Fusarium Head Blight Symptoms Research Articles

The effects of Lr34 and Lr67 on Fusarium head blight resistance and deoxynivalenol accumulation in wheat

AbstractThe resistance gene Lr34 conditions durable disease resistance to many biotrophic wheat pathogens and has been incorporated into many wheat cultivars throughout the world. Lr67 is a similar adult plant resistance gene that also conditions resistance to multiple wheat diseases. Both genes significantly reduce disease severity and work in an additive manner with other rust resistance genes. To determine the effect of Lr34 and Lr67 on Fusarium head blight (FHB), two doubled haploid populations, segregating for each of these genes, were developed in the Thatcher wheat background by crossing near‐isogenic lines. Progeny from these populations were tested in five Fusarium graminearum‐inoculated disease nurseries and assessed for FHB symptoms, using a visual rating index (VRI), and deoxynivalenol (DON) accumulation. Both Lr34 and Lr67 significantly reduced visual symptoms of FHB and DON overall, though those effects were not significant in all environments. The overall reduction in the group of progeny with the resistant allele compared to the group with the susceptible allele for VRI was 9.4% for Lr34 and 6.8% for Lr67, while for DON it was 16.4% for Lr34 and 14.9% for Lr67. These genes represent important tools for improving resistance to FHB and many other diseases in wheat.

Insights into Wheat Genotype‒Sphaerodes mycoparasitica Interaction to Improve Crop Yield and Defence against Fusarium graminearum: An Integration of FHB Biocontrol in Canadian Wheat Breeding Programmes.

Fusarium head blight (FHB) is a major threat to wheat crop production and food security worldwide. The creation of resistant wheat cultivars is an essential component of an integrated strategy against Fusarium graminearum, the primary aetiological agent that causes FHB. The results of this study show that the deployment of proto-cooperative interactions between wheat genotypes and mycoparasitic biocontrol agents (BCAs) can improve crop yield and plant resistance in controlling the devastating effects of FHB on wheat agronomic traits. A Fusarium-specific mycoparasite, Sphaerodes mycoparasitica, was found to be compatible with common and durum wheat hosts, thus allowing the efficient control of F. graminearum infection in plants. Four genotypes of wheat, two common wheat, and two durum wheat cultivars with varying FHB resistance levels were used in this greenhouse study. The BCA treatments decreased FHB symptoms in all four cultivars and improved the agronomic traits such as spike number, spike weight, seed weight, plant biomass, and plant height which are vital to grain yield. Conversely, the F. graminearum 3ADON chemotype treatment decreased the agronomic trait values by up to 44% across cultivars. Spike number, spike weight, and seed weight were the most improved traits by the BCA. A more measurable improvement in agronomic traits was observed in durum wheat cultivars compared to common wheat.

A phase-separated protein hub modulates resistance to Fusarium head blight in wheat

Fusarium head blight (FHB) is a devastating wheat disease. Fhb1, the most widely applied genetic locus for FHB resistance, is conferred by TaHRC of an unknown mode of action. Here, we show that TaHRC alleles distinctly drive liquid-liquid phase separation (LLPS) within a proteinaceous complex, determining FHB susceptibility or resistance. TaHRC-S (susceptible) exhibits stronger LLPS ability than TaHRC-R (resistant), and this distinction is further intensified by fungal mycotoxin deoxynivalenol, leading to opposing FHB symptoms. TaHRC recruits a protein class with intrinsic LLPS potentials, referred to as an "HRC-containing hub." TaHRC-S drives condensation of hub components, while TaHRC-R comparatively suppresses hub condensate formation. The function of TaSR45a splicing factor, a hub member, depends on TaHRC-driven condensate state, which in turn differentially directs alternative splicing, switching between susceptibility and resistance to wheat FHB. These findings reveal a mechanism for FHB spread within a spike and shed light on the roles of complex condensates in controlling plant disease.

