Functional Differentiation of the Succinate Dehydrogenase Subunit SdhC Governs the Sensitivity to SDHI Fungicides, ROS Homeostasis, and Pathogenicity in Fusarium asiaticum.

Succinate dehydrogenase (SDH) is an integral component of the tricarboxylic acid cycle (TCA) and respiratory electron transport chain (ETC), targeted by succinate dehydrogenase inhibitors (SDHIs). Fusarium asiaticum is a prominent phytopathogen causing Fusarium head blight (FHB) on wheat. Here, we characterized the functions of the FaSdhA, FaSdhB, FaSdhC1, FaSdhC2, and FaSdhD subunits. Deletion of FaSdhA, FaSdhB, or FaSdhD resulted in significant growth defects in F. asiaticum. The FaSdhC1 or FaSdhC2 deletion mutants exhibited substantial reductions in fungal growth, conidiation, virulence, and reactive oxygen species (ROS). The FaSdhC1 expression was significantly induced by pydiflumetofen (PYD). The ΔFaSdhC1 mutant displayed hypersensitivity to SDHIs, whereas the ΔFaSdhC2 mutant exhibited resistance against most SDHIs. The transmembrane domains of FaSdhC1 are essential for regulating mycelial growth, virulence, and sensitivity to SDHIs. These findings provided valuable insights into how the two SdhC paralogues regulated the functional integrity of SDH, ROS homeostasis, and the sensitivity to SDHIs in phytopathogenic fungi.

Functional Plasticity, Redundancy, and Specificity of Lanosterol 14α-Demethylase in Regulating the Sensitivity to DMIs in Calonectria ilicicola.

Cytochrome P450 sterol 14α-demethylase (CYP51) is a key enzyme involved in the sterol biosynthesis pathway and serves as a target for sterol demethylation inhibitors (DMIs). In this study, the 3D structures of three CPY51 paralogues from Calonectria ilicicola (C. ilicicola) were first modeled by AlphaFold2, and molecular docking results showed that CiCYP51A, CiCYP51B, or CiCYP51C proteins individually possessed two active pockets that interacted with DMIs. Our results showed that the three paralogues play important roles in development, pathogenicity, and sensitivity to DMI fungicides. Specifically, CiCYP51A primarily contributed to cell wall integrity maintenance and tolerance to abiotic stresses, and CiCYP51B was implicated in sexual reproduction and virulence, while CiCYP51C exerted negative regulatory effects on sterol 14α-demethylase activity within the ergosterol biosynthetic pathway, revealing its genus-specific function in C. ilicicola. These findings provide valuable insights into developing rational strategies for controlling soybean red crown rot caused by C. ilicicola.

Identification and Genetic Dissection of Resistance to Red Crown Rot Disease in a Diverse Soybean Germplasm Population.

Red crown rot (RCR) disease caused by Calonectria ilicicola negatively impacts soybean yield and quality. Unfortunately, the knowledge of the genetic architecture of RCR resistance in soybeans is limited. In this study, 299 diverse soybean accessions were used to explore their genetic diversity and resistance to RCR, and to mine for candidate genes via emergence rate (ER), survival rate (SR), and disease severity (DS) by a multi-locus random-SNP-effect mixed linear model of GWAS. All accessions had brown necrotic lesions on the primary root, with five genotypes identified as resistant. Nine single-nucleotide polymorphism (SNP) markers were detected to underlie RCR response (ER, SR, and DS). Two SNPs colocalized with at least two traits to form a haplotype block which possessed nine genes. Based on their annotation and the qRT-PCR, three genes, namely Glyma.08G074600, Glyma.08G074700, and Glyma.12G043600, are suggested to modulate soybean resistance to RCR. The findings from this study could serve as the foundation for breeding RCR-tolerant soybean varieties, and the candidate genes could be validated to deepen our understanding of soybean response to RCR.

Resistance mechanism of Phomopsis longicolla to fludioxonil is associated with modifications in PlOS1, PlOS4 and PlOS5.

Phomopsis longicolla, a causal agent of soybean root rot, stem blight, seed decay, pod and stem canker, which seriously affects the yield and quality of soybean production worldwide. The phenylpyrrole fungicide fludioxonil exhibits a broad spectrum and high activity against phytopathogenic fungi. In this study, the baseline sensitivity of 100 P. longicolla isolates collected from the main soybean production areas of China to fludioxonil were determined. The result showed that the EC50 values of all the P. longicolla isolates ranged from 0.013 to 0.035 µg/ml. Furthermore, 12 fludioxonil-resistance (FluR) mutants of P. longicolla were generated from 6 fludioxonil-sensitive (FluS) isolates. and the resistance factors (RF) of 12 FluR mutants were >3500. Sequence alignment showed that multiple mutation types were found in PlOS1, PlOS4 or/and PlOS5 of FluR mutants. All the FluR mutants exhibited fitness penalty in mycelial growth, conidiation, virulence and osmo-adaptation. Under fludioxonil or NaCl treatment condition, the glycerol accumulation was significantly increased in FluS isolates, but was slightly increased in FluR mutants, and the phosphorylation level of most FluR mutants was significantly decreased when compared to the FluS isolates. Additionally, positive cross-resistance was observed between fludioxonil and procymidone but not fludioxonil and pydiflumetofen, pyraclostrobin or fluazinam. This is first reported that the baseline sensitivity of P. longicolla to fludioxonil, as well as the biological and molecular characterizations of P. longicolla FluR mutants to fludioxonil. These results can provide scientific directions for controlling soybean diseases caused by P. longicolla using fludioxonil.

