Fusarium Head Blight In Wheat Research Articles

FgUbiH Is Essential for Vegetative Development, Energy Metabolism, and Antioxidant Activity in Fusarium graminearum

Fusarium head blight in wheat is mainly caused by Fusarium graminearum and results in significant economic losses. Coenzyme Q (CoQ) is ubiquitously produced across organisms and functions as a hydrogen carrier in energy metabolism. While UbiH in Escherichia coli serves as a hydroxylase in CoQ biosynthesis, its role in phytopathogenic fungi is not well understood. This study explored the role of the hydroxylase FgUbiH in F. graminearum. Using a FgUbiH deletion mutant, we observed reduced hyphal growth, conidial production, germination, toxin synthesis, and pathogenicity compared to the wild-type. A transcriptome analysis indicated FgUbiH’s involvement in regulating carbohydrate and amino acid metabolism. Deletion of FgUbiH impaired mitochondrial function, reducing adenosine triphosphate synthesis and increasing reactive oxygen species. Additionally, genes related to terpene skeleton synthesis and aldehyde dehydrogenase were downregulated. Our results underscore the importance of FgUbiH in F. graminearum’s growth, toxin production, and energy metabolism, aiding in the development of strategies for disease management.

Construction of a comprehensive meteorological risk index for wheat Fusarium head blight prediction based on more than a half-century of monitoring data.

Fusarium head blight (FHB) represents a critical threat to wheat production globally, not only reducing yields but also contaminating crops with harmful mycotoxins. This study aimed to elucidate new spatiotemporal patterns of FHB incidence and to develop a comprehensive meteorological risk index to enhance scientific prevention and control of the disease. Through the analysis of annual and decadal variations from 1965 to 2023, the study assessed FHB trends across four agricultural regions (I, II, III, and IV) in Jiangsu Province, located in the middle and lower reaches of the Yangtze River-a hotspot for FHB in China. Key findings include: Since 1965, Regions I and III consistently exhibited higher FHB incidence rates compared to Regions II and IV. Post-2000, there was a notable increase in years with high incidence rates, with Region III overtaking Region I as the region with the highest incidence. Since 2010, occurrences of FHB reaching the most severe grade (Grade 5) have surpassed those in previous decades across all regions. The study also revealed a stronger correlation between meteorological factors (cumulative precipitation, number of days with rainfall ≥ 0.1 mm, total rainy days with ≥ 2 and ≥3 consecutive days of rain, total rainy days with both average daily air temperature ≥ 15 °C and daily rainfall ≥ 0.1 mm, days with average daily relative humidity ≥ 85%, cumulative sunshine hours, and cumulative cloudy days) and the FHB incidence rates during the heading-flowering-grain filling period in Regions I, II, and III, compared to the heading-flowering period alone. This indicates that optimal temperature and high humidity during the grain filling stage significantly contribute to the final FHB incidence rates. Despite the less apparent correlation between temperature changes and disease rates, the significant warming trend observed since 2000 has likely fostered conditions conducive to the proliferation of FHB. The comprehensive meteorological risk index, constructed to incorporate key meteorological factors during the heading-flowering-filling period, showed a strong correlation with actual disease incidences. The index demonstrated fitting accuracy rates of 84.7% for Region I, 72.9% for Region II, 83.1% for Region III, and 90.9% for Region IV, underscoring its effectiveness in predicting FHB occurrences. This tool offers both convenience and practicality, providing valuable insights for strategically managing FHB risks based on local weather conditions.

Fusarium head blight of wheat: current knowledge on associated species and their mycotoxins, pathogenicity diversity, and management strategies

Fusarium head blight of wheat: current knowledge on associated species and their mycotoxins, pathogenicity diversity, and management strategies

Mps1-Targeted Molecular Design of Melatonin for Broad-Spectrum Antifungal Agent Discovery.

