Deoxynivalenol and nivalenol in commercial wheat grain related to Fusarium head blight epidemics in southern Brazil

Inhibition mechanism of fusarium graminearum growth by g-C3N4 homojunction and its application in barley malting

The increase of deoxynivalenol (DON) caused by Fusarium graminearum (F. graminearum) during the malting process is a serious safety problem. In our work, the inhibition mechanism of F. graminearum growth by g-C3N4 homojunction and its application in barley malting were studied. The reason why the growth activity of F. graminearum decreased after photocatalysis by g-C3N4 homojunction was that under visible light irradiation, a large amount of •O2- elicited by g-C3N4 homojunction destroyed the cell structure of F. graminearum, leading to the deficiency of cell membrane selective permeability and serious disorder of intracellular metabolism. The application of photocatalysis technology in malting can effectively inhibit the growth of F. graminearum and the accumulation of ergosterol was reduced by 30.55 %, thus reducing the DON content in finished malt by 31.82 %. Meanwhile, the physicochemical indexes of barley malt after photocatalytic treatment still met the requirements of second class barley malt in Chinese light industry standard QB/T 1686-2008. Our work provides a new idea for the control of fungal contamination in barley malt.

Paralogous FgIDO genes with differential roles in tryptophan catabolism, fungal development and virulence in Fusarium graminearum

Indoleamine 2,3-dioxygenase (Ido) is a tryptophan-degrading enzyme that is widely distributed across species. Ido catalyzes the first step of tryptophan (TRP) degradation and drives the de novo synthesis of nicotinamide adenine dinucleotide (NAD⁺) coenzymes via the kynurenine (KYN) pathway. The budding yeast Saccharomyces cerevisiae possesses a single IDO gene (BNA2) that is responsible for NAD⁺ synthesis, whereas a number of fungal species contain multiple IDO genes. However, the biological roles of IDO paralogs in plant pathogens remain unclear. In the current study, we identified three FgIDOs from the wheat head blight fungus Fusarium graminearum. FgIDOA/B/C expression was significantly induced upon TRP treatment. Targeted disruption of FgIDOA and/or FgIDOB caused different levels of NAD⁺ auxotrophy, thus resulting in pleotropic phenotypic defects. Loss of FgIDOA resulted in abnormal conidial morphology, reduced mycelial growth, decreased virulence in wheat heads and reduced deoxynivalenol accumulation. Exogenous addition of KYN or various intermediates involved in the KYN pathway rescued auxotrophy of the mutants. Metabolomics analysis revealed shifts toward alternative TRP degradation pathways to melatonin and indole derivatives in mutants lacking FgIDOB. Upregulation of partner genes in auxotrophic mutants and the capacity to rescue the auxotroph by overexpressing a partner gene indicated functional complementation among FgIDOA/B/C. Taken together, the results of this study provide insights into differential roles in paralogous FgIDOs and how fungal TRP catabolism modulates fungal development and virulence.

Deoxynivalenol and zearalenone in Brazilian barley destined for brewing

Barley is an important cereal worldwide. However, fungal contamination during pre and postharvest is a recurrent problem for barley production, causing a direct impact on the quality of the grains and their by-products due to spoilage and mycotoxin accumulation. The Fusarium graminearum species complex is the main contaminant during preharvest and some species can produce deoxynivalenol and zearalenone, important mycotoxins that represent a risk to human and animal health. This study evaluated the fungal diversity and the levels of DON and ZEN in barley grains produced in Brazil. The results showed high frequency (60%) of Fusariumcontamination in barley grains. Additionally, mycotoxin levels ranged from 46 to 2074 µg/kg for DON and from 74 to 556 µg/kg for ZEN. Co-occurrence of DON and ZEN was observed in 40% of the samples and 30% of barley samples had DON and ZEN levels higher than the maximum levels established by Brazilian and European legislations.   .

Current Review of Mycotoxin Biodegradation and Bioadsorption: Microorganisms, Mechanisms, and Main Important Applications

Mycotoxins are secondary metabolites produced by fungi. Food/feed contamination by mycotoxins is a great threat to food safety. The contamination can occur along the food chain and can cause many diseases in humans and animals, and it also can cause economic losses. Many detoxification methods, including physical, chemical, and biological techniques, have been established to eliminate mycotoxins in food/feed. The biological method, with mycotoxin detoxification by microorganisms, is reliable, efficient, less costly, and easy to use compared with physical and chemical ones. However, it is important to discover the metabolite's toxicity resulting from mycotoxin biodegradation. These compounds can be less or more toxic than the parent. On the other hand, mechanisms involved in a mycotoxin's biological control remain still unclear. Mostly, there is little information about the method used by microorganisms to control mycotoxins. Therefore, this article presents an overview of the most toxic mycotoxins and the different microorganisms that have a mycotoxin detoxification ability. At the same time, different screening methods for degradation compound elucidation are given. In addition, the review summarizes mechanisms of mycotoxin biodegradation and gives some applications.

