Verticillium Wilt Of Cotton Research Articles

Chitin synthases containing myosin motor-like domain are required for cell wall integrity and virulence of vascular wilt pathogen Verticillium dahliae

Verticillium wilt (VW) of cotton poses a serious threat to the quality and yield of cotton. Verticillium dahliae is the primary causal agent of cotton VW. Moreover, V. dahliae can infect more than 200 species of dicotyledonous plants. The fungal cell wall plays a crucial role in its growth, development and pathogenicity. However, the mechanism of cell wall synthesis in V. dahliae and its role in pathogenesis remains unclear. In this study, we identified two chitin synthase (CHS) genes VdChs5 and VdChs7 containing myosin motor-like domain (MMD) and characterized their role in virulence of V. dahliae. The results showed that the functions of VdChs5 and VdChs7 were largely redundant, and target deletion of both VdChs5 and VdChs7 in V. dahliae did not affect vegetative growth, but reduced conidial production. ΔVdChs5Chs7 deletion mutant failed to colonize and proliferate in cotton vascular tissue, and exhibited significantly reduced virulence on cotton, suggesting that VdChs5 and VdChs7 are necessary for pathogenesis. In addition, the thickness of the cell wall in ΔVdChs5Chs7 showed significantly decreased, and ΔVdChs5Chs7 mutant exhibited hypersensitivity to cell wall perturbing agents and reactive oxygen species (ROS), indicating that VdChs5 and VdChs7 play key roles in cell wall integrity. Further, host-induced gene silencing (HIGS) silenced transcripts of VdChs5 and VdChs7 in susceptible cotton (Gossypium hirsutum L. acc. TM-1) enhanced resistance to cotton VW. Taken together, our data demonstrated that VdChs5 and VdChs7 play pivotal roles in proliferation, cell wall integrity, and pathogenicity, and provided a novel strategy to improve Verticillium wilt resistance in cotton and other susceptible host plants.

Biocontrol potential of Bacillus amyloliquefaciens YZU-SG146 from Fraxinus hupehensis against Verticillium wilt of cotton

Verticillium wilt of cotton is an economically important disease caused by Verticillium dahliae. Microbial-mediated biological control has become a sustainable alternative because of its environmental friendliness. In this study, strain YZU-SG146 (G146) was isolated from Fraxinus hupehensis plants and screened for its antagonistic activity against mycelial growth of a broad-spectrum of phytopathogenic fungi belonging to Sclerotium, Magnaporthe, Alternaria, Phytophthora, Rhizoctonia, Fusarium, Bipolaris and Colletotrichum genera. G146 was identified as Bacillus amyloliquefaciens on the bases of morphological characteristics, 16S rDNA and gyrB gene analysis. G146 inhibited the mycelial growth and spore germination of V. dahliae by 89.22% and 68.20%, respectively. In a potting test, the control efficiency of G146 against Verticillium wilt of cotton was 84.21%. Moreover, G146 significantly promoted the growth of cotton seeds and seedlings such as root length, seedling length and seedling dry weight. The plant growth-promoting (PGP) traits in vitro screening showed that G146 secreted siderophores, indoleacetic acid (IAA), cellulase, proteases and amylase. It also produced Macrolactin (mlnABE), bacilysin, Chrysin, Sclareol, Emodin-8-glucoside and Hydroxygenkwanin based on liquid chromatography-mass spectrometry (LC-MS) analysis. G146 induced resistance to infection of V. dahliae and it was found that reactive oxygen species burst in cotton leaves and lignification in cotton hypocotyls. This study revealed that B. amyloliquefaciens G146 had high potential to be used as a biocontrol agent to control Verticillium wilt of cotton. This is the first report of endophytic bacteria of F. hupehensis to control Verticillium wilt of cotton.

Transcriptome Analysis Reveals That C17 Mycosubtilin Antagonizes Verticillium dahliae by Interfering with Multiple Functional Pathways of Fungi.

