Jul 2026· Journal of Fungi· Vol 12, pp. 532· 0 citations· 92 references
Medicine
TL;DR
The results suggest that Afap1 and AflatfA appear to be promising targets for the development of new antifungal agents, as their inhibition may increase the sensitivity of A. flavus to environmental stress and reduce the aflatoxin production of the fungus and the use of azoles (AflatfA) in the antifungal protection of maize.
Abstract
The bZIP type transcription factors (bZIPs) are global regulators governing vegetative growth, development, stress defense and secondary metabolism, including mycotoxin production in filamentous fungi. In this work, we constructed and phenotypically characterized gene deletion and complementation mutants of some bZIPs, including Afap1, AflatfA, LziP, AflatfB and bZIP6 in Aspergillus flavus. Environmental and fungicide stress responses, as well as aflatoxin production of the mutants in both surface cultures and infected maize kernels, were studied. Phenotypic characterization of the mutants revealed that Afap1 and AflatfA were involved in the oxidative (H2O2, menadione, tert-butyl hydroperoxide), cell wall integrity (Congo Red) and heavy metal (CdCl2) stress responses of A. flavus. In addition, the Afap1 and AflatfA gene deletions decreased the diamide and prothioconazole tolerances of the fungus, respectively. The ΔLziP strain showed increased growth in the presence of diamide, while reduced colony diameters were observed after exposure to CdCl2 and fludioxonil. The ΔAflatfB gene deletion mutant was also sensitive to tBOOH, while azoxystrobin and prothioconazole fungicides significantly inhibited the growth of ΔbZIP6. When aflatoxin (AFB1) production was measured in surface cultures, decreased AFB1 levels were detected only in the ΔAflatfA gene deletion mutant strain. However, in corn kernel infection assays, the ΔAfap1, ΔAflatfA, and ΔAflatfB mutants were characterized by significantly reduced aflatoxin production, while the deletion of bZIP6 almost completely abolished AFB1 biosynthesis. Our results suggest that Afap1 and AflatfA appear to be promising targets for the development of new antifungal agents, as their inhibition may increase the sensitivity of A. flavus to environmental stress, simultaneously reducing the aflatoxin production of the fungus and the use of azoles (AflatfA) in the antifungal protection of maize. In addition, bZIP6 may also be considered as an attractive target for further studies when aiming to eliminate aflatoxin production and minimize the use of azoxystrobin and prothioconazole in maize crop protection.
It is demonstrated that MrFTRP1 exerts a dual-regulatory functioning as a positive regulator of conidiation and pathogenesis but a negative regulator of environmental stress tolerance, which expands the understanding of the regulatory diversity within the C6 TF family and identifies him as a promising target for the genetic improvement of mycoinsecticides.
Chentian Jiang, Hao Wu, You-Gui Tong et al.· Journal of Invertebrate Path...· 0 citations
A physical interaction is identified between AaSlt2 and Swi6/RlmA, suggesting that these components are critical for cell wall synthesis, which advances the understanding of pathogenic mechanisms of A. alternata and proposes potential strategies for controlling postharvest diseases.
Rong Li, Yiyang Liu, Li Li et al.· Virulence· 0 citations
Background: Aspergillus flavus is an important aflatoxigenic fungus associated with contamination of maize, wheat, peanuts and other stored crops. Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic secondary metabolite, and its biosynthesis is controlled by clustered structural and regulatory genes, including aflR, aflS, aflD, aflM, aflP and aflQ. Objective: This study evaluated the inhibitory effects of cinnamon, clove and thyme essential oils on A. flavus growth, AFB1 production and relative expression of selected aflatoxin biosynthetic genes under controlled in vitro conditions. Methods: An aflatoxigenic A. flavus isolate was exposed to essential oils at 0.25, 0.50 and 1.00 µL/mL. Radial growth inhibition was determined on potato dextrose agar, while mycelial dry weight and AFB1 production were evaluated in yeast extract sucrose broth. AFB1 was quantified by HPLC with fluorescence detection. Relative expression of aflR, aflS, aflD, aflM, aflP and aflQ was determined by RT-qPCR using β-tubulin as the reference gene and the 2^-ΔΔCt method. Results: The results showed a concentration-dependent decrease in fungal growth, biomass and AFB1 production. Cinnamon oil produced the strongest inhibition, reducing radial growth by 54.3% and AFB1 production by 81.7% at 1.00 µL/mL. Clove oil reduced AFB1 by 73.4%, whereas thyme oil reduced it by 65.2% at the same concentration. RT-qPCR analysis showed downregulation of all tested biosynthetic genes, with aflR and aflD showing the most consistent suppression. Cinnamon oil reduced aflR expression to 0.24-fold and aflD expression to 0.19-fold compared with the untreated control. Conclusion: The findings demonstrate that essential oils, particularly cinnamon and clove oils, reduced AFB1 production through both growth inhibition and transcriptional suppression of key aflatoxin biosynthetic genes. These results support the use of plant-derived essential oils as natural anti-aflatoxigenic agents in strategies aimed at reducing crop contamination.