Melatonin, a multifunctional class of natural products, has demonstrated antifungal activity, making it a promising candidate for developing antifungal agents. The mitogen-activated protein kinase (Mps1) within fungal pathogens has a target inhibitory effect of melatonin in fungi. We use a virtual screening strategy to design melatonin derivatives based on the melatonin-Mps1 targeting model. Of these, a multiflorane-substitution compound M-12 emerges as a potent antifungal agent, exhibiting broad-spectrum efficacy against eight phytopathogenic fungal species, and effectively reduces the severity of tomato gray mold, Fusarium head blight in wheat, Sclerotinia stem rot in rape, and peach brown rot. M-12 half-maximal effective concentration values (5.50 μM against Botrytis cinerea, 5.21 μM against Fusarium graminearum, 10.6 μM against Rhizoctonia solani, and 9.02 μM against Sclerotinia sclerotiorum) are better than those of commercial broad-spectrum fungicide azoxystrobin (55.0, 23.2, 46.5, and 17.7 μM, respectively). Antifungal activity of enantiomer (S)-M-12 (5.02 μM) is significantly greater than its (R)-enantiomer (23.6 μM) against B. cinerea. Molecular docking and transcriptome analysis reveal that M-12 achieves its antifungal effects by inhibiting Mps1 kinase, thereby suppressing fungal growth and virulence.

First Report of Fusarium compactum Causing Fusarium Head Blight of Wheat in China.

Fusarium head blight (FHB), a devastating wheat disease caused by several species of Fusarium, threatens global wheat yield and quality (Erenstein et al. 2022). In August 2023, wheat spikes exhibiting clear FHB symptoms were observed in fields in Yunnan, China (24°16'46″ N, 102°29'46″ E), with an incidence rate of approximately 10%. Diseased wheat spikes exhibited a bleached, wilted appearance, with abundant orange sporodochia on the glumes, similar to previous reports (Osborne et al. 2007). Twenty-four symptomatic spikes were collected from a single field, and sporodochia were washed with sterile water to prepare a spore suspension of 1 × 10³ spores/ml, which was inoculated onto potato dextrose agar (PDA) to obtain monosporic cultures. Four reference strains (KUNCC 3418 to KUNCC 3420, and KUNCC 3431) were deposited at the Kunming Institute of Botany Culture Collection, Chinese Academy of Sciences (KUNCC). For species identification, four strains were cultured on PDA and carnation leaf agar (CLA) at 25°C, with incubation under a 12-hour near-UV light/dark cycle on CLA and in complete darkness for 24 hours on PDA. Colonies on PDA grew rapidly, appearing white and loosely flocculent. Abundant pale orange, translucent sporodochia formed on CLA. Sporodochial conidiogenous cells were monophialidic or polyphialidic, subulate to subcylindrical, 9.5-12 μm × 3-3.5 μm. Sporodochial macroconidia were naviculate to fusiform, with an elongate, tapering apical cell and a foot-shaped basal cell, 3-6-septate, 33-67.5 μm × 3.5-5.5 μm. The ITS, tef1-α, rpb1, rpb2, and cam regions were amplified and sequenced using primers ITS1/ITS4, EF-1/EF-2, rpb1-F7/G2R, rpb2-5F2/11aR, and CL1/CL2A, respectively (White et al. 1990; O'Donnell et al. 2000; O'Donnell et al. 2010; Reeb et al. 2004; O'Donnell et al. 1998). These sequences were deposited in GenBank for cam (PP951603 to PP951606), ITS (PP946846 to PP946849), tef-1α (PP719217, PP731572 to PP731574), rpb1 (PP719219, PP737839 to PP737841), and rpb2 (PP719218, PP951607 to PP951609). BLASTn analyses of these sequences showed an identity range of 99.7% to 100% with the epitype strain NRRL 36323 of F. compactum (GenBank: cam = GQ505560, ITS = MH855177, tef-1α = GQ505648, and rpb2 = GQ505826), with base pair matches of 663/665 bp for cam, 488/488 bp for ITS, 641/641 bp for tef-1α, and 892/892 bp for rpb2. Both morphological and BLASTn analyses confirmed these isolates as F. compactum (Leslie & Summerell 2006; Han et al. 2023). Pathogenicity tests were performed by spraying 1 ml of spore suspension (1 × 108 spores/ml) of F. compactum strains onto spikes of the wheat cultivar Yunmai 126 at the flowering stage (n = 9). Controls (n = 9) were treated only with sterile water. Following treatment, the wheat spikes were covered with plastic bags and incubated at 25°C for 10 days. After 14 days, the inoculated spikes turned bleached and dry, showing FHB symptoms, while the wheat spikes in the control treatment remained asymptomatic. The pathogenic fungus re-isolated from all diseased samples was confirmed as F. compactum. It has been frequently reported in association with crown and root rot of wheat, particularly in regions such as Turkey and Iran (Tunali et al. 2008; Besharati et al. 2017). To our knowledge, this is the first report of F. compactum on diseased wheat spikes in China. This finding provides valuable insights into the spread of F. compactum.