Fusarium head blight detection, spikelet estimation, and severity assessment in wheat using 3D convolutional neural networks

Fusarium head blight (FHB) is one of the most significant diseases affecting wheat and other small grain cereals worldwide. Developing FHB-resistant cultivars is critical but requires field and greenhouse disease assessment which are typically laborious and time-consuming. In this work, we developed automated applications based on 3-dimensional (3D) convolutional neural networks (CNN) that detect FHB symptoms expressed in wheat, estimate the total number of spikelets versus the total number of infected spikelets on a wheat head, and subsequently calculate FHB severity index. Such tools are an important step toward the creation of automated and efficient phenotyping methods. The data used to generate the results are 3D point clouds consisting of four color channels – red, green, blue (RGB), and near-infrared (NIR) – collected using a multispectral 3D scanner. Our 3D CNN models for FHB detection achieved 100% accuracy. The influence of the multispectral information on performance was evaluated; the results showed the dominance of the RGB channels over both the NIR (720 nm peak wavelength) and the NIR plus RGB channels combined. Our best 3D CNN models for estimation of total and infected number of spikelets achieved mean absolute errors (MAE) of 1.13 and 1.56, respectively. Our best 3D CNN models for FHB severity estimation achieved 8.6 MAE. A linear regression analysis between the visual FHB severity assessment and the FHB severity predicted by our 3D CNN showed a significant correlation.

The Fusarium graminearum Transporters Abc1 and Abc6 Are Important for Xenobiotic Resistance, Trichothecene Accumulation, and Virulence to Wheat.

The plant pathogenic fungus Fusarium graminearum is the causal agent of Fusarium head blight (FHB) disease on small-grain cereals. F. graminearum produces trichothecene mycotoxins such as deoxynivalenol (DON) that are required for full virulence. DON must be exported outside the cell to cause FHB disease, a process that may require the involvement of membrane-bound transporters. In this study, we show that the deletion of membrane-bound transporters results in reduced DON accumulation as well as reduced FHB symptoms on wheat. Deletion of the ATP-binding cassette (ABC) transporter gene Abc1 results in the greatest reduction in DON accumulation and virulence. Deletion of another ABC transporter gene, Abc6, also reduces FHB symptoms to a lesser degree. Combining deletions fails to reduce DON accumulation or virulence in an additive fashion, even when a ∆abc1 deletion is included. Heterologous expression of F. graminearum transporters in a DON-sensitive strain of yeast confirms Abc1 as a major DON resistance mechanism; furthermore, it suggests that Abc1 is directly participating in DON transport rather than facilitating DON transport though other means. Yeast expression further indicates that multiple transporters, including Abc1, play an important role in resistance to the wheat phytoalexin 2-benzoxazolinone (BOA) and other xenobiotics. Thus, Abc1 may contribute to virulence on wheat both by facilitating export of DON and by providing resistance to the wheat phytoalexin BOA. This research provides useful information that may aid in designing novel management techniques of FHB or other destructive plant diseases.

Hyperspectral Imaging and Selected Biological Control Agents for the Management of Fusarium Head Blight in Spring Wheat.

Fusarium spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination with mycotoxins. The European Union intends to reduce the use of chemical-synthetic plant protection products (csPPP) by up to 50% by the year 2030. To realize this endeavor without significant economic losses for farmers, it is crucial to have both precise early detection of pathogens and effective alternatives for csPPP. To investigate both the early detection of Fusarium head blight (FHB) and the efficacy of selected biological control agents (BCAs), a pot experiment with spring wheat (cv. 'Servus') was conducted under semi-field conditions. Spikes were sprayed with different BCAs prior to inoculation with a mixture of F. graminearum and F. culmorum conidia. While early detection of FHB was investigated by hyperspectral imaging (HSI), the efficiency of the fungal (Trichoderma sp. T10, T. harzianum T16, T. asperellum T23 and Clonostachys rosea CRP1104) and bacterial (Bacillus subtilis HG77 and Pseudomonas fluorescens G308) BCAs was assessed by visual monitoring. Evaluation of the hyperspectral images using linear discriminant analysis (LDA) resulted in a pathogen detection nine days post inoculation (dpi) with the pathogen, and thus four days before the first symptoms could be visually detected. Furthermore, support vector machines (SVM) and a combination of LDA and distance classifier (DC) were also able to detect FHB symptoms earlier than manual rating. Scoring the spikes at 13 and 17 dpi with the pathogen showed no significant differences in the FHB incidence among the treatments. Nevertheless, there is a trend suggesting that all BCAs exhibit a diminishing effect against FHB, with fungal isolates demonstrating greater efficacy compared to bacterial ones.

