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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]

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]

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]

The selection for Fusarium head blight (FHB) resistance is a bit difficult in breeding programs due to the complex inheritance of the resistance genes and the climatic effect on disease vigorous and expression. The present study was performed to assess microsatellite markers related to the resistance against FHB and examine the efficiency of these microsatellite markers while choosing for the resistance genes in all populations derived from a resistant parent. Both recombinant inbred lines (RIL) of Annong1124 (02P67/Aizao87//Yangmai158) and segregating lines of Zhoumai–27 × Shengxuani–6 were evaluated for their resistance to FHB by inoculating with Fusarium graminearum in the greenhouse as well as in the field. A total of 19 and 15 microsatellite markers from the chromosomes 3BS and 5A, respectively, were applied to RIL and each population of Zhoumai–27 (F 2 , F 3 ). On the other hand, seven microsatellite markers from chromosomes 4B were applied to F 2 and F 3 segregating populations but there was a general lack of marker polymorphism on 4B for the employed parents of RIL. The most significant SSR markers were detected on the chromosome 3B and 5A explaining 7.30% and 21.74% of phenotypic variation, respectively, for the resistance in the RIL. The best quantitative trait loci (QTL) were detected on 4B for F 2 and F 3 populations with marker interval of WMC238-GWM66 with the LOD score 40.49 and 41.52, respectively. The phenotypic variations for F 2 and F 3 on chromosome 5A were detected with the account of 0.49 and 2.33 (BARC197-GWM179), respectively. The additive effects on chromosomes 3BS, 4B, and 5A were clearly higher in F3 population as compared to the F 2 population. SSR markers on the chromosome 3BS in addition to SSR markers on 4B and 5A have the potential for improving the wheat cultivars with improved FHB resistance through the use of marker-assisted selection. [ABSTRACT FROM AUTHOR]

Fusarium head blight of wheat is one of the most serious and hazardous crop diseases worldwide. Here, a transcriptomic investigation of Fusarium graminearum reveals a new model for symptomless and symptomatic wheat infection. The predicted metabolic state and secretome of F. graminearum were distinct within symptomless and symptomatic wheat tissues. Transcripts for genes involved in the biosynthesis of the mycotoxin, deoxynivalenol, plus other characterized and putative secondary metabolite clusters increased in abundance in symptomless tissue. Transcripts encoding for genes of distinct groups of putative secreted effectors increased within either symptomless or symptomatic tissue. Numerous pathogenicity-associated gene transcripts and transcripts representing PHI-base mutations that impacted on virulence increased in symptomless tissue. In contrast, hydrolytic carbohydrate-active enzyme (CAZyme) and lipase gene transcripts exhibited a different pattern of expression, resulting in elevated transcript abundance during the development of disease symptoms. Genome-wide comparisons with existing datasets confirmed that, within the wheat floral tissue, at a single time point, different phases of infection co-exist, which are spatially separated and reminiscent of both early and late infection. This study provides novel insights into the combined spatial temporal coordination of functionally characterized and hypothesized virulence strategies. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) and maize stalk rot (MSR), caused by members of the Fusarium graminearum species complex (FGSC), are among the most destructive and economically important diseases in the world. Species identity and the trichothecene chemotype of 312 members of the FGSC from diseased wheat spikes and maize stalks in Henan was determined using phylogenetic analyses and a polymerase chain reaction trichothecene chemotype assay. F. graminearum sensu stricto accounted for more than 93% of the FGSC isolates associated with FHB (N = 168) and MSR (N = 130). The remaining isolates were F. asiaticum. Significant differences were found in the frequencies of the two species within the hosts (P < 0.01). However, the frequencies of the same species in FHB and MSR were similar (P > 0.05) for wheat and maize isolates, indicating that the composition of the FGSC with respect to wheat and maize in these fields varied little. The 15- acetyl-deoxynivalenol (15-ADON) trichothecene chemotype represented 92.7 and 98.5% of isolates from wheat (N = 167) and maize (TV = 130), respectively. However, the 3-acetyl-deoxynivalenol chemotype was found in 6.7% of wheat isolates, and the nivalenol chemotype in 1.5% of MSR isolates and in 0.6% of FHB isolates. Mycelial growth at different concentrations of carbendazim and difenoconazole did not differ between F. graminearum sensu stricto and F. asiaticum. These results suggest that the 15-ADON chemotype of F. graminearum sensu stricto is the predominant pathogen that causes wheat- and maize-related diseases in this region. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) resistance was evaluated for accessions of four Triticum species, including bread wheat (modern and old cultivars), spelt, emmer, and einkorn. Fusarium head infection, Fusarium kernel damage and accumulation of trichothecene toxins (deoxynivalenol, nivalenol) in grains were analysed. Modern bread wheat cultivars were the most susceptible to head infection, and emmer and einkorn accessions were the most resistant. Kernel damage was the least for emmer and spelt and greatest for bread wheat. No significant differences between the four host species were observed for toxin accumulation. However, the greatest amounts of deoxynivalenol were detected in the grains of modern wheat cultivars and the least in old bread wheat cultivars. The greatest amount of nivalenol was detected in einkorn grams and the least in old bread wheat cultivars. Wide variability of resistance of all types in all four species was observed. Accessions resistant to FHB and toxin accumulation in grains were identified. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is the main causal agent of Fusarium head blight (FHB) on wheat and barley. In a previous study, a GIN4-like protein kinase gene, GIL1, was found to be important for plant infection and sexual reproduction. In this study we further characterized the functions of GIL1 kinase in different developmental processes. The Dgil1 mutants were reduced in growth, conidiation, and virulence, and formed whitish and compact colonies. Although phialide formation was rarely observed in the mutants, deletion of GIL1 resulted in increased hyphal branching and increased tolerance to cell wall and cell membrane stresses. The Dgil1 mutants produced straight, elongated conidia lacking of distinct foot cells and being delayed in germination. Compared with the wild type, some compartments in the vegetative hyphae of Dgil1 mutants had longer septal distances and increased number of nuclei, suggesting GIL1 is related to cytokinesis and septation. Localization of the GIL1-GFP fusion proteins to the septum and hyphal branching and fusion sites further supported its roles in septation and branching. Overall, our results indicate that GIL1 plays a role in vegetative growth and plant infection in F. graminearum, and is involved in septation and hyphal branching. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a disease of small grain cereals caused by Fusarium species. The pathogens affect spikes and kernels, resulting in reductions of yield and its quality. The present study was conducted to evaluate variation in the FHB resistance of wheat F2 hybrids derived from 16 crosses between winter wheat cultivars of various origin and with different susceptibility to FHB. Plants were inoculated with a conidial suspension consisting of a mixture of F. culmorum, F. graminearum and F. avenaceum isolates. After harvest 1000-kernel weight, number of kernels per spike and kernel weight per spike were evaluated in inoculated and control plants. Disease symptoms were observed on kernels of infected plants and the percentage of Fusarium-damaged kernels (FDK) was calculated. The data were statistically evaluated using uni- and multivariate analyses. A significant influence of genotype and treatment on all observed characteristics was detected. Contrasts between control and inoculated plants showed that inoculation lowered the mean values of all the yield-related traits significantly (in the statistical sense). Results of uni- and multivariate analyses enabled us to find three cross combinations which exhibited a low FDK percentage and simultaneously a relatively low reduction of 1000-kernel weight after inoculation. They may be promising for breeding wheat with improved resistance to FHB. [ABSTRACT FROM AUTHOR]

