascomycetes.

Coprinoid mushrooms grown on wood of broad-leaf species were collected for the first time in Armenia and dikaryotic mycelial cultures were established. ITS (internal transcribed spacer) sequences identified one species as Coprinopsis strossmayeri and the other as a species closely related to Coprinellus radians. Mycelial growth and morphological features on different media are described. The pearl-white-silky colonies of C. strossmayeri are characterized by mycelial strands and by a light-yellow agar colorization. The species forms chlamydospores intercalary in its hyphae. Some hyphal ends form hyphal loops. Colonies of C. aff. radians have a characteristic yellow pigmentation and stain the agar yellowish. Hyphae are mostly clampless but at some septa, pseudoclamps are seen from which side-branches develop growing along the parental hyphae. In the mycelium of C. aff. radians, hyphal loops, hyphal swellings, cystidia and typical allocysts were observed. Both new species from Armenia show growth optima at

The fungal fruiting body or mushroom is a multicellular structure essential for sexual reproduction. It is composed of dikaryotic cells that contain one haploid nucleus from each mating partner sharing the same cytoplasm without undergoing nuclear fusion. In the mushroom, the pileus bears the hymenium, a layer of cells that includes the specialized basidia in which nuclear fusion, meiosis, and sporulation occur. Coprinopsis cinerea is a well-known model fungus used to study developmental processes associated with the formation of the fruiting body. Here we describe that knocking down the expression of Atr1 and Chk1, two kinases shown to be involved in the response to DNA damage in a number of eukaryotic organisms, dramatically impairs the ability to develop fruiting bodies in C. cinerea, as well as other developmental decisions such as sclerotia formation. These developmental defects correlated with the impairment in silenced strains to sustain an appropriated dikaryotic cell cycle. Dikaryotic cells in which chk1 or atr1 genes were silenced displayed a higher level of asynchronous mitosis and as a consequence aberrant cells carrying an unbalanced dose of nuclei. Since fruiting body initiation is dependent on the balanced mating-type regulator doses present in the dikaryon, we believe that the observed developmental defects were a consequence of the impaired cell cycle in the dikaryon. Our results suggest a connection between the DNA damage response cascade, cell cycle regulation, and developmental processes in this fungus. IN fungal cells, mating-the process equivalent to fertilizationbrings together two haploid nuclei in the same cytoplasm. It is generally thought that this process is essentially followed by nuclear fusion, resulting in a diploid nucleus that either enters meiosis immediately (as occurs in the fission yeast Schizosaccharomyces pombe) or is maintained and proliferates in the diploid state (as happens in the budding yeast Saccharomyces cerevisiae). However, in a large number of fungi, mating does not result in diploid nuclei. Instead, they form dikaryons, cells that contain one haploid nucleus from each mating partner sharing the same cytoplasm for a period of time without undergoing nuclear fusion or meiosis. These dikaryons continue to propagate, and eventually nuclear fusion will take place, which will be followed by meiosis, closing the sexual cycle (Brown and Casselton 2001).Dikaryon cell division, also called conjugate division, represents a big challenge to the cell since it has to ensure that each daughter dikaryon inherits a balance of each parental genome. For that, a complex cell cycle is required that involves distinct mechanisms to maintain heterokaryosis after cell division. For example, for a large number of Basidiomycota (e.g., the mushroom Coprinopsis cinerea), conjugate division includes the formation of a structure known as the clamp connection or clamp cell, as well as the sorting of one of the nuclei to this structure (Casselton 1978;Brown and Casselton 2001). In the...

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