Verticillium wilt is a kind of soil-borne plant fungal disease caused by Verticillium dahliae (Vd). Vd 991 is a strong pathogen causing cotton Verticillium wilt. Previously, we isolated a compound from the secondary metabolites of Bacillus subtilis J15 (BS J15), which showed a significant control effect on cotton Verticillium wilt and was identified as C17 mycosubtilin. However, the specific fungistatic mechanism by which C17 mycosubtilin antagonizes Vd 991 is not clear. Here, we first showed that C17 mycosubtilin inhibits the growth of Vd 991 and affects germination of spores at the minimum inhibitory concentration (MIC). Morphological observation showed that C17 mycosubtilin treatment caused shrinking, sinking, and even damage to spores; the hyphae became twisted and rough, the surface was sunken, and the contents were unevenly distributed, resulting in thinning and damage to the cell membrane and cell wall and swelling of mitochondria of fungi. Flow cytometry analysis with ANNEXINV-FITC/PI staining showed that C17 mycosubtilin induces necrosis of Vd 991 cells in a time-dependent manner. Differential transcription analysis showed that C17 mycosubtilin at a semi-inhibitory concentration (IC50) treated Vd 991 for 2 and 6 h and inhibited fungal growth mainly by destroying synthesis of the fungal cell membrane and cell wall, inhibiting its DNA replication and transcriptional translation process, blocking its cell cycle, destroying fungal energy and substance metabolism, and disrupting the redox process of fungi. These results directly showed the mechanism by which C17 mycosubtilin antagonizes Vd 991, providing clues for the mechanism of action of lipopeptides and useful information for development of more effective antimicrobials.

Transcriptome reveals the molecular mechanism of chaetoviridin A inhibiting the spore germination of Verticillium dahliae

The pathogen Verticillium dahliae causes Verticillium wilt in a number of crops, including cotton Verticillium wilt. Chaetoviridin A, a secondary metabolite of Chaetomium globosum, significantly inhibits the growth of V. dahliae. Spore germination is a major part of the disease cycle. However, the molecular mechanism of chaetoviridin A inhibiting spore germination of V. dahliae is unknown. In this work, we found that chaetoviridin A significantly inhibited spore germination of V. dahliae. Transcriptome analysis showed that DEGs were enriched in linolenic acid metabolism, alpha-Linolenic acid metabolism, Arachidonic acid metabolism and Purine metabolism pathways at 1 h, which were related to cell membrane. At 3 h, DEGs were enriched in the pathways of galactose metabolism, diterpenoid biosynthesis, cysteine and methionine metabolism, and starch and sucrose metabolism, which were mainly related to amino acid metabolism and sugar metabolism. Several genes related to glucose metabolism were identified, mainly including Glucagon endo-1,3-alpha-glucosidase agn1, glucoamylase, maltose O-acetyltransferase, and beta-galactosidase. Stress resistance gene PAL, detoxification gene P450 2C31 and ABA receptor were also down- regulated. These genes may be related to spore germination. These results provide a theoretical basis for chaetoviridin A to control fungal diseases.

Early detection of cotton verticillium wilt based on root magnetic resonance images.

Verticillium wilt (VW) is often referred to as the cancer of cotton and it has a detrimental effect on cotton yield and quality. Since the root system is the first to be infested, it is feasible to detect VW by root analysis in the early stages of the disease. In recent years, with the update of computing equipment and the emergence of large-scale high-quality data sets, deep learning has achieved remarkable results in computer vision tasks. However, in some specific areas, such as cotton root MRI image task processing, it will bring some challenges. For example, the data imbalance problem (there is a serious imbalance between the cotton root and the background in the segmentation task) makes it difficult for existing algorithms to segment the target. In this paper, we proposed two new methods to solve these problems. The effectiveness of the algorithms was verified by experimental results. The results showed that the new segmentation model improved the Dice and mIoU by 46% and 44% compared with the original model. And this model could segment MRI images of rapeseed root cross-sections well with good robustness and scalability. The new classification model improved the accuracy by 34.9% over the original model. The recall score and F1 score increased by 59% and 42%, respectively. The results of this paper indicate that MRI and deep learning have the potential for non-destructive early detection of VW diseases in cotton.

