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

Aspergillus westerdijkiae 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 A. westerdijkiae 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, AwCES, was found to be significantly up-regulated. Compared to the wild-type strain, deletion of AwCES 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 AwCES impaired fungal adaptation to stress environments. Collectively, these findings demonstrate that AwCES plays a critical role in the growth, development, and pathogenicity of A. westerdijkiae.