Blue mold caused by Penicillium italicum is one of the most serious postharvest diseases of citrus fruit. The aim of this study was to investigate the inhibitory effect of a novel oligosaccharide ester, 6-O-β-L-mannopyranosyl-3-O-(2-methylbutanoyl)-4-O-(8-methyldecanoyl)-2-O-(4-methyl-hexanoyl) trehalose (MTE-1), against P. italicum. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM), along with transcriptome and proteome analysis also, were conducted to illuminate the underlying mechanism. Results showed that MTE-1 significantly inhibited P. italicum growth in vitro in a dose-dependent manner. Moreover, MTE-1 suppressed the disease development of citrus fruit inoculated with P. italicum. Furthermore, ultrastructure observation, as well as transcriptome and proteome analysis, indicated that MTE-1 treatment damaged the cell wall and plasma membrane in spores and mycelia of P. italicum. In addition, MTE-1 regulated genes or proteins involved in primary metabolism, cell-wall metabolism, and pathogenicity. These results demonstrate that MTE-1 inhibited P. italicum by damaging cell walls and membranes and disrupting normal cellular metabolism. These findings contribute to the understanding of the possible molecular action of MTE-1. Finally, MTE-1 also provides a new natural strategy for controlling diseases in postharvest fruit.
Keywords: blue mold; cell wall; citrus fruit; gene; protein.