The genome of Fusarium graminearum , a necrotrophic fungal pathogen causing Fusarium head blight (FHB) disease of wheat, barley and other cereal grains, contains five genes putatively encoding for proteins with a cerato-platanin domain. Cerato-platanins are small secreted cysteine-rich proteins possibly localized in the fungal cell walls and also contributing to the virulence. Two of these F. graminearum proteins (FgCPP1 and FgCPP2) belong to the class of SnodProt proteins which exhibit phytotoxic activity in the fungal pathogens Botrytis cinerea and Magnaporthe grisea . In order to verify their contribution during plant infection and fungal growth, single and double gene knock-out mutants were produced and no reduction in symptoms severity was observed compared to the wild type strain on both soybean and wheat spikes. Histological analysis performed by fluorescence microscopy on wheat spikelets infected with mutants constitutively expressing the dsRed confirmed that FgCPPs do not contribute to fungal virulence. In particular, the formation of compound appressoria on wheat paleas was unchanged. Looking for other functions of these proteins, the double mutant was characterized by in vitro experiments. The mutant was inhibited by salt and H 2 O 2 stress similarly to wild type. Though no growth difference was observed on glucose, the mutant grew better than wild type on carboxymethyl cellulose. Additionally, the mutant's mycelium was more affected by treatments with chitinase and β-1,3-glucanase, thus indicating that FgCPPs could protect fungal cell wall polysaccharides from enzymatic degradation. [ABSTRACT FROM AUTHOR]

Aims Fusarium graminearum is a very destructive fungal pathogen that leads to Fusarium head blight ( FHB) in wheat, a disease which costs growers millions of dollars annually both in crop losses and in remediation efforts. Current countermeasures include the deployment of wheat varieties with some resistance to FHB in conjunction with timed fungicide treatments. In this article, we introduce a fungicide based on thymol, a naturally occurring plant phenolic derived from essential oils. To overcome the hydrophobicity of thymol, the thymol active was incorporated into a low-surfactant submicron emulsion with and without a carrier oil. Methods and Results The minimum fungicidal concentration of F. graminearum was found to be both 0·02% for thymol emulsions with and without an oil component. Time-to-kill experiments showed that thymol emulsions were able to inactivate F. graminearum in as little as 10 s at concentrations above 0·06%. Spraying the thymol emulsions (~0·1% range) on the wheat variety Bobwhite demonstrated significant reductions in FHB infection rate (number of infected spikelets). However, with 0·5% thymol, the wheat heads exhibited premature senescence. Transmission and scanning electron micrographs suggest that the mechanism of antifungal action is membrane mediated, as conidia exposed to thymol showed complete organelle disorganization and evidence of lipid emulsification. Conclusion The collective experimental data suggest that thymol emulsions may be an effective naturally derived alternative to the current thymol treatments, and chemical fungicides in ameliorating FHB. Significance and Impact of the Study This is the first thymol-derived nanoemulsion particles resuspended into water and not DMSO, exhibiting the same antibacterial/antifungal activity as previously described thymol and thyme oil treatments. This drastically reduces the environmental footprint thymol will leave if utilized as a fungicide treatment on field crops. [ABSTRACT FROM AUTHOR]

In vitro and inplanta determination and quantification of deoxynivalenol (DON) are a crucial step in food safety. tri13 amplicons of 282 bp and tri3 partial region of 863 bp were obtained from 16 isolates with DON and 15-acetyldeoxynivalenol (15-AcDON) mycotoxin profiles. Similarly, 42 3-acetyldeoxynivalenol (3-AcDON) isolates yielded 282-bp band of tri13 and 583 bp of tri3 gene in multiplex polymerase chain reaction (PCR) assays. None of the isolates were characterized as NIV producers via PCR. All Fusarium isolates have been determined as high-level DON producers (more than 1 ppm) via tri5-tri6 intergenic regions polymorphisms. tri11 expression via reverse transcriptase PCR (RT-PCR) confirmed results obtained at genomic level. High-pressure liquid chromatographic (HPLC) analysis showed that DON and/or acetylated derivatives can be co-produced with NIV. Even if each assay characterized Turkish Fusarium species as high trichothecene producer via PCR assays, HPLC analysis yielded 0-2481 µg/kg level of trichothecene production including DON, 3-AcDON and NIV. In this study, chemotype determination was carried out via multiplex PCR and tri13, and tri3 genes were co-targeted in a single reaction tube. It is posited that this is the first report on low- and high-level DON production differentiation analysis in Fusariumgraminearum isolates via tri5-tri6 intergenic region analysis worldwide. Results showed that high- and low-DON production potential of F. culmorum isolates’ from tri5 to tri6 nucleotide data could be useful in other Fusarium sp. characterization. This study covers the widest range of geographical regions in Turkey to be subjected to comprehensive class B-trichothecene analysis. [ABSTRACT FROM AUTHOR]