Synthesis of Novel Indole Schiff Base Compounds and Their Antifungal Activities

A series of novel indole Schiff base derivatives (2a–2t) containing a 1,3,4-thiadiazole scaffold modified with a thioether group were synthesized, and their structures were confirmed using FT-IR, ¹H NMR, ¹³C NMR, and HR-MS. In addition, the antifungal activity of synthesized indole derivatives was investigated against Fusarium graminearum (F. graminearum), Fusarium oxysporum (F. oxysporum), Fusariummoniliforme (F.moniliforme), Curvularia lunata (C. lunata), and Phytophthora parasitica var. nicotiana (P. p. var. nicotianae) using the mycelium growth rate method. Among the synthesized indole derivatives, compound 2j showed the highest inhibition rates of 100%, 95.7%, 89%, and 76.5% at a concentration of 500 μg/mL against F. graminearum, F. oxysporum, F.moniliforme, and P. p. var. nicotianae, respectively. Similarly, compounds 2j and 2q exhibited higher inhibition rates of 81.9% and 83.7% at a concentration of 500 μg/mL against C. lunata. In addition, compound 2j has been recognized as a potential compound for further investigation in the field of fungicides.

Identification of Wheat LACCASEs in Response to Fusarium graminearum as Potential Deoxynivalenol Trappers

Fusarium graminearum (F. graminearum) can cause huge yield reductions and contamination of grain with deoxynivalenol (DON), and thus is one of the most problematic pathogen of wheat worldwide. Although great efforts have been paid and great achievements have been made to control the pathogens, there is still a wide gap for understanding the mechanism underlying F. graminearum resistance. Plant LACCASEs (LACs) catalyze the oxidative polymerization of monolignols by reinforcing cell-wall of various cell types to provide mechanical support, xylem sap transportation, and defense against pest and pathogens. To date, little has been known about LAC genes in bread wheat and their potential roles in wheat-F. graminearum interaction. Through systematic analysis of the genome-wide homologs and transcriptomes of wheat, a total of 95 Triticum aestivum laccases (TaLACs) were identified, and 14 of them were responsive to F. graminearum challenge. 3D structure modelings of the 14 TaLAC proteins showed that only TaLAC78 contains the entire activity center for oxidation and the others lack the type 1 copper ion ligand (T1Cu). Both amino acid sequence alignment and three-dimensional reconstruction after amino acid mutation showed that the loss of T1Cu is not only related to variation of the key amino acid coordinating T1Cu, but also closely related to the flanking amino acids. Significantly differential temporal expression patterns of TaLACs suggested that their subfunctionalization might occur. Promoter array analysis indicated that the induction of TaLACs may be closely associated with salicylic acid signaling, dehydration, and low-oxygen stress under F. graminearum infection. Molecular docking simulation demonstrated that TaLACs can not only catalyze lignin as a substrate, but also interact with DON, which may be docked into the binding position of the monolignols, where the LACs recognize substrates. The current study provides clues for exploring the novel functions of TaLACs in wheat resistance to F. graminearum, and TaLACs maybe candidates for conferring a high level of resistance against F. graminearum in wheat.

Production of type-B trichothecenes by Fusarium meridionale, F. graminearum, and F. austroamericanum in wheat plants and rice medium

Food security goes beyond food being available; the food needs to be free of contaminants. Trichothecenes mycotoxins, produced by Fusarium fungus, are. among the most frequently found contaminants of wheat. In this study, we evaluated the production of trichothecenes Deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), and nivalenol (NIV) by Fusarium meridionale, F. austroamericanum, and F. graminearum grown in wheat plants and rice medium. Fusarim meridionale was efficient only in the production of NIV (production range (pr) from 1340 to 2864 µg kg^-1 in wheat plant), and F. austroamericanum in the production of 3-AcDON (pr from 50 to 192 µg kg^-1 in wheat plant, and from 986 to 7045 µg kg^-1 in rice medium) and DON (pr from 4076 to 13,701 µg kg^-1 in wheat plant, and from 184 to 43,395 µg kg^-1 in rice medium). Already, F. graminearum was efficient in the production of 3-AcDON only in rice medium (pr from 81 to 2342 µg kg^-1), 15-AcDON in wheat plant (pr from 80 to 295 µg kg^-1) and in rice medium (pr from 436 to 8597 µg kg^-1), and DON also in wheat plant (pr from 7746 to 12,046 µg kg^-1) and in rice medium (pr from 695 to 49,624 µg kg^-1). The specificity of F. meridionale in the production of NIV but not the production of DON could generate a food security problem in regions where this species occurs and the amounts of NIV in grains and derivatives are not regulated in the food chain, as in Brazil.

The FaFlbA mutant of Fusarium asiaticum is significantly increased in nivalenol production

AIMS

Cereals contaminated with type B trichothecene nivalenol (NIV) and its acetylated derivative 4-acetyl-nivalenol (4-AcNIV) are a global mycotoxicological problem threatening the health of humans and livestock. Toxicological studies, quantitative determinations and screening for biodegrading micro-organisms require massive amounts of pure toxins. However, the low yield from fungal cultures and high prices of NIV and 4-AcNIV limit research progress in these areas. This work aimed to select Fusarium asiaticum mutant strains with enhanced production of NIV and 4-AcNIV.

