Integrated transcriptomic and metabolomic analyses reveal TPS1 as a key regulator linking cell wall integrity to aflatoxin production in Aspergillus flavus.
Jul 2026· Journal of food microbiology· Vol 460, pp.
111956
· 0 citations
Medicine
TL;DR
These findings establish TPS1 as a key regulator linking carbon metabolism to morphogenesis, stress response, and virulence, highlighting its potential as a novel intervention target for controlling toxigenic fungi.
Abstract
As a widely distributed opportunistic pathogen, Aspergillus flavus poses a critical challenge to global food safety, principally through the contamination of staple crops with Aflatoxin B1 (AFB1), a highly potent carcinogen and hepatotoxin that accumulates in the food chain and gravely threatens human and animal health. Trehalose-6-phosphate synthase (TPS1) serves as a metabolic gatekeeper, yet its pleiotropic roles in A. flavus morphogenesis and secondary metabolism remain undefined. Here, we demonstrate that TPS1 is indispensable for sclerotial development, stress adaptation, and aflatoxin biosynthesis. Although the TPS1 deletion mutant (ΔTPS1) retained normal vegetative growth on solid media, it exhibited altered pellet morphology in liquid culture and completely lost the ability to produce sclerotia. Physiologically, TPS1 deficiency depleted intracellular trehalose-6-phosphate (T6P) and trehalose pools, leading to compromised cell wall integrity characterized by reduced β-1,3-glucan and chitin content, anomalous septation, and remodeled surface chemistry. Crucially, the mutant showed significantly diminished AFB1 production and attenuated virulence on host substrates (maize, peanut, and onion). Integrated transcriptomic and metabolomic analyses revealed that TPS1 deletion triggered a systemic metabolic rewiring: it disrupts glycolysis, the tricarboxylic acid (TCA) cycle, and fatty acid synthesis, while redirecting flux toward the pentose phosphate pathway. This metabolic shift correlated with the transcriptional downregulation of 23 genes within the AFB1 biosynthetic cluster. Collectively, our findings establish TPS1 as a key regulator linking carbon metabolism to morphogenesis, stress response, and virulence, highlighting its potential as a novel intervention target for controlling toxigenic fungi.
Entomopathogenic fungi such as Beauveria bassiana represent promising alternatives to chemical pesticides, yet their morphogenesis and environmental adaptation depend critically on dynamic cell wall remodeling. Despite the essential role of β-N-acetylhexosaminidase (Hex) in cell wall decomposition, its potential contributions to fungal biocontrol remain unexplored. Here, we identified and functionally dissected a previously uncharacterized homology, Hex2. Notably, Hex2 deficiency led to irregular cell wall structure by elevating chitin, N-glycan contents and protein N-/O-glycosylation levels within it. In addition, ΔHex2 mutant exhibited impaired development, including defects in sporulation, germination, and dimorphic transitions. These developmental defects were likely attributed to aberrant accumulation of cell wall components rather than insufficient ATP production. More interestingly, losing Hex2 enhanced fungal tolerance to oxidative stress cues though upregulation of antioxidant enzyme activities. Despite heightened oxidative-stress resistance, ΔHex2 mutant displayed significantly attenuated virulence against Galleria mellonella larvae, indicating that cell-wall disturbance and developmental defects might constitute the predominant causes of reduced pathogenicity. These findings provide the first insights into the multifaceted roles of intracellular β-N-acetylhexosaminidase Hex2 in B. bassiana, identifying a rational target for engineering insecticides with remained or even enhanced pesticidal efficacy.
Yu Li, Zhi-Hao Yang, Yu-tian Li 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
Fusarium proliferatum causes rice spikelet rot and contaminates grains with fumonisins. Here, we report that the methyltransferase FpLaeA is a global regulator essential for its pathogenicity. Deletion of FplaeA impaired conidiation and led to conspicuous accumulation of β-1,3-glucan. The ΔFplaeA mutant failed to produce fumonisin B1 (FB1), accompanied by the downregulation of the biosynthetic gene cluster, depletion of the precursor alanine, and disruption of sphingolipid homeostasis. It also showed defective invasive hyphal growth and attenuated secretion of pectate lyase (PL) and polygalacturonase (PG). Crucially, infection by ΔFplaeA triggered an activation of jasmonic acid (JA)-mediated defenses, evidenced by elevated JA levels and upregulated expression of JA biosynthetic genes. Our findings position FpLaeA as a key coordinator of fungal pathogenesis and immune evasion, highlighting its potential as a target for integrated control of F. proliferatum and its associated mycotoxin risk.
