Two-component Signaling Pathway Research Articles

Bacterial Histidine Kinase and the Development of Its Inhibitors in the 21st Century.

Bacterial histidine kinase (BHK) is a constituent of the two-component signaling (TCS) pathway, which is responsible for the regulation of a number of processes connected to bacterial pathogenicity, virulence, biofilm development, antibiotic resistance, and bacterial persistence. As BHK regulation is diverse, inhibitors can be developed, such as antibiotic synergists, bacteriostatic/bactericidal agents, virulence inhibitors, and biofilm inhibitors. Inhibition of essential BHK has always been an amenable strategy due to the conserved binding sites of the domains across bacterial species and growth dependence. Hence, an inhibitor of BHK might block multiple TCS regulatory networks. This review describes the TCS system and the role of BHK in bacterial virulence and discusses the available inhibitors of BHK, which is a specific response regulator with essential structural features.

Cytokinin signaling promotes root secondary growth and bud formation in Panax ginseng

BackgroundPanax ginseng, one of the valuable perennial medicinal plants, stores numerous pharmacological substrates in its storage roots. Given its perennial growth habit, organ regeneration occurs each year, and cambium stem cell activity is necessary for secondary growth and storage root formation. Cytokinin (CK) is a phytohormone involved in the maintenance of meristematic cells for the development of storage organs; however, its physiological role in storage-root secondary growth remains unknown. MethodsExogenous CK was repeatedly applied to P. ginseng, and morphological and histological changes were observed. RNA-seq analysis was used to elucidate the transcriptional network of CK that regulates P. ginseng growth and development. The HISTIDINE KINASE 3 (PgHK3) and RESPONSE REGULATOR 2 (PgRR2) genes were cloned in P. ginseng and functionally analyzed in Arabidopsis as a two-component system involved in CK signaling. ResultsPhenotypic and histological analyses showed that CK increased cambium activity and dormant axillary bud formation in P. ginseng, thus promoting storage-root secondary growth and bud formation. The evolutionarily conserved two-component signaling pathways in P. ginseng were sufficient to restore CK signaling in the Arabidopsis ahk2/3 double mutant and rescue its growth defects. Finally, RNA-seq analysis of CK-treated P. ginseng roots revealed that plant-type cell wall biogenesis-related genes are tightly connected with mitotic cell division, cytokinesis, and auxin signaling to regulate CK-mediated P. ginseng development. ConclusionOverall, we identified the CK signaling-related two-component systems and their physiological role in P. ginseng. This scientific information has the potential to significantly improve the field-cultivation and biotechnology-based breeding of ginseng.

Regulation of adhesin synthesis in Aggregatibacter actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans is a gram-negative bacterium associated with periodontal disease and a variety of disseminated extra-oral infections. Tissue colonization is mediated by fimbriae and non-fimbriae adhesins resulting in the formation of a sessile bacterial community or biofilm, which confers enhanced resistance to antibiotics and mechanical removal. The environmental changes experienced by A. actinomycetemcomitans during infection are detected and processed by undefined signaling pathways that alter gene expression. In this study, we have characterized the promoter region of the extracellular matrix protein adhesin A (EmaA), which is an important surface adhesin in biofilm biogenesis and disease initiation using a series of deletion constructs consisting of the emaA intergenic region and a promotor-less lacZ sequence. Two regions of the promoter sequence were found to regulate gene transcription and in silico analysis indicated the presence of multiple transcriptional regulatory binding sequences. Analysis of four regulatory elements, CpxR, ArcA, OxyR, and DeoR, was undertaken in this study. Inactivation of arcA, the regulator moiety of the ArcAB two-component signaling pathway involved in redox homeostasis, resulted in a decrease in EmaA synthesis and biofilm formation. Analysis of the promoter sequences of other adhesins identified binding sequences for the same regulatory proteins, which suggests that these proteins are involved in the coordinate regulation of adhesins required for colonization and pathogenesis.

Mode of autophosphorylation in bacteriophytochromes RpBphP2 and RpBphP3.