METHODS AND RESULTS

A total of 62 NIV-producing F. asiaticum strains were isolated and compared regarding their ability to produce NIV. Strain RR108 had the highest yield of NIV among 62 field isolates surveyed and was then genetically modified for higher production. Targeted deletion of the FaFlbA gene, encoding a regulator of G protein signalling protein, resulted in a significant increase in NIV and 4-AcNIV production in the FaFlbA deletion mutant ΔFaFlbA. The expression of three TRI genes involved in the trichothecene biosynthetic pathway was upregulated in ΔFaFlbA. ΔFaFlbA produced the highest amount of NIV and 4-AcNIV when cultured in brown long-grain rice for 21 days, and the yields were 2.07 and 2.84 g kg^-1 , respectively. The mutant showed reduced fitness, including reduced conidiation, loss of perithecial development and decreased virulence on wheat heads, which makes it biologically safe for large-scale preparation and purification of NIV and 4-AcNIV.

CONCLUSIONS

The F. asiaticum mutant strain ΔFaFlbA presented improved production of NIV and 4-AcNIV with reduced fitness and virulence in plants.

SIGNIFICANCE AND IMPACT OF THE STUDY

Targeted deletion of the FaFlbA gene resulted in increased NIV and 4-AcNIV production. Our results provide a practical approach using genetic modification for large-scale mycotoxin production.

Survey of Freshly Harvested Oat Grains from Southern Brazil Reveals High Incidence of Type B Trichothecenes and Associated Fusarium Species

The current study investigated the fungal diversity in freshly harvested oat samples from the two largest production regions in Brazil, Paraná (PR) and Rio Grande do Sul (RS), focusing primarily on the Fusarium genus and the presence of type B trichothecenes. The majority of the isolates belonged to the Fusarium sambucinum species complex, and were identified as F. graminearum sensu stricto (s.s.), F. meridionale, and F. poae. In the RS region, F. poae was the most frequent fungus, while F. graminearum s.s. was the most frequent in the PR region. The F. graminearum s.s. isolates were 15-ADON genotype, while F. meridionale and F. poae were NIV genotype. Mycotoxin analysis revealed that 92% and 100% of the samples from PR and RS were contaminated with type B trichothecenes, respectively. Oat grains from PR were predominantly contaminated with DON, whereas NIV was predominant in oats from RS. Twenty-four percent of the samples were contaminated with DON at levels higher than Brazilian regulations. Co-contamination of DON, its derivatives, and NIV was observed in 84% and 57.7% of the samples from PR and RS, respectively. The results provide new information on Fusarium contamination in Brazilian oats, highlighting the importance of further studies on mycotoxins.

Key Global Actions for Mycotoxin Management in Wheat and Other Small Grains

Mycotoxins in small grains are a significant and long-standing problem. These contaminants may be produced by members of several fungal genera, including Alternaria, Aspergillus, Fusarium, Claviceps, and Penicillium. Interventions that limit contamination can be made both pre-harvest and post-harvest. Many problems and strategies to control them and the toxins they produce are similar regardless of the location at which they are employed, while others are more common in some areas than in others. Increased knowledge of host-plant resistance, better agronomic methods, improved fungicide management, and better storage strategies all have application on a global basis. We summarize the major pre- and post-harvest control strategies currently in use. In the area of pre-harvest, these include resistant host lines, fungicides and their application guided by epidemiological models, and multiple cultural practices. In the area of post-harvest, drying, storage, cleaning and sorting, and some end-product processes were the most important at the global level. We also employed the Nominal Group discussion technique to identify and prioritize potential steps forward and to reduce problems associated with human and animal consumption of these grains. Identifying existing and potentially novel mechanisms to effectively manage mycotoxin problems in these grains is essential to ensure the safety of humans and domesticated animals that consume these grains.

Are Demethylation Inhibitor Plus Quinone Outside Inhibitor Fungicide Premixes During Flowering Worthwhile for Fusarium Head Blight Control in Wheat? A Meta-Analysis

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is best controlled with demethylation inhibitor (DMI) fungicides during flowering. However, the use of premixes of DMI and quinone outside inhibitor (QoI) fungicides to control FHB has increased in Brazil. Data on FHB severity and wheat yields measured in field experiments conducted in Brazil were gathered from both peer- and nonpeer-reviewed sources published from 2000 to 2018. After selection criteria were applied, 73 field trials from 35 bibliographic sources were identified, among which 50% of the data were obtained from cooperative network trials conducted after 2011. To be included in the analysis, DMI plus QoI premixes or tebuconazole were tested in at least 14 trials and 3 years. Four premixes met the criteria. Estimates of percent control (and respective 95% confidence intervals) by a network model fitted to the log of the treatment means ranged from 44.1% (pyraclostrobin plus metconazole applied once; 32.4 to 53.7) to 64.3% (pyraclostrobin plus metconazole; 58.4 to 69.3); the latter did not differ from tebuconazole (59.9%; 53.6 to 65.3). Yield response was statistically similar for pyraclostrobin plus metconazole (532.1 kg/ha; 441 to 623) and trifloxystrobin plus prothioconazole (494.9 kg/ha; 385 to 551), and both differed statistically from a group composed of tebuconazole (448.2 kg/ha; 342 to 554), trifloxystrobin plus tebuconazole (468.2 kg/ha; 385 to 551), azoxystrobin plus tebuconazole (462.4 kg/ha; 366 to 558), and pyraclostrobin plus metconazole applied once (413.7 kg/ha; 308 to 518). The two categories of FHB index (7% cutoff) and yield (3,000 kg/ha cutoff), both in the nontreated check, did not explain the heterogeneity in the estimates. Considering only the fungicide effects on yield, two sequential sprays of tebuconazole or one spray of pyraclostrobin plus metconazole as management choices are likely more profitable than DMI plus QoI premixes sprayed twice during flowering.

