The hemibiotrophic fungus Magnaporthe oryzae causes rice blast, a devastating plant disease, by transitioning from biotrophic to necrotrophic growth, which triggers host cell death. This trophic shift is essential for nutrient acquisition and disease progression, culminating in conidiation. However, the molecular mechanisms underlying this transition are not well understood. Here, by screening 298 candidate effector proteins upregulated during late infection stages, we identified six necrotrophic effectors (NEEs) from M. oryzae, with MoNee6 exhibiting a particularly important role in virulence. MoNee6 functions as a nuclease that specifically localizes to rice chloroplasts and degrades chloroplast DNA, directly inducing host cell death. Nevertheless, MoNee6 is unstable within the chloroplast and is degraded by the rice chloroplast caseinolytic protease (Clp). To improve host resistance, we engineered OsClpP1 as a nuclear-encoded, chloroplast-targeted protein by fusing it to a chloroplast transit peptide, thereby enabling its expression independent of the native chloroplast-genome-encoded function. This modification enhanced Clp-mediated degradation of MoNee6 and substantially reduced the severity of rice blast. Our findings reveal a previously unrecognized interaction between an effector and the chloroplast that drives the biotrophic-to-necrotrophic transition, and they demonstrate an effective strategy for engineering chloroplast-targeted defence mechanisms against M. oryzae.

In an investigation exploring endophytic microbiota from agricultural crops, an aerobic, non-motile, Gram-negative, coccobacillus-shaped bacterial isolate, designated as strain NGMCC 1.201697T, was isolated from maize roots in Hunan Province, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NGMCC 1.201697T belonged to the genus Paracoccus, showing the highest sequence similarity to Paracoccus broussonetiae CPCC 101403T (99.86%). The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) were 98.57% and 87.90% between the novel isolate and its closest phylogenetic relative. However, phenotypic characterization further differentiated the isolate from P. broussonetiae CPCC 101403T. The isolate showed enhanced environmental tolerance adaptability (growth in 0–8% NaCl and 4–37 °C), unique enzymatic activities (esterase C4, β-glucosidase, L-proline arylamidase, and β-galactosidase), and expanded metabolic capabilities (D-mannitol, D-cellobiose, saccharose, and so on). The major polar lipids consisted of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylglycerol (PG), two unidentified glycolipids (GLs) and four unidentified phospholipids (PLs). The predominant respiratory quinone was ubiquinone-10, and the major fatty acid was summed feature 8 (C18:1 ω7c, 69.42%). The DNA G + C content was 64.49 mol%. Based on results of these analyses, strain NGMCC 1.201697T represents a novel subspecies of Paracoccus broussonetiae, for which the name Paracoccus broussonetiae subsp. drimophilus subsp. nov. is proposed. The type-strain is NGMCC 1.201697T (=CGMCC 1.61958T =JCM 37104T).

Penicillium is a common, widespread and economically important genus. In an investigation of endophytic Penicillium species associated with trifoliate orange in China, a novel species in Penicillium section Exilicaulis, namely P. sinense was isolated from the leaves of Citrus trifoliata L. in Changsha, Hunan, China. It is different from other Penicillium species morphological comparisons and phylogenetic analyses. Multi-locus (CaM, ITS, RPB2 and TUB) phylogenetic analysis confirmed that P. sinense is distinct from other species. A synopsis of the morphological characters of the new species is provided. The biocontrol potential of P. sinense was measured by the confrontation test between P. sinense and common pathogenic fungi. The results of the study provided a strain resource for screening effective antagonistic Penicillium strains and biological control of fungal diseases.

Rice blast caused by Magnaporthe oryzae poses a major threat to world food supply. Conditions conducive to the disease include insufficient light. Our previous studies found that light-dependent phosphorylation of light-harvesting complex II protein (LHCB5) mediates rice immunity; however, the underlying mechanisms, in particular, the upstream regulators of LHCB5 phosphorylation, remain unknown. Here, we show that OsLIKE1 functions as a lectin receptor-like kinase (LecRLK) to play a critical role in rice resistance against M. oryzae. OsLIKE1 interacts with and phosphorylates LHCB5. In addition, we find two phosphorylation sites in the kinase domain of OsLIKE1 important for its auto-phosphorylation and phosphorylation of LHCB5. Moreover, we find that variation in light-induced OsLIKE1 expression is driven by specific single-nucleotide polymorphisms (SNPs) within the promoter region. These SNPs promote the auto-phosphorylation of OsLIKE1 to phosphorylate LHCB5 and activate its immune function against the blast fungus. Collectively, these findings elucidate the mechanism by which light regulates OsLIKE1-dependent defense in rice and support SNP-based rice breeding programs that increase disease resistance. Light-dependent phosphorylation can modulate rice blast immunity. Here the authors show that the receptor-like kinase OsLIKE1 phosphorylates LHCB5 to confer blast resistance and identify SNPs that could potentially be used to breed resistant cultivars.

