Transcriptomic and biochemical analyses revealed antifungal mechanism of trans-anethole on Aspergillus flavus growth

Synthesis, Antifungal Activity, and Action Mechanism of Anethole-Derived Amide-Urea Compounds

In order to develop new antifungal molecules and explore further applications of natural products, 25 novel amide-urea compounds were synthesized from anethole in this work by a few simple reactions, and structural confirmation was conducted using 1H-nuclear magnetic resonance (1H-NMR), 13C-NMR, high-resolution mass spectrometry, and Fourier transform infrared spectroscopy. Preliminary bioactivity tests were performed against eight plant pathogens. The results demonstrated that all compounds exhibited antifungal activity against the tested fungi, and 5p exhibited the most potent antifungal activity. To explore the action mechanism of the antifungal compounds, the inhibitory activity of 5p against succinate dehydrogenase (SDH) was evaluated and found to be comparable to that of boscalid. Furthermore, the binding mode of the compound to SDH was simulated by molecular docking, and similarities between 5p and boscalid's binding with SDH were identified. The results indicate that further investigation of compound 5p may prove beneficial in determining its potential as a fungicide.

FgUbiH Is Essential for Vegetative Development, Energy Metabolism, and Antioxidant Activity in Fusarium graminearum

Fusarium head blight in wheat is mainly caused by Fusarium graminearum and results in significant economic losses. Coenzyme Q (CoQ) is ubiquitously produced across organisms and functions as a hydrogen carrier in energy metabolism. While UbiH in Escherichia coli serves as a hydroxylase in CoQ biosynthesis, its role in phytopathogenic fungi is not well understood. This study explored the role of the hydroxylase FgUbiH in F. graminearum. Using a FgUbiH deletion mutant, we observed reduced hyphal growth, conidial production, germination, toxin synthesis, and pathogenicity compared to the wild-type. A transcriptome analysis indicated FgUbiH's involvement in regulating carbohydrate and amino acid metabolism. Deletion of FgUbiH impaired mitochondrial function, reducing adenosine triphosphate synthesis and increasing reactive oxygen species. Additionally, genes related to terpene skeleton synthesis and aldehyde dehydrogenase were downregulated. Our results underscore the importance of FgUbiH in F. graminearum's growth, toxin production, and energy metabolism, aiding in the development of strategies for disease management.

Identification of the Ilex macrocarpa anthracnose pathogen and the antifungal potential of the cell-free supernatant of Bacillus velezensis against Colletotrichum fioriniae

Introduction

Anthracnose is a significant fungal disease that affects tree growth and development, with Colletotrichum spp. exhibiting host non-specificity and targeting various organs, making disease control challenging.

Methods

This study aimed to identify the pathogenic species causing anthracnose in Ilex macrocarpa in Nanchong, Sichuan Province, and screen effective fungicides, particularly biological ones. The pathogen was identified as Colletotrichum fioriniae through morphological observation, pathogenicity assays, and molecular biological methods. Three biological and five chemical fungicides were evaluated for their effects on the mycelial growth and spore germination rate of the pathogen.

Results

The results indicated that prochloraz was the most effective chemical fungicide, while the cell-free supernatant (CFS) of Bacillus velezensis had the most significant inhibitory effect among the biological fungicides. Transcriptome analysis revealed that the CFS of B. velezensis significantly reduced the expression of genes associated with ribosomes, genetic information processing, membrane lipid metabolism, and sphingolipid biosynthesis in C. fioriniae. Additionally, the glutathione pathway's expression of various genes, including key genes such as GST, GFA, Grx, TRR, and POD, was induced. Furthermore, the expression of 17 MFS transporters and 9 ABC transporters was increased. Autophagy-related ATGs were also affected by the B. velezensis CFS.

Discussion

These findings suggest that the B. velezensis CFS may inhibit C. fioriniae through interference with ribosomes, genetic information processing, cell membrane metabolism, and energy metabolism. These results provide potential target genes for the B. velezensis CFS and insights into the antifungal mechanism by which B. velezensis inhibits C. fioriniae.

Mechanism of inactivation of Aspergillus flavus spores by dielectric barrier discharge plasma

Dielectric barrier discharge plasma (DBDP) displays strong against fungal spores, while its precise mechanism of spore inactivation remains inadequately understood. In this study, we applied morphological, in vivo and in vitro experiments, transcriptomics, and physicochemical detection to unveil the potential molecular pathways underlying the inactivation of Aspergillus flavus spores by DBDP. Our findings suggested that mycelium growth was inhibited as observed by SEM after 30 s treatment at 70 kV, meanwhile spore germination ceased and clustering occurred. It led to the release of cellular contents and subsequent spore demise by disrupting the integrity of spore membrane. Additionally, based on the transcriptomic data, we hypothesized that the induction of spore inactivation by DBDP might be associated with downregulation of genes related to cell membranes, organelles (mitochondria), oxidative phosphorylation, and the tricarboxylic acid cycle. Subsequently, we validated our transcriptomic findings by measuring the levels of relevant enzymes in metabolic pathways, such as superoxide dismutase, acetyl-CoA, total dehydrogenase, and ATP. These physicochemical indicators revealed that DBDP treatment resulted in mitochondrial dysfunction, redox imbalance, and inhibited energy metabolism pathways. These findings were consistent with the transcriptomic results. Hence, we concluded that DBDP accelerated spore rupture and death via ROS-mediated mitochondrial dysfunction, which does not depend on cell membranes.