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Trichothecenes are sesquiterpenoid toxins produced by diverse ascomycetes, including Fusarium. The trichothecene analog deoxynivalenol (DON) produced by the Fusarium head blight (FHB) pathogen Fusarium graminearum is a virulence factor on wheat and a major food and feed safety concern. In Fusarium, the trichothecene biosynthetic gene (TRI) cluster consists of 7–14 genes. Most TRI cluster genes are conserved and their specific roles in trichothecene biosynthesis have been determined. An exception is TRI14, which is not required for DON synthesis in vitro but is required for spread of F. graminearum in wheat heads. In the current study, gene expression analyses revealed that TRI14 was highly induced in infected wheat heads. We demonstrated that TRI14 was not only required for F. graminearum spread but also important for initial infection in wheat. Although a prior study did not detect DON in infected seeds, our analyses showed significantly less DON and fungal biomass in TRI14-mutant (designated ∆tri14)-inoculated heads than wild-type-inoculated heads. Gene expression comparison showed that the level of expression of TRI genes was similar in the wheat tissues infected with ∆tri14 or the wild type, indicating the reduced toxin levels caused by ∆tri14 may be due to less fungal growth. ∆tri14 also caused less lesion and grew less in wheat coleoptiles than the wild type. The growth of ∆tri14 in carboxymethylcellulose medium was more sensitive to hydrogen peroxide than the wild type. The data suggest that TRI14 plays a critical role in F. graminearum growth, and potentially protects the fungus from plant defense compounds. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a devastating fungal disease of hexaploid wheat (Triticum aestivum). Several genetic loci were previously identified that control FHB resistance in wheat, including Fhb1. Fhb7, a major QTL conferring resistance to FHB, controlling for mycotoxin deoxynivalenol (DON) production, has been introgressed into soft red winter wheat (SRWW). As an exotic QTL, Fhb7 is associated with linkage drag, affecting agronomic and end-use quality performance. This study outlines a breeding strategy for introducing and pyramiding Fhb7 into SRWW breeding populations that already possessed Fhb1 and harbored some additional disease-resistance genes. In addition to the Fhb1-Fhb7 pyramiding, we developed gene-based markers for both genes and examined them on 57 SRWW breeding lines. Our data showed that 15 out of 57 breeding lines possessed both Fhb1 and Fhb7 resistant alleles. Two years of phenotypic data from the inoculated and misted irrigation field showed that the combination of Fhb1-Fhb7 lowers mycotoxin DON accumulation in kernels, which provides protection for end-users and the milling industry. The Fhb gene-pyramided lines, with the additional regionally important disease resistance genes, produced in this breeding pipeline showed reasonable agronomic traits and can be used in crossing programs for the widespread introgression in elite wheat cultivars. [ABSTRACT FROM AUTHOR]

To develop an effective control strategy to defeat Fusarium head blight (FHB) disease, fungal isolates must be stored for long term. We then evaluated the survival, morphological and pathogenic stability of four pathogens stored as fungal suspensions (spores and hyphae) in sterile distilled water at 4°C after 96 months of preservation. It was observed that the tested 16 FHB isolates were viable after the different time points of storage (6, 12, 18, 24, 30, 36, 60, 90 and 96 months) with no morphological alteration and contamination by bacteria or other fungi. Survival was completely independent of the duration of storage. In addition, all isolates did not lose the infection ability, which could be an indicator of keeping their pathogenicity. All tested Fusarium isolates maintained the similar level of pathogenicity that they had prior to preservation. In general, there were no impacts on Fusarium radial growth, morphological characteristics and pathogenicity for all FHB isolates after 8 years of storage in cold water. These findings suggest that Castellani's method is an inexpensive and easy technique for long-term storage of F. culmorum, F. verticillioides, F. solani and F. equiseti, and can be especially utilized in the creation of stock collections of limited resources. [ABSTRACT FROM AUTHOR]

Pathogenicity assessment of Fusarium head blight (FHB) species is crucial for disease management in wheat because of the ineffective control measures of pathogens is due to variability among their populations. Ideally, two or more experiments should be conducted and the data should be compared to examine whether the ranking in pathognicity is constant. The objective of this study was to evaluate pathogenicity involved in artificial inoculations and in previous analyzed in vitro and field tests in 16 isolates of four FHB species. Two pathogenicity criteria: disease incidence (DI) of head inoculation and disease severity (DS) of floret inoculation were analyzed in a growth chamber on two Syrian durum and bread wheat cultivars with known in vitro and field reactions to FHB. There were significant differences in pathogenicity intra- and inter-species and in susceptibility between wheat cultivars, suggesting that assessment for disease resistance requires the use of aggressive isolates or a mixture of isolates representative of the FHB diversity. The four FHB species did not vary in their DI and DS because of the relative similarity in pathogenic level among the 16 fungal isolates. The values of DI and DS were significantly correlated with standardized area under disease progress curve values previously obtained in vitro and the values of DI under field conditions, indicating that growth chamber indices can predict pathogenicity at the earliest and latest wheat development stages during FHB infection. Artificial inoculation data confirmed in vitro and field results in which the bread cultivar was more resistant to FHB infection than durum, highlighting that the assessment of resistance level is repeatable and stable under several experimental conditions. The two tested wheat cultivars were shown to exhibit acceptable resistance levels to both initial fungal infection (Type I resistance) and disease spread (type II resistance). The present research shows that Syrian wheat plants could be new resistant donors with favorable agronomical characteristics in FHB-wheat breeding programs. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), also known as scab, is a devastating fungal disease of wheat that causes significant losses in grain yield and quality. Quantitative inheritance and cumbersome phenotyping make FHB resistance a challenging trait for direct selection in wheat breeding. Genomic selection to predict FHB resistance traits has shown promise in several studies. Here, we used univariate and multivariate genomic prediction models to evaluate the prediction accuracy (PA) for different FHB traits using 476 elite and advanced breeding lines developed by South Dakota State University hard winter wheat breeding program. These breeding lines were assessed for FHB disease index (DIS), and percentage of Fusarium damaged kernels (FDK) in three FHB nurseries in 2018, 2019, and 2020 (TP18, TP19, and TP20) and were evaluated as training populations (TP) for genomic prediction (GP) of FHB traits. We observed a moderate PA using univariate models for DIS (0.39 and 0.35) and FDK (0.35 and 0.37) using TP19 and TP20, respectively, while slightly higher PA was observed (0.41 for DIS and 0.38 for FDK) when TP19 and TP20 (TP19 + 20) were combined to leverage the advantage of a large training population. Although GP with multivariate approach including plant height and days to heading as covariates did not significantly improve PA for DIS and FDK over univariate models, PA for DON increased by 20% using DIS, FDK, DTH as covariates using multi-trait model in 2020. Finally, we used TP19, TP20, and TP19 + 20 in forward prediction to calculate genomic-estimated breeding values (GEBVs) for DIS and FDK in preliminary breeding lines at an early stage of the breeding program. We observed moderate PA of up to 0.59 for DIS and 0.54 for FDK, demonstrating the promise in genomic prediction for FHB resistance in earlier stages using advanced lines. Our results suggest GP for expensive FHB traits like DON and FDK can facilitate the rejection of highly susceptible materials at an early stage in a breeding program. [ABSTRACT FROM AUTHOR]