Plant pathogenic fungi release cell wall-degrading enzymes (CWDEs), which are significant weapons for breaking down plant cell walls, although only a few reports focus on their pathogenesis. The current study demonstrates that MoFco1, a conserved α-L-fucosidase in several pathogenic fungi, degrades the hemicellulose component XXFG and contributes to the pathogenicity of Magnaporthe oryzae. In addition, MoFco1 enzyme activity is essential for its pathogenic function, as the enzyme activity mutation induced pathogenesis defects identical to the ΔMofco1 mutant. We further performed a structure-based virtual screening targeting MoFco1 and discovered 0989, which binds to MoFco1 and effectively inhibits M. oryzae pathogenesis. In brief, our study reveals the pathogenic mechanism of MoFco1 and explored the application of structure-based virtual screening in plant protection.

The genus Paenibacillus, known for its diverse sources, is a valuable reservoir of antimicrobial compounds, enzymes and other valuable chemicals, with applications in medicine, agriculture, and bioremediation. Despite this, Paenibacillus strains, particularly those isolated from unique environments, remain underexplored, limiting our understanding of their potential, capabilities and taxonomic classifications. The gut microbiome of large herbivores, such as rhinoceroses, harbors underexplored microbial diversity with unique metabolic capabilities. In this study, a Gram-stain-negative, facultatively aerobic, motile, spore-forming, rod-shaped bacterial strain, NGMCC 1.200843T (= CGMCC 1.64763T = JCM 37214T), was isolated from fresh rhinoceros feces and characterized its taxonomic status and metabolic potential. Phylogenetic, phenotypic, and chemotaxonomic analyses confirmed the isolate as a novel species within the genus Paenibacillus, closely related to Paenibacillus lautus DSM 3035T (98.62% 16S rRNA gene similarity). The average nucleotide identity (ANI) and the digital DNA-DNA hybridization values were below the threshold for species delineation. The major cellular fatty acids were anteiso-C15:0, C16:0 and iso-C16:0 (> 10%) and the polar lipid profile contained diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), two unidentified phospholipids (PL1-2) and one phosphatidyl choline (PC). The total DNA G + C content was 49.69 mol%. The isolate exhibited significant phosphate solubilization and starch hydrolysis activities in plate assays, suggesting a role in nutrient cycling within the rhinoceros gut. We propose the name Paenibacillus ilasis sp. nov. for this strain. These findings enhance our understanding of gut microbial diversity in herbivores and lay the foundation for future applications in agriculture or industry.

IntroductionThe intestinal microbiota plays a crucial role in health and disease. This study aimed to assess the composition and functional diversity of the intestinal microbiota in donkeys and cows by examining samples collected from different segments of the digestive tract using two distinct techniques: direct swab sampling and faecal sampling.ResultsIn this study, we investigated and compared the effects of multiple factors on the composition and function of the intestinal microbial community. Approximately 300 GB of metagenomic sequencing data from 91 samples obtained from various segments of the digestive tract were used, including swabs and faecal samples from monogastric animals (donkeys) and polygastric animals (cows). We assembled 4,004,115 contigs for cows and 2,938,653 contigs for donkeys, with a total of 9,060,744 genes. Our analysis revealed that, compared with faecal samples, swab samples presented a greater abundance of Bacteroidetes, whereas faecal samples presented a greater abundance of Firmicutes. Additionally, we observed significant variations in microbial composition among different digestive tract segments in both animals. Our study identified key bacterial species and pathways via different methods and provided evidence that multiple factors can influence the microbial composition. These findings provide new insights for the accurate characterization of the composition and function of the gut microbiota in microbiome research.ConclusionsThe results obtained by both sampling methods in the present study revealed that the composition and function of the intestinal microbiota in donkeys and cows exhibit species-specific and region-specific differences. These findings highlight the importance of using standardized sampling protocols to ensure accurate and consistent characterization of the intestinal microbiota in various animal species. The implications and underlying mechanisms of these associations provide multiple perspectives for future microbiome research.

