Biological Control of Green Mold in Simulated Post-harvest Chain of Citrus Fruit: Efficacy of Candida oleophila Strain O and Molecular Insight into Elicitation of Host Immune System

Managing post-harvest decays in citrus fruit without relying on conventional pesticides presents a significant challenge in modern Plant Pathology. This study aimed to evaluate the efficacy of the biological control agent Candida oleophila strain O in controlling green mold caused by Penicillium digitatum throughout various stages of the post-harvest supply chain. Using a series of in vivo experiments, different scenarios of P. digitatum infections in clementine tangerine, orange, and lemon fruit were examined, with treatments applied before, during or after infection. The study simulated typical conditions of the citrus supply chain, including picking, processing in packinghouses, and transportation, as well as cold storage and shelf-life phases. Results indicated that C. oleophila exhibited significant efficacy in reducing green mold symptoms, even at shelf-life temperatures, making it a practical alternative to conventional fungicides. Additionally, the study provided insights into the molecular mechanisms underlying the defensive response of citrus fruit to C. oleophila treatment, with up-regulation of defense-related genes observed across different fruit types. Overall, this study underscores the potential of C. oleophila as a sustainable and effective solution for managing post-harvest decays in citrus fruit within the complexities of the supply chain.