Análisis de la expresión del gen TRI5 de Fusarium graminearum en coleóptilos de trigo y maíz.

The necrotrophic fungus F. graminearum is responsible for causing Fusarium head blight in wheat and ear rotin maize. This fungal infection leads to reduced crop yields and contamination of the crops with mycotoxinslike trichothecene deoxynivalenol (DON), which can cause poisoning in animals and humans. The productionof DON is facilitated by a set of genes, with the TRI5 gene encoding trichodiene synthase being a key player.While some factors that can activate the TRI5 gene in wheat are known, it's unclear whether this gene isactivated when the fungus infects wheat or maize coleoptiles. This study reveals that using ammonium sulfateas a nitrogen source induces the expression of the TRI5 gene in minimal media. In wheat coleoptiles, F.graminearum forms infection structures at 5 days post-infection (dpi), where the induction of the TRI5 geneoccurs. On the other hand, there is no TRI5 gene induction in maize coleoptiles. Finally, the TRI5 geneexpression in plants was confirmed using semi-quantitative PCR, validating the induction in wheat coleoptilesat 5 dpi.

Influence of Wheat Cultivars, Infection Level, and Climate after Anthesis on Efficacy of Fungicide for Control of Fusarium Head Blight in the Huang-Huai-Hai Plain of China

Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, causes significant losses in grain yield and quality of wheat (Triticum aestivum) by inducing floret sterility. Grains become contaminated with mycotoxins, especially deoxynivalenol (DON), making them unsuitable for consumption. To clarify the impact of wheat cultivar resistance, infection level, and climate after anthesis on the efficacy of a fungicide for the control of FHB, we treated two moderately susceptible cultivars and 11 susceptible cultivars with fungicide (48% phenamacril + tebuconazole) at anthesis over two years. FHB incidence (INC), disease severity index (DSI), Fusarium-damaged kernels, DON contamination, thousand-kernel weight, and yield were evaluated under artificially inoculated and naturally infected field trials in 2018 and 2021. The results of multi-factor variance analysis show that the control efficacy with respect to INC and DSI is affected by cultivar, fungicide, infection level, and climatic conditions including the average daily temperature, average daily relative humidity, and total rainfall from anthesis to 21 days after anthesis (p < 0.01). Notably, cultivar resistance (deviance = 13.34, 9.55, and 11.22) is more important than fungicide (deviance = 5.77, 6.66, and 6.69) to control the efficacy of INC, DSI, and DON. The results also suggest that infection level appears to be more important than cultivars and fungicide to control the efficacy of INC, and more important than fungicide to control the efficacy of DSI. Total rainfall is more important than other climatic factors. Our results reveal that fungicide is more effective in moderately susceptible cultivars (‘Zhengmai 9023’ and ‘Xinong 979’, 89.5%~98.9%) and some susceptible cultivars than in other susceptible cultivars (‘Zhengmai 7698’ and ‘Zhoumai 27’, 51.9%~67.2%). Thus, integrating cultivar resistance with fungicide application can be an effective strategy for the management of FHB and DON in winter wheat in the Huang-huai-hai Plain of China.

Early and late responses to Fusarium Head blight in durum wheat: Focus on phenylpropanoid biosynthetic pathway