Gut microbes play a vital role in the health and disease of animals, especially in relation to pathogen infections. Chinchillas, ferrets, and marmots are commonly used as important laboratory animals for infectious disease research. Here, we studied the bacterial and fungal microbiota and discovered that chinchillas had higher alpha diversity and a higher abundance of bacteria compared to marmots and ferrets by using the metabarcoding of 16S rRNA genes and ITS2, coupled with co-occurrence network analysis. The dominant microbes varied significantly among the three animal species, particularly in the gut mycobiota. In the ferrets, the feces were dominated by yeast such as Rhodotorula and Kurtzmaniella, while in the chinchillas, we found Teunomyces and Penicillium dominating, and Acaulium, Piromyces, and Kernia in the marmots. Nevertheless, the dominant bacterial genera shared some similarities, such as Clostridium and Pseudomonas across the three animal species. However, there were significant differences observed, such as Vagococcus and Ignatzschineria in the ferrets, Acinetobacter and Bacteroides in the chinchillas, and Bacteroides and Cellvibrio in the marmots. Additionally, our differential analysis revealed significant differences in classification levels among the three different animal species, as well as variations in feeding habitats that resulted in distinct contributions from the host microbiome. Therefore, our data are valuable for monitoring and evaluating the impacts of the microbiome, as well as considering potential applications.

A novel Gram-positive, anaerobic, nonspore-forming, rod-shaped bacterium, designated strain NGMCC 1.200840 T, was isolated from the alpacas fresh feces. The taxonomic position of the novel strain was determined using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed strain NGMCC 1.200840 T was a member of the genus Clostridium and closely related to Clostridium tertium DSM 2485 T (98.16

Regulator of G-protein signaling (RGS) proteins exhibit GTPase-accelerating protein activities to govern G-protein function. In the rice blast fungus Magnaporthe oryzae, there is a family of at least eight RGS and RGS-like proteins (MoRgs1 to MoRgs8), each exhibiting distinct or shared functions in the growth, appressorium formation, and pathogenicity. MoRgs3 recently emerged as one of the crucial regulators that senses intracellular oxidation during appressorium formation. To explore this unique regulatory mechanism of MoRgs3, we identified the nucleoside diphosphate kinase MoNdk1 that interacts with MoRgs3. MoNdk1 phosphorylates MoRgs3 under induced intracellular reactive oxygen species levels, and MoRgs3 phosphorylation is required for appressorium formation and pathogenicity. In addition, we showed that MoRgs3 phosphorylation determines its interaction with MoCrn1, a coronin-like actin-binding protein homolog, which regulates MoRgs3 internalization. Finally, we provided evidence demonstrating that MoRgs3 functions in MoMagA-mediated cAMP signaling to regulate normal appressorium induction. By revealing a novel signal perception mechanism, our studies highlighted the complexity of regulation during the appressorium function and pathogenicity of the blast fungus. IMPORTANCE:We report that MoRgs3 becomes phosphorylated in an oxidative intracellular environment during the appressorium formation stage. We found that this phosphorylation is carried out by MoNdk1, a nucleoside diphosphate kinase. In addition, this phosphorylation leads to a higher binding affinity between MoRgs3 and MoCrn1, a coronin-like actin-binding protein that was implicated in the endocytic transport of several other RGS proteins of Magnaporthe oryzae. We further found that the internalization of MoRgs3 is indispensable for its GTPase-activating protein function toward the Gα subunit MoMagA. Importantly, we characterized how such cellular regulatory events coincide with cAMP signaling-regulated appressorium formation and pathogenicity in the blast fungus. Our studies uncovered a novel intracellular reactive oxygen species signal-transducing mechanism in a model pathogenic fungus with important basic and applied implications.