UDP-glucosyltransferase HvUGT13248 confers type II resistance to Fusarium graminearum in barley.

Fusarium head blight (FHB) of barley (Hordeum vulgare) causes yield losses and accumulation of trichothecene mycotoxins (e.g. deoxynivalenol [DON]) in grains. Glucosylation of DON to the nontoxic DON-3-O-glucoside (D3G) is catalyzed by UDP-glucosyltransferases (UGTs), such as barley UGT13248. We explored the natural diversity of UGT13248 in 496 barley accessions and showed that all carried potential functional alleles of UGT13248, as no genotypes showed strongly increased seedling sensitivity to DON. From a TILLING population, we identified 2 mutant alleles (T368I and H369Y) that, based on protein modeling, likely affect the UDP-glucose binding of UGT13248. In DON feeding experiments, DON-to-D3G conversion was strongly reduced in spikes of these mutants compared to controls, and plants overexpressing UGT13248 showed increased resistance to DON and increased DON-to-D3G conversion. Moreover, field-grown plants carrying the T368I or H369Y mutations inoculated with Fusarium graminearum showed increased FHB disease severity and reduced D3G production. Barley is generally considered to have type II resistance that limits the spread of F. graminearum from the infected spikelet to adjacent spikelets. Point inoculation experiments with F. graminearum showed increased infection spread in T368I and H369Y across the spike compared to wild type, while overexpression plants showed decreased spread of FHB symptoms. Confocal microscopy revealed that F. graminearum spread to distant rachis nodes in T368I and H369Y mutants but was arrested at the rachis node of the inoculated spikelet in wild-type plants. Taken together, our data reveal that UGT13248 confers type II resistance to FHB in barley via conjugation of DON to D3G.

NX Trichothecenes Are Required for Fusarium graminearum Infection of Wheat.

Fusarium graminearum causes Fusarium head blight (FHB) on wheat and barley and contaminates grains with various mycotoxins that are toxic to humans and animals. Deoxynivalenol (DON), a type B trichothecene, is an essential virulence factor that is required for F. graminearum to spread within a wheat head. Recently, novel type A trichothecenes NX-2 and NX-3 (NX) have been found in F. graminearum. NX trichothecenes lack a keto group at the C8 position. To determine if NX trichothecenes play a role similar to that of DON during F. graminearum infection, deletion mutants of TRI5, the first gene for trichothecene biosynthesis, were generated from strains PH-1, NRRL46422, and NRRL44211 (hereafter 44211) representing the 15-acetyl-DON, 3-acetyl-DON, and NX chemotypes. No trichothecene production was detected in any of the Δtri5 mutants in cultures or inoculated wheat heads. FHB symptoms were restricted to the inoculated wheat spikelets when point-inoculated with the Δtri5 mutants, confirming the necessity of NX and DON for FHB spread. Furthermore, whole-head dip inoculations revealed significant reductions in disease and fungal biomass in wheat heads inoculated with 44211Δtri5 compared with 44211. Introduction of the native 44211 TRI5 and a Trichoderma arundinaceum TRI5 ortholog in the 44211Δtri5 mutant complemented trichothecene production in vitro; however, introducing both TRI5 partially restored wild-type levels of NX in infected heads. Our results demonstrate that NX trichothecenes play an important role in Fusarium graminearum initial infection as well as FHB spread. Thus, TRI5 may serve as an ideal target to control plant infection, FHB spread, and mycotoxin production simultaneously. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

First Report of Fusarium sibiricum Causing Fusarium Head Blight of Wheat in China

First Report of <i>Fusarium sibiricum</i> Causing Fusarium Head Blight of Wheat in China

Boosting Immunity and Management against Wheat Fusarium Diseases by a Sustainable, Circular Nanostructured Delivery Platform.

