The global APSES transcription factor PeStuA modulates growth, development, stress response, hydrophobicity, patulin...

Penicillium expansum, a destructive postharvest pathogen responsible for blue mold decay and produces the mycotoxin patulin, leading to considerable economic and food safety concerns. The APSES transcription factors are essential regulators in fungi, but their functions are not well understood in P. expansum. Here, we screened five members of the APSES family in P. expansum. Combining these findings with previous studies, only PEX2_045870 exhibited relatively stable and high expression during early infection stages. We constructed knockout and complementation strains of this gene and analyzed their phenotypes to investigate the role of PeStuA in P. expansum. PeStuA deletion severely inhibited growth (28.91% reduction in colony diameter), spore formation ability and hydrophobicity. And ΔPeStuA mutant exhibited markedly heightened sensitivity to osmotic stress (NaCl/KCl) and cell wall integrity stress (SDS/CR), with a 50% inhibition rate under cell wall stress. Pathogenicity test on apple showed reduction in diameter by 49.18% and fruit softening. Crucially, ΔPeStuA showed complete loss of patulin production (HPLC-UV quantification), accompanied by downregulation of patulin biosynthetic genes. RNA-seq analysis revealed 1826 significantly differently expressed genes in ΔPeStuA, including carbon metabolism, spore formation, MAPK signaling pathways, cell wall degradation enzymes and secondary metabolism in P. expansum. Collectively, this work aims to elucidate PeStuA acts as a central regulatory factor that coordinates growth, stress responses, hydrophobicity, pathogenicity and secondary metabolism in P. expansum. These findings provide novel insights and potential targets for post-harvest disease control strategies.