Near-infrared spectroscopy as a tool for rapid screening of deoxynivalenol in wheat flour and its applicability in the industry

This study aimed to evaluate the applicability and efficiency of Near-Infrared Spectroscopy (NIR) by using dispersive NIR and Fourier Transform NIR to analyse 267 samples of Brazilian wheat flour contaminated with deoxynivalenol (DON). For this, Partial Least-squares Discriminant Analysis (PLS-DA) and Principal Component Analysis-Linear Discriminant Analysis (PC-LDA) were used as discriminatory methods. Next, the samples were classified according to the maximum tolerated limits (MTL) for DON in Brazil, 750 μg kg^-1, and two groups were established for the calibration set: category A (≤450 μg kg^-1), non-contaminated or below the MTL; and category B (>450 μg kg^-1), contaminated or above the MTL. Validation samples through PLS-DA showed correct classification rates in the range of 85-87.5% and presented a 10-15% error; for PC-LDA, the hit rate was over 85% with an error of 10-15%. The present findings demonstrate that NIR is an excellent alternative method to classify wheat flour samples according to DON content.

Mitigation of nivalenol using alcoholic fermentation and magnetic field application

This study aimed at evaluating mitigation of nivalenol (NIV) in alcoholic fermentation with magnetic field application (MF). Mitigation was related to both the glutathione (GSH) redox molecule and the enzyme peroxidase (PO), which were synthesized by Saccharomyces cerevisiae US-05. Conditions under evaluation were NIV (0.2 µg mL^-1), MF application (35 mT) and simultaneous use of mycotoxin and MF. The GSH content and the PO activity were increased when the culture contained NIV and the alcohol profile was altered after 48 h of fermentation. At the end of the alcoholic fermentation, NIV was mitigated by 56.5%. Therefore, this process is a promising method to reduce contamination by NIV, although the mycotoxin affects the chemical characteristics of the final product.

Dietary Intake of Mycotoxin Susceptible Foods by Brazilian Nursing Mothers

Background:

The human milk has several health benefits to the mother and child, and it is the ideal form of nutrition for infants. However, some food contaminants such as mycotoxins can be transferred from the mother to the child through breast milk.

Objective:

To access the dietary intake of mycotoxin susceptible foods by nursing mothers.

Methods:

The dietary intake of mycotoxin susceptible foods was investigated by interviewing nursing mothers (n = 86), who were registered donors of the Human Milk Bank (HMB) of Blumenau (Brazil), through a food frequency questionnaire (FFQ). The mothers were contacted and those who agreed to answer the FFQ were recruited for the study group. The interview was conducted individually, face to face with each mother, by a trained researcher. The FFQ was divided into three food Groups (vegetables, animal and beverages, respectively), considered most prone to mycotoxins contamination. Socio-demographic characteristics of the mothers were also obtained.

Results:

The FFQ revealed a high weekly intake of foods susceptible to fungi and mycotoxin contamination. Consumption of wheat, coffee and cow’s milk was reported by 52, 44 and 51% of the mothers, respectively. The consumption of those foods occurred daily to more than 7 times per week.

Conclusion:

The study revealed that Brazilian nursing mothers frequently consume foods susceptible to mycotoxin contamination, especially wheat and its by-products. Brazilian health, environmental and agriculture authorities should pay permanent attention by applying monitoring programs to grains and cereals - both imported and domestically produced - as they are highly susceptible to fungi and mycotoxin contamination, which can be transferred to infants via breastfeeding, apart from harming the general population health.

