Comparative transcriptome analysis revealing dormant conidia and germination associated genes in Aspergillus species: an essential role for AtfA in conidial dormancy. (December 2016)

• Record Type: Journal Article
• Authors: Hagiwara, Daisuke; Takahashi, Hiroki; Kusuya, Yoko; Kawamoto, Susumu; Kamei, Katsuhiko; Gonoi, Tohru
• Is Part Of: BMC genomics. Volume 17:Number 1(2016)
• Page Start: 1
• Page End: 18
• Publication Date: 2016-12
• Subjects: Conidia -- Dormancy -- Germination -- Aspergillus -- AtfA -- Transcriptome; Genomes -- Periodicals; Gene mapping -- Periodicals; Genomics -- Periodicals; Base Sequence -- Periodicals; Chromosome Mapping -- Periodicals; Genetic Techniques -- Periodicals; Sequence Analysis, DNA -- Periodicals; 572.8605
• DOI: 10.1186/s12864-016-2689-z
• Languages: English
• ISSNs: 1471-2164

Abstract

Abstract Background 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 acrossAspergillus fumigatus, Aspergillus niger, andAspergillus oryzae . Results We found transcripts of 687, 694, and 812 genes were enriched in the resting conidia compared with hyphae inA. fumigatus, A. niger, andA. 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 threeAspergillus 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 thatcalA -family genes encoding a thaumatin-like protein were extraordinary expressed in early germination stage in allAspergillus species tested here. InA. 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-associatedcalA and an abnormal metabolic activity were detected in the resting conidia of theatfA mutant, suggesting that AtfA was involved in the retention of conidial dormancy. Conclusions A comparison among transcriptomes of hyphae, resting conidia, and 1 h-grown conidia in the threeAspergillus 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 inAspergillus conidial dormancy.