ZfpA-Dependent Quorum Sensing Shifts in Morphology and Secondary Metabolism in Aspergillus flavus
Benjamin Otoo1, Dante G Calise2, Sung Chul Park2
1Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Abstract:
Development of the fungal pathogen Aspergillus flavus involves the balance of asexual spores (conidia) and overwintering hardened hyphal masses (sclerotia). This balance is achieved by an oxylipin-based density-dependent mechanism regulating the switch from sclerotia to conidia as population density increases in A. flavus. Here, we show the transcription factor ZfpA, required for normal oxylipin synthesis, regulates the morphology switch. ZfpA overexpression (OE::zfpA) accelerates the shift leading to increased conidial production and reduced sclerotial production under conditions normally supporting sclerotia formation. In contrast, zfpA deletion (ΔzfpA) produces more sclerotia than wild-type control. These morphology changes are coupled with changes in tissue-specific secondary metabolites. Specifically, the production of four sclerotial metabolites (oxyasparasone A, hydroxyaflatrem, aflavinine, and kotanin) decreases in OE::zfpA whereas the hyphal metabolite aspergillic acid is upregulated in this mutant. Chemical profiling of OE::zfpA compared to a double mutant where the aspergillic acid non-ribosomal synthetase was deleted in the OE::zfpA background confirmed synthesis of known aspergillic acid pathway products as well as putative Val-derived pyrazinones involved in metal chelation. These findings offer valuable insights into the quorum sensing networks connecting fungal development and tissue-specific secondary metabolite production.
Insights
The transcription factor ZfpA regulates the balance between conidia and sclerotia in Aspergillus flavus. ZfpA influences fungal development and secondary metabolite production, impacting pathogen virulence.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Aspergillus flavus development relies on balancing asexual spores (conidia) and sclerotia.
- Oxylipin-based mechanisms and population density regulate the switch between these developmental forms.
- Understanding this balance is crucial for controlling fungal pathogens.
Purpose of the Study:
- To investigate the role of transcription factor ZfpA in regulating the morphology switch in Aspergillus flavus.
- To determine how ZfpA affects oxylipin synthesis and secondary metabolite production.
- To elucidate the connection between fungal development and quorum sensing.
Main Methods:
- Genetic manipulation of Aspergillus flavus, including gene deletion (ΔzfpA) and overexpression (OE::zfpA).
- Analysis of fungal morphology (conidia and sclerotia production).
- Chemical profiling of secondary metabolites using techniques like mass spectrometry.
Main Results:
- ZfpA overexpression (OE::zfpA) accelerated the conidia production and reduced sclerotia.
- ZfpA deletion (ΔzfpA) resulted in increased sclerotia production compared to wild-type.
- Morphological changes correlated with altered production of tissue-specific secondary metabolites, including decreased sclerotial metabolites and increased hyphal metabolite aspergillic acid.
Conclusions:
- ZfpA is a key regulator of the morphology switch in Aspergillus flavus.
- ZfpA influences the production of secondary metabolites linked to fungal development.
- Findings provide insights into quorum sensing networks governing fungal development and metabolite synthesis.