Characterization of the Fusarium sambucinum species complex and detection of multiple mycotoxins in Brazilian barley samples

This study investigated the fungal diversity in Brazilian barley samples, focusing on the Fusarium sambucinum species complex and the presence of multiple mycotoxins: aflatoxins B1, B2, G1, G2 beauvericin (BEA), enniatins (ENNs) A, A1, B, and B1, deoxynivalenol (DON), fumonisins (FB) B1 and B2, HT-2 and T-2 toxins, nivalenol (NIV) and ochratoxin A (OTA) from two different regions, São Paulo (SP) and Rio Grande do Sul (RS). The majority of the isolates belonged to the Fusarium sambucinum species complex (FSAMSC), with F. graminearum s.s. characterized as the major contaminant. F. meridionale and F. poae were the second most frequent fungi isolated from SP and RS, respectively. All of the F. graminearum s.s. isolates demonstrated 15-ADON genotype, whereas F. poae and F. meridionale were all NIV. The majority of the F. cortaderiae isolates were NIV, with only one 3-ADON genotype. Mycotoxin analysis revealed that none of the samples were contaminated by aflatoxins, OTA, FB2 and type A trichothecenes, however, all of the samples were contaminated with at least one Fusarium toxin. Contamination by DON, ZEA, ENNB and ENNB1 levels were significantly higher in RS. Co-contamination of BEA, DON, ENNs, NIV and ZEA in 18.5% and 24.2% of the analyzed samples was observed, from SP and RS respectively. More than 20% of the samples from RS presented DON and ZEA levels above the regulations established by Europe and Brazil. The results provide further information on the FSAMSC from South America and detected multiple Fusarium toxins in barley samples. This highlights the importance for further studies on the possible interactions of these mycotoxins in order to determine potential risks to animal health.

The Inhibitory Potential of Selected Essential Oils on Fusarium spp. Growth and Mycotoxins Biosynthesis in Maize Seeds

Owing to their rich chemical composition, essential oils (EOs) have many interesting properties, including antimicrobial activities. The presence of Fusarium and their secondary metabolites, mycotoxins, in cereal crops is a serious problem in agriculture, which consequently affects food quality. The aim of the present study was to investigate the effects of selected EOs on the growth of Fusarium graminearum and F. culmorum and the biosynthesis of mycotoxins in maize seeds. Chromatographic analysis of ergosterol as a fungal growth indicator showed a significant inhibition of Fusarium growth (83.24–99.99%) compared to the control samples, which as a consequence resulted in a reduction in mycotoxin concentrations. The addition of cinnamon, palmarosa, orange, and spearmint EOs was shown to be the most effective in reducing zearalenone concentration (99.10–99.92%). Deoxynivalenol analysis confirmed a very high reduction of this compound at the application all tested EOs (90.69–100%). The obtained results indicated that EOs have a great potential to inhibit growth of Fusarium fungi as well as reduce the concentration of mycotoxins in maize seed.

Chemical Activation of the Ethylene Signaling Pathway Promotes Fusarium graminearum Resistance in Detached Wheat Heads

Plant signaling hormones such as ethylene have been shown to affect the host response to various pathogens. Often, the resistance responses to necrotrophic fungi are mediated through synergistic interactions of ethylene (ET) with the jasmonate signaling pathway. On the other hand, ET is also an inducer of senescence and cell death, which could be beneficial for some invading necrotrophic pathogens. Fusarium graminearum, a causative agent in Fusarium head blight of wheat, is a hemibiotrophic pathogen, meaning it has both biotrophic and necrotrophic phases during the course of infection. However, the role of ET signaling in the host response to Fusarium spp. is unclear; some studies indicate that ET mediates resistance, while others have shown that it is associated with susceptibility. These discrepancies could be related to various aspects of different experimental designs, and suggest that the role of ET signaling in the host response to FHB is potentially dependent on interactions with some undetermined factors. To investigate whether wheat genotype can influence the ET-mediated response to FHB, the effect of chemical treatments affecting the ET pathway was studied in six wheat genotypes in detached-head assays. ET-inhibitor treatments broke down resistance to both initial infection and disease spread in three resistant wheat genotypes, whereas ET-enhancer treatments resulted in reduced susceptibility in three susceptible genotypes. The results presented here show that the ET signaling can mediate FHB resistance to F. graminearum in different wheat backgrounds.

Assessment of mycotoxin exposure and risk characterization using occurrence data in foods and urinary biomarkers in Brazil

This study aimed to assess the exposure of Brazilian residents (N = 86) from rural areas to multiple mycotoxins and characterize the associated risk in two sampling periods (SP) (April-May and December/2016). Mycotoxins in food and urine samples were determined by liquid chromatography coupled to tandem mass spectrometry. Mean probable daily intake (PDI) values based on occurrence data in foods in both SP varied from 0.007 to 0.013, 0.069 to 1.002, 0.119 to 0.321 and 0.013-0.156 μg kg^-1 body weight (bw) day^-1 for aflatoxins (AFs), deoxynivalenol (DON), fumonisins (FBs) and zearalenone (ZEN), respectively. Mean PDI values based on urinary biomarkers were 0.001, 84.914, 0.031, 0.377 and 0.002 μg kg^-1 bw day^-1 for AFB₁, DON, ochratoxin A (OTA), FB₁ and ZEN, respectively. Hazard quotient (HQ) calculated using food data revealed a potential health concern for ZEN in 2nd SP. HQ > 1 based on urinary biomarkers were observed for DON in the two SP. Although OTA was not detected in any food sample, the HQ based on urinary OTA levels was >1 in the 1st SP. Margin of exposure values for AF from food and urine data in the 1st SP were below 10,000, indicating potential health risks.