Durum wheat is among the cereal crops most susceptible to Fusarium Head Blight (FHB), a fungal disease that can lead to significant yield losses. Despite this, only limited research efforts have been directed towards understanding FHB resistance in durum wheat. Wheat grains naturally contain phenolic compounds, and anthocyanins are particularly present in the so-called pigmented wheat genotypes, such as purple pericarp ones. In this study the effects of the biotic stress caused by Fusarium graminearum infection on phenylpropanoid biosynthetic pathway in durum wheat spikes were explored, considering three genotypes with different susceptibility (including a purple pericarp genotype), and two time points (an early stage time point: 2 days post infection, and a late stage time point: 21 days post infection). At early infection stage, the F. graminearum infection triggered upregulation of all the considered genes involved in the phenylpropanoid pathway in the resistant genotype, while, in the purple pericarp genotype, the infection caused an increase in quercetin accumulation in the soluble fraction of spike extract. At late infection stage, the infection caused (in all the genotypes) a degradation of secondary cell wall and the release of the hydroxycinnamic acids esterified with arabinoxylans (ferulic acid and p-coumaric acid) and lignin-derived monomers (vanillic acid). Furthermore, chalcone synthase gene (CHS) and the transcription factor Ppm1 (Purple pericarp MYB 1) were boosted in the pigmented genotype due to infection at late infection stage. These findings contribute to the understanding of host-pathogen interactions for future breeding programs focused on improving FHB resistance in durum wheat varieties, with a particular focus on pigmented genotypes.

Research on the Identification of Wheat Fusarium Head Blight Based on Multispectral Remote Sensing from UAVs

Research on the Identification of Wheat Fusarium Head Blight Based on Multispectral Remote Sensing from UAVs

Testing the efficacy of a newly released fungicide, Sphaerex, for control of Fusarium Head Blight in wheat

Fusarium head blight (FHB) is a destructive disease of wheat and other small-grain cereals. FHB causes reduction in crop yield due to pre-mature bleaching of spikes. Additionally, it deteriorates the crop quality due to the production of mycotoxins. An integrated management strategy is needed to effectively manage this disease. One of the most important strategies in the FHB management toolbox is chemical control. Fungicides start losing their efficacy over time due to the development of fungicide resistance in the pathogens. This necessitates the development and testing of new fungicides with multiple active ingredients or modes of action. In this 3-year study, we evaluated the effectiveness of a new fungicide with multiple active ingredients, Sphaerex (a proprietary mix of metconazole and prothioconazole) in an FHB-susceptible soft red winter wheat cultivar, Shirley in the eastern United States. Sphaerex provided significantly better control over untreated plots for FHB Incidence, FHB Severity, and DON content across all three years. The level of control of FHB and DON by Sphaerex was found to be similar to that provided by other standard FHB fungicides. The yield of the fungicide-treated plots was statistically similar to that of the untreated plots.

A Glutathione S-Transferase from Thinopyrum ponticum Confers Fhb7 Resistance to Fusarium Head Blight in Wheat.

Fusarium head blight (FHB), mainly incited by Fusarium graminearum, has caused great losses in grain yield and quality of wheat globally. Fhb7, a major gene from 7E chromosome of Thinopyrum ponticum, confers broad resistance to multiple Fusarium species in wheat and has recently been cloned and identified as encoding a glutathione S-transferase (GST). However, some recent reports raised doubt about whether GST is the causal gene of Fhb7. To resolve the discrepancy and validate the gene function of GST in wheat, we phenotyped Fhb7 near-isogenic lines (Jimai22-Fhb7 versus Jimai22) and GST overexpressed lines for FHB resistance. Jimai22-Fhb7 showed significantly higher FHB resistance with a lower percentage of symptomatic spikelets, Fusarium-damaged kernels, and deoxynivalenol content than susceptible Jimai22 in three experiments. All the positive GST transgenic lines driven by either the maize ubiquitin promoter or its native promoter with high gene expression in the wheat cultivar 'Fielder' showed high FHB resistance. Only one maize ubiquitin promoter-driven transgenic line showed low GST expression and similar susceptibility to Fielder, suggesting that high GST expression confers Fhb7 resistance to FHB. Knockout of GST in the Jimai22-Fhb7 line using CRISPR-Cas9-based gene editing showed significantly higher FHB susceptibility compared with the nonedited control plants. Therefore, we confirmed GST as the causal gene of Fhb7 for FHB resistance. Considering its major effect on FHB resistance, pyramiding Fhb7 with other quantitative trait loci has a great potential to create highly FHB-resistant wheat cultivars.

The effect of quantitative wheat resistance on the aggressiveness of Fusarium graminearum.

