Endophytic bacterium suppresses mycelial growth of and decreases its pathogenicity to postharvest fruits.

Apple ( Borkh.), one of the most economically important fruits widely consumed worldwide, has been suffering from apple ring rot caused by , which dramatically affects its quality and yield. In the present study, we demonstrated that , isolated from Chinese leek (), significantly suppressed the mycelial growth and propagation of , respectively, further displayed a considerably inhibitory effect on the apple ring rot of postharvest fruits. In addition, significantly improved the total soluble solid/titrable acidity (TSS/TA) ratio and soluble sugar/titrable acidity (SS/TA) ratio and drastically maintained the fruit firmness. Further analysis manifested that substantially induced the defense-related genes such as MdGLU, MdPAL, MdPOD, MdCAL, and transcription factors related to the resistance to , including MdWRKY15, MdPUB29, MdMyb73, and MdERF11 in apple fruits. Meanwhile, considerably restrained the expressions of the pathogenicity-related genes in , including the BdCYP450, BdADH, BdGHY, BdATS, Bdα/β-HY, and BdSTR. By inference, inhibited the apple ring rot on postharvest fruits by activating the defense system of apple fruit and repressing the pathogenic factor of The study provided a theoretical basis and a potential alternative to manage the apple ring rot on postharvest fruits.