Effect of water activity and temperature on growth and trichothecene production by Fusarium meridionale

Fusarium meridionale has been frequently isolated from soybean in Argentina and showed similar pathogenicity as F. graminearum sensu stricto. However, no data on their growth and mycotoxin production under different environmental conditions are yet available. The aims of this study were: to determine the effect of temperature, water activity (aW) and strain on growth of F. meridionale and to evaluate deoxynivalenol (DON) and nivalenol (NIV) production in a soybean based medium. The results showed that optimal conditions for F. meridionale growth were at 25 °C and 0.98-0.99 aW. Deoxynivalenol production was favored at 25 °C and 0.96 aW while NIV production was strain-dependent, being 30 °C and 0.98 aW optimal conditions for F. meridionale B2300 strain and 20 °C and 0.98 aW for F. meridionale F5043 and F. meridionale 5048 strains. These conditions are similar to those observed at pre-harvest stage in soybean crop, thus control strategies need to be considered to reduce the risk of the occurrence of DON and NIV in harvested grains.

Fusarium subtropicale, sp. nov., a novel nivalenol mycotoxin-producing species isolated from barley (Hordeum vulgare) in Brazil and sister to F. praegraminearum

Surveys were conducted in commercial wheat and barley fields in the south central production regions of state of Paraná, Brazil, from 2011 to 2015. Spikes displaying visible Fusarium head blight symptoms were collected and the pathogen isolated from the tissues. The 754 Fusarium isolates recovered were identified by a high-throughput multilocus genotyping assay (MLGT) designed to identify trichothecene toxin-producing fusaria (i.e., formerly B-clade, but referred to here as F. sambucinum species complex lineage 1 [FSAMSC-1]) together with sequencing a portion of the translation elongation factor 1-α (TEF1) gene. One strain was discovered that appeared to be closely related to but phylogenetically distinct from F. praegraminearum based on the relatively low 97.7% TEF1 identity and positive genotype obtained with one of the two F. praegraminearum species-specific MLGT probes. Molecular phylogenetic analyses of a 10-gene data set resolved this novel FSAMSC-1 species and F. praegraminearum as sisters. Formally described herein as F. subtropicale, it is phenotypically distinct from the 22 other FSAMSC-1 species in that it produces mostly 1-3-septate macroconidia. Whole-genome sequence data were used to predict its potential to produce mycotoxins. Chemical analyses confirmed that F. subtropicale could produce the mycotoxins 4,15-diacetylnivalenol, butenolide, culmorin, and fusarin C in vitro, and the pathogenicity experiment revealed that F. subtropicale could infect but not spread in susceptible hard red spring wheat cultivar "Norm."

Quantitative Review of the Effects of Triazole and Benzimidazole Fungicides on Fusarium Head Blight and Wheat Yield in Brazil

Triazole and benzimidazole fungicides have been used for controlling Fusarium head blight (FHB) in wheat for over two decades. In Brazil, it was only during the last five years that uniform fungicide trials for FHB control have been established yearly, thus contributing to a new large body of fungicide efficacy data for this country. A systematic review of both peer- and non-peer-reviewed studies on chemical control conducted since 2000 in Brazil was performed. Fungicides of interest were the triazoles tebuconazole (TEBU_1x and TEBU_2x) and propiconazole (PROP_2x), and the benzimidazole carbendazim (CARB_2x). Most fungicides were applied twice, the first at early to mid-flowering and the second 7 to 10 days later. Only TEBU was tested as one or two applications, and thus four treatments were evaluated. For these fungicides, there were 35 trials reporting FHB index and 48 reporting mean yield. Network meta-analytic models were fitted to the data of the log of the means of FHB index for each fungicide and for the nontreated check. The meta-analytic estimates were used to obtain control efficacy ( C¯ ), or percent disease reduction relative to the nontreated check. The absolute mean difference ( D¯ ) in yield (kg/ha) between the fungicide-treated and the nontreated check plots was also estimated. Yield response relative to the nontreated check ( Y¯ ) was also calculated based on the difference in the logs of the means of yield between fungicide-treated and nontreated check. The TEBU_1x, TEBU_2x, and CARB_2x treatments performed similarly with regards to control efficacy (= 59%, 53% and 55%, respectively), and although better than PROP_2x (47%), the difference was marginally significant. Yield response ( D¯ ) was highest for TEBU_2x, ( D¯ = 558 kg/ha, Y¯ = 19.2%) followed by PROP_2x (497 kg/ha, 16.0%), TEBU_1x (457 kg/ha, 17.3%), and CARB_2x (456 kg/ha, 12.8%). For an average 2016 scenario of fungicide plus application costs (F_C = $18 U.S./ha) and average wheat price (W_P = $215 U.S./MT), the probability of breaking even on the financial investment in the four treatments ranged from 59 to 63%. For 140 scenarios (four fungicides) created based on the combination of five W_P ($133 to 266 U.S./MT) and seven F_C ($5 to 35 U.S./ha), the probability of breaking even was >50% for all but two scenarios. The information may serve as a guide for planning future trials and provides a baseline and first step toward optimizing FHB management in Brazil.