Little is known about the selection pressures acting on plant pathogen populations, especially those applied by quantitative forms of resistance. Fusarium graminearum causes Fusarium Head Blight (FHB) in wheat, producing significant yield losses and mycotoxin contamination. Quantitative host resistance is the best method to control FHB. However, there needs to be more understanding of how disease resistance affects the evolution of plant pathogens. This study aimed to determine if the presence or absence of wheat resistance influenced the fitness components and genomic regions of F. graminearum. Thirty-one isolates from highly susceptible and 25 isolates from moderately resistant wheat lines were used. Isolate aggressiveness was measured by area under the disease progress curve (AUDPC), visually damaged kernels, and deoxynivalenol contamination. In vitro growth rate and spore production were also measured. Two whole-genome scans for selection were conducted with 333,297 SNPs. One scan looked for signatures of selection in the entire sample and the other scan was for divergent selection between the isolates from moderately resistant wheat and highly susceptible wheat. The population of isolates from highly susceptible wheat was primarily aggressive. Several regions of the F. graminearum genome with signatures for selection were identified. The moderately resistant wheat varieties used in this study did not select more aggressive isolates, suggesting that quantitative resistance is a durable method to control FHB.

Fusarium species causing head blight in wheat and barley show no vertical races

On a global scale, Fusarium head blight (FHB) is one of the most noxious diseases of wheat and barley. One or two Fusarium species out of 17 pathogens implicated in the complex FHB disease do not have vertical races following infection in bread wheat; however, no reports support this observation in durum wheat and barley. To end this, 16 fungal isolates of varying aggressiveness of four Fusarium species were tested on eight bread and durum wheat and barley cultivars covering a wide range from moderate resistance to susceptibility. Nine pathogenic components obtained under in vitro, growth chamber and field conditions were measured to determine whether true vertical races exist within the four tested Fusarium species. Although combined analysis of bio-experiments showed that isolate × cultivar interactions were significant, this relationship was unstable over experiments. However, the tested three bread wheat, three durum wheat and two barley cultivars showed consistent resistance to fungal isolates within each tested species, showing that F. culmorum, F. solani, F. verticillioides, and F. equiseti do not have vertical races. Our data concluded that the resistance to FHB in wheat and barley was of the horizontal and non-species specific type. There was no signal for any vertical genes in all tested Fusarium species. Consequently, the resistance genes in sources presently employed in breeding programs are not expected to succumb to new FHB races in the near future. To our best knowledge, this is the first report to show the absence of vertical Fusarium races upon infection durum wheat and barley, and is harmony with earlier reports conduced with bread wheat infected with F. graminearum and F. culmorum.

Utilizing zinc oxide nanoparticles as an environmentally safe biosystem to mitigate mycotoxicity and suppress Fusarium graminearium colonization in wheat

The biosynthesis of zinc oxide nanoparticles (ZnONPs) offers great potential for plant disease management due to their potent antimicrobial properties and environmental safety. However, the precise mechanisms underlying their antifungal mode of action and role in suppressing mycotoxins remain unclear. This study aims to elucidate the mechanisms by which ZnONPs suppress the pathogenic fungus Fusarium graminearium, known to cause Fusarium head blight in wheat. Additionally, it investigates how ZnONPs mitigate the production of mycotoxins, which pose risks to humans and ruminants. The study demonstrates that ZnONPs, bioproduced by Pseudomonas poae (P. poae), inhibit not only fungal growth, colony formation, and spore germination, but also significantly reduce mycotoxin production of F. graminearium by inhibiting the synthesis of deoxynivalenol (DON), downregulating the FgTRI gene, and causing morphological alterations of the toxisomes. The results also highlight that ZnONPs exert significant effects on fungi through multiple mechanisms, including cell wall damage and the generation of reactive oxygen species (ROS). Moreover, ZnONPs effectively inhibit F. graminearium in wheat leaves and coleoptiles. Fluorescence microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy all show that ZnONPs stop F. graminearium from getting into wheat plants and colonising them. Overall, the findings of this study provide evidence that ZnONPs are highly effective in reducing F. graminearium colonization in wheat plants and effectively decreasing mycotoxin production through multiple pathways.

Wheat Fusarium Head Blight Automatic Non-Destructive Detection Based on Multi-Scale Imaging: A Technical Perspective.