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Fusarium Head Blight of wheat, caused by the filamentous fungus Fusarium graminearum, leads to devastating global food shortages and economic losses. While many studies have addressed the responses of both wheat and F. graminearum during their interaction, the possibility of fungal chemotropic sensing enabling pathogenicity remains unexplored. Based on recent findings linking the pheromone-sensing G-protein-coupled receptor Ste2 to host-directed chemotropism in Fusarium oxysporum, we investigated the role of the Ste2 receptor and its downstream signaling pathways in mediating chemotropism of F. graminearum. Interestingly, a chemotropic response of growing hyphae towards catalytically active Triticum aestivum 'Roblin' cultivar secreted peroxidases was detected, with deletion of STE2 in F. graminearum leading to loss of the observed response. At the same time, deletion of STE2 significantly decreased infection on germinating wheat coleoptiles, highlighting an association between Ste2, chemotropism and infection by F. graminearum. Further characterization revealed that the peroxidase-directed chemotropism is associated with stimulation of the fungal cell wall integrity mitogen-activated protein kinase signaling cascade. Altogether, this study demonstrates conservation of Ste2-mediated chemotropism by Fusarium species, and its important role in mediating pathogenicity. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a severe disease of wheat (Triticum aestivum L.). Qfhb1 is the most important quantitative trait locus (QTL) for FHB resistance. We previously identified wheat gene WFhb1-1 (aka WFhb1-c1) as a candidate for FHB resistance gene. Here we report that WFhb1-1 has been cloned. The gene (GenBank # KU304333.1) consists of a single exon, encoding a putative membrane protein of 127 amino acids. WFhb1-1 protein produced in Pichia pastoris inhibits growth of both F. graminearum and P. pastoris in culture. Western Blotting with anti- WFhb1-1 antibody revealed a significant decrease (p < 0.01) in WFhb1-1 accumulation, 12 hours post Fusarium inoculation in non-Qfhb1-carrier wheat but not in Qfhb1-carrier wheat. Overexpressing WFhb1-1 in non-Qfhb1-carrier wheat led to a significant decrease (p < 0.01) in Fusarium-damaged rachis rate, Fusarium-diseased kernel rate and DON content in harvested kernels, while silencing WFhb1-1 in Qfhb1-carrier wheat resulted in a significant increase (p < 0.01) in FHB severity. Therefore, WFhb1-1 is an important FHB resistance gene with a potential antifungal function and probably a key functional component of Qfhb1 in wheat. A model regarding how WFhb1-1 functions in FHB resistance/susceptibility is hypothesized and discussed. [ABSTRACT FROM AUTHOR]

Background: This study was conducted to estimate Fusarium head blight (FHB) and crown rot (FCR) disease incidence on wheat and their interaction with cultural methods (cultivar types, planting time, seed rate, crop rotation, and fertilizer practices) that are used in wheat cropping system in the south of Iraq, Basra province. Results: The results showed that the mean average of FHB and FCR was 27.2% and 31%, respectively. This displays that very nearly one-third of wheat crop planted in those 14 fields were infected by both diseases but not very severely, except in two fields (D and HM), which were devastating, 54% and 71% and 41% and 52% for FHB and FCR, respectively. The highest level of incidence for both diseases was associated with the earlier and latest planting dates 28 Oct. and 10 Dec., while the lowest was with 1, 10, and 23 Nov. A 200 and 120 kg/ha were the highest and lowest seed rates used in this study. The selected wheat fields differed in their pre-crop rotations (legume, corn, sorghum, okra, and continuous cropping system of wheat) in a previous year. The amount of added fertilizers (urea, DAP, and NPK) to the studied fields was in a high variation. The seven wheat cultivars examined in this study showed different levels of susceptibility to both diseases. Conclusion: The results verified that most of the agricultural practices examined in this study were associated with positive correlation for FHB and FCR in the occurrence of disease incidence. Except the cultivar type and fertilizer application had unclear relationship with the incidence of both diseases. [ABSTRACT FROM AUTHOR]

Fusarium Head Blight (FHB) is the number one floral disease of cereals and poses a serious health hazard by contaminating grain with the harmful mycotoxin deoxynivalenol (DON). Fungi adapt to fluctuations in their environment, coordinating development and metabolism accordingly. G-protein coupled receptors (GPCRs) communicate changes in the environment to intracellular G-proteins that direct the appropriate biological response, suggesting that fungal GPCR signalling may be key to virulence. Here we describe the expansion of non-classical GPCRs in the FHB causing pathogen, Fusarium graminearum, and show that class X receptors are highly expressed during wheat infection. We identify class X receptors that are required for FHB disease on wheat, and show that the absence of a GPCR can cause an enhanced host response that restricts the progression of infection. Specific receptor sub-domains are required for virulence. These non-classical receptors physically interact with intracellular G-proteins and are therefore bona fide GPCRs. Disrupting a class X receptor is shown to dysregulate the transcriptional coordination of virulence traits during infection. This amounts to enhanced wheat defensive responses, including chitinase and plant cell wall biosynthesis, resulting in apoplastic and vascular occlusions that impede infection. Our results show that GPCR signalling is important to FHB disease establishment. [ABSTRACT FROM AUTHOR]

High occurrence of Fusarium poae (FP) and Fusarium langsethiae (FL) and their mycotoxins nivalenol (NIV) and T‐2/HT‐2 have been observed in Swiss oats. Early prediction of mycotoxin levels is important for farmers and the cereal industry to minimize the risk of contaminated food and feed. Therefore, climate chamber experiments were conducted to investigate the influence of different temperatures (10, 15, 20 °C) and durations (4, 8, 12 h) at 99% relative humidity (RH) on the infection of oats with FP and FL. In addition, to discover the most susceptible period of oats, artificial FL inoculations were conducted at different growth stages. Field experiments were performed to observe the dispersal of these fungal species within the field and to investigate the weather conditions that influence the dispersal. The climate chamber experiments revealed higher contamination with NIV and T‐2/HT‐2 in the 10 °C treatments and with a prolonged humidity duration of 12 h 99% RH. Inoculations of oat plants at early (DC 61) and mid (DC 65) anthesis, led to higher FL infection and T‐2/HT‐2 accumulation in the grains compared with treatments at earlier growth stages, which might be due to an increased susceptibility during anthesis. No indication for spore dispersal was observed in the field experiments. The results obtained, together with the cropping factors that influence infection and mycotoxin production, could be used as a first step in developing forecasting models to predict the contamination of oats with the mycotoxins NIV and T‐2/HT‐2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Dead biocontrol agent cells support growth of Fusarium graminearum in liquid culture. • Bipolar conidial germination and hyphal branching stimulated by dead antagonist cells. • Dead cells reduced live cell inhibition of bipolar conidial germination and branching. • Dead cells increased FHB severity, incidence and DON content of wheat grain. • Dead cells nullified disease reduction trend seen when treating with live cells alone. Abstract Microbially-based plant disease control products have achieved commercial market success, but the efficacy of biocontrol products is sometimes deemed inconsistent. Declines in product viability before or after application results in a mixture of non-viable and viable antagonist cells being present on infection courts. We hypothesized that these non-viable cells could provide a nutritive benefit to plant pathogen propagules and thereby reduce the efficacy and consistency of performance of a biocontrol product. We tested this hypothesis on the pathogen Fusarium graminearum , an important causal agent of Fusarium head blight (FHB) of wheat, and a yeast antagonist Papiliotrema flavescens (formerly Cryptococcus flavescens) strain OH 182.9 3C. When F. graminearum was grown in a liquid basal salts medium without carbon or nitrogen but supplemented with increasing levels of non-viable cells of strain OH 182.9 3C, the amount of pathogen biomass produced increased (P ≤ 0.05) with each sequentially higher level of non-viable cell amendment tested. Total conidial germination of F. graminearum on membranes was initially greatest in the control and least when conidia were combined with live cells of antagonist OH 182.9 3C. Though the presence of dead cells initially resulted in reduced conidial germination, the treatment increased bipolar germination of conidia after 6 h compared to the control (89% and 45%, respectively) (P ≤ 0.05, FPLSD). Treatment with a combination of dead and live cells supported more bipolar germination than live cells alone (51% and 29%, respectively). After 12 h, dead cells had a similar stimulating effect on the branching of germ tubes and negated the reduction in branching seen when treating with live cells alone. Scanning electron microscopy indicated that the presence of non-viable cells of P. flavescens OH 182.9 3C modified the ectotrophic growth of F. graminearum on wheat lemma tissues. In greenhouse experiments, live cells of P. flavescens tended to reduce FHB incidence, severity and the deoxynivalenol content of spring wheat grain compared to the control but treatment with live cells amended with dead cells increased all of these disease parameters compared to the live cells only treatment (P ≤ 0.05, FPLSD). Results indicate that non-viable antagonist cells present in a biocontrol cell treatment can reduce disease control efficacy or even cause the biocontrol treatment to support a net adverse effect on plant health. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) compromises the processing suitability and nutritional value of grain, and it causes significant crop losses. The aim of the study was to develop models for the classification of wheat (Triticum aestivum L.) kernels infected with fungi and healthy wheat kernels. Wheat kernels were classified with the use of Decision Tree, Rule-based, Bayes, Lazy, Meta and Function classifiers, as well as multilayer perceptron (MLP), radial basis function (RBF) and probabilistic neural networks (PNN). Twenty textures were selected from RGB, Lab, XYZ colour spaces each, for every wheat variety and each kernel side. Accuracy ranged from 82% for the dorsal side of kernels for Naive Bayes and IBk classifiers to 100% for the ventral side of kernels for IBk, FLDA and Naive Bayes classifiers. Classification accuracy was highest in the model based on texture attributes from Lab colour space. The final model of 20 attributes from Lab colour space was applied to a set of kernels from all wheat varieties, analysed on the ventral side. The accuracy of the classification model ranged from 94% to 98%, depending on the applied classifier. The models developed with the use of neural networks were characterised by overall classification accuracy of above 99% for MLP networks, above 96% for RBF networks and above 97% for PNN. The developed models indicate that analyses should be performed on the ventral side of kernels based on textures from Lab colour space. [ABSTRACT FROM AUTHOR]