Key message: Fusarium head blight and Septoria tritici blotch resistances are complex traits and can be improved efficiently by genomic selection modeling main and epistatic effects. Abstract: Enhancing the resistance against Fusarium head blight (FHB) and Septoria tritici blotch (STB) is of central importance for a sustainable wheat production. Our study is based on a large experimental data set of 2325 inbred lines genotyped with 12,642 SNP markers and phenotyped in multi-environmental trials for FHB and STB resistance as well as for plant height. Our objectives were to (1) investigate the impact of plant height on FHB and STB severity, (2) examine the potential of marker-assisted selection, and (3) study the prediction ability of genomic selection modeling main and epistatic effects. We observed low correlations between plant height and FHB ( r = −0.15; P < 0.05) as well as STB severity ( r = −0.17; P < 0.05) suggesting negligible morphological resistances. Cross-validation in combination with association mapping revealed absence of large effect QTL impeding an efficient pyramiding of different resistance loci through marker-assisted selection. The prediction ability of genomic selection was high amounting to 0.6 for FHB and 0.5 for STB resistance. Therefore, genomic selection is a promising tool to improve FHB and STB resistance in wheat. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the safety quality of wheat kernels and more specifically the infection of wheat by Fusarium culmorum . We have developed a new non-destructive methodology based on multispectral imaging and chemometrics to detect wheat contamination. This method has been applied to evaluate the tolerance to Fusarium Head Blight (FHB) on six accessions of durum wheat. Two of the accessions are parental lines, one susceptible and one resistant to Fusarium , and the other four are their offspring lines. Multispectral images of dorsal and ventral sides of all kernels were acquired with an in-house imaging system and processed with chemometrical tools, including principal component analysis (PCA) and multiple linear regression (MLR). According to the quantitative PCR (qPCR) results, PCA was able to detect infested kernels and to identify affected areas with kernels. Moreover, regression analysis of the images allowed the degree of contamination for each pixel to be estimated, and thus mapping of contamination for each kernel. [ABSTRACT FROM AUTHOR]

Fusarium head blight ( FHB) in small grain cereals is primarily caused by the members of the Fusarium graminearum species complex. These produce mycotoxins in infected grains, primarily deoxynivalenol ( DON); acetylated derivatives of DON, 3-acetyl- DON (3- ADON) and 15-acetyl- DON (15- ADON); and nivalenol ( NIV). This study reports the isolation of Fusarium cerealis in infected winter wheat heads for the first time in Canada. A phylogenetic analysis based on the TRI101 gene and F. graminearum species-specific primers revealed two species of Fusarium: F. graminearum sensu stricto (127 isolates) and F. cerealis (five isolates). Chemotype determination based on the TRI3 gene revealed that 65% of the isolates were 3- ADON, 31% were 15- ADON and 4% were NIV producers. All the F. cerealis isolates were of NIV chemotype. Fusarium cerealis isolates can often be misidentified as F. graminearum as the morphological characteristics are similar. Although the cultural and macroconidial characteristics of F. graminearum and F. cerealis isolates were similar, the aggressiveness of these isolates on susceptible wheat cultivar Roblin and moderately resistant cultivar Carberry differed significantly. The F. graminearum 3- ADON isolates were most aggressive, followed by F. graminearum 15- ADON and F. cerealis NIV isolates. The findings from this study confirm the continuous shift of chemotypes from 15- ADON to 3- ADON in North America. In Canada, the presence of NIV is limited to barley samples and the discovery of NIV-producing F. cerealis species in Canadian wheat fields may pose a serious concern to the Canadian wheat industry in the future. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a devastating disease that causes significant reductions in yield and quality in wheat, rye, and triticale. In triticale, knowledge of the genetic architecture of FHB resistance is missing but essential due to modern breeding requirements. In our study, four doubled-haploid triticale populations (N = 120 to 200) were evaluated for resistance to FHB caused by artificial inoculation with Fusarium cul- morum in four environments. DArT markers were used to genotype triticale populations. Seventeen quantitative trait loci (QTL) for FHB resis tance were detected across all populations; six of them were derived from rye genome and located on chromosomes 4R, 5R, and 7R, which are here reported for the first time. The total cross-validated ratio of the explained phenotypic variance for all detected QTL in each population was 41 to 68%. In all, 17 QTL for plant height and 18 QTL for heading stage were also detected across all populations; 3 and 5 of them, respectively, were overlapping with QTL for FHB. In conclusion, FHB resistance in triticale is caused by a multitude of QTL, and pyramiding them contributes to higher resistance. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a serious threat worldwide due to its dramatic consequences and effects on small grain cereal production such as yield and quality losses and most importantly mycotoxin contamination. Durum wheat ( Triticum durum Desf.) is particularly susceptible to FHB. Enhancing resistance has proven difficult due to the narrow genetic variation for this trait in the durum wheat gene pool. Broadening the genetic basis by incorporating resistance alleles from wild and cultivated relatives is a promising approach for durum resistance breeding. This review summarizes the current information on sources available for FHB resistance improvement in durum wheat which include wild and cultivated tetraploid wheat, hexaploid wheat and alien species. The genetic basis of FHB resistance of a few tetraploid sources in the T. durum background has been dissected by QTL mapping. So far, thirteen QTL with small to moderate effects have repeatedly been detected on 11 chromosomes with alleles improving FHB resistance deriving from relatives and durum wheat itself. Notably, the QTL found in tetraploid wheat populations largely overlap with the QTL identified in hexaploid wheat suggesting a common genetic basis of FHB resistance. FHB resistance breeding by allele introgression into durum wheat is feasible, and QTL pyramiding appears a practicable strategy for durum resistance breeding. [ABSTRACT FROM AUTHOR]