Ling Wang, Shaoqing Tang, Weiyang Liao et al.· Journal of Agricultural and...· 0 citations
Verticillium dahliae
is a soilborne fungal pathogen that causes Verticillium wilt in cotton and many other crops. While siderophore-associated iron acquisition is recognized as crucial, its precise connections to fungal development, stress adaptation, and host colonization remain incompletely elucidated. This study identifies the VdOMO protein as a putative SidA-family L-ornithine N5-monooxygenase through phylogenetic and pairwise sequence analyses. Analyses of independent deletion mutants and a complemented strain showed that
VdOMO
contributes to conidial morphology and production, microsclerotium formation, and melanization, growth on selected carbon sources, cell wall integrity, and adaptation to alkaline, salt, and oxidative stresses. Although final visible disease symptoms were comparable among inoculated groups,
ΔVdOMO
mutants exhibited reduced vascular browning, diminished fungal biomass accumulation at early infection stages, and impaired cellophane penetration. A representative
ΔVdOMO
mutant also displayed decreased biomass-normalized extracellular chrome azurol S (CAS)-reactive iron-chelating activity and intracellular iron accumulation, both of which were restored to wild-type levels upon complementation. Furthermore,
VdOMO
deletion was linked to iron-condition-dependent alterations in the expression of genes involved in iron regulation, siderophore biosynthesis, and siderophore transport. Collectively, these findings underscore a significant role for
VdOMO
in siderophore-associated iron acquisition, fungal development, stress adaptation, and the early stages of host colonization in
V. dahliae
.
Yusha Du, Lixinyu Sun, Kangwei Xie et al.· Frontiers in Plant Science· 0 citations
It is shown that the hyphae of the filamentous fungus Trichoderma guizhouense can differentiate into typical terminal and intercalary chlamydospores characterized by double-layered spherical or ellipsoidal cell walls with accumulated lipid bodies and nuclei, indicating the entry of cells into dormancy.
Yiting Hou, Yifan Li, Cheng Chen et al.· Applied and Environmental Mi...· 0 citations
Brucella melitensis, a facultative intracellular pathogen, relies on membrane integrity and homeostasis to resist host defenses and establish infection. The plsC gene encodes 1-acyl-sn-glycerol-3-phosphate acyltransferase, a key enzyme in the glycerophospholipid pathway that catalyzes the synthesis of phosphatidic acid, an essential precursor for membrane lipid formation. However, its role in B. melitensis virulence remains poorly understood. Here, we constructed a plsC deletion mutant (ΔplsC) and a complemented strain (ΔplsC-Com) in B. melitensis strain M5 and characterized their phenotypes. Deletion of plsC impaired bacterial growth in nutrient-limited media, reduced tolerance to hydrogen peroxide and polymyxin B, and decreased lipid synthesis while increasing outer membrane permeability. Ultrastructural analysis revealed surface roughness, cytoplasmic voids, and nucleoid condensation in the mutant. Although ΔplsC retained normal adhesion and invasion capabilities in RAW264.7 macrophages and HeLa cells, its intracellular survival was specifically attenuated in macrophages at 48 h post-infection. In a mouse model, ΔplsC showed significantly reduced colonization of the spleen and liver and induced fewer and smaller liver granulomas as compared with the parental and complemented strains. These results demonstrate that PlsC is essential for maintaining membrane homeostasis and stress resistance in Brucella, which in turn supports its survival within professional phagocytes and full virulence in vivo. Our study suggests a critical link between phospholipid metabolism and Brucella pathogenicity.
Fazhi Xu, Yao Feng, Mengsi Li et al.· Veterinary Research· 0 citations