Time series transcriptomics using A. fumigatus MFIG001 and sltA null strains

Germination of inhaled A. fumigatus conidia is necessary sequitur for infection. Germination of conidia starts with breaking of dormancy which is initiated by an increase of the cellular perimeter in a process termed isotropic growth. This swelling phase is followed by polarized growth, resulting in the formation of a germ tube. The multinucleate tubular cells exhibit tip growth from the hyphae after which lateral branches emerge to form the mycelial network. The regulatory mechanisms governing conidial germination are not well defined. In this study, we identified a novel role for the transcription factor SltA in the orchestration of germination and hyphal development. Conidia lacking sltA fail to appropriately regulate isotropic growth and begin to swell earlier and subsequently switch to polarized growth faster. Additionally, hyphal development is distorted in a sltA null isolate as hyphae are hyper-branching, wider, and show branching at the apical tip. A transcriptome analysis of different stages of early growth was carried out to assess the regulatory role of SltA. Germination of conidia is crucial within its asexual life cycle and plays a critical role during the infection in the human host. Precluding germination could be a promising strategy considering the role of germination in Aspergillus spp. pathogenicity. With an expanding knowledge of germination and its different morphotypes, more advances can be made towards potential anti germination targets for therapy.