Inhibitory effects and mechanisms of physcion against Penicillium choerospondiatis, a serious pathogen in Phyllanthus emblica fruits

Emblica blue mold, a fungal disease caused by Penicillium choerospondiatis , poses a major threat to the industry of Phyllanthus emblica . Currently, resistance to chemical fungicides has been a challenge to its effectiveness on this disease. To explore an effective botanical fungicide as alternatives for chemical fungicides to inhibit P. choerospondiatis , 10 botanical fungicides were selected for antifungal activity test against P. choerospondiatis mycelial growth. Results showed that physcion was the most effective one with a 50 % effective concentration (EC 50 ) of 3.30 mg/L. Furthermore, physcion had a strong inhibition activity to spore germination and pathogenicity of P. choerospondiatis , both in vitro and in vivo . Its antifungal mechanisms investigations indicated that physcion could alter the mycelium morphology, disrupt cell membrane integrity, increase cell membrane permeability, reduce ergosterol content, and induce excessive reactive oxygen species (ROS). Moreover, transcriptome analysis revealed that physcion might interfere with ergosterol biosynthesis and oxidoreductase activity, leading to significant cell membrane dysfunction and oxidative stress in P. choerospondiatis . This study lays the groundwork for elucidating how physcion harms the pathogen and provides promising insights into eco-friendly alternatives for controlling this postharvest disease in P. choerospondiatis .