PeAP1-mediated oxidative stress response plays an important role in the growth and pathogenicity of Penicillium expansum .

Penicillium expansum is the causal agent of post-harvest blue mold in various fruits and serves as a model for understanding fungal pathogenicity and mycotoxin production. The relevance of oxidative stress response in the growth and virulence of P. expansum has been largely unexplored. Here, we identify the transcriptional factor PeAP1 as a regulator of oxidative stress response in P. expansum . Gene expression and protein abundance of PeAP1, as well as its nuclear localization, are specifically induced by H 2 O 2 . Deletion of PeAP1 results in increased sensitivity to H 2 O 2 , and PeAP1 mutants exhibit a variety of defects in hyphal growth and virulence. PeAP1 prevents the accumulation of both intracellular H 2 O 2 during vegetative growth and host-derived H 2 O 2 during biotrophic growth. Application of an antioxidant glutathione and a NADPH oxidase inhibitor, diphenylene iodonium, to the PeAP1 mutant partially restored fungal growth and virulence. RNA sequencing analysis revealed 144 H 2 O 2 -induced PeAP1 target genes, including four antioxidant-related genes, PeGST1 , PePrx1 , PePrx2 , and PeTRX2 , that were also demonstrated to be involved in oxidative stress response and/or virulence. Collectively, our results demonstrate the global regulatory role of PeAP1 in response to oxidative stress and provide insights into the critical role of the PeAP1-mediated oxidative stress response to regulate growth and virulence of P. expansum . IMPORTANCE Reactive oxygen species are the core of host plant defense and also play a vital role in the successful invasion of host plants by pathogenic fungi. Despite its importance, the relevance of oxidative stress response in fungal growth and virulence is poorly understood in P. expansum . In this study, we reveal that the transcription factor PeAP1 acts as a central regulator of oxidative stress response in P. expansum and that there is a major link between PeAP1-mediated oxidative stress response and fungal growth and virulence. To explore the underlying mechanisms, we performed comparative transcriptomic studies and identified a number of H 2 O 2 -induced PeAP1 target genes, including four novel ones, PePrx1 , PePrx2 , PeGST1 , and PeTRX2 , whose functions were linked to PeAP1 and pathogenicity. These findings provide novel insights into the regulation mechanism of PeAP1 on growth and virulence, which might offer promising targets for control of blue mold and patulin contamination.