The effects and interrelationships of intercropping on Cotton Verticillium wilt and soil microbial communities

BackgroundCotton Verticillium wilt, causing by Verticillium dahliae, has seriously affected the yield and quality of cotton. The incidence of Verticillium wilt in cotton fields has been on the rise for many years, especially after straw has been returned to the fields. Intercropping can reduce the incidence of soil borne diseases and is often used to control crop diseases, but the relationship between the effects of intercropping on microbial communities and the occurrence of plant diseases is unclear. This research explored the relationship between soil microbial community structure and Cotton Verticillium wilt in interplanting of cotton-onion, cotton-garlic, cotton-wheat and cotton monocultures. Amplicon sequencing applied to the profile of bacterial and fungal communities.ResultsThe results showed that the disease index of Cotton Verticillium wilt was significantly reduced after intercropping with cotton-garlic and cotton-onion. Chao1 and Sobs indices were not significantly different in the rhizosphere soil and pre-plant soils of the four planting patterns, but the pre-plant fungal shannon index was significantly lower in the cotton-onion intercropping plot than in the other three plots. PCoA analysis showed that the soil microbial communities changed to a certain extent after intercropping, with large differences in the microbial communities under different cropping patterns. The abundance of Chaetomium was highest in the cotton-garlic intercropping before planting; the abundance of Penicillium was significantly higher in the cotton-wheat intercropping than in the other three systems.ConclusionCotton-garlic and cotton-onion interplanting can control Cotton Verticillium wilt by affecting the soil microbial community. Fungi of the genera Chaetomium and Penicillium may be associated with plant disease resistance.

Soil bacterial community response to continuous cropping of cotton.

Long-term continuous cropping may result in the outbreak and proliferation of soil-borne diseases, as well as reduction in annual crop production. Overcoming the obstacles of continuous cropping is critical for the long-term growth of modern agriculture. Soil microbes are essential for plant health, but the consequences of continuous cropping on soil microbiome are still poorly understood. This study analyzed changes in soil bacterial community composition of Aksu (AKS) and Shihezi (SHZ) in Xinjiang Province during 1-20 years of continuous cropping by 16S amplicon sequencing. The results showed that the incidence of cotton Verticillium wilt rose with the number of cropping years. The bacterial alpha diversity in the AKS soil grew as the number of continuous cropping years increased, however it declined in the SHZ soil. The results of beta diversity analysis showed that there were significant differences in soil bacterial communities between different continuous cropping years and between different soils. The results of community composition changes at the level of main phyla and genus showed that the relative abundance of Actinobacteria, Bacteroidetes and Streptomyces decreased with the increase of continuous cropping years in the AKS and the SHZ soils. In addition, Actinobacteria, Propionibacteriales, and Nocardioidaceae were significantly enriched during the early stages of continuous cropping. Network analysis showed that long-term (≥8 years) continuous cropping interfered with the complexity of soil bacterial co-occurrence networks and reduced collaboration between OTUs. These findings suggested that continuous cropping and soil origin jointly affected the diversity and structural of bacterial communities, and the loss of Nocardioidaceae and Streptomyces in Actinobacteria might be one of the reasons of continuous cropping obstacles.

Effect of incorporation of broccoli residues into soil on occurrence of verticillium wilt of spring-sowing-cotton and on rhizosphere microbial communities structure and function.