Phytochromes are red-light photoreceptors that regulate a wide range of physiological processes in plants, fungi and bacteria. Canonical bacteriophytochromes are photosensory histidine kinases that undergo light-dependent autophosphorylation, thereby regulating cellular responses to red light via two-component signaling pathways. However, the molecular mechanism of kinase activation remains elusive for bacteriophytochromes. In particular, the directionality of autophosphorylation is still an open question in these dimeric photoreceptor kinases. In this work, we perform histidine kinase assays on two tandem bacteriophytochromes RpBphP2 and RpBphP3 from the photosynthetic bacterium Rhodopseudomonas palustris. By examining the kinase activities of full-length bacteriophytochromes and two loss-of-function mutants under different light conditions, we demonstrate that RpBphP2 and RpBphP3 undergo light-dependent trans-phosphorylation between protomers in both homodimeric and heterodimeric forms. We have further determined the crystal structure of the histidine kinase domains of RpBphP2 at 3.19Å resolution. Based on structural comparisons and homology modeling, we also present a model to account for the actions of trans-autophosphorylation in bacteriophytochromes.

Histidine Kinase Sln1 and cAMP/PKA Signaling Pathways Antagonistically Regulate Sporisorium scitamineum Mating and Virulence via Transcription Factor Prf1.

Many prokaryotes and eukaryotes utilize two-component signaling pathways to counter environmental stress and regulate virulence genes associated with infection. In this study, we identified and characterized a conserved histidine kinase (SsSln1), which is the sensor of the two-component system of Sln1–Ypd1–Ssk1 in Sporisorium scitamineum. SsSln1 null mutant exhibited enhanced mating and virulence capabilities in S. scitamineum, which is opposite to what has been reported in Candida albicans. Further investigations revealed that the deletion of SsSLN1 enhanced SsHog1 phosphorylation and nuclear localization and thus promoted S. scitamineum mating. Interestingly, SsSln1 and cAMP/PKA signaling pathways antagonistically regulated the transcription of pheromone-responsive transcription factor SsPrf1, for regulating S. scitamineum mating and virulence. In short, the study depicts a novel mechanism in which the cross-talk between SsSln1 and cAMP/PKA pathways antagonistically regulates mating and virulence by balancing the transcription of the SsPRF1 gene in S. scitamineum.

Comprehensive Phosphoproteomic Analysis of Nostoc flagelliforme in Response to Dehydration Provides Insights into Plant ROS Signaling Transduction.

Terrestrial cyanobacteria, originated from aquatic cyanobacteria, exhibit a unique mechanism for drought adaptation during long-term evolution. To elucidate this diverse adaptive mechanism exhibited by terrestrial cyanobacteria from the post-translation modification aspect, we performed a global phosphoproteome analysis on the abundance of phosphoproteins in response to dehydration using Nostoc flagelliforme, a kind of terrestrial cyanobacteria having strong ecological adaptability to xeric environments. A total of 329 phosphopeptides from 271 phosphoproteins with 1168 phosphorylation sites were identified. Among these, 76 differentially expressed phosphorylated proteins (DEPPs) were identified for each dehydration treatment (30, 75, and 100% water loss), compared to control. The identified DEPPs were functionally categorized to be mainly involved in a two-component signaling pathway, photosynthesis, energy and carbohydrate metabolism, and an antioxidant system. We concluded that protein phosphorylation modifications related to the reactive oxygen species (ROS) signaling pathway might play an important role in coordinating enzyme activity involved in the antioxidant system in N. flagelliforme to adapt to dehydration stress. This study provides deep insights into the extensive modification of phosphorylation in terrestrial cyanobacteria using a phosphoproteomic approach, which may help to better understand the role of protein phosphorylation in key cellular mechanisms in terrestrial cyanobacteria in response to dehydration.

Glucose-6-Phosphate Acts as an Extracellular Signal of SagS To Modulate Pseudomonas aeruginosa c-di-GMP Levels, Attachment, and Biofilm Formation.

