Abstract: The antimicrobial activity and mechanism of a mustard essential oil inclusion complex against the rambutan pathogen Aspergillus aculeatus by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and transcriptomics. It was found that the inclusion complex significantly inhibited the growth of Aspergillus aculeatus with a half-maximum effective concentration (EC50) of 1.00 g/L. SEM showed significant changes in the morphology of hyphae, conidia and apical cysts, and a significantly decreased number of spore apical cysts after treatment with the complex. TEM showed that the hyphal cells became no longer full, the cell wall became thin, the cell membrane boundary became blurred, and serious lysis was observed inside the cells. The transcriptomics results showed that there were 1 057 differentially expressed genes identified, of which 528 were up-regulated and the rest were down-regulated. Furthermore, eight differentially expressed genes were confirmed by real-time fluorescence quantitative polymerase chain reaction (qPCR), indicating that the trend of changes in the gene expression levels was consistent with the transcriptomic sequencing results. The antifungal mechanism may involve damaging the cell structure, affecting DNA and RNA synthesis and metabolism, inhibiting related enzyme activities, influencing the transmembrane transport capacity, inhibiting mitosis, and decreasing energy metabolism.

Key words: mustard essential oil inclusion complex; Aspergillus aculeatus; transcriptome; quantitative real-time polymerase chain reaction; antimicrobial mechanism