Abstract Fusarium head blight (FHB) is a major cereal crop disease, caused most frequently by the fungus Fusarium graminearum. We have previously demonstrated that F. graminearum can utilize SA as sole source of carbon to grow. In this current study, we further characterized selected four fungal SA-responsive genes that are predicted to encode salicylic acid (SA)-degrading enzymes and we used a gene replacement approach to characterize them further. These included two genes predicted to encode a salicylate 1-monooxygenase, FGSG_03657 and FGSG_09063 , a catechol 1, 2-dioxygenase gene, FGSG_03667 , and a 2, 3-dihydroxybenzoic acid decarboxylase gene, FGSG_09061. For each gene, three independent gene replacement strains were assayed for their ability to degrade salicylic acid in liquid culture. Salicylate 1-monooxygenase FGSG_03657 and catechol 1, 2-dioxygenase FGSG_03667 were shown to be essential for SA degradation, while a loss of 2, 3-dihydroxybenzoic acid decarboxylase FGSG_09061 caused only a partial reduction of SA degradation and a loss of salicylate 1-monooxygenase FGSG_09063 had no effect when compared to wild type culture. Salicylate 1-monooxygenase FGSG_03657 and catechol 1, 2-dioxygenase FGSG_03667 were identified as the first two key enzyme steps of SA degradation via catechol in the β-ketoadipate pathway. Expression profiles for all four genes were also determined in liquid culture and in planta. Salicylate 1-monooxygenase FGSG_03657 and catechol 1, 2-dioxygenase FGSG_03667 were co-expressed and their expression was substrate dependent in liquid culture; however their expression was uncoupled in planta. Disruption of the gene for catechol 1, 2-dioxygenase FGSG_03667 was shown to have no effect on fungal virulence on wheat. Our results with 2, 3-dihydroxybenzoic acid decarboxylase FGSG_09061 raise the possibility of an alternate non-oxidative decarboxylation pathway for the conversion of SA to catechol via 2, 3-dihydrozybenzoic acid and for a connection between the oxidative and the non-oxidative decarboxylation pathways for SA conversion. Highlights • Identification of the salicylate 1-monooxygnease used by Fusarium graminearum to metabolise salicylic acid. • Identification of the catechol 1, 2-dioxygenase used by Fusarium graminearum to metabolise catechol. • Expression profile of four salicylic acid-induced genes in cultures treated with either salicylic acid or catechol. • Evidence that the metabolism of salicylic acid is not essential for pathogenicity of Fusarium graminearum on wheat. [ABSTRACT FROM AUTHOR]

Fusarium poae is one of the Fusarium species commonly detected in wheat kernels affected by Fusarium Head Blight. Fusarium poae produces a wide range of mycotoxins including nivalenol (NIV). The effect of temperature on colony growth and NIV production was investigated in vitro at 5–40 °C with 5 °C intervals. When the data were fit to a Beta equation (R 2  ≥ 0.97), the optimal temperature was estimated to be 24.7 °C for colony growth and 27.5 °C for NIV production. The effects of temperature on infection incidence, fungal biomass, and NIV contamination were investigated by inoculating potted durum wheat plants at full anthesis; inoculated heads were kept at 10–40 °C with 5 °C intervals for 3 days and then at ambient temperature until ripening. Temperature significantly affected the incidence of floret infection and fungal biomass (as indicated by DNA amount) in the affected heads but did not affect NIV content in the head tissue. Inoculation of potted plants with F. poae did not reduce yield. [ABSTRACT FROM AUTHOR]

Effective control of Fusarium-mycotoxin accumulation in grain affected by Fusarium head blight (FHB) (caused by Fusarium graminearum) begins with selecting moderately resistant wheat cultivars; however, little is known about how this resistance affects mycotoxin levels in the stem. A study was conducted from 2011 to 2014 in a mist-irrigated FHB nursery in Urbana, IL to determine whether the FHB resistance class of a cultivar (very susceptible, susceptible, moderately susceptible, and moderately resistant) affects the concentration of Fusarium mycotoxins in the stem. FHB incidence, FHB severity, and Fusarium-damaged kernel ratings were collected and used to calculate FHB index; incidence, severity, and kernel damage (ISK) index; and deoxynivalenol (DON), incidence, severity, and kernel damage (DISK) index. Grain was assayed for levels of DON, and the bottom 25 cm of plant stems was collected from each plot and assayed for DON, 3-acetyl-deoxynivalenol (3ADON), and 15-acetyl-deoxynivalenol (15ADON). Significant differences in DON concentration in the grain were detected among cultivars (P = 0.0001) and for the concentration of all DON (P = 0.003), 3ADON (P = 0.03), and 15ADON (P < 0.0001) in the stem. Significant differences among resistance classes were observed for FHB index value (P < 0.0001), ISK index (P = 0.006), and DISK index (P = 0.004). In all years of this study, the concentration of DON in the grain and the concentrations of all mycotoxins in the stem were consistently lower in the moderately resistant cultivars. All three indices were poor indicators of mycotoxin concentrations in the stem. Overall, the selection of a moderately resistant cultivar provides effective control of DON accumulation in the grain and mycotoxin accumulation in the stem. [ABSTRACT FROM AUTHOR]

The interaction between bread wheat (Triticum aestivum L.) plants and four filamentous species of the Fusarium genus (the causal agent of Fusarium head blight, FHB) was analyzed in an in vitro Petri-dish assay. Pathogenicity criteria as well as germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction were investigated in seeds and six-day-old seedlings showing a moderately level of quantitative resistance, after inoculations with 16 FHB isolates. AUDPCstandard did differentiate FHB isolates and the other two pathogenicity criteria did not. It was not possible to cluster the isolates based on their species origins because of similarity in pathogenic level among the 16 fungal isolates. Cultivar-specific pathogenicity has been detected. The values of disease incidence and disease severity involved in previous artificial head and floret inoculations showed significant correlation with AUDPCstandard: r=0.653** and r=0.559*, respectively. AUDPCstandard could be of potential use in evaluating the pathogenicity of FHB in adult wheat plants. [ABSTRACT FROM AUTHOR]

Abstract Fusarium head blight (FHB) is a destructive disease of small grain cereals with Fusarium graminearum as one of the most important causal agents. FHB not only can reduce yield and quality of grains, but also lead to accumulation of mycotoxins in grain, thereby threatening human and animal health. In this study, we observed that epoxiconazole exhibits strong inhibitory effects on both carbendazim-resistant and phenamacril-resistant isolates using mycelial growth inhibition assays. The artificially inoculated field trials further showed that epoxiconazole increased the control efficacy of FHB by being able to control carbendazim-resistant and phenamacril-resistant isolates. Epoxiconazole triggered DON production and Tri5 expression in vitro. However, in addition to increased FHB control efficacy and grain yield, decreased DON levels were measured in field trials after epoxiconazole applications. FHB control, grain yields and DON levels were significantly correlated with each other, suggesting that the visual disease rating can be used as an indicator of grain yields and mycotoxin contamination. Meanwhile, the frequency of carbendazim-resistant alleles in F. graminearum populations was dramatically reduced after epoxiconazole applications. In addition, epoxiconazole seed treatments had no effect on seed germination but phytotoxicity was apparent through growth inhibition of wheat seedlings. Overall, these findings of this study provide useful information for wheat protection programs against toxigenic fungi responsible for FHB and the consequent mycotoxin accumulation in grains. Graphical Abstract Unlabelled Image Highlights • Epoxiconazole exhibits strong activity and can be used to manage fungicide resistance in F. graminearum. • Epoxiconazole has a phytotoxic effect to wheat as seed treatment. • Epoxiconazole exhibits increased FHB control and grain yield and decreased mycotoxin levels. • FHB control, grain yield and mycotoxin levels affected by epoxiconazole were significantly correlated. • Epoxiconazole exhibits a greening effect during the late period of wheat. [ABSTRACT FROM AUTHOR]