Fusarium head blight (FHB) and Fusarium crown rot (FCR) are managed by the application of imidazole fungicides, which will be strictly limited by 2030, as stated by the European Green Deal. Here, a novel and eco-sustainable nanostructured particle formulation (NPF) is presented by following the principles of the circular economy. Cellulose nanocrystals (CNC) and resistant starch were obtained from the bran of a high amylose (HA) bread wheat and employed as carrier and excipient, while chitosan and gallic acid were functionalized as antifungal and elicitor active principles. The NPF inhibited conidia germination and mycelium growth, and mechanically interacted with conidia. The NPF optimally reduced FHB and FCR symptoms in susceptible bread wheat genotypes while being biocompatible on plants. The expression level of 21 genes involved in the induction of innate immunity was investigated in Sumai3 (FHB resistant) Cadenza (susceptible) and Cadenza SBEIIa (a mutant characterized by high-amylose starch content) and most of them were up-regulated in Cadenza SBEIIa spikes treated with the NPF, indicating that this genotype may possess an interesting genomic background particularly responsive to elicitor-like molecules. Quantification of fungal biomass revealed that the NPF controlled FHB spread, while Cadenza SBEIIa was resistant to FCR fungal spread. The present research work highlights that the NPF is a powerful weapon for FHB sustainable management, while the genome of Cadenza SBEIIa should be investigated deeply as particularly responsive to elicitor-like molecules and resistant to FCR fungal spread.

Prouzrokovač sušice klasa i lista strnih žita (Magnaporthe oryzae) - pojava i rizici za proizvodnju u Srbiji

Magnaporthe oryzae (anamorph Pyricularia oryzae) is the causal agent of wheat blast. Apart from being a pathogen of commercially significant plant species, it also infects weeds. Within the species M. oryzae, several pathotypes exist, with the pathotype Magnaporthe oryzae Triticum (MoT) infecting wheat and several other grass species. M. oryzae was first discovered in Brazil in 1985 and has since posed a threat to wheat production in various parts of the world, including Bangladesh and European Union countries. The MoT pathogen can infect all above-ground parts of the plant, but the most common symptoms appear on the ears and closely resemble symptoms of fusarium head blight. During the 2022/2023 growing season, precipitation levels in April and May at the Rimski šančevi exceeded seventeen-year averages, while the temperature in May was within the multi-year average range. These conditions created a favorable environment for the emergence of M. oryzae. Microscopic examination of infected ears revealed the presence of conidia from the asexual generation of Pyricularia oryzae. Considering that MoT is not classified as a quarantine pathogen in many EU countries, this study highlights the risk of the presence of M. oryzae in Serbia, as well as the importance of monitoring the occurrence of M. oryzae in weeds, grasses, and cereal grains to take timely action in protecting crops from this pathogen.

Deep-Learning Approach for Fusarium Head Blight Detection in Wheat Seeds Using Low-Cost Imaging Technology

Modern techniques that enable high-precision and rapid identification/elimination of wheat seeds infected by Fusarium head blight (FHB) can help to prevent human and animal health risks while improving agricultural sustainability. Robust pattern-recognition methods, such as deep learning, can achieve higher precision in detecting infected seeds using more accessible solutions, such as ordinary RGB cameras. This study used different deep-learning approaches based on RGB images, combining hyperparameter optimization, and fine-tuning strategies with different pretrained convolutional neural networks (convnets) to discriminate wheat seeds of the TBIO Toruk cultivar infected by FHB. The models achieved an accuracy of 97% using a low-complexity design architecture with hyperparameter optimization and 99% accuracy in detecting FHB in seeds. These findings suggest the potential of low-cost imaging technology and deep-learning models for the accurate classification of wheat seeds infected by FHB. However, FHB symptoms are genotype-dependent, and therefore the accuracy of the detection method may vary depending on phenotypic variations among wheat cultivars.