I. Mezeal· Jurnal MIPA dan Pembelajaran...· 0 citations
It is shown that the understudied bZIP transcription factor PnAda1 is an important downstream component of this PnPf2-regulatory network, and current understanding of the transcriptional network underlying virulence, metabolism and stress adaptation in an important fungal wheat pathogen is expanded.
S. Morikawa, Leon Lenzo, Keshara Colomba Thanthrige et al.· bioRxiv· 0 citations
Trichothecium roseum is a highly destructive postharvest pathogenic fungus that causes pink mold rot in various fruit and leads to significant agricultural and economic losses. Phytoene is crucial for phytopathogens, but the molecular mechanism by which the phytoene synthase gene crtB regulates fungal pathogenicity remains largely unclear. In this study, we evaluated the functions of TrcrtB a phytoene synthase, in T. roseum via in vivo and in vitro assays. Our results showed that knock-out of TrcrtB showed inhibition of production of phytoene and its relevant downstream metabolites, such as lycopene, carotenes and carotenal, resulting in colorless colony and branching at the mycelial edges in the knockout mutant ΔTrcrtB. Compared with the wild type (WT) strain, the colony expansion was significantly reduced 35% at 5 days post-inoculation (dpi), and conidiation was notably decreased to 45%, 36%, and 70% at 3, 5, and 7 dpi in ΔTrcrtB in vitro. Scanning electron microscope observation revealed similar results. Moreover, the ΔTrcrtB showed higher sensitivity to abiotic stresses than WT, as evidenced by inhibition rates of ΔTrcrtB colony expansion up to 71.76% (menadione), 47.73% (Congo red), 23.01% (SDS), and 17.13% (KCl). The pathogenicity of ΔTrcrtB was dramatically impaired by decreasing the rotten area up to 85.26% on apple fruit and 70.30% on pears fruit. These results suggest that TrcrtB and phytoene are critical for development, stress tolerance and pathogenicity of T. roseum. Collectively, our study highlights the roles of TrcrtB and phytoene in the pathogenic fungus T. roseum, providing new insights into the molecular mechanisms of pink rot pathogenesis.
Maize is frequently contaminated with aflatoxins (AFs) and fumonisins (FBs), posing a significant global food safety threat. Understanding how environmental factors regulate fungal toxigenesis under global warming is crucial. This study systematically investigated the in vitro stress responses of Aspergillus flavus, Aspergillus parasiticus, and Fusarium verticillioides (strains isolated from contaminated maize) across broad gradients of temperature (15-40 °C) and water activity (0.93-0.995 aw). Phenotypically, primary and secondary metabolism exhibited striking divergence: A. flavus grew optimally at 30 °C and 0.98 aw, yet intriguingly accumulated peak AFB2 specifically under severe drought stress (0.93 aw). A. parasiticus showed broad thermal adaptability for growth, but its AFB1 production was strictly confined to 25 °C. F. verticillioides maximized FB1 at 20 °C and 0.98 aw,. Transcriptomics revealed novel regularity underlying these patterns: under drought stress, A. flavus AFB2 biosynthesis uniquely decoupled from the classical aflM-dependent pathway via metabolic flux redirection; lepI was identified as an unprecedentedly strict temperature-dependent switch for A. parasiticus AFB1; and a FUM13-centric hub network coordinated FB1 synthesis in F. verticillioides. These findings provide a theoretical basis for developing targeted mycotoxin mitigation strategies under environmental factors change.
Xiyu Cao, Xuran Fu, Jiadi Sun et al.· Food microbiology· 0 citations