Two mutants ( tri6Δ and noxABΔ) of the fungal pathogen Fusarium graminearum were assessed for their ability to prime immune responses in wheat (cv. Roblin) against challenge with pathogenic F. graminearum. Priming treatments generated Fusarium head blight ( FHB)-resistant wheat phenotypes and reduced the accumulation of fungal mycotoxins in infected tissues. Microarray analysis identified 260 transcripts that were differentially expressed during the priming period. Expression changes were observed in genes associated with immune surveillance systems, signalling cascades, antimicrobial compound production, oxidative burst, secondary metabolism, and detoxification and transport. Specifically, genes related to jasmonate, gibberellin and ethylene biosynthesis exhibited differential expression during priming. In addition, the induction of the phenylpropanoid pathways that lead to flavonoid, coumarin and hydroxycinnamic acid amide accumulation was also observed. This study highlights the utility of nonpathogenic mutants to both elicit and delineate stages of defence responses in wheat. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a devastating disease in wheat (Triticum aestivum L.), and growing resistant cultivars is one of the most effective strategies to minimize its damage. Huangcandou (HCD) is a Chinese wheat landrace that shows a high level of resistance to FHB spread within a spike (type II). To identify quantitative trait loci (QTLs) for FHB resistance in HCD, 190 recombinant inbred lines (RILs) were developed from HCD × 'Jagger'. Jagger is a susceptible hard winter wheat from Kansas. The population was evaluated for the percentage of symptomatic spikelets (PSSs) per spike after single-floret inoculation in three greenhouse experiments. Initial marker screening identified 261 polymorphic simple sequence repeats (SSRs) between the parents. Analysis of these markers in the RIL population identified five QTLs, three from HCD and two from Jagger chromosomes. Two of the three QTLs from HCD were mapped on the short arms of chromosomes 3B, one in the distal end (3BSd) and another near the centromere (3BSc); the third was on the short arm of 3A (3AS). The QTL on 3BSd coincides with the previously reported Fhb1 and explained 26.1% of phenotypic variation. The QTL on 3AS explained up to 10.0% of phenotypic variation. The two QTLs from Jagger on chromosomes 2D and 6D explained 9.5% and 6.7% of phenotypic variations, respectively. A combination of QTLs from HCD and Jagger can enhance FHB type II resistance in wheat. [ABSTRACT FROM AUTHOR]

Predicting major Fusarium head blight (FHB) epidemics allows for the judicious use of fungicides in suppressing disease development. Our objectives were to investigate the utility of boosted regression trees (BRTs) for predictive modeling of FHB epidemics in the United States, and to compare the predictive performances of the BRT models with those of logistic regression models we had developed previously. The data included 527 FHB observations from 15 states over 26 years. BRTs were fit to a training data set of 369 FHB observations, in which FHB epidemics were classified as either major (severity ≥ 10%) or non-major (severity < 10%), linked to a predictor matrix consisting of 350 weatherbased variables and categorical variables for wheat type (spring or winter), presence or absence of corn residue, and cultivar resistance. Predictive performance was estimated on a test (holdout) data set consisting of the remaining 158 observations. BRTs had a misclassification rate of 0.23 on the test data, which was 31% lower than the average misclassification rate over 15 logistic regression models we had presented earlier. The strongest predictors were generally one of mean daily relative humidity, mean daily temperature, and the number of hours in which the temperature was between 9 and 30°C and relative humidity ≥ 90% simultaneously. Moreover, the predicted risk of major epidemics increased substantially when mean daily relative humidity rose above 70%, which is a lower threshold than previously modeled for most plant pathosystems. BRTs led to novel insights into the weather-epidemic relationship. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) of wheat and barley has been extensively researched worldwide; in contrast, there is limited information on the effects of environmental conditions on Fusarium toxin accumulation in oat grains. More than 300 samples of oat grain from various regions of the United Kingdom from 2006 to 2008 were analyzed for mycotoxin contamination due to infection by Fusarium spp. HT2 and T2 toxins were the two most commonly detected, and their concentrations in individual samples were highly correlated. Hourly weather data were obtained from meteorological recording stations near most of the sampling sites. Statistical modeling was applied to both the original toxin (HT2 plus T2) data and the toxin data adjusted for oat cultivars and number of cereal crops in the previous four seasons. Accumulation of HT2 and T2 toxin was positively correlated with warm and wet conditions during early May and dry conditions thereafter. Using a collection of 51 environmental variables summarized over three lengths (10, 15, and 20 days) of time periods encompassing early May, late May, and early July, all-subsets regression showed that many models, consisting of three to six predictor variables, could be identified with similar explanatory strength for the effect of environmental conditions on toxin accumulation. Most important predictor variables were related to wet conditions during the early-May period, which was before anthesis. These results suggest that the predominant period for Fusarium langsethiae infection of oat is likely to be before rather than during anthesis, as for other head blight pathogens. These empirical models may be further improved by using quantified pathogen biomass within the grains and weather predictor variables summarized in relation to plant growth stages (instead of calendar times). [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) of wheat, caused principally byFusarium graminearumin Canada, results in accumulation of mycotoxins in the grain. The fungus produces deoxynivalenol (DON) and its acetylated forms 3-ADON or 15-ADON. Increasing numbers ofF. graminearumisolates collected in Manitoba between 1998 and 2004 were of the 3-ADON chemotype, whereas prior to 1998, the 15-ADON chemotype was considered the only significant cause of FHB in North America. Between 2008 and 2012, a series of studies were conducted at Carman (2008, 2009) and Glenlea, Manitoba (2008–2012) to monitor the ratio of 3-ADON to 15-ADON chemotypes recovered after wheat plots were artificially inoculated, usually in a 1:1 ratio of 3-ADON:15-ADON isolates ofF. graminearum. Additional studies were conducted under controlled conditions. In 2008, the majority of isolates recovered from both Carman and Glenlea were of the 3-ADON chemotype. In subsequent years, however, the ratio was closer to 1:1 or sometimes with a slight predominance of 15-ADON isolates. Under controlled conditions, recovery of 15-ADON isolates predominated at lower incubation temperatures (18–22°C) whereas at 28°C, 3-ADON isolates were more prevalent. At moderate temperature (24°C), results were mixed – seven samples had a 1:1 ratio, three had higher recovery of 3-ADON isolates, and two had higher recovery of 15-ADON. However, an examination of weather variables over the 5-year period of the field studies showed no correlation between recovery of chemotype and temperature or precipitation. [ABSTRACT FROM AUTHOR]