Abstract The Fusarium graminearum species complex (FGSC), the causal agents of Fusarium head blight (FHB) in wheat, has the different geographically distributed species. Our previous study suggested that a DMI fungicide metconazole exhibits a strong fungicidal activity in mycelial growth of Chinese FHB pathogens and metconazole is currently a most effective compound of commercial fungicides for controlling FHB in China. In the current study, metconazole-resistant F. graminearum mutants were induced by chemical taming and their molecular and biological characteristics were determined. Compared to the corresponding parental strains, three mutation genotypes (two single mutations G443S and D243N, and a combined mutation E103Q&V157 L) were observed in the FgCYP51A of metconazole-resistant mutants. In addition to FgCYP51A mutation, all the mutants had no change on sequences of FgCYP51B and FgCYP51C and promotor sequences of FgCYP51 s, but expression patterns of FgCYP51 s were different. Compared to the corresponding parental strains, overexpression of FgCYP51A , FgCYP51B and FgCYP51C was observed in the mutant conferring D243N mutation, overexpression of FgCYP51A and FgCYP51B was observed in the mutant conferring E103Q&V157L mutations, and overexpression of FgCYP51A was observed in the mutant conferring G443S mutation. Biological fitness of the mutants conferring D243N mutation or E103Q&V157 L mutations significantly decreased in comparison to the corresponding parental strains, suggesting a fitness penalty. The mutants conferring G443S mutation had no change in biological fitness as compared with the parental strain, indicating that the G443S mutation may emerge in field resistant populations of F. graminearum in the future. In addition, a positive cross resistance between metconazole and other tested DMI fungicides was observed in the mutants conferring D243N mutation or E103Q&V157L mutations, but no cross resistance between metconazole and ipconazole or prochloraz was observed in the mutants conferring G443S mutation. Therefore, we concluded that the mutation genotype of FgCYP51A may cause the differences of biological fitness, cross-resistance and FgCYP51 s overexpression patterns. Such information will increase our understanding of resistance mechanism of F. graminearum to DMIs and could provide new reference data for the management of FHB. Graphical abstract Unlabelled Image Highlights • Three mutation genotypes of CYP51A were first reported in F. graminearum. • The mutants conferring D243N or E103Q&V157 L suffered a fitness penalty. • The mutants conferring G443S had no fitness penalty, showing a high resistant risk. • Cross resistance patterns differ in the mutants conferring different genotype. • Over expression of CYP51s differ in the mutants conferring different genotype. [ABSTRACT FROM AUTHOR]

Key message: Functional markers were developed based on the critical sequence deletion of TaHRC in the Fhb1 region and validated to be diagnostic in a worldwide wheat collection.Abstract: Wheat Fusarium head blight (FHB) is a devastating disease in wheat and barley worldwide. Growing FHB-resistant cultivars is an effective strategy to minimize FHB damage in wheat production. Fhb1 is a quantitative trait locus for FHB resistance with the largest effect on disease severity identified to date. With this study, we developed diagnostic DNA markers for Fhb1 by comparing the genomic sequences in Fhb1 region between near-isogenic lines contrasting in Fhb1 alleles and phenotypic effects of the markers. Two markers were developed based on a deletion mutation in an gene encoding a putative histidine-rich calcium-binding protein (TaHRC) and validated in different types of populations. Haplotype or sequence analyses of the two markers in the three sets of diversity panels demonstrated that they are diagnostic for Fhb1, and superior to all previously used markers in selection accuracy. They also have the advantages of low cost, easy assay, and are suitable for breeding programs with either high- or low-throughput marker laboratories. [ABSTRACT FROM AUTHOR]

Summary: The wheat head blight fungus Fusarium graminearum has two highly similar beta‐tubulin genes with overlapping functions during vegetative growth but only TUB1 is important for sexual reproduction. To better understand their functional divergence during ascosporogenesis, in this study we characterized the sequence elements important for stage‐specific functions of TUB1. Deletion of TUB1 blocked the late but not initial stages of perithecium formation. Perithecia formed by tub1 mutant had limited ascogenous hyphae and failed to develop asci. Silencing of TUB1 by MSUD also resulted in defects in ascospore formation. Interestingly, the 3′‐UTR of TUB1 was dispensable for growth but essential for its function during sexual reproduction. RIP mutations that specifically affected Tub1 functions during sexual reproduction also were identified in two ascospore progeny. Furthermore, site‐directed mutagenesis showed that whereas the non‐editable mutations at three A‐to‐I RNA editing sites had no effects, the N347D (not T362D or I368V) edited mutation affected ascospore development. In addition, the F167Y, but not E198K or F200Y, mutation in TUB1 conferred tolerance to carbendazim and caused a minor defect in sexual reproduction. Taken together, our data indicate TUB1 plays an essential role in ascosporogenesis and sexual‐specific functions of TUB1 require stage‐specific RNA processing and Tub1 expression. [ABSTRACT FROM AUTHOR]

Directional climate change can potentially cause a nested pattern of species occurrences as species move or go extinct. That is, species-poor communities may become a nested subset of species-rich communities. There is a precedent for understanding these patterns in the context of historical climate change but few researchers have studied these patterns in the context of recent changes to climate. Here we show the value of nestedness analyses for understanding plant community responses to reduced annual rainfall using data on seedling establishment in restored jarrah forest between the years of 1992 and 2010. Specifically, we recorded the annual seedling establishment of species assemblages in plots 15 months after restoration. We tested to what extent jarrah-forest assemblages that established in low (<1000 mm) rainfall years were nested within assemblages that established in years of moderate (1000–1200 mm) and high (>1200 mm) rainfall, and whether assemblages established following lower standard restoration practice were nested subsets of those following higher standard practices. We also tested how both types of nestedness patterns varied among trait groups defined by status (i.e., native or non-native), life-form and seed size. We found high support for species and trait assemblages that established in dry years being a nested subset of assemblages that established in years of moderate rainfall, and consistently low support for nestedness of high in low, and moderate in low, rainfall years. Nestedness patterns associated with restoration practice were as we predicted. Recruitment failure in low rainfall years was the most parsimonious explanation for nestedness patterns associated with rainfall (i.e., selective environmental tolerance). Nestedness patterns associated with restoration practice were explained by differential seed dispersal of species via topsoil and their tolerance of inferior restoration practice. Taken together, we demonstrate the application of the nestedness approach for understanding community responses to climate change in a restoration context. Indeed, generalising species responses to climate change by linking these to ecological processes and traits will help to meet the current global demand for forest restoration. Therefore, we anticipate our findings will interest practitioners working to restore the world’s forests under climate change. [ABSTRACT FROM AUTHOR]

The mycotoxin deoxynivalenol (DON) serves as a plant disease virulence factor for the fungi Fusarium graminearum and F. culmorum during the development of Fusarium head blight (FHB) disease on wheat. A wheat cytochrome P450 gene from the subfamily CYP72A, TaCYP72A, was cloned from wheat cultivar CM82036. TaCYP72A was located on chromosome 3A with homeologs present on 3B and 3D of the wheat genome. Using gene expression studies, we showed that TaCYP72A variants were activated in wheat spikelets as an early response to F. graminearum, and this activation was in response to the mycotoxic Fusarium virulence factor deoxynivalenol (DON). Virus induced gene silencing (VIGS) studies in wheat heads revealed that this gene family contributes to DON resistance. VIGS resulted in more DON-induced discoloration of spikelets, as compared to mock VIGS treatment. In addition to positively affecting DON resistance, TaCYP72A also had a positive effect on grain number. VIGS of TaCYP72A genes reduced grain number by more than 59%. Thus, we provide evidence that TaCYP72A contributes to host resistance to DON and conclude that this gene family warrants further assessment as positive contributors to both biotic stress resistance and grain development in wheat. [ABSTRACT FROM AUTHOR]