Calculation of solvation force in molecular dynamics simulation by deep-learning method.

Electrostatic calculations are generally used in studying the thermodynamics and kinetics of biomolecules in solvent. Generally, this is performed by solving the Poisson-Boltzmann equation on a large grid system, a process known to be time consuming. In this study, we developed a deep neural network to predict the decomposed solvation free energies and forces of all atoms in a molecule. To train the network, the internal coordinates of the molecule were used as the input data, and the solvation free energies along with transformed atomic forces from the Poisson-Boltzmann equation were used as labels. Both the training and prediction tasks were accelerated on GPU. Formal tests demonstrated that our method can provide reasonable predictions for small molecules when the network is well-trained with its simulation data. This method is suitable for processing lots of snapshots of molecules in a long trajectory. Moreover, we applied this method in the molecular dynamics simulation with enhanced sampling. The calculated free energy landscape closely resembled that obtained from explicit solvent simulations.

The HOG-pathway related AaOS1 leads to dicarboximide-resistance in field strains of Alternaria alternata and contributes, together with the Aafhk1, to mycotoxin production and virulence.

BACKGROUND: Garlic leaf spot (GLS) caused by Alternaria alternata is one of the main diseases in the garlic production areas, and its management heavily relies on dicarboximide fungicides. However, the efficacy of dicarboximides against the GLS disease has decreased year on year. RESULTS: In the present study, 10 of 148 A. alternata strains separated from Jiangsu Province were moderately resistant (MR) to a dicarboximide fungicide procymidone (ProMR). Positive cross-resistance was observed between Pro and iprodione (Ipro) or fludioxonil (Fld), but not between Pro and fluazinam or azoxystrobin. Mutations at AaOS1, but not Aafhk1, were confirmed to confer the Pro resistance by constructing replacement mutants, whereas mutations at both AaOS1 and Aafhk1 decreased the gene expression level of AapksI, as well as the ability to produce mycotoxin AOH (polyketide-derived alternariol) and virulence. Additionally, more genes (AaOS1 and Aafhk1) harboring the mutations experienced a larger biological fitness penalty. CONCLUSION: To our knowledge, this is the first report on Pro resistance selected in garlic fields, and mutations at AaOS1 of A. alternata causing a decreased ability to produce the mycotoxin AOH. © 2024 Society of Chemical Industry.

Phenamacril and carbendazim regulate trichothecene mycotoxin synthesis by affecting ROS levels in F. asiaticum.

Fusarium head blight caused by Fusarium asiaticum is an important cereal crop disease, and the trichothecene mycotoxins produced by F. asiaticum can contaminate wheat grain, which is very harmful to humans and animals. To effectively control FHB in large areas, the application of fungicides is the major strategy; however, the application of different types of fungicides has varying influences on the accumulation of trichothecene mycotoxins in F. asiaticum. In this study, phenamacril inhibited trichothecene mycotoxin accumulation in F. asiaticum; however, carbendazim (N-1H-benzimidazol-2-yl-carbamic acid, methyl ester) induced trichothecene mycotoxin accumulation. Additionally, phenamacril led to a lower level of reactive oxygen species (ROS) by inducing gene expression of the catalase and superoxide dismutase (SOD) pathways in F. asiaticum, whereas carbendazim stimulated ROS accumulation by inhibiting gene expression of the catalase and SOD pathways. Based on these results, we conclude that phenamacril and carbendazim regulate trichothecene mycotoxin synthesis by affecting ROS levels in F. asiaticum.

Overexpression of FgPtp3 Is Involved in Fludioxonil Resistance in Fusarium graminearum by Inhibiting the Phosphorylation of FgHog1.

Fusarium graminearum is the main causal agent of Fusarium head blight (FHB), a destructive disease in cereal crops worldwide. Resistance to fludioxonil has been reported in F. graminearum in the field, but its underlying mechanisms remain elusive. In this study, 152 fludioxonil-resistant (FR) mutants of F. graminearum were obtained by selection in vitro. The FR strains exhibited dramatically impaired fitness, but only 7 of the 13 analyzed strains possessed mutations in genes previously reported to underlie fludioxonil resistance. Comparison between the FR-132 strain and its parental strain PH-1 using whole genome sequencing revealed no mutations between them, but transcriptome analysis, after the strains were treated with 0.5 µg/mL fludioxonil, revealed 2778 differently expressed genes (DEGs) mapped to 96 KEGG pathways. Investigation of DEGs in the MAPK pathway showed that overexpression of the tyrosine protein phosphatase FgPtp3, but not FgPtp2, enhanced fludioxonil resistance. Further analysis found that FgPtp3 interacted directly with FgHog1 to regulate the phosphorylation of Hog1, and overexpressed FgPtp3 in PH-1 could significantly suppress the phosphorylation of FgHog1 and hinder signal transmission of the HOG-MAPK pathway. Overall, FgPtp3 plays a significant role in regulating fludioxonil resistance in F. graminearum.

