The Genome and Development-Dependent Transcriptomes of Pyronema confluens: A Window into Fungal Evolution

Abstract

Fungi are a large group of eukaryotes found in nearly all ecosystems. More than 250 fungal genomes have already been sequenced, greatly improving our understanding of fungal evolution, physiology, and development. However, for the Pezizomycetes, an early-diverging lineage of filamentous ascomycetes, there is so far only one genome available, namely that of the black truffle, Tuber melanosporum, a mycorrhizal species with unusual subterranean fruiting bodies. To help close the sequence gap among basal filamentous ascomycetes, and to allow conclusions about the evolution of fungal development, we sequenced the genome and assayed transcriptomes during development of Pyronema confluens, a saprobic Pezizomycete with a typical apothecium as fruiting body. With a size of 50 Mb and ∼13,400 protein-coding genes, the genome is more characteristic of higher filamentous ascomycetes than the large, repeat-rich truffle genome; however, some typical features are different in the P. confluens lineage, e.g. the genomic environment of the mating type genes that is conserved in higher filamentous ascomycetes, but only partly conserved in P. confluens. On the other hand, P. confluens has a full complement of fungal photoreceptors, and expression studies indicate that light perception might be similar to distantly related ascomycetes and, thus, represent a basic feature of filamentous ascomycetes. Analysis of spliced RNA-seq sequence reads allowed the detection of natural antisense transcripts for 281 genes. The P. confluens genome contains an unusually high number of predicted orphan genes, many of which are upregulated during sexual development, consistent with the idea of rapid evolution of sex-associated genes. Comparative transcriptomics identified the transcription factor gene pro44 that is upregulated during development in P. confluens and the Sordariomycete Sordaria macrospora. The P. confluens pro44 gene (PCON_06721) was used to complement the S. macrospora pro44 deletion mutant, showing functional conservation of this developmental regulator.

Sugar transporters in the black truffle Tuber melanosporum: from gene prediction to functional characterization

“…KP718607) is 1578 bp in length and encodes for a putative protein of 525 amino acids. Tmel2281 presents from 67% to 75% identity with putative high affinity glucose transporters (Colletotrichum higginsianum CCF36074, Pyronema omphalodes XP_001938670) (Traeger et al, 2013). In the phylogenetic tree (Fig.…”

Simple Genetic Tools to Study Fruiting Body Development in Fungi

“…Fruiting body mutants are now available for many fungi other than P. anserina, including Sordaria macrospora [27], N. crassa [28], A. nidulans [29] and Coprinopsis cinerea (formely Coprinus cinereus) [30,31] and could be analyzed using similar methods. They are complementary to the now more widespread large scale analyses of transcriptomes during fruiting body development as performed in the ascomycetes Fusarium graminearum and Fusarium verticilloides [32][33][34], N. crassa [35,36], S. macrospora [37], Pyronema confluens [38], Tuber melanosporum [39][40][41], Cordyceps militaris [42] and Ophiocordyceps sinensis [43], as well as in the basidiomycetes C. cinerea [44], Moniliophthora perniciosa [45], Agrocybe aegerita [46], Lentinula edodes [47,48], Auricularia polytricha [49] and Ganoderma lucidum [50].…”

Six Key Traits of Fungi: Their Evolutionary Origins and Genetic Bases

“…The striatininteracting phosphatases and kinases complex has recently been characterized in Sordaria macrospora as a significant component of internal signaling pathways involved in fruiting body development (65,66). Several transcription factors impact fruiting body development, morphology, and morphogenesis (for more details see references [67][68][69][70]. Structural and effector genes are recruited from the cellular morphogenesis toolkit, among other genes for cell wall modifications, cytoskeletal proteins, and genes involved in protein and cell wall component biosynthesis or coding for cell wallassociated proteins.…”