Cotton verticillium wilt (CVW) represented a typical plant soil-borne disease and resulted in widespread economic losses in cotton production. However, the effect of broccoli residues (BR) on verticillium wilt of spring-sowing-cotton was not clear. We investigated the effects of BR on CVW, microbial communities structure and function in rhizosphere of two cotton cultivars with different CVW resistance using amplicon sequencing methods. Results showed that control effects of BR on CVW of susceptible cultivar (cv. EJ-1) and resistant cultivar (cv. J863) were 58.49% and 85.96%, and the populations of V. dahliae decreased by 14.31% and 34.19%, respectively. The bacterial diversity indices significantly increased in BR treatment, while fungal diversity indices significantly decreased. In terms of microbial community composition, the abilities to recruit bacteria and fungi were enhanced in BR treatment, including RB41, Gemmatimonas, Pontibacter, Streptomyces, Blastococcus, Massilia, Bacillus, and Gibberella, Plectosphaerella, Neocosmospora, Aspergillus and Preussia. However, the relative abundances of Sphingomonas, Nocardioides, Haliangium, Lysobacter, Penicillium, Mortierella and Chaetomidium were opposite tendency between cultivars in BR treatment. According to PICRUSt analysis, functional profiles prediction showed that significant shifts in metabolic functions impacting KEGG pathways of BR treatment were related to metabolism and biosynthesis. FUNGuild analysis indicated that BR treatment altered the relative abundances of fungal trophic modes. The results of this study demonstrated that BR treatment decreased the populations of V. dahliae in soil, increased bacterial diversity, decreased fungal diversity, changed the microbial community structure and function, and increased the abundances of beneficial microorganisms.

Effect of volatile compounds produced by the cotton endophytic bacterial strain Bacillus sp. T6 against Verticillium wilt

BackgroundVerticillium wilt, caused by the fungus Verticillium dahliae, leads to significant losses in cotton yield worldwide. Biocontrol management is a promising means of suppressing verticillium wilt. The purpose of the study was to obtain and analyze endophytic bacteria with Verticillium wilt-resistant activities from the roots of Gossypium barbadense ‘Xinhai15’ and to explore the interactions between the soil and plants.ResultsAn endophytic bacterium Bacillus sp. T6 was obtained from the Verticillium wilt-resistant cotton G. barbadense ‘Xinhai15’, which showed significant antagonistic abilities against cotton Verticillium wilt. The bioassay results indicated that the strain possessed strong antagonistic abilities that inhibited V. dahliae spore germination and mycelial growth without contact, and thus it was speculated that the active factor of the bacteria might be volatile compounds. A total of 46 volatile substances were detected via headspace solid-phase microextraction and gas chromatography–mass spectrometry analysis. The pure product verification experiment confirmed that the styrene produced by the T6 strain was the main virulence factor. Transcriptome analysis showed that following styrene induction, 247 genes in V. dahliae, including four hydrolase genes, eight dehydrogenase genes, 11 reductase genes, 17 genes related to transport and transfer were upregulated. Additionally, 72 genes, including two chitinase genes, two protease genes, five transport-related genes, and 33 hypothetical protein genes, were downregulated. The quantitative real-time PCR results confirmed that the expression of the four genes VDAG_02838, VDAG_09554, VDAG_045572, and VDAG_08251 was increased by 3.18, 78.83, 2.71, and 2.92 times, respectively, compared with the uninduced control group.ConclusionsThe research provides a new reference for the development and application of the volatile compounds of endophytic bacteria as new biocontrol agents for the control of Verticillium wilt and as biological preservatives for agricultural products.