Co-occurrence and distribution of deoxynivalenol, nivalenol and zearalenone in wheat from Brazil

Fusarium mycotoxins deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) were investigated in wheat from the 2009 and 2010 crop years. Samples (n = 745) from commercial fields were collected in four wheat producing regions (WPR) which differed in weather conditions. Analyses were performed using HPLC-DAD. Contamination with ZEN, DON and NIV occurred in 56, 86 and 50%, respectively. Also, mean concentrations were different: DON = 1046 µg kg(-1), NIV < 100 µg kg(-1) and ZEN = 82 µg kg(-1). Co-occurrence of ZEN, DON and NIV was observed in 74% of the samples from 2009 and in 12% from 2010. Wet/cold region WPR I had the highest mycotoxin concentration. Wet/moderately hot region WPR II had the lowest mycotoxin levels. Furthermore, the mean concentration of each mycotoxin was higher in samples from 2009 as compared with those from 2010. Precipitation during flowering or harvest periods may explain these results.

Trichothecene Genotypes of the Fusarium graminearum Species Complex Isolated from Brazilian Wheat Grains by Conventional and Quantitative PCR

We compared two well-established methods, fungal isolation followed by conventional PCR and DNA analysis by quantitative PCR (qPCR), to define trichothecene genotypes in Brazilian wheat grains from different locations. For this purpose, after fungal isolation from 75 wheat samples, 100 isolates of the Fusarium graminearum species complex (FGSC) were genotyped by PCR to establish their trichothecene profile. For profiling by qPCR, DNA was extracted from the wheat samples and analyzed. The methods provided similar and divergent results. The FGSC isolates were classified as NIV (55%), 15-ADON (43%), and 3-ADON (2%). Analysis by qPCR showed 100% contamination with 15-ADON strains in all wheat samples, 80% contamination with the NIV genotype, and only 33.3% contamination with 3-ADON strains. Further analysis revealed that 96% of all quantified DNA was attributed to the 15-ADON profile, while 3.4% was attributed to NIV and only 0.06% to 3-ADON. A positive correlation was observed between 15-ADON genotype DNA concentration and deoxynivalenol (DON) content in the wheat samples. The high frequency of fungi, DNA levels and positive correlation with DON strongly indicate that 15-ADON producers are the main trichothecene genotype in Brazilian wheat grains. Surprisingly, although many isolates (55%) carried the NIV genotype and this genotype was identified in 80% of the wheat samples, only 3.4% of fungal DNA was in fact from NIV producers. Although, our findings showed that each method provided a different perspective about the trichothecene profile, DNA analysis by qPCR gave us new insight about fungal contamination levels in Brazilian wheat grains. Nevertheless, both techniques should be used to obtain more robust results.

Toxicokinetics and tissue distribution of nivalenol in broiler chickens

Nivalenol (NIV), a type B trichothecene mycotoxin, is mainly produced by the fungi of Fusarium genus, which naturally occurs in agricultural commodities. Consumers are particularly concerned over the toxicity and safety of NIV in food animal products. To evaluate the toxicokinetics and persistence of residues of NIV, NIV was administered intravenously (iv) or orally (po) to broiler chickens at a dosage of 0.8 mg/kg body weight. The concentration of NIV in the plasma and various tissues was detected using liquid chromatography tandem-mass spectrometry. The plasma concentration of NIV in broilers could be measured up to 24 h and 12 h after iv and po administration, respectively. The value of elimination half-life of NIV was 5.27 ± 0.82 h and 2.51 ± 0.88 h after iv and po administration, respectively. The absolute oral bioavailability was 3.98 ± 0.08%. NIV was detected in the intestine, kidney, muscle, heart and liver after po administration. Regarding tissue residues, largest quantities of NIV were found in the small intestine. These results suggest that NIV is absorbed from the gastrointestinal tract with low bioavailability and it has the ability to diffuse into various tissues of broilers.

Disease Risk, Spatial Patterns, and Incidence-Severity Relationships of Fusarium Head Blight in No-till Spring Wheat Following Maize or Soybean

The first large-scale survey of Fusarium head blight (FHB) in commercial wheat fields in southern Brazil was conducted over three years (2009 to 2011). The objectives were to: (i) evaluate whether increased FHB risk is associated with within-field maize residue; (ii) determine the spatial pattern of FHB incidence; and (iii) quantify the relationship between FHB incidence and severity. FHB was assessed in a total of 160 fields between early milk and dough. Incidence ranged from 1.0 to 89.9% (median = 25%) and severity from 0.02 to 18.6% (median = 1.3%). FHB risk was neither lower nor higher in wheat following maize than in wheat following soybean. Only 18% of fields were classified as having aggregated patterns of FHB-symptomatic spikes. A binary power law description of the variances was consistent with an overall random pattern of the disease. These results conform with the hypothesis that FHB epidemics in southern Brazil are driven by sufficient atmospherically-transported inoculum from regional sources. The incidence-severity relationship was coherent across growing season, growth stage, and previous crop; one common fitted curve described the relationship across all observations. Estimating severity from incidence may be useful in reducing the workload in epidemiological surveys.