Fusarium head blight (FHB) is a major threat to global wheat production. Recent reviews of wheat FHB focused on pathology or comprehensive prevention and lacked a summary of advanced detection techniques. Unlike traditional detection and management methods, wheat FHB detection based on various imaging technologies has the obvious advantages of a high degree of automation and efficiency. With the rapid development of computer vision and deep learning technology, the number of related research has grown explosively in recent years. This review begins with an overview of wheat FHB epidemic mechanisms and changes in the characteristics of infected wheat. On this basis, the imaging scales are divided into microscopic, medium, submacroscopic, and macroscopic scales. Then, we outline the recent relevant articles, algorithms, and methodologies about wheat FHB from disease detection to qualitative analysis and summarize the potential difficulties in the practicalization of the corresponding technology. This paper could provide researchers with more targeted technical support and breakthrough directions. Additionally, this paper provides an overview of the ideal application mode of the FHB detection technologies based on multi-scale imaging and then examines the development trend of the all-scale detection system, which paved the way for the fusion of non-destructive detection technologies of wheat FHB based on multi-scale imaging.

Lightweight U-Net-Based Method for Estimating the Severity of Wheat Fusarium Head Blight

Wheat Fusarium head blight is one of the major diseases affecting the yield and quality of wheat. Accurate and rapid estimation of disease severity is crucial for implementing disease-resistant breeding and scientific management strategies. Traditional methods for estimating disease severity are complex and inefficient, often failing to provide accurate assessments under field conditions. Therefore, this paper proposes a method using a lightweight U-Net model for segmenting wheat spike disease spots to estimate disease severity. Firstly, the model employs MobileNetv3 as its backbone for feature extraction, significantly reducing the number of parameters and computational demand, thus enhancing segmentation efficiency. Secondly, the backbone network has been augmented with a lightweight Coordinate Attention (CA) module, which integrates lesion position information through channel attention and aggregates features across two spatial dimensions. This allows the model to capture long-range feature correlations and maintain positional information, effectively enhancing the segmentation of wheat spike disease spots while ensuring the model’s lightweight and efficient characteristics. Lastly, depthwise separable convolutions have been introduced in the decoder in place of standard convolutions, further reducing the model’s parameter count while maintaining performance. Experimental results show that the model’s segmentation Mean Intersection over Union (MIoU) reached 88.87%, surpassing the U-Net model by 3.49 percentage points, with a total parameter count of only 4.52 M, one-sixth of the original model. The improved model demonstrates its capability to segment individual wheat spike disease spots under field conditions and estimate the severity of infestation, providing technical support for disease identification research.

Investigating the mechanisms of isochorismate synthase: An approach to improve salicylic acid synthesis and increase resistance to Fusarium head blight in wheat

Salicylic acid (SA), a vital endogenous hormone, plays a crucial role in plant growth and the response to abiotic and biotic stress. Isochorismate synthase (ICS) and phenylalanine ammonia lyase (PAL) are critical rate-limiting enzymes for SA synthesis. Fusarium head blight (FHB) seriously threatens the safety of wheat production, but increasing the content of SA can enhance FHB resistance. However, the pathway of SA synthesis and regulation in wheat remains unknown. In this study, three wheat ICS (TaICSA, TaICSB, and TaICSD) were identified, and their functions were validated in vitro for isomerizing chorismate to isochorismate. The mutation of one or two homoeoalleles of TaICSA, TaICSB, and TaICSD in the wheat variety ‘Cadenza’ reduced SA levels under ultraviolet treatment and Fusarium graminearum infection, further enhancing sensitivity to FHB. Overexpression of TaICSA can significantly enhance SA levels and resistance to FHB. To further study SA synthesis pathways in wheat and avoid interference with pathogenicity related genes, the leaves of wild-type Cadenza and different TaICS mutant lines were subjected to ultraviolet treatment for transcriptomic analysis. The results showed that 37 PALs might be involved in endogenous SA synthesis, and 82 WRKY and MYB family transcription factors may regulate the expression of ICS and PAL. These results were further confirmed by RT-PCR. In conclusion, this study expands our knowledge of SA biosynthesis and identifies TaICSA, as well as several additional candidate genes that encode transcription factors for regulating endogenous SA levels, as part of an efficient strategy for enhancing FHB resistance in wheat.

Control of Fusarium Head Blight of Wheat with Bacillus velezensis E2 and Potential Mechanisms of Action.

