# The hyphae-specific C2H2 transcription factor HscA regulates development, stress response, and mycotoxin production in Aspergillus species

## TL;DR

This study identifies a new transcription factor, HscA, that is important for the growth, stress response, and toxin production in two types of Aspergillus fungi.

## Contribution

The study introduces and characterizes a novel hyphae-specific C2H2 zinc finger transcription factor, HscA, in Aspergillus species.

## Key findings

- HscA is essential for normal asexual and sexual development in Aspergillus nidulans and Aspergillus flavus.
- Deletion of HscA leads to increased sensitivity to stress and reduced mycotoxin production in both species.
- HscA is crucial for conidial formation in A. flavus and may act as a virulence factor.

## Abstract

The zinc cluster family is the largest group of transcription factors involved in regulating fungal growth, morphology, and differentiation in Aspergillus species. In this study, we investigated hyphae-specific zinc cluster transcription factors and characterized a novel hyphae-specific Cys2His2 zinc finger transcription factor, designated HscA, in the model fungus Aspergillus nidulans and the toxigenic fungus Aspergillus flavus. Phenotypic analyses demonstrated that HscA is essential for normal asexual and sexual development in A. nidulans and A. flavus. Deletion of hscA resulted in elevated sensitivity to cell wall stress agents and an ion depletion stressor. Moreover, the hscA null mutant exhibited decreased production of sterigmatocystin in A. nidulans and aflatoxin B1 in A. flavus. Conidial production in the kernel was decreased in the ΔhscA strain compared to the control in A. flavus. Overall, these results suggest that HscA plays a pivotal role in fungal development, stress tolerance, and mycotoxin production in Aspergillus species.

Fungal growth and development are closely regulated by a variety of transcription factors. This study identified and characterized a hyphae-specific Cys2His2 zinc finger transcription factor in two Aspergillus species. HscA contains a Cys2His2 zinc finger domain and plays a crucial role in appropriate fungal development in A. nidulans and A. flavus. Particularly, HscA is involved in stress tolerance in both hyphal and conidial stages. We further demonstrated that HscA acts as a positive regulator of sterigmatocystin production in A. nidulans and is essential for proper aflatoxin B1 production in A. flavus. Additionally, our findings indicate that HscA is crucial for conidial formation in kernel assays, implying that HscA may function as a virulence factor. Overall, these findings enhance our understanding of mycotoxin production and fungal pathogenicity in Aspergillus species.