Galactosyltransferase GhRFS6 interacting with GhOPR9 involved in defense against Verticillium wilt in cotton

The soil-borne fungus Verticillium dahliae causes Verticillium wilt (VW), one of the most devastating diseases of cotton. In a previous study showed that GhOPR9 played a positive role in resistance of cotton to VW through the regulation of the Jasmonic acid (JA) pathway. Furtherly, we also found that GhOPR9 interacted with a sucrose galactosyltransferase GhRFS6. Raffinose synthase (RFS) plays a key role in plant innate immunity, including the abiotic stress of drought, darkness. However, there were few reports on the effects of RFS on biotic stress. In this study, we verified the function of GhRFS6 to VW. The expression analysis showed that the GhRFS6 may be regulated by various stresses, and it was upregulated under Vd076 and Vd991 pressures. Inhibition of GhRFS6 expression, hydrogen peroxide (H2O2) content, lignin content, cell wall thickness and a series of defense responses were decreased, and the resistance of cotton to V. dahliae was decreased. In addition, this study showed that GhRFS6 has glycosyltransferase activity and can participate in the regulation of α-galactosidase activity and raffinose and inositol synthesis. And that galactose was accumulated in cotton roots after GhRFS6 silencing, which is beneficial for the colonization and growth of V. dahliae. Furthermore, overexpression of GhRFS6 in Arabidopsis thaliana enhanced plant resistance to V. dahliae. In GUS staining, the promoter expression position of GhRFS6 was also altered after V. dahliae infection. Meanwhile, GhRFS6 has also been shown to resist VW through the regulation of the JA pathway. These results suggest that GhRFS6 is a potential molecular target for improving cotton resistance to VW.

Effects of different crop rotations on the incidence of cotton Verticillium wilt and structure and function of the rhizospheric microbial community

Effects of different crop rotations on the incidence of cotton Verticillium wilt and structure and function of the rhizospheric microbial community

A Novel Intelligent System for Dynamic Observation of Cotton Verticillium Wilt.

Verticillium wilt is one of the most critical cotton diseases, which is widely distributed in cotton-producing countries. However, the conventional method of verticillium wilt investigation is still manual, which has the disadvantages of subjectivity and low efficiency. In this research, an intelligent vision-based system was proposed to dynamically observe cotton verticillium wilt with high accuracy and high throughput. Firstly, a 3-coordinate motion platform was designed with the movement range 6,100 mm × 950 mm × 500 mm, and a specific control unit was adopted to achieve accurate movement and automatic imaging. Secondly, the verticillium wilt recognition was established based on 6 deep learning models, in which the VarifocalNet (VFNet) model had the best performance with a mean average precision (mAP) of 0.932. Meanwhile, deformable convolution, deformable region of interest pooling, and soft non-maximum suppression optimization methods were adopted to improve VFNet, and the mAP of the VFNet-Improved model improved by 1.8%. The precision-recall curves showed that VFNet-Improved was superior to VFNet for each category and had a better improvement effect on the ill leaf category than fine leaf. The regression results showed that the system measurement based on VFNet-Improved achieved high consistency with manual measurements. Finally, the user software was designed based on VFNet-Improved, and the dynamic observation results proved that this system was able to accurately investigate cotton verticillium wilt and quantify the prevalence rate of different resistant varieties. In conclusion, this study has demonstrated a novel intelligent system for the dynamic observation of cotton verticillium wilt on the seedbed, which provides a feasible and effective tool for cotton breeding and disease resistance research.

Assessing the severity of cotton Verticillium wilt disease from in situ canopy images and spectra using convolutional neural networks