ABSTRACTIn Pseudomonas aeruginosa, the orphan two-component sensor SagS contributes both to transition to biofilm formation and to biofilm cells gaining their heightened tolerance to antimicrobials. However, little is known about the identity of the signals or conditions sensed by SagS to induce the switch to the sessile, drug-tolerant mode of growth. Using a modified Biolog phenotype assay to screen for compounds that modulate attachment in a SagS-dependent manner, we identified glucose-6-phosphate to enhance attachment in a manner dependent on the glucose-6-phosphate concentration and SagS. The stimulatory effect was not limited to the attachment since glucose-6-phosphate likewise enhanced biofilm formation and also enhanced the expression of select biofilm marker genes. Moreover, exposure to glucose-6-phosphate coincided with decreased swarming motility but increased cellular cyclic-di-GMP (c-di-GMP) levels in biofilms. No such response was noted for compounds modulating attachment and biofilm formation in a manner independent of SagS. Modulation of c-di-GMP in response to glucose-6-phosphate was due to the diguanylate cyclase NicD, with NicD also being required for enhanced biofilm formation. The latter was independent of the sensory domain of NicD but dependent on NicD activity, SagS, and the interaction between NicD and SagS. Our findings indicate that glucose-6-phosphate likely mimics a signal or conditions sensed by SagS to activate its motile-sessile switch function. In addition, our findings provide new insight into the interfaces between the ligand-mediated two-component system signaling pathway and c-di-GMP levels.IMPORTANCE Pathogens sense and respond to signals and cues present in their environment, including host-derived small molecules to modulate the expression of their virulence repertoire. Here, we demonstrate that the opportunistic pathogen Pseudomonas aeruginosa responds to glucose-6-phosphate. Since glucose-6-phosphate is primarily made available due to cell lysis, it is likely that glucose-6-phosphate represents a cross-kingdom cell-to-cell signal that enables P. aeruginosa to adapt to the (nutrient-poor) host environment by enhancing biofilm formation, cyclic-di-GMP, and the expression of genes linked to biofilm formation in a concentration- and SagS-dependent manner.

IPhosD-PseAAC: Identification of phosphoaspartate sites in proteins using statistical moments and PseAAC

Phosphoaspartate is one of the major components of eukaryotes and prokaryotic two-component signaling pathways, and it communicates the signal from the sensor of histidine kinase, through the response regulator, to the DNA alongside transcription features and initiates the transcription of correct response genes. Thus, the prediction of phosphoaspartate sites is critical, and its experimental identification can be expensive, time-consuming, and tedious. For this purpose, we propose iPhosD-PseAAC, a new computational model for predicting phosphoaspartate sites in a particular protein sequence using Chou’s 5-steps rues: (1) Benchmark dataset. (2) The feature extraction techniques such as pseudo amino acid composition (PseAAC), statistical moments, and position relative features. (3) For the classification, artificial neural network AAN will be used. (4) In this step, 10-fold cross-validation and self-consistency testing will be used for validation. For self-consistency testing, 100% Acc is achieved, whereas, for 10-fold crossvalidation 95.14% Acc, 95.58% Sn, 94.70% Sp and 0.95 MCC are observed. (5). The final step is the development of a user-friendly web server for the ease of users. Thus, the iPhosD-PseAAC is the first and novel predictor for accurate and efficient identification of phosphoaspartate sites.

Barley HISTIDINE KINASE 1 (HvHK1) coordinates transfer cell specification in the young endosperm

Cereal endosperm represents the most important source of the world's food; nevertheless, the molecular mechanisms underlying cell and tissue differentiation in cereal grains remain poorly understood. Endosperm cellularization commences at the maternal-filial intersection of grains and generates endosperm transfer cells (ETCs), a cell type with a prominent anatomy optimized for efficient nutrient transport. Barley HISTIDINE KINASE1 (HvHK1) was identified as a receptor component with spatially restricted expression in the syncytial endosperm where ETCs emerge. Here, we demonstrate its function in ETC fate acquisition using RNA interference-mediated downregulation of HvHK1. Repression of HvHK1 impairs cell specification in the central ETC region and the development of transfer cell morphology, and consecutively defects differentiation of adjacent endosperm tissues. Coinciding with reduced expression of HvHK1, disturbed cell plate formation and fusion were observed at the initiation of endosperm cellularization, revealing that HvHK1 triggers initial cytokinesis of ETCs. Cell-type-specific RNA sequencing confirmed loss of transfer cell identity, compromised cell wall biogenesis and reduced transport capacities in aberrant cells and elucidated two-component signaling and hormone pathways that are mediated by HvHK1. Gene regulatory network modeling was used to specify the direct targets of HvHK1; this predicted non-canonical auxin signaling elements as the main regulatory links governing cellularization of ETCs, potentially through interaction with type-B response regulators. This work provides clues to previously unknown molecular mechanisms directing ETC specification, a process with fundamental impact on grain yield in cereals.

