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Trichothecenes are sesquiterpenoid mycotoxins produced by fungi from the order Hypocreales, including members of the Fusarium genus that infect cereal grain crops. Different trichothecene-producing Fusarium species and strains have different trichothecene chemotypes belonging to the Type A and B class. These fungi cause a disease of small grain cereals, called Fusarium head blight, and their toxins contaminate host tissues. As potent inhibitors of eukaryotic protein synthesis, trichothecenes pose a health risk to human and animal consumers of infected cereal grains. In 2009, Foroud and Eudes published a review of trichothecenes in cereal grains for human consumption. As an update to this review, the work herein provides a comprehensive and multi-disciplinary review of the Fusarium trichothecenes covering topics in chemistry and biochemistry, pathogen biology, trichothecene toxicity, molecular mechanisms of resistance or detoxification, genetics of resistance and breeding strategies to reduce their contamination of wheat and barley.

Fusarium head blight (FHB) causes significant grain loss and contamination of grains with harmful mycotoxins, especially deoxynivalenol (DON). Fusarium resistance and DON accumulation have been extensively investigated in various cultivars; however, the level of DON-3-O-glucoside (D3G) has not been as carefully studied. In this study, we measured accumulated DON and D3G levels in CIMMYT wheat elite germplasm using an analytical method validated in-house. Co-occurring nivalenol (NIV) and ergostrerol (ERG) were also analyzed. LC-MS/MS and LC-UV analyses were applied to the 50 CIMMYT elite wheat lines. D3G showed rather high correlation with DON (r = 0.82), while FHB symptoms showed slight correlation with DON and D3G (r = 0.36 and 0.32, respectively). D3G/DON ratio varied widely from 8.1 to 37.7%, and the ratio was not related with FHB resistance in this dataset.

Fusarium head blight (FHB) is a devastating disease of wheat worldwide. In addition to reducing the yield of the crop, the causal pathogens also produce mycotoxins that can contaminate the grain. The development of resistant wheat varieties is one of the best ways to reduce the impact of FHB. To develop such varieties, breeders must expose germplasm lines to the pathogen in the field and assess the disease reaction. Phenotyping breeding materials for resistance to FHB is time-consuming, labor-intensive, and expensive when using conventional protocols. To develop a reliable and cost-effective high throughput phenotyping system for assessing FHB in the field, we focused on developing a method for processing color images of wheat spikes to accurately detect diseased areas using deep learning and image processing techniques. Color images of wheat spikes at the milk stage were collected in a shadow condition and processed to construct datasets, which were used to retrain a deep convolutional neural network model using transfer learning. Testing results showed that the model detected spikes very accurately in the images since the coefficient of determination for the number of spikes tallied by manual count and the model was 0.80. The model was assessed, and the mean average precision for the testing dataset was 0.9201. On the basis of the results for spike detection, a new color feature was applied to obtain the gray image of each spike and a modified region-growing algorithm was implemented to segment and detect the diseased areas of each spike. Results showed that the region growing algorithm performed better than the K-means and Otsu’s method in segmenting diseased areas. We demonstrated that deep learning techniques enable accurate detection of FHB in wheat based on color image analysis, and the proposed method can effectively detect spikes and diseased areas, which improves the efficiency of the FHB assessment in the field.

Fusarium Head Blight (FHB) is a major fungal disease in wheat caused by , inducing severe yield losses. Biological control agents (BCAs) can be an effective and sustainable approach to mitigate this phytopathogen. In this study, subsp. LMG19352 was used as a BCA to mitigate on wheat ears. Moreover, we aimed to assess the impact of BCA inoculation on non-target microorganisms present on the wheat spikes. Therefore, we evaluated shifts in the fungal and bacterial spicosphere microbiome (i) over time from flowering to mid-grain filling stage and (ii) across inoculations with and/or subsp. LMG19352. FHB symptoms were determined by multispectral imaging, and Illumina MiSeq was used to amplify 16S V3-V4 rDNA for bacteria and ITS2 for fungi, whereafter a correlation network analysis was performed. The biocontrol potential of subsp. LMG19352 against was confirmed, as FHB symptoms were significantly reduced. Based on the microbial abundances, subsp. LMG19352 compensated for shifts in the spicosphere microbiome community induced by FHB. These results were supported by a network analysis, revealing a more complex and stable microbiome in the presence of the BCA compared to the infected control. To our knowledge, this study is the first to reveal the potential of a bacterial BCA to temper shifts in the wheat microbiome caused by a phytopathogen, and thereby acting as a promising BCA.