Verticillium wilt (VW) is a common soilborne disease of cotton. It occurs mainly in the seedling and boll-opening stages and severely impairs the yield and quality of the fiber. Rapid and accurate identification and evaluation of VW severity (VWS) forms the basis of field cotton VW control, which has great significance to cotton production. Cotton VWS values are conventionally measured using in-field observations and laboratory test diagnoses, which require abundant time and professional expertise. Remote and proximal sensing using imagery and spectrometry have great potential for this purpose. In this study, we performed in situ investigations at three experimental sites in 2019 and 2021 and collected VWS values, in situ images, and spectra of 361 cotton canopies. To estimate cotton VWS values at the canopy scale, we developed two deep learning approaches that use in situ images and spectra, respectively. For the imagery-based method, given the high complexity of the in situ environment, we first transformed the task of healthy and diseased leaf recognition to the task of cotton field scene classification and then built a cotton field scenes (CFS) dataset with over 1000 images for each scene-unit type. We performed pretrained convolutional neural networks (CNNs) training and validation using the CFS dataset and then used the networks after training to classify scene units for each canopy. The results showed that the DarkNet-19 model achieved satisfactory performance in CFS classification and VWS values estimation (R2 = 0.91, root-mean-square error (RMSE) = 6.35%). For the spectroscopy-based method, we first designed a one-dimensional regression network (1D CNN) with four convolutional layers. After dimensionality reduction by sensitive-band selection and principal component analysis, we fitted the 1D CNN with varying numbers of principal components (PCs). The 1D CNN model with the top 20 PCs performed best (R2 = 0.93, RMSE = 5.77%). These deep learning-driven approaches offer the potential of assessing crop disease severity from spatial and spectral perspectives.

Efficacy evaluation and mechanism of Bacillus subtilis EBS03 against cotton Verticillium wilt

BackgroundIn our previous study, a strain EBS03 with good biocontrol potential was screened out of 48 strains of cotton endophyte Bacillus subtilis by evaluating the controlling effect against cotton Verticillium wilt. However, its mechanism for controlling Verticillium wilt remains unclear. The objective of this study was to further clarify its controlling effect and mechanism against cotton Verticillium wilt.ResultsThe results of confrontation culture test and double buckle culture test showed that the inhibitory effects of EBS03 volatile and nonvolatile metabolite on mycelium growth of Verticillium dahliae were 70.03% and 59.00%, respectively; the inhibitory effects of sporulation and microsclerotia germination were 47.16% and 70.06%, respectively. In the greenhouse test, the EBS03 fermentation broth root irrigation had the highest controlling effect at 87.11% on cotton Verticillium wilt, and significantly promoted the growth of cotton seedlings. In the field experiment, the controlling effect of EBS03 fermentation broth to cotton Verticillium wilt was 42.54% at 60 days after cotton sowing, and the boll number per plant and boll weight in EBS03 fermentation broth seed soaking, root irrigation, and spraying treatments significantly increased by 19.48% and 7.42%, 30.90% and 2.62%, 15.99% and 9.20%, respectively. Furthermore, EBS03 improved the resistance of cotton leaves against the infection of V. dahliae, and induced the outbreak of reactive oxygen species and accumulation of callose. In addition, the results of real time fluorescent quantitative polymerase chain reaction (RT-qPCR) detection showed that EBS03 significantly induced upregulation expression level of defense-related genes PAL, POD, PPO, and PR10 in cotton leaves, enhanced cotton plant resistance to V. dahliae, and inhibited colonization level of this fungal pathogen in cotton.ConclusionBacillus subtilis EBS03 has a good biological defense capability, which can inhibit the growth and colonization level of V. dahliae, and activate the resistance of cotton to Verticillium wilt, thus increase cotton yield.

Metabolites from Bacillus subtilis J-15 Affect Seedling Growth of Arabidopsis thaliana and Cotton Plants.

Bacillus subtilis J-15 is a plant growth-promoting rhizobacteria isolated from the soil rhizosphere of cotton and is resistant to cotton verticillium wilt. This study evaluated the effects of metabolites of J-15 (J-15-Ms), including mycosubtilin, on plant growth using Arabidopsis and cotton plants. The results showed that J-15-Ms promoted Arabidopsis seeding growth at lower concentrations of 0.2 μg/mL but inhibited the growth at higher concentrations, such as 20 μg/mL. Similar results were obtained in cotton. Thus, J-15-Ms-treated plants showed low-concentration-induced growth promotion and high-concentration-induced growth inhibition. The J-15-Ms components were analyzed by liquid chromatography-mass spectrometry. Correlation analysis using the J-15 genomic databases suggested that J-15 may synthesize indoleacetic acid via the indole-3-pymvate pathway and indole-3-acetamide pathway. Treatment with mycosubtilin, a purified peptide from J-15-Ms, showed that the peptide promoted Arabidopsis growth at a low concentration (0.1 μg/mL) and inhibited plant growth at high concentrations (higher than 1 μg/mL), which also significantly increased plant lateral root number. Transcriptomic analysis showed that mycosubtilin might promote lateral root development and inhibit plant primary root growth by regulating the expression of the plant hormone signaling pathway. This study reveals the mechanism of Bacillus subtilis J-15 in affecting plant growth.

