title: Comparative transcriptome analysis revealing dormant conidia and germination associated genes in Aspergillus species: an essential role for AtfA in conidial dormancy.
abstract: Fungal conidia are usually dormant unless the extracellular conditions are right for germination. Despite the importance of dormancy, little is known about the molecular mechanism underlying entry to, maintenance of, and exit from dormancy. To gain comprehensive and inter-species insights, transcriptome analyses were conducted across Aspergillus fumigatus, Aspergillus niger, and Aspergillus oryzae.
  
  
  
  We found transcripts of 687, 694, and 812 genes were enriched in the resting conidia compared with hyphae in A. fumigatus, A. niger, and A. oryzae, respectively (conidia-associated genes). Similarly, transcripts of 766, 1,241, and 749 genes were increased in the 1 h-cultured conidia compared with the resting conidia (germination-associated genes). Among the three Aspergillus species, we identified orthologous 6,172 genes, 91 and 391 of which are common conidia- and germination-associated genes, respectively. A variety of stress-related genes, including the catalase genes, were found in the common conidia-associated gene set, and ribosome-related genes were significantly enriched among the germination-associated genes. Among the germination-associated genes, we found that calA-family genes encoding a thaumatin-like protein were extraordinary expressed in early germination stage in all Aspergillus species tested here. In A. fumigatus 63 % of the common conidia-associated genes were expressed in a bZIP-type transcriptional regulator AtfA-dependent manner, indicating that AtfA plays a pivotal role in the maintenance of resting conidial physiology. Unexpectedly, the precocious expression of the germination-associated calA and an abnormal metabolic activity were detected in the resting conidia of the atfA mutant, suggesting that AtfA was involved in the retention of conidial dormancy.
  
  
  
  A comparison among transcriptomes of hyphae, resting conidia, and 1 h-grown conidia in the three Aspergillus species revealed likely common factors involved in conidial dormancy. AtfA positively regulates conidial stress-related genes and negatively mediates the gene expressions related to germination, suggesting a major role for AtfA in Aspergillus conidial dormancy.
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan. dhagi@chiba-u.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hagiwara
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.|Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kusuya
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kawamoto
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kamei
authors.affiliation: Medical Mycology Research Center (MMRC), Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8673, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Gonoi
mesh_terms: D001230:Aspergillus / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D005656:Fungal Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D063990:Gene Ontology; D056726:Genetic Association Studies; D059014:High-Throughput Nucleotide Sequencing; D019655:Quantitative Trait, Heritable; D012331:RNA, Fungal; D013172:Spores, Fungal / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D059467:Transcriptome
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D014157:Transcription Factors
keywords: Aspergillus; AtfA; Conidia; Dormancy; Germination; Transcriptome