TheFusarium species Fusarium graminearum and Fusarium culmorum, which are responsible for Fusarium head blight (FHB) disease, reduce world-wide cereal crop yield and, as a consequence of their mycotoxin production in cereal grain, impact on both human and animal health. Their study is greatly promoted by the availability of the genomic sequence of F. graminearum and transcriptomic resources for both F. graminearum and its cereal hosts. Functional genomic, proteomic and metabolomic studies, in combination with targeted mutagenesis or transgenic studies, are unravelling the complex mechanisms involved in Fusarium infection, penetration and colonization of host tissues, and host avoidance thereof. This review illuminates and integrates emerging knowledge regarding the molecular crosstalk between Fusarium and its small-grain cereal hosts. An understanding of the complexity of the host-pathogen interactions will be instrumental in designing new efficient strategies for the control of FHB disease.

Fusarium head blight (FHB) stands out as one of the most devastating wheat diseases and leads to significantly grain yield losses and quality reductions in epidemic years. Exploring quantitative trait loci (QTL) for FHB resistance is a critical step for developing new FHB-resistant varieties. We previously constructed a genetic map of unigenes (UG-Map) according to the physical positions using a set of recombinant-inbred lines (RILs) derived from the cross of ‘TN18 × LM6’ (TL-RILs). Here, the number of diseased spikelets (NDS) and relative disease index (RDI) for FHB resistance were investigated under four environments using TL-RILs, which were distributed across 13 chromosomes. A number of 36 candidate genes for NDS and RDI from of 19 stable QTLs were identified. The average number of candidate genes per QTL was 1.89, with 14 (73.7%), two (10.5%), and three (15.8%) QTLs including one, two, and 3–10 candidate genes, respectively. Among the 24 candidate genes annotated in the reference genome RefSeq v1.1, the homologous genes of seven candidate genes, including TraesCS4B02G227300 for QNds/Rdi-4BL-4553, TraesCS5B02G303200, TraesCS5B02G303300, TraesCS5B02G303700, TraesCS5B02G303800 and TraesCS5B02G304000 for QNds/Rdi-5BL-9509, and TraesCS7A02G568400 for QNds/Rdi-7AL-14499, were previously reported to be related to FHB resistance in wheat, barely or Brachypodium distachyon. These genes should be closely associated with FHB resistance in wheat. In addition, the homologous genes of five genes, including TraesCS1A02G037600LC for QNds-1AS-2225, TraesCS1D02G017800 and TraesCS1D02G017900 for QNds-1DS-527, TraesCS1D02G018000 for QRdi-1DS-575, and TraesCS4B02G227400 for QNds/Rdi-4BL-4553, were involved in plant defense responses against pathogens. These genes should be likely associated with FHB resistance in wheat.Key MessageWe identified a number of 36 candidate genes for FHB resistance from 19 stable QTLs. Of these, 12 candidate genes should be highly associated with FHB resistance in wheat.

Background Lignin is one of the main components of the cell wall and is directly associated with plant development and defence mechanisms in plants, especially in response to Fusarium graminearum (Fg) infection. Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) is the main regulator determining the efficiency of lignin synthesis and composition. Although it has been characterized in many plants, to date, the importance of the CCoAOMT family in wheat is not well understood. Results Here, a total of 21 wheat CCoAOMT genes ( TaCCoAOMT ) were identified through an in silico genome search method and they were classified into four groups based on phylogenetic analysis, with the members of the same group sharing similar gene structures and conserved motif compositions. Furthermore, the expression patterns and co-expression network in which TaCCoAOMT is involved were comprehensively investigated using 48 RNA-seq samples from Fg infected and mock samples of 4 wheat genotypes. Combined with qRT-PCR validation of 11 Fg -responsive TaCCoAOMT genes, potential candidates involved in the FHB response and their regulation modules were preliminarily suggested. Additionally, we investigated the genetic diversity and main haplotypes of these CCoAOMT genes in bread wheat and its relative populations based on resequencing data. Conclusions This study identified and characterized the CCoAOMT family in wheat, which not only provided potential targets for further functional analysis, but also contributed to uncovering the mechanism of lignin biosynthesis and its role in FHB tolerance in wheat and beyond.