Early Monitoring of Cotton Verticillium Wilt by Leaf Multiple “Symptom” Characteristics

Early diagnosis of cotton verticillium wilt (VW) and accurate assessment of the disease degree are important prerequisites for preventing the large-scale development of cotton VW. Hyperspectral techniques have been widely used for monitoring the extent of plant diseases, but early detection of VW disease in cotton remains a challenge. In this study, the Boruta algorithm was used to select the key physiological characteristics (leaf temperature, chlorophyll a content, and equivalent water thickness) of cotton leaves at the early stage of VW disease, and then the Relief-F algorithm was used to select the spectral features indicating multiple “symptoms” of cotton VW disease at the early stage. In addition, a new cotton VW early monitoring indicator (CVWEI) was constructed by combining the weights of the new index and related bands using a hierarchical analysis (AHP) and entropy weighting method (EWM). The study showed that the physiological indices constructed under VW stress were better indicators of VW disease than traditional vegetation indices; CVEWI achieved a high accuracy of 95% in the test set, with a Kappa coefficient of 0.89; and the test set R2 was 0.73 and RMSE was 3.15% for monitoring disease severity, compared to the optimal classification constructed using a single spectral index. The results may provide new ideas and methods for early and accurate monitoring of VW and other fungal diseases.

Defense Mechanisms of Cotton Fusarium and Verticillium Wilt and Comparison of Pathogenic Response in Cotton and Humans.

Cotton is an important economic crop. Fusarium and Verticillium are the primary pathogenic fungi that threaten both the quality and sustainable production of cotton. As an opportunistic pathogen, Fusarium causes various human diseases, including fungal keratitis, which is the most common. Therefore, there is an urgent need to study and clarify the resistance mechanisms of cotton and humans toward Fusarium in order to mitigate, or eliminate, its harm. Herein, we first discuss the resistance and susceptibility mechanisms of cotton to Fusarium and Verticillium wilt and classify associated genes based on their functions. We then outline the characteristics and pathogenicity of Fusarium and describe the multiple roles of human neutrophils in limiting hyphal growth. Finally, we comprehensively compare the similarities and differences between animal and plant resistance to Fusarium and put forward new insights into novel strategies for cotton disease resistance breeding and treatment of Fusarium infection in humans.

Genome-Wide Identification of the NAC Transcription Factors in Gossypium hirsutum and Analysis of Their Responses to Verticillium wilt.

The NAC transcription factors (NACs) are among the largest plant-specific gene regulators and play essential roles in the transcriptional regulation of both biotic and abiotic stress responses. Verticillium wilt of cotton caused by Verticillium dahliae (V. dahliae) is a destructive soil-borne disease that severely decreases cotton yield and quality. Although NACs constitute a large family in upland cotton (G. hirsutum L.), there is little systematic investigation of the NACs’ responsive to V. dahliae that has been reported. To further explore the key NACs in response to V. dahliae resistance and obtain a better comprehension of the molecular basis of the V. dahliae stress response in cotton, a genome-wide survey was performed in this study. To investigate the roles of GhNACs under V. dahliae induction in upland cotton, mRNA libraries were constructed from mocked and infected roots of upland cotton cultivars with the V. dahliae-sensitive cultivar “Jimian 11” (J11) and V. dahliae-tolerant cultivar “Zhongzhimian 2” (Z2). A total of 271 GhNACs were identified. Genome analysis showed GhNACs phylogenetically classified into 12 subfamilies and distributed across 26 chromosomes and 20 scaffolds. A comparative transcriptome analysis revealed 54 GhNACs were differentially expressed under V. dahliae stress, suggesting a potential role of these GhNACs in disease response. Additionally, one NAC090 homolog, GhNAC204, could be a positive regulator of cotton resistance to V. dahliae infection. These results give insight into the GhNAC gene family, identify GhNACs’ responsiveness to V. dahliae infection, and provide potential molecular targets for future studies for improving V. dahliae resistance in cotton.

