Inter- and intra-species heterogeneity in germination of Aspergillus conidia

Aspergilli are among the most abundant fungi worldwide. They degrade organic material and can be pathogens of plants and animals. Aspergilli spread by forming high numbers of conidia. Germination of these stress resistant asexual spores is characterized by a swelling and a germ tube stage. Here, we show that conidia of Aspergillusniger,Aspergillusoryzae,Aspergillusclavatus, Aspergillusnidulans and Aspergillusterreus show different swelling and germ tube formation dynamics in pure water or in water supplemented with (in)organic nutrients. Apart from inter-species heterogeneity, intra-species heterogeneity was observed within spore populations of the aspergilli except for A.terreus. Sub-populations of conidia differing in size and/or contrast showed different swelling and germ tube formation dynamics. Together, data imply that aspergilli differ in their competitive potential depending on the substrate. Moreover, results suggest that intra-species heterogeneity provides a bet hedging mechanism to optimize survival of aspergilli.

Automated summary

Aspergilli, including Aspergillusniger, Aspergillusoryzae, Aspergillusclavatus, Aspergillusnidulans, and Aspergillusterreus, are highly abundant fungi with the ability to degrade organic material and act as pathogens. This study found that the swelling and germ tube formation dynamics of conidia from these Aspergillus species differed in pure water and water supplemented with various nutrients. Intra-species heterogeneity was also observed, except for A.terreus, with sub-populations of conidia showing different dynamics based on size and/or contrast. These findings suggest that aspergilli exhibit different competitive potentials and have bet hedging mechanisms to optimize survival.