Influence of genetic diversity of seventeen Beauveria bassiana isolates from different hosts on virulence by comparative genomics

BackgroundBeauveria bassiana (B. bassiana) is a famous entomopathogenic fungus that could parasitize on hundreds of insect species, which are being used as an environmentally friendly mycoinsecticide. Nevertheless, the possible effect of genetic diversity of these B. bassiana isolates from different hosts on virulence has not been explored before. In order to explore that issue, we compared the genome sequences among seventeen B. bassiana isolates from 17 different insects using whole genome re-sequencing, with B. bassiana strain ARSEF 2860 as the reference genome.ResultsThere were a total of 10,098 missense mutated genes, 720 positively selected genes were identified in 17 strains of B. bassiana. Among these, two genes with high frequency mutations encode the toxin-producing non-ribosomal peptide synthase (NRPS) protein. Seven genes undergoing positive selection were enriched in the two-component signaling pathway that is known to regulate the fungal toxicity. In addition, the domain changes of three positively selected genes are also directly related to the virulence plasticity. Besides, the functional categorization of mutated genes showed that most of them involved in the biological functions of toxic proteins involved in.ConclusionsBased on our data, our results indicate that several mutated genes and positively selected genes may underpin virulence of B. bassiana towards hosts during infection process, which provide an insight into the potential effects of natural variation on the virulence of B. bassiana, which will be useful in screening out potential virulence factors in B. bassiana.

Two-component signaling pathways modulate drug resistance of Staphylococcus aureus (Review).

As the issues surrounding antibiotic-resistant strains of Staphylococcus aureus (S. aureus) are becoming increasingly serious concerns, it is imperative to investigate new therapeutic targets to successfully treat patients with S. aureus infections. The two-component signal transduction system is one of the primary pathways by which bacteria adapt to the external environment, and it serves an important role in regulating virulence gene expression, cell wall synthesis, biofilm formation and bacterial activity. There are 17 two-component signaling pathways in S. aureus, among which WalKR/VicSR/YycGF, AirSR/YhcSR, vancomycin resistance associated regulator/sensor and LytRS have been demonstrated to serve vital roles in regulating bacterial resistance, and are hypothesized to be potential targets for the treatment of S. aureus infections. The present review assesses the mechanism of the two-component signaling pathways associated with the development of S. aureus resistance.

Constraints on the expansion of paralogous protein families.

Duplication and divergence is a major mechanism by which new proteins and functions emerge in biology. Consequently, most organisms, in all domains of life, have genomes that encode large paralogous families of proteins. For recently duplicated pathways to acquire different, independent functions, the two paralogs must acquire mutations that effectively insulate them from one another. For instance, paralogous signaling proteins must acquire mutations that endow them with different interaction specificities such that they can participate in different signaling pathways without disruptive cross-talk. Although duplicated genes undoubtedly shape each other's evolution as they diverge and attain new functions, it is less clear how other paralogs impact or constrain gene duplication. Does the establishment of a new pathway by duplication and divergence require the system-wide optimization of all paralogs? The answer has profound implications for molecular evolution and our ability to engineer biological systems. Here, we discuss models, experiments, and approaches for tackling this question, and for understanding how new proteins and pathways are born.

Artificial signaling in mammalian cells enabled by prokaryotic two-component system.

Augmenting live cells with novel signal transduction capabilities is a key objective in genetic engineering and synthetic biology. We showed earlier that two-component signaling pathways could function in mammalian cells, albeit while losing their ligand sensitivity. Here we show how to transduce small molecule ligands in a dose-dependent fashion into gene expression in mammalian cells using two-component signaling machinery. First, we engineer mutually complementing truncated mutants of a histidine kinase unable to dimerize and phosphorylate the response regulator. Next, we fuse these mutants to protein domains capable of ligand-induced dimerization, which restores the phosphoryl transfer in a ligand-dependent manner. Cytoplasmic ligands are transduced by facilitating mutant dimerization in the cytoplasm, while extracellular ligands trigger dimerization at the inner side of a plasma membrane. These findings point to the potential of two-component regulatory systems as enabling tools for orthogonal signaling pathways in mammalian cells.

Homeostatic control of cell wall hydrolysis by the WalRK two-component signaling pathway in Bacillus subtilis.

Bacterial cells are encased in a peptidoglycan (PG) exoskeleton that protects them from osmotic lysis and specifies their distinct shapes. Cell wall hydrolases are required to enlarge this covalently closed macromolecule during growth, but how these autolytic enzymes are regulated remains poorly understood. Bacillus subtilis encodes two functionally redundant D,L-endopeptidases (CwlO and LytE) that cleave peptide crosslinks to allow expansion of the PG meshwork during growth. Here, we provide evidence that the essential and broadly conserved WalR-WalK two component regulatory system continuously monitors changes in the activity of these hydrolases by sensing the cleavage products generated by these enzymes and modulating their levels and activity in response. The WalR-WalK pathway is conserved among many Gram-positive pathogens where it controls transcription of distinct sets of PG hydrolases. Cell wall remodeling in these bacteria may be subject to homeostatic control mechanisms similar to the one reported here.