Proper crop management is an important strategy in reducing Fusarium head blight (FHB) and deoxynivalenol (DON) concentrations in spring wheat (Triticum aestivum). A field study was conducted for three growing seasons to investigate FHB severity, Fusarium-damaged kernels (FDK), and DON concentrations and their inter-relationships as affected by planting and harvesting dates and nitrogen application. Cultivar 'AC Brio' was planted on three dates at approximately 10-d intervals starting from the last week of April. Five nitrogen (N) treatments were 0, 60 and 100 kg N ha−1 applied as starter, 60 (starter) + 40 kg N ha−1 as top-dress and 60 + 40 kg N ha−1 foliar spray at boot stage. Later planting increased FDK and DON concentration and the effects were greater in coarse-textured than in a fine-textured soil. DON concentration sometimes doubled when harvest was delayed after physiological maturity. Nitrogen treatments per se had no effects on FDK and DON. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) or scab, caused by Fusarium graminearum Schwabe [sexual stage Gibberella zeae (Schwein.) Petch], is a destructive disease of small grain cereals. Fusarium graminearum produces the mycotoxin deoxynivalenol (DON), which accumulates in and lowers the value and quality of grain. Field experiments were conducted from 2007 to 2009 to determine if two winter wheat cultivars varying in FHB phenotype response differentially accumulated DON. Secondary objectives were to model the relationship between FHB severity and DON, determine if environment (= year) influenced DON accumulation in the two cultivars, and measure the percentage of Fusarium-damaged kernels (FDK) in the two cultivars. The cultivar ‘Harry’ with a moderately resistant FHB phenotype consistently accumulated more DON (P ≤ 0.0358) than ‘2137’ with a susceptible phenotype. The relationship between FHB severity and DON was linear and positive for both cultivars in all three years (0.32 ≤ R2 ≤ 0.60; 0.0053 ≤ P ≤ 0.1092). Environment (= year) had a significant effect (P < 0.0001) on DON accumulation in both cultivars, and this effect was attributed to differences in rainfall amount and duration in the months of May and June. DON accumulation was highest in 2008 (average of 33.2 ppm in ‘Harry’ and 21.2 ppm in ‘2137’) when there was steady, above-average rainfall in May and June. FDK was highest in 2008 and was higher in ‘Harry’ (64%) than in ‘2137’ (46%). The results from this study suggest that a winter wheat cultivar with a moderately resistant FHB phenotype can be susceptible to FDK and DON accumulation. Based on these results, there is a need to standardize the criteria (FHB intensity, FDK, DON) for characterizing wheat cultivars as resistant or susceptible to FHB. [ABSTRACT FROM PUBLISHER]

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]

The leaf rust resistance gene Lr19 and Fusarium head blight (FHB) resistance quantitative trait loci (QTL) derived from the wild wheatgrass Lophopyrum ponticum have been located on chromosome 7E. The main objectives of the present study were to develop a genetic map of chromosome 7E and map the two resistance loci using a population of 237 F recombinant inbred lines (RILs) derived from a cross between two Thatcher- L. ponticum substitution lines, K11463 (7el(7D)) and K2620 (7el(7D)). 532 G-SSR, E-SSR and STS markers from wheat chromosome group 7 were screened in the parent lines. Of these, 118 markers were polymorphic, with a polymorphism frequency of 22.2%. A genetic map of L. ponticum chromosome 7E was constructed with 64 markers, covering 95.76 cM, with an average genetic distance of 1.47 cM between markers. The major FHB resistance locus, temporarily assigned as FhbLoP, was mapped to the very distal region of the long arm of chromosome 7E within a 3.71 cM interval flanked by Xcfa2240 and Xswes19, which accounts for 30.46% of the phenotypic variance. Lr19 was bracketed by Xwmc273 and XBE404744, with a map distance of 1.54 and 1.43 cM from either side, respectively. The closely linked markers identified in this study will be helpful for marker-assisted introgression of the L. ponticum-derived FhbLoP and Lr19 genes into elite cultivars of wheat, and the development of a genetic map will accelerate the map-based cloning of these two genes. [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]

In wheat (Triticum aestivum L.), Fusarium head blight (FHB) resistance is an important breeding target to reduce yield losses and mycotoxin contamination. We hypothesized that cleistogamous (CL, closed flowering) cultivars have a lower risk of FHB infection than chasmogamous (CH, opened flowering) cultivars because FHB infection usually occurs in the inside of florets or extracted anthers and FHB resistance in CL cultivars decreases mycotoxin accumulation. To test these hypotheses, we produced 126 recombinant inbred lines (RILs) derived from a cross between common wheat varieties 'U24' (CL variety) and 'Saikai 165' (CH variety). Although 'U24' and 'Saikai 165' are both resistant to FHB infection, 'U24' is susceptible to FHB spread, grain deterioration, and mycotoxin accumulation compared with 'Saikai 165'. Among the RILs, there were significant differences in all of the tested traits. Although the CL RILs showed less initial FHB infection than CH RILs, there were no significant differences in grain deterioration and mycotoxin accumulation between the 2 groups. An FHB-resistant quantitative trait locus (QTL) located on chromosome 3BS increased resistance to FHB spread, grain deterioration, and mycotoxin accumulation; however, not all CL RILs with this QTL accumulated less mycotoxin than 'Saikai 165'. [ABSTRACT FROM AUTHOR]

New sources of partial resistance to Fusarium head blight (FHB) in wheat have been identified over the past decade; however, little is known of their breeding value. A 20 parent partial diallel that included resistant genotypes from the U.S., Europe, China and South America was used to evaluate the potential of these sources of resistance as parents in wheat breeding programs. Eight plants replication of each of 190 crosses and 20 parents were point-inoculated with Fusarium graminearum under greenhouse conditions in two replicated experiments. Both general (GCA) and specific combining ability (SCA) were significant. Most of the variance for FHB severity was associated with additive genes; however, estimates for SCA ranged from highly negative to highly positive in both resistant × resistant and resistant × susceptible crosses which suggest that improving FHB resistance through gene pyramiding strategies based on additive genetic variation may be complicated by interaction effects that condition FHB resistance. [ABSTRACT FROM AUTHOR]

The level of the fungal toxin deoxynivalenol (DON) in milled flour and its partitioning between flour and bran of 15 spring wheat (Triticum aestivum) lines with different levels of Fusarium head blight (FHB; mainly caused by Fusarium graminearum) resistance was investigated in Hokkaido, Japan between 2004 and 2007. The DON levels in flour (DONf) and bran (DONb) showed positive linear relationships with DON levels in whole kernels (DONk) (R² = 0.94, n = 60, P ⩽0.01 and R² = 0.93, n = 60, P ⩽0.01, respectively). Results indicated that the DON partitioning ratio between flour and bran is primarily related to the level of DONk, and the DON level was approximately doubled in DONb and halved in DONf for any level of DONk. Only one pattern of DON partitioning supported the conventional strategy to select FHB-resistant lines. [ABSTRACT FROM AUTHOR]

