Oxygenase Ppo-Regulated Moldy Volatiles Affect Growth, Pathogenicity and Patulin Biosynthesis of Penicillium expansum Through G Protein Signaling

Precocious sexual inducer (psi)-producing oxygenases (Ppos) participate in the production of C8 moldy volatile compounds (MVOCs), and these compounds could act as signal molecules modulating G protein signaling cascades, which participates in the growth and development, secondary metabolisms and pathogenicity of filamentous fungi. In this study, PePpoA and PePpoC proteins were identified in <i>Penicillium expansum</i>. The deletion of <i>ppoA</i> decreased C8 MVOC production in <i>P. expansum</i>, while they were not detected in the <i>ΔppoC</i> strain (<i>p</i> < 0.05). In addition, down-regulated cAMP/PKA and PKC/PLC signaling showed in the two mutants (<i>p</i> < 0.05). The two mutants showed slow colony growth and down-regulated expression of genes regulating spore development (<i>abaA</i>, <i>wetA</i>, <i>brlA</i> and <i>vosA</i>) with broken morphology of spore and hyphae. In addition, the two mutants had decreased pathogenicity on apple fruit and less patulin production in vitro and in vivo. Compared with <i>ΔppoA</i> strain, the deletion of <i>ppoC</i> inhibited G protein signaling pathways more, and the <i>ΔppoC</i> strain had more defective growth and development as well as reduced pathogenicity and patulin production (<i>p</i> < 0.05). Therefore, PePpoC proteins affect more growth and development, patulin biosynthesis and pathogenicity of <i>P. expansum</i> by regulating C8 MVOC-mediated G protein signaling transduction.