The novel spore-specific regulator SscA governs Aspergillus conidiogenesis.

Abstract

A major group of fungi produces asexual spores (conidia) for propagation and infection. Despite the critical role of conidia, the underlying mechanism of spore formation, integrity, and viability is not fully elucidated. In this study, we have identified and investigated the role of the spore-specific transcription factor (TF) SscA in three representative Aspergillus species. Comparative transcriptomic analyses have revealed that 25 TF encoding genes showed higher mRNA levels in conidia than in hyphae in three species. Functional and transcriptomic analyses of the 25 genes have identified SscA as a key TF for conidial formation, maturation, germination, integrity, amino acid production, and secondary metabolism in Aspergillus nidulans conidia. Importantly, the roles of SscA are conserved in other Aspergillus species. Altogether, our study demonstrates that SscA is a novel spore-specific TF that governs production of intact and functional conidial formation in Aspergillus species. ImportanceFilamentous fungi produce myriads of asexual spores are main reproductive particles and act as infectious or allergenic agents. Although the serial of asexual sporogenesis is coordinated by various genetic regulators, there remain uncharacterized transcription factors in Aspergillus. To understand the underlying mechanism of spore formation, integrity, and viability, we have performed comparative transcriptomic analyses on three representative Aspergillus species and found a novel spore-specific transcription factor, SscA. SscA has a major role in conidial formation, maturation and dormancy, and germination in Aspergillus nidulans. Transcriptomic data indicate that SscA coordinates conidial wall integrity, amino acid production, and secondary metabolism in A. nidulans conidia. Furthermore, the roles of SscA are conserved in other Aspergillus species. Our findings that the novel SscA has broad functions in Aspergillus conidia will help to understand conidiogenesis of Aspergillus species.