The Fusarium 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. [ABSTRACT FROM AUTHOR]

Abstract: Recent surveys have identified increased predominance of Fusarium poae causing FHB (Fusarium Head Blight) of wheat in Europe. Several studies revealed a correlation between levels of F. poae DNA and nivalenol (NIV) and enniatins (ENNs) in highly contaminated cereal grain. In this study, F. poae specific TaqMan assays and mycotoxin analysis were performed on 48 asymptomatically contaminated wheat grain samples obtained from six different locations in northern Poland in 2006 and 2007. TaqMan assays revealed the presence of F. poae DNA in all samples analyzed, however the amounts of target DNA between the samples differed. Mycotoxin analysis revealed the presence of 13 toxins in the grain analyzed, however only ENN B and B1 were detected at quantifiable concentrations. A significant positive correlation was revealed between F. poae DNA (R =0.75) and monthly mean rainfalls recorded in May (a month before wheat anthesis) in both years. Additionally, a significant positive correlation was found between levels of ENN B+B1 (R =0.49) and rainfalls in May, however, no correlation was found between the quantity F. poae DNA and the level of ENN B+B1. This paper confirms the increasing importance of F. poae in the FHB complex of wheat in Poland. [Copyright &y& Elsevier]

Genetic diversity in relation to Fusarium head blight (FHB) resistance was investigated among 295 European winter wheat cultivars and advanced breeding lines using 47 wheat SSR markers. Twelve additional wheat lines with known FHB resistance were included as reference material. At least one SSR marker per chromosome arm, including SSR markers reported in the literature with putative associations with QTLs for FHB resistance, were assayed to give an even distribution of SSR markers across the wheat genome. A total of 404 SSR alleles were detected. The number of alleles per locus ranged from 2 to 21, with an average of 8.6 alleles. The polymorphism information content of the SSR markers ranged from 0.13 ( Xwmc483) to 0.87 ( Xwmc607), with an average of 0.54. Cluster analysis was performed by both genetic distance-based and model-based methods. In general, the dendrogram based on unweighted pair-group method with arithmetic averages showed similar groupings to the model-based analysis. Seven clusters were identified by the model-based method, which did not strictly correspond to geographical origin. The FHB resistance level of the wheat lines was evaluated in field trials conducted over multiple years or locations by assessing the following traits: % FHB severity, % FHB incidence, % diseased kernels, in spray inoculation trials, and % FHB spread and % wilted tips, in point inoculation trials. Association analysis between SSR markers and the FHB disease traits detected markers significantly associated with FHB resistance, including some that have not been previously reported. The percentage of variance explained by each individual marker was, however, rather low. Haplotype analysis revealed that the FHB-resistant European wheat lines do not contain the 3BS locus derived from Sumai 3. The information generated in this study will assist in the selection of parental lines in order to increase the efficiency of breeding efforts for FHB resistance. [ABSTRACT FROM AUTHOR]

During 2 years and at five locations in Europe, 56 winter wheat genotypes were evaluated for resistance to Fusarium head blight (FHB). The genotypes were both parents and selected recombinants taken from the following populations previously tested for FHB resistance: ‘Arina’/‘Forno’, ‘Arina’/‘Riband’, ‘Dream’/‘Lynx’, G16-92/‘Hussar’, ‘Renan’/‘Récital’, SVP-72017 × ‘Capo’ and ‘Capo’/‘Sumai-3’. In addition, a few control lines were included. FHB resistance was evaluated in replicated experiments under artificial inoculation, disease severity was assessed by repeated visual scorings. The highest level of FHB resistance was found in lines selected from crosses of FHB-resistant winter wheat × ‘Sumai-3’. The best lines selected from crosses of moderately resistant winter wheat with susceptible winter wheat were similar in their resistance response to the resistant parent. The level of FHB resistance was correlated with stability of resistance. Susceptible wheat lines tended to exhibit severe symptoms under high disease pressure. The symptoms on resistant lines remained comparatively low even under high disease pressure. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is an important disease of wheat crops. The incidence of diseased spikelets in the population is most naturally estimated by sampling ears of wheat and counting the number of infected spikelets, X, and the total number of spikelets, Y, on each ear. However, there is usually much more variation from ear to ear in the number of infected spikelets than in the total number of spikelets and in practice it is common to obtain a larger sample of X values than Y values. In this paper, we investigate the relative efficiencies of these alternative sampling procedures. Based on historical data, we show that for the levels of disease incidence typically encountered, the latter sampling scheme is indeed more efficient. The results are relevant to estimating disease incidence in other crops. [ABSTRACT FROM AUTHOR]

1H NMR measurements on protein-free extracts from wheat leaf and stem tissue were used to investigate the biochemical correlates of partial resistance to fungal species implicated in the Fusarium head blight (FHB) disease complex. The wheat genotypes included five commercial wheat cultivars and 116 wheat genotypes, from the CIMMYT international FHB breeding programme in Mexico, that had been bred for FHB disease resistance, utilizing exotic, typically Chinese, resistance sources. Principal component analysis of the nuclear magentic resonance (NMR)-derived metabolite profiles revealed distinct separation of the commercial wheat cultivars from the majority of the CIMMYT wheat genotypes with the commercial cultivars exhibiting markedly higher carbohydrate concentrations. A cross-validated partial least squares (PLS) regression model of the metabolite profile against the partial disease resistance component latent period (delay in sporulation of the fungus on the plant tissue) predicted latent periods that were significantly correlated with the experimentally determined values ( R2 = 0.34, P < 0.001). Identified metabolites that were found in plants with shorter latent periods (higher disease susceptibility) included choline, the single most influential metabolite in the PLS model, betaine, the amino acids glutamine, glutamate and alanine, trans-aconitate and sucrose. Metabolites related to increased disease resistance included glucose and unassigned resonances in the carbohydrate and aromatic regions of the NMR spectra. The current study has demonstrated the potential of metabolite profiling as a tool for marker-assisted selection in commercial breeding for resistance to FHB in wheat. [ABSTRACT FROM AUTHOR]