Occurrence of the Fusarium incarnatum-equiseti Species Complex Causing Fusarium Head Blight of Wheat in Mexico.

Fusarium head blight (FHB) is one of the most important diseases affecting wheat production worldwide. In Mexico, Fusarium boothii and F. avenaceum are the dominant species causing FHB of wheat (Cerón-Bustamante et al. 2018). During the 2017 to 2019 surveys, FHB symptoms were observed in wheat fields in the Highlands region of Mexico. Symptomatic spike samples were collected from 19 wheat fields in five states (Tlaxcala, Hidalgo, Puebla, Estado de México, and Morelos). Fusarium-like colonies were consistently isolated on potato dextrose agar (PDA) and 95 monoconidial isolates were obtained. Morphological features of seven isolates were consistent with the description of the Fusarium incarnatum-equiseti species complex (Xia et al. 2019). On PDA, colonies exhibited white and fluffy aerial mycelia, with diffused pink pigment on the reverse side after 7 days of incubation at 25℃. On carnation leaf agar (CLA), macroconidia (n = 100) were hyaline, falcate, with 3 to 6 septa, measuring 25.2 to 43.1 × 2.8 to 5.1 μm, and foot-shaped basal cell. Chlamydospores were ellipsoidal or subglobose and produced in chains. These seven isolates were selected for multilocus phylogenetic analysis and pathogenicity tests. Isolates were deposited in the Culture Collection of Phytopathogenic Fungi of the Department of Agricultural Parasitology at the Chapingo Autonomous University under acc. nos. UACH428 to UACH434. For molecular identification, genomic DNA was extracted, and the internal transcribed spacer (ITS) region, partial sequences of translation elongation factor 1-alpha (EF1-α) and the second largest subunit of RNA polymerase II (RPB2) genes were amplified, and sequenced with the primer sets ITS5/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and RBP2-5F/RPB2-7R (Liu et al. 1999), respectively. A phylogenetic tree, including published ITS, EF1-α, and RPB2 sequence data, was constructed for the Fusarium incarnatum-equiseti species complex (FIESC) based on Maximum Likelihood. Three species of the FIESC were identified into F. pernambucanum (five isolates), F. sulawesiense (one isolate), and F. clavum (one isolate). The sequences were deposited in GenBank with accession nos. OL347713 to OL347719 for ITS, OL365078 to OL365084 for EF1-α, and OL365072 to OL365077 for RPB2. The pathogenicity of the isolates was confirmed on wheat cv. Nana F2007 at the flowering stage in a glasshouse assay. The heads of 20 wheat plants were sprayed with a conidial suspension (1 × 105 spores/ml) of each isolate. Ten plants mock-inoculated with sterilized water served as the controls. All plants were placed in a moist chamber for 48 h. At 10 days after inoculation, typical FHB symptoms were visible on the inoculated plants, whereas the control plants remained asymptomatic. The pathogenicity test was repeated twice with similar results. The fungi were reisolated from the infected heads and found to be morphologically identical to the isolates used for inoculation, fulfilling Koch's postulates. Previously, three isolates of Fusarium sp. belonging to the FIESC, were associated with FHB of wheat in Mexico (Cerón-Bustamante et al. 2018); however, this is the first report of F. pernambucanum, F. sulawesiense, and F. clavum causing FHB of wheat in Mexico and worldwide (Farr and Rossman 2021). Further studies should be focused on determining the distribution, prevalence, and toxigenic potential of the isolates of the FIESC associated with wheat diseases in Mexico.