The current study determined the levels of soil fungistasis against a soil-borne pathogen inoculum, Fusarium graminearum (Fg, a major causal agent of Fusarium Head Blight (FHB)), in 31 wheat fields by quantifying Fg growth after a 15-day incubation period using qPCR in autoclaved versus non-autoclaved soils. The results were used to define the six most Fg-resistant and the six most Fg-conducive soils. By using a metabarcoding approach, the diversity of the bacterial communities was significantly higher in Fg-resistant soils than in Fg-conducive soils. Microbial taxa potentially contributing to Fg-fungistasis of soil were selected if they were significantly more prevalent and/or abundant in Fg-resistant soils than in Fg-conducive soils. Some of these candidate indicators, e.g. Pseudomonas spp. and Bacillus spp., have been reported previously as effective biocontrol agents against plant pathogens. Correlation-based network analysis further showed that the members of the bacterial communities in Fg-resistant soils were more connected than in Fg-conducive soils. Moreover, network modules was found significantly correlated with certain edaphic abiotics factors (such as the soil manganese and nitrogen content) and Fg-fungistasis. Such observations may suggest and emphasize, although conceptual, the importance of synergistic rather than individual effects of network members, and the nutrient use efficiency in contributing to Fg-resistance of soils in wheat fields in France.

Methods used to assess climate change risk for crop diseases often assume that both host and pathogen are present. Consequently, model output may misrepresent future growing seasons, due to a failure to reflect likely change at the landscape- and farm-scale and its impact on disease risk. In this study, data defining the spatial coverage of crops in Scotland were combined with spatially coherent, probabilistic climate change data to project the future risk of Fusarium head blight (FHB) in wheat. Primary inoculum was initially treated as non-limiting, and a widely accepted crop-disease-climate model for FHB risk assessment was used to project the risk of disease occurrence in over 50,000 crop locations. Primary inoculum was then treated as limiting, and an atmospheric dispersion model was used to modify projections according to the risk of inoculum dispersal from overwintering refugia to crop locations. In both cases it was predicted that FHB hazard will decrease in Scotland over time. Consequences for the species composition of the FHB complex and therefore the associated mycotoxin hazard were considered. To guide adaptation strategies, we also considered agronomic scenarios regarding potential climate-change-driven shifts in agricultural practices and planting patterns, and their effects on disease risk. We found that opportunities exist for increased cultivation of crops that are potent sources of Fusarium or Gibberella inoculum, and for movement of crops away from coastal areas vulnerable to sea-level rise, with little additional risk of FHB. These projections, made by considering the temporal and spatial coincidence of host and pathogen species under various climate change scenarios, suggest that improved control of FHB might not be a high priority for future food security in Scotland.

Background Fusarium head blight (FHB), primarily caused by Fusarium graminearum, is a major threat to wheat production and food security worldwide . Breeding stably and durably resistant cultivars is the most effective approach for managing and controlling the disease. The success of FHB resistance breeding relies on identification of an effective resistant germplasm. We conducted a genome-wide association study (GWAS) using the high-density wheat 90 K single nucleotide polymorphism (SNP) assays to better understand the genetic basis of FHB resistance in natural population and identify associated molecular markers. Results The resistance to FHB fungal spread along the rachis (Type II resistance) was evaluated on 171 wheat cultivars in the 2016–2017 (abbr. as 2017) and 2017–2018 (abbr. as 2018) growing seasons. Using Illumina Infinum iSelect 90 K SNP genotyping data, a genome-wide association study (GWAS) identified 26 loci (88 marker-trait associations), which explained 6.65–14.18% of the phenotypic variances. The associated loci distributed across all chromosomes except 2D, 6A, 6D and 7D, with those on chromosomes 1B, 4A, 5D and 7A being detected in both years. New loci for Type II resistance were found on syntenic genomic regions of chromsome 4AL ( QFhb-4AL , 621.85–622.24 Mb) and chromosome 5DL ( QFhb-5DL , 546.09–547.27 Mb) which showed high collinearity in gene content and order. SNP markers wsnp_JD_c4438_5568170 and wsnp_CAP11_c209_198467 of 5D, reported previously linked to a soil-borne wheat mosaic virus (SBWMV) resistance gene, were also associated with FHB resistance in this study. Conclusion The syntenic FHB resistant loci and associated SNP markers identified in this study are valuable for FHB resistance breeding via marker-assisted selection.