title: Analysis of Circadian Rhythms in the Basal Filamentous Ascomycete Pyronema confluens.
abstract: Many organisms use circadian clocks to adapt to daily changes in the environment. Major insights into the molecular mechanisms of circadian oscillators have been gained through studies of the model organism Neurospora crassa; however, little is known about molecular components of circadian clocks in other fungi. An important part of the N. crassa circadian clock is the frequency (frq) gene, homologs of which can be found in Sordariomycetes, Dothideomycetes, and Leotiomycetes, but not Eurotiomycetes. Recently, we identified a frq homolog in Pyronema confluens, a member of the early-diverging Pezizomycete lineage of filamentous ascomycetes. The P. confluens FRQ shares many conserved domains with the N. crassa FRQ. However, there is no known morphological phenotype showing overt circadian rhythmicity in P. confluens. To investigate whether a molecular clock is present, we analyzed frq transcription in constant darkness, and found circadian oscillation of frq with a peak in the subjective morning. This rhythm was temperature compensated. To identify additional clock-controlled genes, we performed RNA sequencing of two time points (subjective morning and evening). Circadian expression of two morning-specific genes was verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR) over a full time course, whereas expression of two putative morning-specific and five putative evening-specific genes could not be verified as circadian. frq expression was synchronized, but not entrained by light. In summary, we have found evidence for two of the three main properties of circadian rhythms (free-running rhythm, temperature compensation) in P. confluens, suggesting that a circadian clock with rhythmically expressed frq is present in this basal filamentous ascomycete.
authors.affiliation: Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Traeger
authors.affiliation: Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780 Bochum, Germany minou.nowrousian@rub.de.
authors.forename: Minou
authors.initials: M
authors.lastname: Nowrousian
mesh_terms: D000595:Amino Acid Sequence; D057906:Circadian Clocks / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics* / Q000528:radiation effects; D054730:Protein Interaction Domains and Motifs; D016415:Sequence Alignment; D013696:Temperature
chemical_list: C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins
keywords: Pyronema confluens; circadian clock; clock-controlled genes; frequency; light-entrainment