Functional analysis of apple defense protein MdACBP and screening of interacting proteins with Penicillium expansum

As the primary fungal pathogen of apple (Malus domestica) blue mold, Penicillium expansum severely affects the post-harvest quality of apples. Protein-protein interactions play a crucial role in plant resistance to biotic stress. Here, we re-analyse the previously obtained proteomic data from apples infected with Penicillium expansum and identify numerous differentially expressed proteins that may significantly contribute to their defence mechanisms. The MdACBP protein is expressed during the defence response of apples against P. expansum infection and exhibits a high binding affinity for acyl-CoA and phospholipids, suggesting a crucial role in the apple defence mechanism. In this study, through bioinformatics analysis, subcellular localization, yeast two-hybrid assays, and interaction site prediction, we identified MdACBP as a member of the ACBP1 family, localised in the cytoplasm. During P. expansum infection, MdACBP interacts with A0A0A2IS21 (Pe25) with a confidence score of 0.8783. In conclusion, our findings suggest that MdACBP and Pe25 act together to defend against P. expansum infection in apples, providing a theoretical basis for the prevention of P. expansum induced blue mold in apples.