Tiger puffer ( Takifugu rubripes ) is a promising species for aquaculture production because of its high commercial value and limited supply. The growth performance and physiological metabolism of subadult tiger pufferfish reared in offshore sea cage aquaculture system (OSCS) and recirculating aquaculture system (RAS) were examined in this study. Results showed that the final body weight, specific growth rate and plasm growth hormone of the female tiger puffer reared in the OSCS were significantly higher than those of the fish reared in the RAS. The condition factor and gonadosomatic index of the female tiger puffer were significantly higher than those of the male tiger puffer cultured in the OSCS and the RAS. By contrast, the hepatosomatic index, viscerosomatic index and survival rate of the tiger puffer did not significantly change. Female fish reared in the OSCS with the significantly higher hepatic alkaline phosphatase activities and lower aspartate aminotransferase compared with those of fish reared in the RAS. The hepatic pyruvate kinase and Na + -K + ATPase activities of the female or male fish in the OSCS were significantly higher than those of the female or male fish in the RAS, respectively. The mRNA expression of somatic growth axis-related genes ( igf1 , igf2 , igf1r , igf2r , ghr1 , ghr2 ) of the female tiger puffer reared in the OSCS was significantly higher than that of the fish reared in the RAS. These results indicated that the growth performance and metabolic state of the female tiger puffer reared in the OSCS were better than those of the fish in the RAS, the OSCS was more suitable than the RAS for the short-term culture of subadult tiger puffer. These findings enhanced our understanding of the combined land (RAS) and sea (OSCS) alternative aquaculture model of tiger puffer. [ABSTRACT FROM AUTHOR]

Key message: The major QTL for FHB resistance from hexaploid wheat line PI 277012 was successfully introgressed into durum wheat and minor FHB resistance QTL were detected in local durum wheat cultivars. A combination of these QTL will enhance FHB resistance of durum wheat.Abstract: Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of durum wheat. To combat the disease, great efforts have been devoted to introgress FHB resistance from its related tetraploid and hexaploid wheat species into adapted durum cultivars. However, most of the quantitative trait loci (QTL) for FHB resistance existing in the introgression lines are not well characterized or validated. In this study, we aimed to identify and map FHB resistance QTL in a population consisting of 205 recombinant inbred lines from the cross between Joppa (a durum wheat cultivar) and 10Ae564 (a durum wheat introgression line with FHB resistance derived from the hexaploid wheat line PI 277012). One QTL (Qfhb.ndwp-2A) from Joppa and two QTL (Qfhb.ndwp-5A and Qfhb.ndwp-7A) from 10Ae564 were identified through phenotyping of the mapping population for FHB severity and DON content in greenhouse and field and genotyping with 90K wheat Infinium iSelect SNP arrays. Qfhb.ndwp-2A explained 14, 15, and 9% of the phenotypic variation, respectively, for FHB severity in two greenhouse experiments and for mean DON content across the two greenhouse environments. Qfhb.ndwp-5A explained 19, 10, and 7% of phenotypic variation, respectively, for FHB severity in one greenhouse experiment, mean FHB severity across two field experiments, and mean DON content across the two greenhouse experiments. Qfhb.ndwp-7A was only detected for FHB severity in the two greenhouse experiments, explaining 9 and 11% of the phenotypic variation, respectively. This study confirms the existence of minor QTL in North Dakota durum cultivars and the successful transfer of the major QTL from PI 277012 into durum wheat. [ABSTRACT FROM AUTHOR]

Bacillus thuringiensis israelensis biological larvicides represent a good approach to support vector borne diseases control programs targeting earlier aquatic larval stages to limit their adult mosquito spreading. BUPM98, a Tunisian B. thuringiensis israelensis strain, is highly active against Aedes aegypti larvae. For the production of BUPM98 bioinsecticide, an agricultural by-product medium consisting of gruel and soybean meal has been optimized. Optimization of the medium composition was performed with statistical methodology based on experimental designs. Accordingly, the optimum toxin production was 2375.36 ± 48.52 mg/L at the following conditions: K 2 HPO 4 : 60 mM, pH: 7.6 and soybean meal: 32 g/L, which led to an improvement of 30% compared to the starting conditions. The impact of water quality on the effectiveness of BUPM98 delta-endotoxins against Culex pipiens larvae was investigated. Indeed, under field conditions, the direct application of BUPM98 fermentation product in stagnant water pools reduced the immature density of C. pipiens larvae by more than 95% after 48 h of treatment. Prolonged residual action was observed until 14 days. In conclusion, BUPM98, a local strain of B. thuringiensis israelensis , is very promising bioinsecticide for mosquito population management in Tunisia. [ABSTRACT FROM AUTHOR]

Background: Fusarium head blight (FHB) of wheat in North America is caused mostly by the fungal pathogen Fusarium graminearum (Fg). Upon exposure to Fg, wheat initiates a series of cellular responses involving massive transcriptional reprogramming. In this study, we analyzed transcriptomics data of four wheat genotypes (Nyubai, Wuhan 1, HC374, and Shaw), at 2 and 4 days post inoculation (dpi) with Fg, using RNA-seq technology. Results: A total of 37,772 differentially expressed genes (DEGs) were identified, 28,961 from wheat and 8811 from the pathogen. The susceptible genotype Shaw exhibited the highest number of host and pathogen DEGs, including 2270 DEGs associating with FHB susceptibility. Protein serine/threonine kinases and LRR-RK were associated with susceptibility at 2 dpi, while several ethylene-responsive, WRKY, Myb, bZIP and NAC-domain containing transcription factors were associated with susceptibility at 4 dpi. In the three resistant genotypes, 220 DEGs were associated with resistance. Glutathione S-transferase (GST), membrane proteins and distinct LRR-RKs were associated with FHB resistance across the three genotypes. Genes with unique, high up-regulation by Fg in Wuhan 1 were mostly transiently expressed at 2 dpi, while many defense-associated genes were up-regulated at both 2 and 4 dpi in Nyubai; the majority of unique genes up-regulated in HC374 were detected at 4 dpi only. In the pathogen, most genes showed increased expression between 2 and 4 dpi in all genotypes, with stronger levels in the susceptible host; however two pectate lyases and a hydrolase were expressed higher at 2 dpi, and acetyltransferase activity was highly enriched at 4 dpi. Conclusions: There was an early up-regulation of LRR-RKs, different between susceptible and resistant genotypes; subsequently, distinct sets of genes associated with defense response were up-regulated. Differences in expression profiles among the resistant genotypes indicate genotype-specific defense mechanisms. This study also shows a greater resemblance in transcriptomics of HC374 to Nyubai, consistent with their sharing of two FHB resistance QTLs on 3BS and 5AS, compared to Wuhan 1 which carries one QTL on 2DL in common with HC374. [ABSTRACT FROM AUTHOR]

A general highly efficient solvent-free esterification of phytosterols with edible magnesium oxide and Span-60 emulsifier catalyst system has been developed. The edible emulsifier dramatically promotes the catalyzing activity of the metal oxide in the reaction. The loading of the magnesium oxide is as low as 0.1 wt% to phytosterols and far lower than the known ones. As demonstrated by the results of scanning electro-microscopy (SEM), the synergistic effect of emulsifier and magnesium oxide presumably results from elimination of nano-scale interfacial barrier between phytosterols and fatty acids and facilitation of mass transfer of reaction agents. The mild, environmentally benign, and highly effective nature of this catalytic transformation suggests its great potential applications. [ABSTRACT FROM AUTHOR]

The resistance to Fusarium head blight (FHB) in wheat is mainly via the restrain of fungal expansion through spike rachis (type II resistance). In order to unravel the resistance mechanisms, Brachypodium distachyon 21 (Bd21), a monocotyledonous model plant, was previously proved to interact with F. graminearum , while the disease development in spike still needs to be explored in detail. Herein, it is found that the fungal spores mainly germinate on pistil of Bd21, then the hyphae rapidly extend to the bottom of floret and enter spike rachis, similar with the infection progress in wheat. However, structural difference of spike rachis was found between Brachypodium and wheat. It was found that the spread of the fungus through the rachis node of inoculated spikelets is an important index for the evaluation of type II FHB resistance in Brachypodium under optimal conditions at 28 °C and 50%–70% humidity. To verify the feasibility of this strategy, the transcription factor TaTGA2 was overexpressed in Bd21, and transgenic plants were found to show improved resistance to F. graminearum in both spikes and detached leaves, which was further supported by the increased disease severity when silencing TaTGA2 in the wheat cultivar “Sumai 3” or in tilling “Kronos” mutants. Except for Bd21, another 49 Brachypodium germplasms were further screened for FHB resistance, and three moderately susceptible germplasms, namely, PI 317418, W6-39284, and PI 254868, feasible for transformation, were determined to be better hosts than Bd21 when evaluating heterologous genes that positively regulate FHB resistance. The present study also observed variations in the levels of FHB resistance between coleoptiles and spikes or transgenic plants and natural germplasms. [ABSTRACT FROM AUTHOR]

