A Combined Analysis of Transcriptome and Proteome Reveals the Inhibitory Mechanism of a Novel Oligosaccharide Ester against Penicillium italicum

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.