Development of a Light-Dependent Protein Histidine Kinase.

Phosphorylation plays a critical role in facilitating signal transduction in prokaryotic and eukaryotic organisms. Our study introduces a tool for investigation of signal diffusion in a biochemical regulation network through the design and characterization of a light-stimulated histidine kinase that consists of the LOV domain from YtvA from Bacillus subtilis and the histidine kinase domain Sln1 from Saccharomyces cerevisiae. We show that blue light can be used as a trigger for modulation of the phosphorylation events in this engineered two-component signal transduction pathway in a eukaryotic cell. At the same time, we demonstrate the robustness of LOV domains and their utility for designing fusion proteins for signal transduction that can be triggered with (blue) light, providing a ready toolkit to design blue light dependent two-component signalling pathways.

Metabolic adaptability shifts of cell membrane fatty acids of Komagataeibacter hansenii HDM1-3 improve acid stress resistance and survival in acidic environments.

Komagataeibacter hansenii HDM1-3 (K. hansenii HDM1-3) has been widely applied for producing bacterial cellulose (BC). The yield of BC has been frequently limited by the acidification during sugar metabolism, due to the generation of organic acids such as acetic acid. In this study, the acid resistance mechanism of K. hansenii HDM1-3 has been investigated from the aspect of metabolic adaptability of cell membrane fatty acids. Firstly, we observed that the survival rate of K. hansenii HDM1-3 was decreased with lowered pH values (adjusted with acetic acids), accompanied by increased leakage rate. Secondly, the cell membrane adaptability in response to acid stress was evaluated, including the variations of cell membrane fluidity and fatty acid composition. The proportion of unsaturated fatty acids was increased (especially, C18-1w9c and C19-Cyc), unsaturation degree and chain length of fatty acids were also increased. Thirdly, the potential molecular regulation mechanism was further elucidated. Under acid stress, the fatty acid synthesis pathway was involved in the structure and composition variations of fatty acids, which was proved by the activation of both fatty acid dehydrogenase (des) and cyclopropane fatty acid synthase (cfa) genes, as well as the addition of exogenous fatty acids. The fatty acid synthesis of K. hansenii HDM1-3 may be mediated by the activation of two-component sensor signaling pathways in response to the acid stress. The acid resistance mechanism of K. hansenii HDM1-3 adds to our knowledge of the acid stress adaptation, which may facilitate the development of new strategies for improving the industrial performance of this species under acid stress.

Changes in transcriptome expression profiles and functional analysis of differentially expressed genes during mycelium-to-yeast transformation of Sporothrix schenckii

Objective To compare and analyze the differences in the transcriptomics between mycelium and early yeast phases of Sporothrix schenckii (S. schenckii) , and to realize the changes in transcriptome expression profiles during mycelium-to-yeast transformation. Methods A standard strain of S. schenckii (ATCC 10268) was subjected to 96-hour culture with Sabouraud medium at 25 ℃ or 36-hour culture with brain-heart infusion medium at 37 ℃ to obtain the mycelium and yeast form of S. schenckii, and then, their transcriptomes were sequenced. Functional annotation was performed for screened unigenes by comparison using several databases (such as NR, Swiss-Prot, KEGG, COG, KOG, GO and Pfam) , coding sequence prediction, and gene expression analysis in each sample. Finally, the differentially expressed genes were subjected to pattern clustering, functional annotation and enrichment analysis. Results A total of 14.76 Gb valid data (clean data) were obtained, and functional annotation results were acquired in 28 094 of 43 863 assembled unigene clusters. Compared with S. schenckii in mycelium phase, there were 10 969 up-regulated genes and 199 down-regulated genes in S. schenckii in yeast phase. These differentially expressed genes were involved in protein phosphorylation, intracellular protein transport, cellular protein modification, small guanosine triphosphate-mediated signal transduction, vesicle-mediated transport, translation, intracellular signal transduction, microtubule formation, adenosine triphosphate synthesis, coupled proton transport and so on. Sixteen genes in the mitogen-activated protein kinase (MAPK) pathway and two-component signaling pathway, which were two important signal transduction pathways involved in fungal morphogenesis, and 16 genes involved in chitin synthesis and metabolism were all confirmed to be up-regulated in S. schenckii in yeast phase. Conclusions Compared with S. schenckii in mycelium phase, great changes in gene expression profiles were observed in S. schenckii in yeast phase. These differentially expressed genes are involved in many functions, suggesting that the dimorphic transition of S. schenckii is regulated by a multi-gene network system. Key words: Sporothrix; Hyphae; Transcriptome; Gene expression profiling; Differential gene expression analysis; Yeast phase