Fusarium Head Blight (FHB) has emerged in spring wheat production in Pacific Northwest during the last decade due to factors including climate changes, crop rotations, and tillage practices. A breeding population with 170 spring wheat lines was established and screened over a 2-year period in multiple locations for FHB incidence (INC), severity (SEV), and deposition of the mycotoxin, deoxynivalenol (DON). A genome-wide association study suggested that the detectable number of genetic loci and effects are limited for marker-assisted selection. In conjunction with the success of breeding on FHB resistance in other programs, genomic selection (GS) was suggested as a better option. To evaluate the prediction accuracy of GS in the current breeding population, we conducted a variety of validations by varying proportions of testing populations and cohorts based on both FHB resistance and market class, including soft white spring (SWS), hard white spring (HWS), and hard red spring (HRS). We found that INC had higher heritability, higher correlation across years and locations, and higher prediction accuracy than SEV and DON. Prediction accuracy varied among the scenarios that restricted the testing population to a certain cohort. For a small set of newly developed or introduced lines (<17), prediction accuracy will be about 60% if the lines have similar genetic relationships as those among the current 170-line training population. However, we expect a lower prediction accuracy if new lines are selected for a specific characteristic, such as FHB resistance or market class. With the exception of DON in the SWS lines, the current training population is capable of making reasonably accurate predictions for FHB-resistant lines in most of the major market classes. For SWS, adding more lines or further phenotyping is required to improve prediction accuracy. These results demonstrate the potential and challenges of GS, especially for developing FHB-resistant varieties in the SWS market class. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a destructive fungal disease in wheat worldwide. Efforts have been carried out to combat this disease, and the pore-forming toxin-like (PFT) gene at the quantitative trait locus (QTL) Fltbl was isolated and found to confer resistance to FHB in Sumai 3. In this study, we characterized PFT in 348 wheat accessions. Four haplotypes of PFT were identified. The wild haplotype of PFT had higher resistance than other haplotypes and explained 13.8% of phenotypic variation in FHB resistance by association analysis. PFT was highly expressed during early flowering and increased after Fusarium grartiinearum treatment in Sumai 3. Analysis of the 5' flanking sequence of PFT predicted that the cis elements of the PFT promoter were related to hormones and biological defense responses. However, PFT existed not only in the FHB-resistant accessions but also in some susceptible accessions. These results suggested that FHB resistance in a diverse range of wheat genotypes is partially conditioned by PFT. The profiling of FHB resistance and the PFT locus in this large collection of wheat germplasm may prove helpful for incorporating FHB resistance into wheat breeding programs, although more work is needed to reveal the exact role of the QTL Fhbl in conferring resistance to fungal spread. [ABSTRACT FROM AUTHOR]

Key message: The dwarfing gene Rht24 on chromosome 6A acts in the wheat population ‘Solitär × Bussard’, considerably reducing plant height without increasing Fusarium head blight severity and delaying heading stage.Abstract: The introduction of the Reduced height (Rht)-B1 and Rht-D1 semi-dwarfing genes led to remarkable increases in wheat yields during the Green Revolution. However, their utilization also brings about some unwanted characteristics, including the increased susceptibility to Fusarium head blight. Thus, Rht loci that hold the potential to reduce plant height in wheat without concomitantly increasing Fusarium head blight (FHB) susceptibility are urgently required. The biparental population ‘Solitär × Bussard’ fixed for the Rht-1 wild-type alleles, but segregating for the recently described gibberellic acid (GA)-sensitive Rht24 gene, was analyzed to identify quantitative trait loci (QTL) for FHB severity, plant height, and heading date and to evaluate the effect of the Rht24 locus on these traits. The most prominent QTL was Rht24 on chromosome 6A explaining 51% of genotypic variation for plant height and exerting an additive effect of − 4.80 cm. For FHB severity three QTL were detected, whereas five and six QTL were found for plant height and heading date, respectively. No FHB resistance QTL was co-localized with QTL for plant height. Unlike the Rht-1 semi-dwarfing alleles, Rht24b did not significantly affect FHB severity. This demonstrates that the choice of semi-dwarfing genes used in plant breeding programs is of utmost consideration where resistance to FHB is an important breeding target. [ABSTRACT FROM AUTHOR]

Management of Fusarium graminearum-associated mycotoxins in wheat grain has been extensively evaluated, but little is known about management of mycotoxins in straw. Two research trials were conducted at four locations from 2011 to 2014. The objective of the first trial was to determine the efficacy of fungicides, and the objective of the second trial was to evaluate the use of integrated disease management strategies, for the control of Fusarium head blight (FHB) and reducing the concentration of the Fusarium mycotoxins deoxynivalenol, 3-acetyl-deoxynivalenol, and 15-acetyl-deoxynivalenol in straw. In the first trial, it was determined that demethylation inhibitor (DM1) fungicides did not offer significant (P ≤ 0.05) reductions of mycotoxin concentrations in the straw compared with a no-fungicide control treatment, but significant (P ≤ 0.05) reductions in mycotoxin concentration were observed in the control when compared with treatments with the application of quinone outside inhibitor (Qol)-containing fungicides. In the second trial, mycotoxin concentrations in the straw were significantly (P ≤ 0.05) reduced in the moderately resistant cultivar compared with the susceptible cultivar, but were not affected by the use of a fungicide. The practices typically used to manage Fusarium mycotoxins in wheat grain, especially the selection of resistant cultivars and not using a Qol fungicide, may be an effective means to reduce mycotoxin concentrations in the straw. [ABSTRACT FROM AUTHOR]

K20 is a novel amphiphilic aminoglycoside capable of inhibiting many fungal species. K20's capabilities to inhibit Fusarium graminearum the causal agent wheat Fusarium head blight (FHB) and to this disease were examined. K20 inhibited the growth of F. graminearum (minimum inhibitory concentrations, 7.8–15.6 mg L −1 ) and exhibited synergistic activity when combined with triazole and strobilurin fungicides. Application of K20 up to 720 mg L −1 to wheat heads in the greenhouse showed no phytotoxic effects. Spraying wheat heads in the greenhouse with K20 alone at 360 mg L −1 lowered FHB severity below controls while combining K20 with half–label rates of Headline (pyraclostrobin) improved its disease control efficacy. In field trials, spraying K20 at 180 mg L −1 and 360 mg L −1 combined with half-label rates of Headline, Proline 480 SC (prothioconazole), Prosaro 421 SC (prothioconazole + tebuconazole), and Caramba (metconazole) reduced FHB indices synergistically. In addition, the K20 plus Proline 480 SC combination reduced levels of the mycotoxin deoxinivalenol by 75 % compared to the control. These data suggest that K20 may be useful as a fungicide against plant diseases such as FHB particularly when combined with commercial fungicides applied at below recommended rates. [ABSTRACT FROM AUTHOR]

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Comparison of two storage techniques (Castellani's method and freezing) was carried out for 16 isolates of four Fusarium head blight species and 54 isolates of Cochliobolus sativus causing spot blotch and common root rot. The viability, purity and morphological stability of cultures were verified for a one year period. Duplicate isolates were stored as a fungal suspension in sterile distilled water at 4 °C, and fungal cultures by freezing at –16 °C. The viability of 70 isolates was 100% for the two storage methods. Morphological alternations and pathogenic contaminations were not detected. All isolates were able to retain viability, purity and morphological stability by the two tested storage methods for over 12 months. Castellani's method and freezing were found to be safe, easy, inexpensive and reliable. [ABSTRACT FROM AUTHOR]