Biological characterization and in vitro fungicide screenings of a new causal agent of wheat Fusarium head blight in Tibet, China.

Wheat (Triticum aestivum L.) is an important cereal crop, widely grown throughout the temperate zones, and also suitable for cultivation at higher elevations. Fusarium head blight (FHB) is a highly destructive disease of wheat throughout the globe. In July 2020, serious wheat FHB symptoms were observed in open fields located in Linzhi City, southeast of Tibet, China. The causal agent was identified as Fusarium avenaceum (Fr.) Sacc. by amplification and sequencing of the internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (EF-1α) gene, and RNA polymerase II subunit (RPB-2) gene, as well as by morphological characterization. Koch’s postulates were confirmed by a pathogenicity test on healthy spikes, including re-isolation and identification. To our knowledge, this is the first report of F. avenaceum causing FHB on wheat in Tibet, China. Moreover, to determine pathogen characteristics that may be useful for future disease management, the utilization of different carbon and nitrogen resources, temperature, light, and ultraviolet (UV) irradiation on mycelium growth and conidia germination were studied. Soluble starch and peptone were the best carbon, and nitrogen source for the pathogen respectively. The optimal temperatures for the pathogen’s mycelium growth and conidia germination were 15–20°C, matching the average temperature during the growing season in Linzhi (Tibet). Meanwhile, alternating 8-h light and 16-h dark was shown to be conducive to mycelia growth, and complete darkness facilitated conidia germination. In addition, UV Irradiation of 48 MJ/cm2, approximately 100 times of the local condition, did not inhibit the germination of conidia. Furthermore, in vitro screening of effective fungicides was conducted. Among the seven tested pesticides, carbendazim showed the best inhibition rate, with an EC50 (concentration for 50% of maximal effect) value of 2.1 mg/L. Propiconazole also showed sufficient inhibitory effects against F. avenaceum, with an EC50 value of 2.6 mg/L. The study provides insights into the newly identified causal agent of wheat FHB in Tibet, China, as well as first pathogen characteristics and promising candidate substances for its management.

Wheat Seed Coating with Streptomyces sp. Strain DEF39 Spores Protects against Fusarium Head Blight.

Streptomycetes are promising candidates for the biological control of Fusarium Head Blight (FHB) in wheat. Studies involving the use of streptomycetes as biological control agents (BCAs) have been limited to the application when the wheat plant is developed, close to the infection on the spike during flowering. Here, we tested the effects of seed treatment with the Streptomyces sp. DEF39 spores before sowing on FHB symptoms’ development. The seed treatment protected the plant from infection by Fusarium graminearum by 49% (p = 0.04). We traced Streptomyces sp. DEF39 in plant organs using strain-specific primers here developed, showing that the streptomycete acts as an endophyte, colonizing the plant tissues up to the spike as well as the roots. This work suggests that it is possible to use a streptomycete as a seed coating BCA, able to partially protect wheat from FHB disease.

Mycotoxin DON Accumulation in Wheat Grains Caused by Fusarium Head Blight Are Significantly Subjected to Inoculation Methods.

The disease severity and mycotoxin DON content in grains caused by fusarium head blight (FHB) have been two prioritized economical traits in wheat. Reliable phenotyping is a prerequisite for genetically improving wheat resistances to these two traits. In this study, three inoculation methods: upper bilateral floret injection (UBFI), basal bilateral floret injection (BBFI), and basal rachis internode injection (BRII), were applied in a panel of 22 near-isogenic lines (NILs) contrasting in Fhb1 alleles. The results showed that inoculation methods had significant influence on both disease severity and mycotoxin accumulation in grains, and the relationship between them. UBFI method caused chronic FHB symptom characterized as slow progress of the pathogen downward from the inoculation site, which minimized the difference in disease severity of the NILs, but, unexpectedly, maximized the difference in DON content between them. The BBFI method usually caused an acute FHB symptom in susceptible lines characterized as premature spike death (PSD), which maximized the difference in disease severity, but minimized the difference in DON content in grains between resistant and susceptible lines. The BRII method occasionally caused acute FHB symptoms for susceptible lines and had relatively balanced characteristics of disease severity and DON content in grains. Therefore, two or more inoculation methods are recommended for precise and reliable evaluation of the overall resistance to FHB, including resistances to both disease spread within a spike and DON accumulation in grains.