Abstract Intestinal microbiota plays a crucial role in the health and diseases. However, very little is known about the impact of sampling methods on assessing intestinal microbiota. In this study, we investigated and compared the influence of sampling methods on the intestinal microbial community composition and function using approximately 300 GB of metagenomic sequencing data from 91 samples representing different digestive tract segment with swab and fecal samples of monogastric (donkeys) and polygastric (cows) animals. We assembled 4,004,115 (cow) and 2,938,653 (donkey) contigs, and got 9,060,744 genes showing the swab sampling revealed a higher abundance of Bacteroidetes, while the fecal sampling showed a relatively higher proportion of Firmicutes. In addition, we observed the significant variations in the microbial composition between different digestive tract segments in both animals. Finally, our study identified several key species and pathways in different of sampling methods and provided evidence that sampling methods can influence their co-abundance relationship, which expands our current knowledge using appropriate sampling methods to accurately characterize the gut microbiota composition and function.

The active structural change of actin cytoskeleton is a general host response upon pathogen attack. This study characterized the function of the cotton (Gossypium hirsutum) actin-binding protein VILLIN2 (GhVLN2) in host defense against the soilborne fungus Verticillium dahliae. Biochemical analysis demonstrated that GhVLN2 possessed actin-binding, -bundling, and -severing activities. A low concentration of GhVLN2 could shift its activity from actin bundling to actin severing in the presence of Ca2+. Knockdown of GhVLN2 expression by virus-induced gene silencing reduced the extent of actin filament bundling and interfered with the growth of cotton plants, resulting in the formation of twisted organs and brittle stems with a decreased cellulose content of the cell wall. Upon V. dahliae infection, the expression of GhVLN2 was downregulated in root cells, and silencing of GhVLN2 enhanced the disease tolerance of cotton plants. The actin bundles were less abundant in root cells of GhVLN2-silenced plants than in control plants. However, upon infection by V. dahliae, the number of actin filaments and bundles in the cells of GhVLN2-silenced plants was raised to a comparable level as those in control plants, with the dynamic remodeling of the actin cytoskeleton appearing several hours in advance. GhVLN2-silenced plants exhibited a higher incidence of actin filament cleavage in the presence of Ca2+, suggesting that pathogen-responsive downregulation of GhVLN2 could activate its actin-severing activity. These data indicate that the regulated expression and functional shift of GhVLN2 contribute to modulating the dynamic remodeling of the actin cytoskeleton in host immune responses against V. dahliae.

A Gram-negative strain, anaerobic, non-motile, non-spore-forming, rod-shaped bacterial strain named as NGMCC 1.200684 (T) was isolated from the fresh feces of rhinoceros in Beijing Zoo. Based on 16S rRNA gene sequences, phylogenetic analysis indicated that strain NGMCC 1.200684 (T) belonged to the genus Bacteroides and was most strongly related to the type strain of Bacteroides uniformis ATCC -8492 (T) (96.88%). The G + C content of the genomic DNA was determined to be 46.62%. Between strains NGMCC 1.200684 (T) and B. uniformis ATCC -8492 (T), the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) were 93.89 and 67.60%, respectively. Strain NGMCC 1.200684 (T) can produce acid from fermentation of several substrates, including glucose, mannitol, lactose, saccharose, maltose, salicin, xylose, cellobiose, mannose, raffinose, sorbitol, trehalose, D.galactose, and maltotriose. The major cellular fatty acids (> 10%) were identified as anteiso.C-15:0, iso.C-15:0, iso.C-14:0, and iso.C-17:0 3.OH. The polar lipid profiles of strain NGMCC 1.200684 T were determined to contain diphosphatidyl glycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, and two unknown amino-phospholipids. Based on phenotypic, phylogenetic, and chemotaxonomic characteristics, a novel species of the genus Bacteroides, Bacteroides rhinocerotis sp. nov. is proposed. The type strain is NGMCC 1.200684 (T) (= CGMCC 1.18013 (T) = JCM -35702 (T)).

