Targeting the Effector AwCES to Attenuate Virulence in the Postharvest Pathogen Aspergillus westerdijkiae

<i>Aspergillus westerdijkiae</i> is a common pathogenic fungus responsible for postharvest fruit rot in pears, causing substantial economic losses. This fungus also produces ochratoxin A (OTA), which poses serious health risks to humans. During host colonization, fungal pathogens secrete effectors to facilitate invasion. Under host-mimicking culture conditions, transcriptomic analysis of <i>A. westerdijkiae</i> at 24 and 72 h post-inoculation (hpi), combined with signal peptide prediction, identified 272 and 214 up-regulated secreted protein-encoding genes, respectively. Among these, a carboxylesterase gene, <i>AwCES</i>, was found to be significantly up-regulated. Compared to the wild-type strain, deletion of <i>AwCES</i> resulted in reduced conidial production and germination rate. Further studies revealed that the deletion mutant showed significantly attenuated virulence on pear fruit. Moreover, the loss of <i>AwCES</i> impaired fungal adaptation to stress environments. Collectively, these findings demonstrate that <i>AwCES</i> plays a critical role in the growth, development, and pathogenicity of <i>A. westerdijkiae</i>.