To determine the relationship between incidence (1; proportion of diseased spikes) and severity (S; mean proportion of diseased spikelets per spike) for Fusarium head blight of wheat and to determine if severity could be predicted reliably from incidence data, disease assessments were made visually at multiple sample sites in artificially and naturally inoculated research and production fields between 1999 and 2002. Ten distinct data sets were collected. Mean disease intensity ranged from 0.023 to 0.975 for incidence and from 0.0003 to 0.808 for severity. A model based on complementary log-log transformation of incidence and severity performed well for all data sets, based on calculated coefficients of determination and random residual plots. The I-S relationship was consistent among years and locations, with similar slopes for all data sets. For 7 of the 10 data sets and for the pooled data from all locations and years, the estimated slope from the fit of the model ranged from 1.03 to 1.26. Time of disease assessment affected the relationship between incidence and severity; however, the estimated slopes from each assessment time were also close to I. Based on the width of the 95% prediction interval, severity was estimated more precisely at lower incidence values than at higher values. The number of sampling units and the index of dispersion of disease incidence had only minor effects on the precision with which S was predicted from 1. The estimation of mean S from 1 would substantially reduce the time required to assess Fusarium head blight in field surveys and treatment comparisons, and the observed relationship between I and S could be used to identify genotypes with some types of disease resistance. [ABSTRACT FROM AUTHOR]

Fusarium head blight has been more severe when infection occurs during anthesis, indicating that floral organs may be important infection courts. Choline acetate and glycinebetaine have been extracted from wheat and reported to be growth stimulants of Fusarium graminearum. They are hypothesized to enhance infection and tissue colonization. Growth of E graminearum was examined on media amended with extracts from floral parts of nine wheat genotypes with various Fusarium head blight resistance levels. Results indicated no significant effect of anther, palea, or lemma extracts on radial growth when compared with unamended controls. Effects on spore germination and hyphal growth of F. graminearum by choline, betaine, and an equimolar mixture at concentrations ranging from 0.01 to 1,000 µM also were examined. Spore germination was not significantly (P ≤ 0.05) affected by choline, betaine, or a combination of the compounds compared with unamended controls. Radial hyphal growth also was not consistently affected (P ≤ 0.05) by choline or betaine when compared with controls. Equimolar mixtures of the two compounds showed significant slight reduction in growth rate at higher concentrations when compared with controls. The reduction in growth rate was due to higher concentrations of betaine. Results of this study indicate that endogenous compounds in floral parts may not be associated with wheat resistance to F. graminearum. [ABSTRACT FROM AUTHOR]

Fusarium culmorum is one of the most important Fusarium species causing head blight infections in wheat, rye, and triticale. It is known as a potent mycotoxin producer with deoxynivalenol (DON), 3-acetyl deoxynivalenol (3-ADON), and nivalenol (NIV) being the most prevalent toxins. In this study, the effect of winter cereal species, host genotype, and environment on DON accumulation and Fusarium head blight (FHB) was analysed by inoculating 12 rye, eight wheat, and six triticale genotypes of different resistance levels with a DON-producing isolate at three locations in 2 years (six environments). Seven resistance traits were assessed, including head blight rating and relative plot yield. In addition, ergosterol, DON and 3-ADON contents in the grain were determined. A growth-chamber experiment with an artificially synchronized flowering date was also conducted with a subset of two rye, wheat and triticale genotypes. Although rye genotypes were, on average, affected by Fusarium infections much the same as wheat genotypes, wheat accumulated twice as much DON as rye. Triticale was least affected and the grain contained slightly more DON than rye. In the growth-chamber experiment, wheat and rye again showed similar head blight ratings, but rye had a somewhat lower relative head weight and a DON content nine times lower than wheat (3.9 vs. 35.3 mg/kg). Triticale was least susceptible with a five times lower DON content than wheat. Significant (P=0.01) genotypic variation for DON accumulation existed in wheat and rye. The differences between and within cereal species in the field experiments were highly influenced by environment for resistance traits and mycotoxin contents. Nevertheless, mean mycotoxin content of the grain could not be associated with general weather conditions in the individual environments. Strong genotype–environment interactions were found for all cereal species. This was mainly due to three wheat varieties and one rye genotype being environmentally extremely unstable. The more resistant entries, however, showed a higher environmental stability of FHB resistance and tolerance to DON accumulation. Correlations between resistance traits and DON content were high in wheat (P=0.01), with the most resistant varieties also accumulating less DON, but with variability in rye. In conclusion, the medium to large genotypic variation in wheat and rye offers good possibilities for reducing DON content in the grains by resistance selection. Large confounding effects caused by the environment will require multiple locations and/or years to evaluate FHB resistance and mycotoxin accumulation. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe (telomorph=Gibberella zeae (Schw.)), is an important wheat disease world-wide. Production of deoxynivalenol (DON) by F. graminearum in infected wheat grain is detrimental to livestock and is also a safety concern in human foods. An international collection of 116 wheat lines was evaluated for FHB resistance and concentration of DON in grain. Plants were inoculated with mixed isolates of F. graminearum in the greenhouse by injecting conidia into a single spikelet of each spike and in the field by scattering F. graminearum-infected wheat kernels on the soil surface. FHB symptoms were evaluated by visual inspection in both the greenhouse and field, and DON was analysed by HPLC. Significant differences in FHB ratings and DON levels were observed among cultivars. In the greenhouse test, visual symptoms varied from no spread of FHB from the inoculated spikelet to spread throughout the spike, and DON levels ranged from trace levels to 283 mg/kg. In the field test, DON ranged from 2.8 to 52 mg/kg. The greenhouse test identified 16 wheat lines from various origins that accumulated less than 2 mg/kg DON. These lines may be useful as sources for breeding wheat cultivars with lower DON levels. Correlation coefficients were significant between FHB symptom ratings, seed quality traits, and DON levels. Thus, the percentage of scabbed spikelets and kernels can be generally used to predict DON levels in harvested wheat grain. In breeding programmes, selection for plants having few scabbed spikelets and scabbed kernels is most likely to result in low DON levels. [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]

