CPT on the inhibitory activity against Penicillium expansum and control of blue mold

Camptothecin (CPT), a natural alkaloid, exhibits potent antitumor and antifungal properties. Penicillium expansum is one of the most devastating pathogens affecting temperate fruit. Its infection can severely reduce fruit storage quality and commercial value. This study demonstrated that CPT exhibited excellent antifungal activity for P. expansum and also inhibited its accumulation of patulin. Notably, CPT (5 μg/mL) resulted in statistically significant and substantial inhibition of colony growth, spore germination, sporulation, and biomass accumulation. Gene expression analyses revealed that spore development-related genes were markedly downregulated following CPT exposure. This led to dramatic morphological damage in P. expansum spores and hyphae, as well as extensive leakage of intracellular nucleic acids and proteins. CPT treatment sharply reduced patulin content in both culture and inoculated fruit. CPT application also led to pronounced suppression of key cell wall-degrading enzymes (CWDEs). These including polygalacturonase (PG), pectin lyase (PL), cellulose (Cx), pectin methylesterase (PME), polygalacturonase transeliminase (PGTE), and pectin methylesterase transeliminase (PMTE), which are produced during fruit infection. As a result, lesion expansion was effectively halted. In summary, CPT impaired P. expansum growth by disrupting hyphal and spore development. It also inhibited cell wall-degrading enzyme activity at fruit wound sites, indicating its strong potential to mitigate postharvest blue mold.