Abstract: This work studied the antibacterial effect and mechanism of antimicrobial peptide PAF26 on Monilinia fructicola in postharvest plums. In this experiment, in vitro experiments and inoculation methods were used to study the antimicrobial peptide PAF26’s in vitro antibacterial effect on M. fructicola and the control effect on plum fruit brown rot. The effect of the antibacterial peptide on the structural integrity of M. fructicola and its hemolytic activity were also tested. The results showed that PAF26 could significantly inhibit the growth of Monilinia fructicola, and its minimum inhibitory concentration (MIC) was 64 μmol/L, which could significantly reduce the survival rate of spores. PAF26 could also effectively control the occurrence of Monilinia fructicola in plum fruit. Fluorescent staining with SYTOX Green (SG) and propidium iodide (PI) showed that PAF26 could enhance the permeability of hyphal and conidial membrane. In addition, the extracellular conductivity of Monilinia fructicola mycelia treated with PAF26 was significantly increased. PAF26 at 64 and 128 μmol/L hardly resulted in hemolysis of human red blood cells. The above results indicate that PAF26 can effectively control postharvest brown rot in plums by destroying the integrity of the cell membrane structure and consequently accelerating the death of Monilinia fructicola.

Key words: postharvest plum fruit; antibacterial peptide; Monilinia fructicola; control effect; mechanism