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Open Access Highly Accessed Research article

Transcriptional landscape of Aspergillus niger at breaking of conidial dormancy revealed by RNA-sequencing

Michaela Novodvorska1, Kimran Hayer1, Steven T Pullan1, Raymond Wilson2, Martin J Blythe2, Hein Stam3, Malcolm Stratford1 and David B Archer1*

Author Affiliations

1 School of Biology, University of Nottingham, University Park, Nottingham, NG7 2RD, UK

2 Deep Sequencing Facility, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK

3 DSM Food Specialties, Research and Development, P.O. Box 1, Delft, 2600 MA, The Netherlands

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BMC Genomics 2013, 14:246  doi:10.1186/1471-2164-14-246

Published: 11 April 2013

Abstract

Background

Genome-wide analysis was performed to assess the transcriptional landscape of germinating A. niger conidia using both next generation RNA-sequencing and GeneChips. The metabolism of storage compounds during conidial germination was also examined and compared to the transcript levels from associated genes.

Results

The transcriptome of dormant conidia was shown to be highly differentiated from that of germinating conidia and major changes in response to environmental shift occurred within the first hour of germination. The breaking of dormancy was associated with increased transcript levels of genes involved in the biosynthesis of proteins, RNA turnover and respiratory metabolism. Increased transcript levels of genes involved in metabolism of nitrate at the onset of germination implies its use as a source of nitrogen. The transcriptome of dormant conidia contained a significant component of antisense transcripts that changed during germination.

Conclusion

Dormant conidia contained transcripts of genes involved in fermentation, gluconeogenesis and the glyoxylate cycle. The presence of such transcripts in dormant conidia may indicate the generation of energy from non-carbohydrate substrates during starvation-induced conidiation or for maintenance purposes during dormancy. The immediate onset of metabolism of internal storage compounds after the onset of germination, and the presence of transcripts of relevant genes, suggest that conidia are primed for the onset of germination. For some genes, antisense transcription is regulated in the transition from resting conidia to fully active germinants.

Keywords:
Aspergillus niger; Conidia; Dormancy; Transcriptome; RNA-seq; Antisense transcription