Fusarium Head Blight is a disease of cereal crops that causes severe yield losses and mycotoxin contamination of grain. The main causal pathogen, Fusarium graminearum, produces the trichothecene toxins deoxynivalenol or nivalenol as virulence factors. Nivalenol-producing isolates are most prevalent in Asia but co-exist with deoxynivalenol producers in lower frequency in North America and Europe. Previous studies identified a barley UDP-glucosyltransferase, HvUGT13248, that efficiently detoxifies deoxynivalenol, and when expressed in transgenic wheat results in high levels of type II resistance against deoxynivalenol-producing F. graminearum. Here we show that HvUGT13248 is also capable of converting nivalenol into the non-toxic nivalenol-3-O-β-d-glucoside. We describe the enzymatic preparation of a nivalenol-glucoside standard and its use in development of an analytical method to detect the nivalenol-glucoside conjugate. Recombinant Escherichia coli expressing HvUGT13248 glycosylates nivalenol more efficiently than deoxynivalenol. Overexpression in yeast, Arabidopsis thaliana, and wheat leads to increased nivalenol resistance. Increased ability to convert nivalenol to nivalenol-glucoside was observed in transgenic wheat, which also exhibits type II resistance to a nivalenol-producing F. graminearum strain. Our results demonstrate the HvUGT13248 can act to detoxify deoxynivalenol and nivalenol and provide resistance to deoxynivalenol- and nivalenol-producing Fusarium. [ABSTRACT FROM AUTHOR]

Fusarium head blight, caused by Fusarium graminearum, is one of the most severe diseases on wheat and barley worldwide. Although the genomic data of several strains were published, the intragenomic variation of F. graminearum was not well characterized. Here, we sequenced three Chinese strains and conducted genomewide comparisons. Our data revealed that all the sequenced strains were distinct from each other and over 350 genes were functionally lost in each of them. Variants of each strain were unevenly distributed in a highly conserved pattern along the chromosomes, resulting in a conserved two-speed genome. The fast subgenome has a lower GC content, shorter gene length, and higher variation of exon numbers than the slow subgenome. Genes related to interaction and pathogenicity, under positive selection, and up-regulated in planta were all significantly enriched in the fast subgenome. Furthermore, we found that the fast subgenome coincided with facultative heterochromatin regions that were repressed in vegetative stage but activated during infection as measured by RNA-seq and ChIP-seq data, suggesting that the fast subgenome is epigenetically regulated. Taken together, our data demonstrated that F. graminearum has a highly conserved two-speed genome and the fast subgenome responsible for adaption and infection is under the control of heterochromatin. [ABSTRACT FROM AUTHOR]

Four of the world's most important crops, wheat, barley, rice and maize, in addition to other small grains are susceptible to Fusarium graminearum species complex (FGSC), the most important causal agent of Fusarium head blight (FHB). The major threat from this species complex comes from trichothecene mycotoxins such as deoxynivalenol (DON) and nivalenol (NIV) and their acetylated derivatives, including 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), and 4-acetylnivalenol (4-ANIV). Polymerase chain reaction (PCR) assays are being utilized to quickly identify type B trichothecene genotypes in populations of head blight causing Fusaria. In the current study, 388 isolates collected from different locations in 6 Mexican states between 1995 and 2013 were analyzed by chemotype and sub-chemotype specific markers. It was found that the disease has been predominantly caused by FGSC, while F. crookwellense co-presented as FHB causal agent in Mexico. Both DON and NIV trichothecene genotypes were identified in isolates belonging to FGSC, with the DON genotype predominating. Furthermore, all DON isolates were shown to be the 15-ADON genotype and no 3-ADON genotype was identified. This was the first detailed study on the trichothecene genotypes of Mexican toxigenic Fusarium strains on large scale; wherein we report for the first time the occurrence of FGSC isolates belonging to NIV trichothecene genotype in Mexico. [ABSTRACT FROM AUTHOR]

Phospholipase C (PLC) plays important roles in regulating various biological processes in eukaryotes. Currently, little is known about the function of PLC in filamentous fungi, especially the plant pathogenic fungi. Fusarium graminearum is the causal agent of Fusarium head blight in many cereal crops. BLAST search revealed that Fusarium genome contains six FgPLC genes. Using quantitative RT-PCR, different FgPLC gene expressions in mycelia were analyzed. To investigate the role of FgPLC in F. graminearum biology, a pharmacological study using a known inhibitor of PLC (U73122) was conducted. Results showed that inhibition of FgPLC resulted in significant alterations of mycelial growth, conidiation, conidial germination, perithecium formation, and expressions of Tri5 and Tri6 genes. As expected, the treatment of F. graminearum with U73343, an inactive analog of U73122, showed no effect on F. graminearum biology. Our results suggested strongly that FgPLC plays important roles in F. graminearum growth and development. [ABSTRACT FROM AUTHOR]

Background: Fusarium head blight (FHB) is a severe disease caused by different Fusarium species, which affects a wide range of cereal crops, including wheat. It determines from 10 to 30 % of yield loss in Europe. Chemical fungicides are mainly used to reduce the incidence of FHB, but low environmental impact solutions are looked forward. Applications of soil/rhizobacteria as biocontrol agents against FHB in wheat are described in literature, whereas the potential use of lactobacilli in agriculture has scarcely been explored. Results: The aim of this work was to study the inhibitory effect of two bacterial strains, Lactobacillus plantarum SLG17 and Bacillus amyloliquefaciens FLN13, against Fusarium spp. in vitro and to assess their efficacy in field, coupled to the study of the microbial community profile of wheat seeds. Antimicrobial assays were performed on agar plates and showed that the two antagonistic strains possessed antimicrobial activity against Fusarium spp. In the field study, a mixture of the two strains was applied to durum wheat i) weekly from heading until anthesis and ii) at flowering, compared to untreated and fungicide treated plots. The FHB index, combining both disease incidence and disease severity, was used to evaluate the extent of the disease on wheat. A mixture of the two microorganisms, when applied in field from heading until anthesis, was capable of reducing the FHB index. Microbial community profile of seeds was studied via PCR-DGGE, showing the presence of L. plantarum SLG17 in wheat seeds and thus underlining an endophytic behavior of the strain. Conclusions: L. plantarum SLG17 and B. amyloliquefaciens FLN13, applied as biocontrol agents starting from the heading period until anthesis of wheat plants, are promising agents for the reduction of FHB index. [ABSTRACT FROM AUTHOR]

The article presents a study on the plant disease Fusarium boothii that cause head blight in wheat in the U.S.

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