Microscopic Analysis of the Wetting Morphology and Interfacial Bonding Mechanism of Preoxidised Kovar Alloys with Borosilicate Glass.

This paper investigates the wettability of Kovar alloys with high-borosilicate glass and microscopically analyses the mechanism of wettability and diffusion between Kovar and borosilicate glass. First, Kovar was oxidised at 800 °C for 5, 15, 25, 35, and 60 min to observe the oxide morphology of the Kovar surface layer and to analyse the composition of the oxide layer. To investigate the wetting pattern formations of Kovar and high-borosilicate glass under different wetting temperatures, times, and preoxidation conditions, Kovar and high-borosilicate glass obtained from different oxidation treatments were held at 1060 °C for 20 min for wetting experiments, and the glass-metal wetting interface morphology and elemental distribution were observed using SEM and EDS. The elemental diffusion at the wetting interface between the borosilicate glass and the Kovar with different preoxidation and at the glass spreading boundary was investigated. The longitudinal diffusion of the liquid glass in the metal oxide layer formed a new tight chemical bond of Fe2SiO4, and the lateral diffusion of the liquid glass in the Kovar surface layer formed a black halo.

SurfPB: A GPU-Accelerated Electrostatic Calculation and Visualization Tool for Biomolecules.

In this work, we present SurfPB as a useful tool for the study of biomolecules. It can do many typical calculations, including the molecular surface, electrostatic potential, solvation free energy, entropy, and binding free energy. Among all of the calculations, the entropy calculation is the most time-consuming one. In SurfPB, the calculation can be performed in a vacuum or implicit solvent and accelerated on GPU. The Poisson-Boltzmann equation solver is accelerated on GPU as well. Moreover, we developed a graphical user interface for SurfPB. It allows users to input the parameters and complete the whole calculation in a visual way. The calculated electrostatic potentials are shown on the molecular surface in a three-dimensional scene.

Engineered Exosome-Functionalized Extracellular Matrix-Mimicking Hydrogel for Promoting Bone Repair in Glucocorticoid-Induced Osteonecrosis of the Femoral Head.

Glucocorticoid-induced osteonecrosis of the femoral head (GC-ONFH) is a serious bone disease that often affects young individuals. Bone grafting combined with core decompression is mainly used in the clinic to treat GC-ONFH. However, the outcome is usually not satisfactory, as expected. Here, we report an engineered exosome-functionalized extracellular matrix-mimicking hydrogel for promoting bone repair in GC-ONFH. Compared with Con-Exo, exosomes secreted by bone marrow stem cells (BMSCs) in conventional culture medium, the engineered Li-Exo, exosomes derived from bone marrow stem cells (BMSCs) stimulated by lithium ions, promoted macrophage M2 polarization while inhibiting macrophage M1 polarization. Furthermore, inspired by the fact that hydrogels can serve as desirable carriers of exosomes to facilitate their release in a sustained manner for improved therapeutic efficiency and in vivo application, an extracellular matrix (ECM)-mimicking hydrogel (Lightgel) composed of methacryloylated type I collagen was employed to incorporate Li-Exo/Con-Exo to construct the Lightgel-Li-Exo hydrogel/Lightgel-Con-Exo hydrogel. In vitro studies showed that the Lightgel-Li-Exo hydrogel had the most significant pro-osteogenic and pro-angiogenic activity. Finally, we evaluated the therapeutic effects of the hydrogel in rat models of GC-ONFH. As a result, the Lightgel-Li-Exo hydrogel had the most significant effect on enhancing macrophage M2 polarization, osteogenesis, and angiogenesis to promote bone repair in GC-ONFH. Taken together, this novel engineered exosome-functionalized ECM-mimicking hydrogel could be a promising strategy for osteonecrosis treatment.

Enhanced sampling in explicit solvent by deep learning module in FSATOOL.

FSATOOL is an integrated molecular simulation and data analysis program. Its old molecular dynamics engine only supports simulations in vacuum or implicit solvent. In this work, we implement the well-known smooth particle mesh Ewald method for simulations in explicit solvent. The new developed engine is runnable on both CPU and GPU. All the existed analysis modules in the program are compatible with the new engine. Moreover, we also build a complete deep learning module in FSATOOL. Based on the module, we further implement two useful trajectory analysis methods: state-free reversible VAMPnets and time-lagged autoencoder. They are good at searching the collective variables related to the conformational transitions of biomolecules. In FSATOOL, these collective variables can be further used to construct a bias potential for the enhanced sampling purpose. We introduce the implementation details of the methods and present their actual performances in FSATOOL by a few enhanced sampling simulations.