A gram-positive, facultatively anaerobic, and coccoid or ovoid-shaped bacterium designated M2458T was isolated from the intestinal contents of APPswe/PSΔE9 mouse model of Alzheimer’s disease. With the polyphasic approach, the taxonomic position of the novel isolate was confirmed. Strain M2458T grew well at 37 °C on YCFA agar. Strain M2458T belongs to the family Streptococcaceae and class Bacilli, and it is closed to Lactococcus formosensis NBRC 109475T (97.59% sequence similarity) according to its 16S rRNA gene sequence. In a comparison of two housekeeping genes, rpoA and rpoB, strain M2458T was found to be well separated from Lactococcus formosensis NBRC 109475T. On the basis of whole genome sequences, the DNA G+C content was 38.29 mol%. The phylogentic analysis of the whole genome showed that a different branch was clearly formed in the phylogenetic tree of strain M2458T compared to other strains in the genus Lactococcus. A total of eight genes in strain M2458T are involved in the ‘neurodegenerative disease’ pathway, which involves an annotated protein (glyceraldehyde 3-phosphate dehydrogenase) involved in Alzheimer's disease. In terms of average nucleotide identity and digital DNA–DNA hybridization, strain M2458T was identified as a novel species of the genus Lacococcus. The major fatty acids (> 10% of the total fatty acids) were C18:1ω9c (39.68%), C16:0 (13.26%) and C18:1ω7c (11.52%). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and an unidentified phospholipid. As a result of its genotypic and phenotypic characteristics, strain M2458T was considered to be a new species within the genus Lactococcus; the name Lactococcus intestinalis sp. nov. has been proposed, with type strain M2458T (=JCM 35706 = CGMCC 1.60066).

Abstract Background: As a domesticated species vital to humans, cow and donkey are raised worldwide as a source of agricultural industry and food production. The digestion and absorption must rely on the division of labor and cooperation of all the digestive tract segments and microbes. The microbiota plays an important role in the health, diseases, athletic performance, weight and digestion of food in animals. The composition and function of microbial community are closely related to the animals’ physiological structure. Moreover, experimental techniques, like the sampling method, could also influence the identification results. Results: Here, using approximately 300 GB of metagenomic sequencing data from digestive tract samples from 91 samples that represent six (donkeys) and nine (cows) digestive tract segment with swab and fecal samples of monogastric (donkeys) and polygastric (cows) animals. We assembled 4,004,115 (cow) and 2,938,653 (donkey) microbial metagenome assembled contigs, and obtained 9,060,744 genes with an average of 553bp (range 102bp ~ 10,912bp) were obtained by clustering at 95% identity and 90% coverage. There were certainly influences on the microbiota with two sampling methods and fecal sample was recommended due to more abundant diversity of species compared with swab sample. Besides, microbiota in the stomach was significantly different from other segments and colon held the most abundant bacteria in the other intestine. In addition, the microbial community structure of donkey was obviously different from cow for both dominant and endemic microbes. There were 1,942 genera that were characterized by high Lactobacillus, Clostridium and Prevotella in the donkey while 1,744 genera were recognized in the cow. Differ from the donkey, different segments of the cow had different dominate genera such Prevotellafor the stomach, Kandleria for the small intestine and Clostridium for the hindgut. Conclusions: Overall, we solved the scientific problem of fecal sample could more objectively reflect the intestinal microbial community. Meanwhile, the microbial composition showed the shared and distinct features of digestive tract segments in different type animals. Our experimental design and dataset provides a valuable resource for discovery of performance-enhancing microbes and systematic studies of cow and donkey microbiome.

Seagrass form high productive ecosystems in coastal environments. However, the effects of these coastal plants on the structure and function of the belowground eukaryotic microbiome remain elusive. In this study, we characterized the community of microbial eukaryotes (microeukaryotes) in both vegetated and unvegetated sediments using 18S rRNA gene amplicon sequencing and quantitative PCR. Analysis of sequencing data showed that the eelgrass (Zostera marina) colonization decreased the alpha diversity indices of benthic microeukaryotes. Apicomplexa represented an average of 83% of reads across all samples, with a higher proportion at the vegetated sites. The taxonomic community structure was significantly different between these two types of sediments, for which the concentration of NH4+ in sediment porewater and salinity could account. Phylogenetic analyses of long 18S rRNA genes (around 1,030 bp) indicated these apicomplexan parasites are closely related to gregarine Lecudina polymorpha. Determination of 18S rRNA gene abundances provided evidence that the eelgrass markedly promoted the biomass of the gregarine and all microeukaryotes in the seagrass-colonized sediments and confirmed that the gregarine was hosted by a polychaete species. Significantly higher gene abundances of heterotrophs and mixotrophs were found at the vegetated sites, which could be explained by the finer sediments and short supply of dissolved inorganic nitrogen, respectively. The pigmented protists were more abundant in 18S rRNA gene copies at the lower and higher pH levels than at the intermediate. Nevertheless, the fractions of heterotrophs and phototrophs in the community were significantly related to porewater N:P ratio. These results indicate that seagrass colonization significantly induces an increase in overall biomass and a decrease in diversity of benthic microeukaryotes, making them more heterotrophic. This study also highlights that the hotspot of eukaryotic parasites could be linked with the high productivity of a natural ecosystem.

