Transcriptome sequencing reveals an inhibitory mechanism of Penicillium digitatum by sodium dehydroacetate on citrus fruit

Abstract

Sodium dehydroacetate (SD) has been widely used in various fields due to its high antimicrobial activities. However, the inhibitory mechanisms of SD against fungi, especially on transcriptional level, are still unclear. In this study, the inhibitory property of SD against Penicillium digitatum (imazalil (IMZ)-sensitive P. digitatum (Pds01) and IMZ-resistant P. digitatum (Pdw03) strains) was investigated. Here, we found that SD treatment had a distinct inhibitory effect on Pdw03 strain in vitro and mitigated the disease prevalence of inoculated citrus. Morphology and microstructure observation showed that SD caused remarkable changes in the hyphae of Pds01 and Pdw03. Transcriptomic analysis displayed that SD treatment blocked the expression of genes related to the ribosome, genetic information processing and energy metabolism, while promoting the genes expression related to cell walls degradation, membrane lipid metabolism and biosynthesis of sphingolipid. Among them, the ribosomal pathway was most prominent, and key genes in this pathway (RPSA, RPS9, RPL7A and RPL5) were inhibited by SD treatment in both strains. Moreover, we found that the expression of 12 MFS (major facilitator superfamily) transporters, 6 ABC (ATP-binding cassette transporter) transporters, and 9 glutathione metabolism encoding genes related to SD detoxification were increased. The results of fourier transform infrared spectroscopy (FT-IR) fingerprints further confirmed that SD caused remarkable changes in cell membrane lipids, nucleic acids, proteins and cell wall polysaccharides in both strains. These findings indicated that the interference with ribosome, genetic information processing, cell membrane metabolism and energy metabolism might be closely involved in the antifungal mechanism of SD against P. digitatum. Our results may provide novel insights into the antifungal molecular mechanism of SD against P. digitatum and deepen our understanding of the regulatory network of SD.