Flagellin C decreases the expression of the Gossypium hirsutum cation/proton exchanger 3 gene to promote calcium ion, hydrogen peroxide, and nitric oxide and synergistically regulate the resistance of cotton to Verticillium wilt.

To date, no ideal effective method for controlling Verticillium wilt in upland cotton (Gossypium hirsutum) has been defined. The purpose of this study was to determine the effects and mechanism through which flagellin C (FLiC) regulates the Gossypium hirsutum cation/proton exchanger 3 gene (GhCAX3), induces plant immunity, and increases resistance to Verticillium wilt. The FLiC gene was cloned from an endophytic bacterium (Pseudomonas) isolated from roots of the upland cotton cultivar Zhongmiansuo 41. The biocontrol effects of FLiC purified in vitro on resistant and susceptible upland cotton cultivars were 47.50 and 32.42%, respectively. FLiC induced a hypersensitive response (HR) in leaves of tobacco and immune responses in upland cotton. Transcriptome data showed that treatment with FLiC significantly enriched the calcium antiporter activity-associated disease-resistant metabolic pathway in seedlings. Moreover, FLiC downregulated GhCAX3 expression to increase intracellular calcium ion (Ca2+) content and stimulate increases in the intracellular hydrogen peroxide (H2O2) and nitric oxide (NO) contents. The coordinated regulation of Ca2+, H2O2, and NO enhanced cotton resistance to Verticillium wilt. Furthermore, transgenic Arabidopsis plants overexpressing FLiC showed significantly improved resistance to Verticillium wilt. FLiC may be used as a resistance gene and a regulator to improve resistance to Verticillium dahliae (VD) in upland cotton.

Antifungal effects of volatile organic compounds produced by Trichoderma koningiopsis T2 against Verticillium dahliae.

Volatile organic compounds (VOCs) produced by microorganisms are considered promising environmental-safety fumigants for controlling soil-borne diseases. Verticillium dahliae, a notorious fungal pathogen, causes economically important wilt diseases in agriculture and forestry industries. Here, we determined the antifungal activity of VOCs produced by Trichoderma koningiopsis T2. The VOCs from T. koningiopsis T2 were trapped by solid-phase microextraction (SPME) and tentatively identified through gas chromatography–mass spectrometry (GC/MS). The microsclerotia formation, cell wall-degrading enzymes and melanin synthesis of V. dahliae exposed to the VOC mixtures and selected single standards were examined. The results showed that the VOCs produced by strain T2 significantly inhibited the growth of V. dahliae mycelium and reduced the severity of Verticillium wilt in tobacco and cotton. Six individual compounds were identified in the volatilome of T. koningiopsis T2, and the dominant compounds were 3-octanone, 3-methyl-1-butanol, butanoic acid ethyl ester and 2-hexyl-furan. The VOCs of strain T2 exert a significant inhibitory effect on microsclerotia formation and decreased the activities of pectin lyase and endo-β-1,4-glucanase in V. dahliae. VOCs also downregulated the VdT3HR, VdT4HR, and VdSCD genes related to melanin synthesis by 29. 41-, 10. 49-, and 3.11-fold, respectively. Therefore, T. koningiopsis T2 has potential as a promising biofumigant for the biocontrol of Verticillium wilt disease.