A common symptom in Alzheimer’s disease (AD) is cognitive decline, of which the potential pathogenesis remains unclear. In order to understand the mechanism of gut microbiota in AD, it is necessary to clarify the relationship between gut microbiota and metabolites. Behavioral tests, pathological examination, metagenomics, and metabolomics were applied to analyze the difference of gut microbiota and metabolome between APPswe/PS1ΔE9 (PAP) mice with cognitive decline and age-matched controls, and their possible correlations. Our results showed that PAP mice and health mice had different structures of the bacterial communities in the gut. The abundances and diversities of the bacterial communities in health mice were higher than in PAP mice by metagenomics analysis. The abundances of Libanicoccus massiliensis, Paraprevotella clara, and Lactobacillus amylovorus were significantly increased in PAP mice, while the abundances of Turicibacter sanguinis, Dubosiella newyorkensis, and Prevotella oris were greatly reduced. Furthermore, PAP mice possessed peculiar metabolic phenotypes in stool, serum, and hippocampus relative to WT mice, as is demonstrated by alterations in neurotransmitters metabolism, lipid metabolism, aromatic amino acids metabolism, energy metabolism, vitamin digestion and absorption, and bile metabolism. Microbiota–host metabolic correlation analysis suggests that abnormal metabolism in stool, serum, and hippocampus of PAP mice may be modulated by the gut microbiota, especially T. sanguinis, D. newyorkensis, and P. oris. Therefore, abnormal metabolism activity is associated with gut microbiota in Alzheimer’s disease mice. Our results imply that modifying host metabolism through targeting gut microbiota may be a novel and viable strategy for the prevention and treatment of AD in the future.

In recent years, human gut microbiota have become one of the most promising areas of microorganism research; meanwhile, the inter-relation between the gut microbiota and various human diseases is a primary focus. As is demonstrated by the accumulating evidence, the gastrointestinal tract and central nervous system interact through the gut–brain axis, which includes neuronal, immune-mediated and metabolite-mediated pathways. Additionally, recent progress from both preclinical and clinical studies indicated that gut microbiota play a pivotal role in gut–brain interactions, whereas the imbalance of the gut microbiota composition may be associated with the pathogenesis of neurological diseases (particularly neurodegenerative diseases), the underlying mechanism of which is insufficiently studied. This review aims to highlight the relationship between gut microbiota and neurodegenerative diseases, and to contribute to our understanding of the function of gut microbiota in neurodegeneration, as well as their relevant mechanisms. Furthermore, we also discuss the current application and future prospects of microbiota-associated therapy, including probiotics and fecal microbiota transplantation (FMT), potentially shedding new light on the research of neurodegeneration.

Several studies have revealed that actin depolymerizing factors (ADFs) participate in plant defence responses; however, the functional mechanisms appear intricate and need further exploration. In this study, we identified an ADF6 gene in upland cotton (designated as GhADF6) that is evidently involved in cotton's response to the fungal pathogen Verticillium dahliae. GhADF6 binds to actin filaments and possesses actin severing and depolymerizing activities in vitro and in vivo. When cotton root (the site of the fungus invasion) was inoculated with the pathogen, the expression of GhADF6 was markedly down-regulated in the epidermal cells. By virus-induced gene silencing analysis, the down-regulation of GhADF6 expression rendered the cotton plants tolerant to V. dahliae infection. Accordingly, the abundance of actin filaments and bundles in the root cells was significantly higher than that in the control plant, which phenocopied that of the V. dahliae-challenged wild-type cotton plant. Altogether, our results provide evidence that an increase in filament actin (F-actin) abundance as well as dynamic actin remodelling are required for plant defence against the invading pathogen, which are likely to be fulfilled by the coordinated expressional regulation of the actin-binding proteins, including ADF.