Wheat plants are impacted by Fusarium head blight (FHB) infection, which poses a huge threat to wheat growth, development, storage and food safety. In this study, a fungal strain was isolated from diseased wheat plants and identified as Fusarium asiaticum F1, known to be a member of the Fusarium graminearum species complex, agents causally responsible for FHB. In order to control this disease, new alternatives need to be developed for the use of antagonistic bacteria. Bacillus velezensis E2 (B. velezensis E2), isolated from a previous investigation in our laboratory, showed a notable inhibitory effect on F. asiaticum F1 growth and deoxynivalenol (DON) synthesis in grains. The spore germination of F. asiaticum F1 was significantly reduced and the spores showed vesicular structures when treated with B. velezensis E2. Observations using scanning electron microscopy (SEM) showed that the hyphae of F. asiaticum F1 were shrunken and broken when treated with B. velezensis E2. The RNA-seq results of F1 hyphae treated with B. velezensis E2 showed that differentially expressed genes (DEGs), which were involved in multiple metabolic pathways such as toxin synthesis, autophagy process and glycan synthesis, especially the genes associated with DON synthesis, were significantly downregulated. In summary, those results showed that B. velezensis E2 could inhibit F. asiaticum F1 growth and reduce the gene expression of DON synthesis caused by F1. This study provides new insights and antagonistic mechanisms for the biological control of FHB during wheat growth, development and storage.

Streptomyces pratensis S10 inhibits spread of Fusarium graminearum invasive hyphae and toxisome formation in wheat plants.

Fusarium head blight (FHB) of wheat, mainly caused by Fusarium graminearum, leads to severe economic losses worldwide. Effective management measures for controlling FHB are not available, due to a lack of resistant cultivars. Currently, the utilization of biological control is a promising approach that can be used to help manage FHB. Previous studies have confirmed that Streptomyces pratensis S10 harbors excellent inhibitory effects on F. graminearum. However, there is no information regarding invasive hyphae of F. graminearum are inhibited by S10. Thus, we investigated the effects of S10 on F. graminearum strain PH-1 hyphae extension, toxisome formation, and TRI5 gene expression on wheat plants via microscopic observation. The results showed that S10 effectively inhibited spread of F. graminearum hyphae along the rachis, restricting the infection of neighboring florets via the phloem. In the presence of S10, the hyphal growth is impeded by formation of dense cell wall thickenings in the rachis internode surrounding the F. graminearum infection site, avoiding cell plasmolysis and collapse. We further demonstrated that S10 largely prevented cell-to-cell invasion of fungal hyphae inside wheat coleoptiles using a constitutively green fluorescence protein-expressing F. graminearum strain, PH-1. Importantly, S. pratensis S10 inhibited toxisome formation and TRI5 gene expression in wheat plants during infection. Collectively, these findings indicated that S. pratensis S10 prevents spread of F. graminearum invasive hyphae via the rachis.

A comparison between the role of enniatins and deoxynivalenol in Fusarium virulence on different tissues of common wheat

BackgroundFusarium graminearum and Fusarium avenaceum are two of the most important causal agents of Fusarium head blight (FHB) of wheat. They can produce mycotoxins that accumulate in infected wheat heads, including deoxynivalenol (DON) and enniatins (ENNs), produced by F. graminearum and F. avenaceum, respectively. While the role of DON as a virulence factor in F. graminearum toward wheat is well known, ENNs in F. avenaceum has been poorly explored. Results obtained to-date indicate that ENNs may confer an advantage to F. avenaceum only on particular hosts.ResultsIn this study, with the use of ENN-producing and ENN non-producing F. avenaceum strains, the role of ENNs on F. avenaceum virulence was investigated on the root, stem base and head of common wheat, and compared with the role of DON, using DON-producing and DON non-producing F. graminearum strains. The DON-producing F. graminearum strain showed a significantly higher ability to cause symptoms and colonise each of the tested tissues than the non-producing strain. On the other hand, the ability to produce ENNs increased initial symptoms of the disease and fungal biomass accumulation, measured by qPCR, only in wheat heads, and not in roots or stem bases. LC-MS/MS analysis was used to confirm the presence of ENNs and DON in the different strains, and results, both in vitro and in wheat heads, were consistent with the genetics of each strain.ConclusionWhile the key role of DON on F. graminearum virulence towards three different wheat tissues was noticeable, ENNs seemed to have a role only in influencing F. avenaceum virulence on common wheat heads probably due to an initial delay in the appearance of symptoms.