Uncovering complex microbiome activities via metatranscriptomics during 24\u2009hours of oral biofilm assembly and maturation

BackgroundDental plaque is composed of hundreds of bacterial taxonomic units and represents one of the most diverse and stable microbial ecosystems associated with the human body. Taxonomic composition and functional capacity of mature plaque is gradually shaped during several stages of community assembly via processes such as co-aggregation, competition for space and resources, and by bacterially produced reactive agents. Knowledge on the dynamics of assembly within complex communities is very limited and derives mainly from studies composed of a limited number of bacterial species. To fill current knowledge gaps, we applied parallel metagenomic and metatranscriptomic analyses during assembly and maturation of an in vitro oral biofilm. This model system has previously demonstrated remarkable reproducibility in taxonomic composition across replicate samples during maturation.ResultsTime course analysis of the biofilm maturation was performed by parallel sampling every 2–3 h for 24 h for both DNA and RNA. Metagenomic analyses revealed that community taxonomy changed most dramatically between three and six hours of growth when pH dropped from 6.5 to 5.5. By applying comparative metatranscriptome analysis we could identify major shifts in overall community activities between six and nine hours of growth when pH dropped below 5.5, as 29,015 genes were significantly up- or down- expressed. Several of the differentially expressed genes showed unique activities for individual bacterial genomes and were associated with pyruvate and lactate metabolism, two-component signaling pathways, production of antibacterial molecules, iron sequestration, pH neutralization, protein hydrolysis, and surface attachment. Our analysis also revealed several mechanisms responsible for the niche expansion of the cariogenic pathogen Lactobacillus fermentum.ConclusionIt is highly regarded that acidic conditions in dental plaque cause a net loss of enamel from teeth. Here, as pH drops below 5.5 pH to 4.7, we observe blooms of cariogenic lactobacilli, and a transition point of many bacterial gene expression activities within the community. To our knowledge, this represents the first study of the assembly and maturation of a complex oral bacterial biofilm community that addresses gene level functional responses over time.

Arabidopsis CKI1 mediated two-component signaling in the specification of female gametophyte

ABSTRACTCytokinin independent 1 (CKI1) is a histidine kinase involved in the two-component signaling pathway and acts as a master regulator of central cell specification via CKI1-mediated two-component signaling. In this study, the dynamic distribution of two-component system (TCS) signals was primarily investigated during Arabidopsis embryo sac development. TCS signals were stably detected in female gametophytes cells from the megaspore stage all through to the mature embryo sac stage. CKI1 acts as the primary activator of the TCS signaling pathway in embryo sacs. Accordingly, focusing on CKI1, two alternate models are proposed for female gametophyte cell fate specification. In the first model, CKI1 co-determines the central cell fate in combination with a hypothetical X factor at the micropylar pole, and in the alternate model, CKI1 alone determines the central cell fate.

Molecular Characterization, Fitness, and Mycotoxin Production of Fusarium asiaticum Strains Resistant to Fludioxonil.

Fludioxonil is used in seedborne disease management of various fungal pathogens, including Fusarium asiaticum, the predominant causal agent of Fusarium head blight in China. In this study, we screened resistant strains from a large number of F. asiaticum strains collected from 2012 to 2016 and found that 4 of 1,000 field strains were highly resistant to fludioxonil. The 50% effective concentration values of the resistant strains and induced mutants ranged from 80 to >400 μg/ml. Compared with field-sensitive strains, all field-collected and laboratory-induced resistant strains exhibited fitness defects in traits including mycelial growth, conidial production, pathogenicity, and sensitivity to osmotic conditions. In the presence of fludioxonil, significantly higher glycerol accumulation was found in sensitive strains but not in resistant individuals. The fludioxonil-resistant strains produced lower amounts of glycerol in liquid culture and lower amounts of trichothecene mycotoxins in rice culture and inoculated wheat spikelets than the fludioxonil-sensitive strains. Sequence analyses of the key genes of the two-component histidine kinase signaling pathway showed various amino acid substitutions in the Os1, Os4, and Os5 genes between field-sensitive and resistant strains or mutants. The results of this study suggest a potential risk of fludioxonil resistance development and a possible influence of resistance mutations on fitness parameters and toxin production in F. asiaticum.