Regulation of phenotype and secondary metabolic silencing gene clusters in Aspergillus sydowii by velvet transcription factors

Abstract

The silencing of biosynthetic gene clusters (BGCs) is a widespread phenomenon in fungal secondary metabolism. Traditional environmental induction strategies often fail to effectively activate these silent BGCs, whereas global transcription factor regulation has emerged as a powerful strategy for their activation. Therefore, this study focuses on Velvet family transcription factors VosA and VelB, investigating their functions in Aspergillus sydowii H-1 and their regulatory role in activating silent gene clusters. Phenotypic analyses revealed that AsvelB influence conidiation, colony morphology. Disruption or overexpression of AsvosA or AsvelB resulted in impaired cell wall integrity (CWI). Furthermore, the knockout strains ΔAsvelB and ΔAsvosA exhibited elevated intracellular reactive oxygen species (ROS) levels. These findings highlight their roles in maintaining cellular homeostasis and fungal physiology. Semi-quantitative PCR analysis of 19 type I polyketide synthase (PKS) genes revealed that AsvosA and AsvelB exert global regulatory effects on secondary metabolism in H-1. EVM0012129.1 was identified as a candidate PKS gene highly associated with purple pigment biosynthesis through semi-quantitative PCR and qPCR analyses. Overexpression of AsvosA enhanced purple pigment production specifically in conidia and upregulated EVM0012129.1, further supporting its critical role in pigment synthesis. These findings provide new insights into the regulatory network of AsvosA and AsvelB, highlighting their potential applications in fungal biology and metabolic engineering.