Hydrogen sulphide alleviates Fusarium Head Blight in wheat seedlings.

Hydrogen sulphide (H2S), a crucial gas signal molecule, has been reported to be involved in various processes related to development and adversity responses in plants. However, the effects and regulatory mechanism of H2S in controlling Fusarium head blight (FHB) in wheat have not been clarified. In this study, we first reported that H2S released by low concentrations of sodium hydrosulphide (NaHS) could significantly alleviate the FHB symptoms caused by Fusarium graminearum (F. graminearum) in wheat. We also used coleoptile inoculation to investigate the related physiological and molecular mechanism. The results revealed that FHB resistance was strongly enhanced by the H2S released by NaHS, and 0.3 mM was confirmed as the optimal concentration. H2S treatment dramatically reduced the levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA) while enhancing the activities of antioxidant enzymes. Meanwhile, the relative expressions levels of defence-related genes, including PR1.1, PR2, PR3, and PR4, were all dramatically upregulated. Our results also showed that H2S was toxic to F. graminearum by inhibiting mycelial growth and spore germination. Taken together, the findings demonstrated the potential value of H2S in mitigating the adverse effects induced by F. graminearum and advanced the current knowledge regarding the molecular mechanisms in wheat.

First report of Head blight of wheat caused by Fusarium vorosii in Serbia.

The cosmopolitan species Fusarium graminearum Schwabe directly reduces yield, as well as grain quality of cereals, due to its ability to synthesize mycotoxins. Previously it was considered to be one species occurring on all continents. However, phylogenetic analysis employing the GCPSR method (Genealogical Concordance Phylogenetic Species Recognition) revealed the existence of 15 phylogenetic species within what is now recognised as the Fusarium graminearum Species Complex (FGSC) (Sarver et al. 2011). During 1996-2008, a MRIZP collection of FGSC isolates was established and isolates originating from wheat (5), maize (3) and barely (2) were selected for further study. Morphological features including the appearance of colonies and macroconidia (average size 38.5-53.1 × 4.6-5.4 µm, No 50) of all 10 isolates on PDA were consistent with descriptions of F. graminearum (O'Donnell et al. 2004, Leslie and Summerell 2006). Total DNA was isolated from mycelium removed from 7-day old colonies of single-spore isolates grown on PDA using the DNeasy Plant Mini Kit (Qiagen, Hilden). Further identification was based on amplification and sequencing of elongation factor TEF-1α, histone H3 and β-tubulin in both directions, with primers ef1/ef2, H3-1a/H3-1b and T1/T22, respectively (Jacobs et al. 2010). The sequences were deposited in NCBI under accession numbers MF974399 - MF974408 (TEF-1α), MG063783 - MG063792 (β-tubulin) and MF999139 - MF999148 (histone H3). Sequence analysis was performed using BLAST while genetic similarity was calculated using MEGA 6.0 software. Isolate 1339 originating from wheat (collected at the locality of Kikinda in 2006), shared 100% nucleotide identity with TEF-1α (DQ459745), histone H3 (DQ459728) and β-tubulin (DQ459643) of F. vorosii isolate NRRL37605 (Starkey et al. 2007). The remaining nine isolates were identified as F. graminearum as they shared 99% to 100% nucleotide similarity with F. graminearum NRRL 28439 (O'Donnell et al. 2004). Pathogenicity was tested using artificial inoculations of spikes during wheat flowering (Mesterhazy et al. 1999). Thirty classes were inoculated with each isolate, in three replicates. Inoculum was prepared from 7-day colonies on PDA, and 30 ml of a conidia suspension (1x105 conidia/ml) was used. Control plants were inoculated with sterile water. Three weeks after inoculation, typical Fusarium head blight symptoms were visible on inoculated plants, from which all 10 isolates were successfully reisolated. Control spikes remained symptomless. Disease severity was estimated on the 1-7 scale (Blandino et al. 2012). Average pathogenicity of the F. vorosii isolate 1339 was 1.9, and 2.4 -5.1 of F. graminearum isolates. Toxin production was determined using gas chromatography-tandem mass spectrometry. Kernels inoculated with the 10 isolates were ground and tested for the presence of deoxynivalenol (DON) and its acetyl derivatives 3ADON, 15ADON and NIV. F. vorosii isolate 1339 possessed the 15ADON chemotype, as well as eight F. graminearum isolates, while only one F. graminearum isolate was 3ADON chemotype. To date, F. vorosii has only been detected in Hungary on wheat (Toth et al. 2005) and Korea on barley, corn and rice (Lee et al. 2016). This is the first report of F. vorosii in Serbia, which is of great importance, because it indicates the spread of this toxigenic species. Further studies should be focused on determining the distribution, aggressiveness and toxicological profile of F. vorosii.

