Virtual screening of inhibitor against Penicillium expansum and its application for controlling blue mold decay in apples

Penicillium expansum is a major pathogen critical for the blue mold decay and patulin production in various fruits and vegetables, particularly apples, creating an urgent need to identify safer and more effective compounds for its management. In this study, two pathogenic factors of P. expansum , PeBgl1 and PeSCP, were first time targeted for virtual screening with a database (a combination of TCM Database @ Taiwan and food ingredients database) containing 20,219 molecules, and octyl gallate (OG) was identified as a common candidate inhibitor with high binding energy. Therefore, we investigated the inhibitory impacts of OG against P. expansum and patulin production in vitro and in apples. It’s revealed that OG significantly inhibited the spore germination and mycelia growth by inducing oxidative stress and compromising cell membrane integrity, as well as restrained patulin biosynthesis via suppressing the expression level of patulin synthesis genes including patE, patL , and patK. Molecular docking and dynamics simulation indicated that OG could affect the stability and function of PeBgl1 and PeSCP mainly via Van der Waals forces and hydrogen bonds. qRT-PCR analysis further demonstrated that OG directly inhibited the expression of genes encoding for PeBgl1 and PeSCP. Finally, in vivo application of OG on apples demonstrated that OG can effectively trigger the defensive enzyme system of apples and control the blue mold decay caused by P. expansum . Overall, this study emphasizes the potential of OG as a promising natural compound for the management of blue mold decay and patulin production in the post-harvest fruits and vegetables.