Aggressiveness variation among 16 isolates of four Fusarium species (F. culmorum, F. solani, F. verticillioides and F. equiseti) causing Fusarium head blight (FHB) was studied in vitro. Evaluation of three aggressiveness criteria involved in a Petri-dish test: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction was carried out on the barley cultivar Arabi Aswad. Results showed differences between barley plants inoculated with FHB isolates and control for the three tested aggressiveness criteria. Regarding AUDPCstandard and Petri-dish aggressiveness index which is calculated from the mean value of three aggressiveness criteria, within and among variation was detected. Intra- and inter-species variability was not distinguished for the other two aggressiveness criteria. However, pathogenic level observed among 16 isolates can not be differentiated within the four FHB species. Significant correlation was detected only between AUDPCstandard and Petri-dish aggressiveness index. The results were comparable with those previously obtained using the same fungal isolates on wheat cultivar in vitro. It seems that FHB isolates recovered from wheat spikes and tested on wheat plants showed a similar range of aggressiveness on a barley cultivar, Arabi Aswad. [ABSTRACT FROM AUTHOR]

Fusarium Head Blight (FHB) is a destructive disease of small grain cereals and a major food safety concern. Epidemics result in substantial yield losses, reduction in crop quality, and contamination of grains with trichothecenes and other mycotoxins. A number of different fusaria can cause FHB, and there are significant regional differences in the occurrence and prevalence of FHB pathogen species and their associated mycotoxins. Information on FHB pathogen and mycotoxin diversity in Mexico has been extremely limited, but is needed to improve disease and mycotoxin control efforts. To address this, we used a combination of DNA sequence-based methods and in-vitro toxin analyses to characterize FHB isolates collected from symptomatic wheat in Mexico during the 2013 and 2014 growing seasons. Among 116 Fusarium isolates, we identified five species complexes including nine named Fusarium species and 30 isolates representing unnamed or potentially novel species. Significant regional differences (P < 0.001) in pathogen composition were observed, with F . boothii accounting for >90% of isolates from the Mixteca region in southern Mexico, whereas F . avenaceum and related members of the F . tricinctum species complex (FTSC) accounted for nearly 75% of isolates from the Highlands region in Central Mexico. F. graminearum , which is the dominant FHB pathogen in other parts of North America, was not present among the isolates from Mexico. F . boothii isolates had the 15-acetyldeoxynivalenol toxin type, and some of the minor FHB species produced trichothecenes, such as nivalenol, T-2 toxin and diacetoxyscirpenol. None of the FTSC isolates tested was able to produce trichothecenes, but many produced chlamydosporol and enniatin B. [ABSTRACT FROM AUTHOR]

Summary: The Qfhs.ifa‐5A allele, contributing to enhanced Fusarium head blight resistance in wheat, resides in a low‐recombinogenic region of chromosome 5A close to the centromere. A near‐isogenic RIL population segregating for the Qfhs.ifa‐5A resistance allele was developed and among 3650 lines as few as four recombined within the pericentromeric C‐5AS1‐0.40 bin, yielding only a single recombination point. Genetic mapping of the pericentromeric region using a recombination‐dependent approach was thus not successful. To facilitate fine‐mapping the physically large Qfhs.ifa‐5A interval, two gamma‐irradiated deletion panels were generated: (i) seeds of line NIL3 carrying the Qfhs.ifa‐5A resistance allele in an otherwise susceptible background were irradiated and plants thereof were selfed to obtain deletions in homozygous state and (ii) a radiation hybrid panel was produced using irradiated pollen of the wheat line Chinese Spring (CS) for pollinating the CS‐nullisomic5Atetrasomic5B. In total, 5157 radiation selfing and 276 radiation hybrid plants were screened for deletions on 5AS and plants containing deletions were analysed using 102 5AS‐specific markers. Combining genotypic information of both panels yielded an 817‐fold map improvement (cR/cM) for the centromeric bin and was 389‐fold increased across the Qfhs.ifa‐5A interval compared to the genetic map, with an average map resolution of 0.77 Mb/cR. We successfully proved that the RH mapping technique can effectively resolve marker order in low‐recombining regions, including pericentromeric intervals, and simultaneously allow developing an in vivo panel of sister lines differing for induced deletions across the Qfhs.ifa‐5A interval that can be used for phenotyping. [ABSTRACT FROM AUTHOR]

Abstract: Fusarium head blight (FHB) caused by Fusarium graminearum species complex is a devastating disease that causes extensive yield and quality losses to wheat around the world. Fungicide application and breeding for resistance are among the most important tools to counteract FHB. Biological control is an additional tool that can be used as part of an integrated management of FHB. Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B were selected by their potential to control FHB and deoxynivalenol production. The aim of this work was to test the tolerance of these biocontrol agents to triazole‐based fungicides such as prothioconazole, tebuconazole and metconazole. Bacterial growth was evaluated in Petri dishes using the spread plating technique containing the different fungicides. Bacillus velezensisRC 218 and Streptomyces sp. RC 87B showed better tolerance to fungicides than Brevibacillus sp. RC 263. Complete growth inhibition was observed at concentrations of 20 μg ml−1 for metconazole, 40 μg ml−1 for tebuconazole and 80 μg ml−1 for prothioconazole. The results obtained indicate the possibility of using these biocontrol agents in combination with fungicides as part of an integrated management to control FHB of wheat. Significance and Impact of the Study: This study evaluates the possibility to use biocontrol agents (Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B) in combination with triazole‐based fungicides to control Fusarium head blight in wheat. The evaluation of biocontrol agents′ growth under in vitro conditions was carried out in Petri dishes containing either prothioconazole, tebuconazole or metconazole. Viability studies demonstrated that B. velezensisRC 218 and Streptomyces sp. RC 87B were more tolerant to the fungicides evaluated. Results obtained reflect the possibility to use fungicides at low doses combined with biocontrol agents. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a destructive wheat disease present throughout the world, and host resistance is an effective and economical strategy used to control FHB. Lack of adequate resistance resource is still a main bottleneck for FHB genetics and wheat breeding research. The synthetic-derived bread wheat line C615, which does not carry the Fhb1 gene, is a promising source of FHB resistance for breeding. A population of 198 recombinant inbred lines (RILs) produced by crossing C615 with the susceptible cultivar Yangmai 13 was evaluated for FHB response using point and spray inoculations. As the disease phenotype is frequently complicated by other agronomic traits, we used both traditional and multivariate conditional QTL mapping approaches to investigate the genetic relationships (at the individual QTL level) between FHB resistance and plant height (PH), spike compactness (SC), and days to flowering (FD). A linkage map was constructed from 3,901 polymorphic SNP markers, which covered 2,549.2 cM. Traditional and conditional QTL mapping analyses found 13 and 22 QTL for FHB, respectively; 10 were identified by both methods. Among these 10, three QTL from C615 were detected in multiple years; these QTL were located on chromosomes 2AL, 2DS, and 2DL. Conditional QTL mapping analysis indicated that, at the QTL level, SC strongly influenced FHB in point inoculation; whereas PH and SC contributed more to FHB than did FD in spray inoculation. The three stable QTL (QFhbs-jaas.2AL, QFhbpjaas. 2DS, and QFhbp-jaas.2DL) for FHB were partly affected by or were independent of the three agronomic traits. The QTL detected in this study improve our understanding of the genetic relationships between FHB response and related traits at the QTL level and provide useful information for marker-assisted selection for the improvement of FHB resistance in breeding. [ABSTRACT FROM AUTHOR]