The Small GTPase FgRab1 Plays Indispensable Roles in the Vegetative Growth, Vesicle Fusion, Autophagy and Pathogenicity of Fusarium graminearum.

Rab GTPases are key regulators of membrane and intracellular vesicle transports. However, the biological functions of FgRab1 are still unclear in the devastating wheat pathogen Fusarium graminearum. In this study, we generated constitutively active (CA) and dominant-negative (DN) forms of FgRAB1 from the wild-type PH-1 background for functional analyses. Phenotypic analyses of these mutants showed that FgRab1 is important for vegetative growth, cell wall integrity and hyphal branching. Compared to the PH-1 strain, the number of spores produced by the Fgrab1DN strain was significantly reduced, with obviously abnormal conidial morphology. The number of septa in the conidia of the Fgrab1DN mutant was fewer than that observed in the PH-1 conidia. Fgrab1DN was dramatically reduced in its ability to cause Fusarium head blight symptoms on wheat heads. GFP-FgRab1 was observed to partly localize to the Golgi apparatus, endoplasmic reticulum and Spitzenkörper. Furthermore, we found that FgRab1 inactivation blocks not only the transport of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane but also the fusion of endocytic vesicles with their target membranes and general autophagy. In summary, our results indicate that FgRab1 plays vital roles in vegetative growth, conidiogenesis, pathogenicity, autophagy, vesicle fusion and trafficking in F. graminearum.

A Microbial Fermentation Mixture Reduces Fusarium Head Blight and Promotes Grain Weight but does not impact Septoria tritici blotch

Fusarium graminearum and Zymoseptoria tritici cause economically important diseases of wheat. F. graminearum is one of the primary causal agents of Fusarium head blight (FHB) and Z. tritici is the causal agent of Septoria tritici blotch (STB). Alternative control methods are required in the face of fungicide resistance and EU legislation which seek to cut pesticide use by 2030. Both fungal pathogens have been described as either hemibiotrophs or necrotrophs. A microbial fermentation-based product (MFP) was previously demonstrated to control the biotrophic pathogen powdery mildew, on wheat. Here we investigated if MFP would be effective against the non-biotrophic fungal pathogens of wheat, F. graminearum and Z. tritici. We assessed the impact of MFP on fungal growth, disease control and also evaluated the individual constituent parts of MFP. Antifungal activity towards both pathogens was found in vitro but MFP only significantly decreased disease symptoms of FHB in planta. In addition, MFP was found to improve the grain number and weight, of uninfected and F. graminearum infected wheat heads.