[4S02e] 03. Fermentation Physiology/ Technology - Part 3

5:30 PM - 5:50 PM JST(8:30 AM - 8:50 AM UTC)

[4Ferm-12] Understanding the molecular mechanism of conidial heterogeneity

○Ken Miyazawa¹, Takashi Umeyama¹, Shogo Takatsuka¹, Yasutaka Hoshino¹, Takanori Horiguchi¹, Yasunori Muraosa¹, Yoshitsugu Miyazaki¹ (1. National Institute of Infectious Diseases (Japan))

Keywords:

filamentous fungi,conidia,dormancy breaking,Aspergillus

Dormancy breaking is a common biological phenomenon observed in plant seeds, parasites, and even bacteria, and understanding its molecular mechanisms is essential for the engineered control of these organisms. Conidia, asexual spores of fungi, are clones, but they germinate asynchronously. We recently found that D-galactosamine (D-GalN) more effectively promoted conidial dormancy breaking than D-glucose (D-Glc) in the human pathogenic fungus Aspergillus fumigatus. To identify genes involved in D-GalN-mediated dormancy breaking, we constructed several disruption strains of genes upregulated in the presence of D-GalN, based on RNA-seq results. Contrary to our expectation of finding a mutant unresponsive to D-GalN, the fluG disruptant (ΔfluG) displayed notable phenotypes: it grew earlier than the parental strain in minimal medium with D-Glc, a phenotype similar to that observed under D-GalN conditions. While FluG is essential for conidiation in A. nidulans, it is dispensable in A. fumigatus. Germination rate was ~60% of conidia of the parental strain, while ~95% of ΔfluG, and ~30% was still dormant in the parental strain at 15 h. In addition, quantitative analysis of dormancy breaking with β-1,3-glucan exposure showed that ~90% of ΔfluG conidia broke dormancy compared to ~40% of conidia of the parental strain at 6 h. These results suggest that conidial germination is heterogeneously regulated by FluG, which contributes to survival under diverse conditions, such as nutrient-limited environments.