Fusarium culmorum (W.G. Smith) leads to economic losses in wheat and barley fields in Turkey as well as in many countries worldwide as a result of head blight and crown rot diseases. In this study, in vitro growth capacity of 33 F. culmorum isolates originating from Turkey and the relationship between phenotypic and genetic characteristics obtained based on similarities of FcMgv1, FcStuA and FcVeA genes were investigated. Linear growth rate values were recorded at 4th and 7th days of incubation. The mean linear growth rate values ranged from 7.58±1.06 to 14.7±1.26mm/day. The isolates F2 and 18F with relatively high linear growth values and the isolates 12F and F19 with relatively low linear growth values, were selected to be used in multiloci based genotyping analysis. FcMgv1, FcStuA and FcVeA genes were amplified in lengths of 1733, 2001 and 1898bp, respectively. The genes were sequenced, aligned and then subjected to BLASTn and to maximum likelihood topology analysis. Nucleotide sequence of each gene showed maximum hit with associated genes deposited in NCBI with 0.0-0.0 Evalues and 1188 to 3256 bit scores. Alignment analysis resulted in at least 89% bootstrap support. Moreover, isolates with similar linear growth rates were co-clustered in phylogenetic analysis. The findings obtained in this study showed that the three genes which are essential for fungal survival could be used in genetic characterization analysis and in revealing the associations between their genetic and phenotypic characteristics. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a devastating disease of wheat because of direct detrimental effects on grain yield, quality, and marketability and production of mycotoxins (e.g. deoxynivalenol or DON). Conditions most favourable for the development of FHB are high humidity, frequent rainfall and relatively warm night temperatures at heading, especially in regions where host crop residues are present. These risk factors have resulted in a significant westward expansion of FHB in the Canadian prairies, while favouring continued development in Ontario, Quebec and the Maritimes. Since cultivar selection is a key integrated pest management (IPM) strategy, a systems approach that couples genetic resistance with management tactics is required. Thus, successful FHB mitigation is an ideal case study in Genotype (G) × Environment (E) × Management (M) interactions where more resistant cultivars (G) are grown in at-risk regions (E), and unique approaches to management (M) for sustainable wheat production are required. Since no cultivar is completely resistant to FHB, greater attention to management strategies is needed. The over-arching principle for FHB management is the manipulation of agronomic factors that facilitate completion of critical crop developmental phases, such as flowering, while doing so rapidly and uniformly, as a consequence of early sowing and increased seeding rates. These strategies and the adoption of practices involving proper fungicide selection, and optimal application timings and methods will lead to improved yield stability and quality in high-risk environments. This paper explores the potential synergies that exist for FHB mitigation when appropriate genetics are combined with an array of key agronomic strategies. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), a devastating disease that affects wheat, is caused by a complex of Fusarium species. The overall impact of Fusarium spp. in wheat production arises through the combination of FHB and mycotoxin infection of the grain harvested from infected wheat spikes. Spike infection occurs during opening of flowers and is favoured by high humidity or wet weather accompanied with warm temperatures. Available possibilities for controlling FHB include the use of cultural practices, fungicides and biological approaches. Three cultural practices are expected to be of prime importance in controlling FHB and the production of mycotoxins: soil preparation method (deep tillage), the choice of the preceding crop in the rotation and the selection of appropriate cultivar. [ABSTRACT FROM AUTHOR]

Abstract: Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host‐induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double‐stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi‐mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Key message: Predictabilities for wheat hybrids less related to the estimation set were improved by shifting from single- to multiple-trait genomic prediction of Fusarium head blight severity.Abstract: Breeding for improved Fusarium head blight resistance (FHBr) of wheat is a very laborious and expensive task. FHBr complexity is mainly due to its highly polygenic nature and because FHB severity (FHBs) is greatly influenced by the environment. Associated traits plant height and heading date may provide additional information related to FHBr, but this is ignored in single-trait genomic prediction (STGP). The aim of our study was to explore the benefits in predictabilities of multiple-trait genomic prediction (MTGP) over STGP of target trait FHBs in a population of 1604 wheat hybrids using information on 17,372 single nucleotide polymorphism markers along with indicator traits plant height and heading date. The additive inheritance of FHBs allowed accurate hybrid performance predictions using information on general combining abilities or average performance of both parents without the need of markers. Information on molecular markers and indicator trait(s) improved FHBs predictabilities for hybrids less related to the estimation set. Indicator traits must be observed on the predicted individuals to benefit from MTGP. Magnitudes of genetic and phenotypic correlations along with improvements in predictabilities made plant height a better indicator trait for FHBs than heading date. Thus, MTGP having only plant height as indicator trait already maximized FHBs predictabilities. Provided a good indicator trait was available, MTGP could reduce the impacts of genotype environment × interaction on STGP for hybrids less related to the estimation set. [ABSTRACT FROM AUTHOR]

Summary: The ascomycete fungal pathogen Fusarium graminearum causes the globally important Fusarium head blight (FHB) disease on cereal hosts, such as wheat and barley. In addition to reducing grain yield, infection by this pathogen causes major quality losses. In particular, the contamination of food and feed with the F. graminearum trichothecene toxin deoxynivalenol (DON) can have many adverse short‐ and long‐term effects on human and animal health. During the last decade, the interaction between F. graminearum and both cereal and model hosts has been extensively studied through transcriptomic analyses. In this review, we present an overview of how such analyses have advanced our understanding of this economically important plant–microbe interaction. From a host point of view, the transcriptomes of FHB‐resistant and FHB‐susceptible cereal genotypes, including near‐isogenic lines (NILs) that differ by the presence or absence of quantitative trait loci (QTLs), have been studied to understand the mechanisms of disease resistance afforded by such QTLs. Transcriptomic analyses employed to dissect host responses to DON have facilitated the identification of the genes involved in toxin detoxification and disease resistance. From the pathogen point of view, the transcriptome of F. graminearum during pathogenic vs. saprophytic growth, or when infecting different cereal hosts or different tissues of the same host, have been studied. In addition, comparative transcriptomic analyses of F. graminearum knock‐out mutants with altered virulence have provided new insights into pathogenicity‐related processes. The F. graminearum transcriptomic data generated over the years are now being exploited to build a systems level understanding of the biology of this pathogen, with an ultimate aim of developing effective and sustainable disease prevention strategies. [ABSTRACT FROM AUTHOR]

Summary: Reactive oxygen species (ROS) are associated with various developmental processes and host–pathogen interactions in pathogenic fungi. Peroxidases are a group of ROS‐detoxifying enzymes that are involved in the oxidative stress response and in a variety of physiological processes. In this study, we performed a genome‐wide functional characterization of putative peroxidase genes in Fusarium graminearum, a head blight pathogen of cereal crops. We identified 31 putative peroxidase genes and generated deletion mutants for these genes. Twenty‐six of the deletion mutants showed developmental phenotypes indistinguishable from that of the wild‐type, and five deletion mutants exhibited phenotypic changes in at least one phenotypic category. Four deletion mutants, fca6, fca7, fpx1 and fpx15, showed increased sensitivity to extracellular H2O2. Deletion mutants of FCA7 also exhibited reduced virulence and increased trichothecene production compared with those of the wild‐type strain, suggesting that Fca7 may play an important role in the host–pathogen interaction in F. graminearum. To identify the transcription factors (TFs) regulating FCA6, FCA7, FPX1 and FPX15 in response to oxidative stress, we screened an F. graminearum TF mutant library for growth in the presence of H2O2 and found that multiple TFs co‐regulated the expression of FCA7 under oxidative stress conditions. These results demonstrate that a complex network of transcriptional regulators of antioxidant genes is involved in oxidative stress responses in this fungus. Moreover, our study provides insights into the roles of peroxidases in developmental processes and host–pathogen interactions in plant‐pathogenic fungi. [ABSTRACT FROM AUTHOR]

Summary: Fusarium culmorum is a soil‐borne fungal pathogen which causes foot and root rot and Fusarium head blight on small‐grain cereals, in particular wheat and barley. It causes significant yield and quality losses and results in the contamination of kernels with type B trichothecene mycotoxins. Our knowledge of the pathogenicity factors of this fungus is still limited. A transposon tagging approach based on the mimp1/impala double‐component system has allowed us to select a mutant altered in multiple metabolic and morphological processes, trichothecene production and virulence. The flanking regions of mimp1 were used to seek homologies in the F. culmorum genome, and revealed that mimp1 had reinserted within the last exon of a gene encoding a hypothetical protein of 318 amino acids which contains a ROGDI‐like leucine zipper domain, supposedly playing a protein–protein interaction or regulatory role. By functional complementation and bioinformatic analysis, we characterized the gene as the yeast Rav2 homologue, confirming the high level of divergence in multicellular fungi. Deletion of FcRav2 or its orthologous gene in F. graminearum highlighted its ability to influence a number of functions, including virulence, trichothecene type B biosynthesis, resistance to azoles and resistance to osmotic and oxidative stress. Our results indicate that the FcRav2 protein (and possibly the RAVE complex as a whole) may become a suitable target for new antifungal drug development or the plant‐mediated resistance response in filamentous fungi of agricultural interest. [ABSTRACT FROM AUTHOR]