Regional and field-specific factors affect the composition of fusarium head blight pathogens in subtropical no-till wheat agroecosystem of Brazil

A multiyear survey of >200 wheat fields in Paraná (PR) and Rio Grande do Sul (RS) states was conducted to assess the extent and distribution of Fusarium graminearum species complex (FGSC) diversity in the southern Brazilian wheat agroecosystem. Five species and three trichothecene genotypes were found among 671 FGSC isolates from Fusarium head blight (FHB)-infected wheat heads: F. graminearum (83%) of the 15-acetyldeoxynivalenol (15-ADON) genotype, F. meridionale (12.8%) and F. asiaticum (0.4%) of the nivalenol (NIV) genotype, and F. cortaderiae (2.5%) and F. austroamericanum (0.9%) with either the NIV or the 3-ADON genotype. Regional differences in FGSC composition were observed, with F. meridionale and the NIV type being significantly (P<0.001) more prevalent in PR (>28%) than in RS (≤9%). Within RS, F. graminearum was overrepresented in fields below 600 m in elevation and in fields with higher levels of FHB incidence (P<0.05). Species composition was not significantly influenced by previous crop or the stage of grain development at sampling. Habitat-specific differences in FGSC composition were evaluated in three fields by characterizing a total of 189 isolates collected from corn stubble, air above the wheat canopy, and symptomatic wheat kernels. Significant differences in FGSC composition were observed among these habitats (P<0.001). Most strikingly, F. meridionale and F. cortaderiae of the NIV genotype accounted for the vast majority (>96%) of isolates from corn stubble, whereas F. graminearum with the 15-ADON genotype was dominant (>84%) among isolates from diseased wheat kernels. Potential differences in pathogenic fitness on wheat were also suggested by a greenhouse competitiveness assay in which F. graminearum was recovered at much higher frequency (>90%) than F. meridionale from four wheat varieties inoculated with an equal mixture of F. graminearum and F. meridionale isolates. Taken together, the data presented here suggest that FGSC composition and, consequently, the trichothecene contamination in wheat grown in southern Brazil is influenced by host adaptation and pathogenic fitness. Evidence that F. meridionale and F. cortaderiae with the NIV genotype are regionally significant contributors to FHB may have significant implications for food safety and the economics of cereal production.

Mycoflora and deoxynivalenol in whole wheat grains (Triticum aestivum L.) from Southern Brazil

The fungal species Fusarium graminearum is related to deoxynivalenol (DON) formation. The aim of this study was to evaluate mycoflora and DON occurrence in 53 whole wheat grain samples collected in Southern Brazil during the 2012 crop. Wheat grains showed adequate values of water activity ranging from 0.48 to 0.72, within the required limits of moisture content, ranging from 9.1% to 13.9%. In addition, low counts of fungal colonies, ranging from 10 to 8.2 × 10(2), were found. For Fusarium genera, there was predominance of Fusarium verticillioides (34%) and F graminearum (30.2%). For Aspergillus species, 37.7% of Aspergillus flavus was determined. Regarding the Penicillium species, Penicillium digitatum (49%) was the most found species. DON was detected in 47.2% (25 out of 53) of the samples analysed, with levels ranging from 243.7 to 2281.3 µg kg(-1) (mean: 641.9 µg kg(-1)).

Natural occurrence of deoxynivalenol and zearalenone in wheat from Jiangsu province, China

A three-year (2010-2012) survey was conducted to assess the prevalence and concentrations of deoxynivalenol (DON) and zearalenone (ZEN) in wheat from several regions of Jiangsu province, China, which are heavily impacted by Fusarium head blight. A total of 180 wheat samples were obtained from the infected fields that spread 21 counties. DON and ZEN levels were determined by liquid chromatography-mass spectrometry (LC-MS/MS). DON was found in 74.4% of samples at levels ranging from 14.52 to 41157.13 μg/kg (mean 488.02 μg/kg), while ZEN was found in 12.8% of samples at levels ranging from 10.13 to 3048.88 μg/kg (mean 73.04 μg/kg). In years and regions of higher rainfall, DON and ZEN levels were higher in samples. These results are necessary to take a vigilant attitude to prevent human intake of trichothecenes and protect human's health from the risk of exposure to these toxins.

Inhibition of Fusarium graminearum growth and mycotoxin production by phenolic extract from Spirulina sp

Fusarium graminearum is a fungal species complex pathogenic occurring worldwide, mainly associated with cereal crops. The most important Fusarium mycotoxins are fumonisins, zearalenone and trichothecenes. The availability of efficient control measures that are less harmful to both the environment and the consumers is urgent. For such, phenolic acids (PAs) from natural sources are known to reduce fungal contaminations. This work aimed to identify the PAs present in a culture extract of Spirulina algae (strain LEB-18) and evaluate its effect on mycelial growth rate, glucosamine level, amylase activity and mycotoxin production by four strains of two lineages of F. graminearum. Results showed that amendment of potato dextrose media with LEB-18 extract (3% w/v), which was mainly composed by gallic acid, greatly reduced radial growth of fungal colonies compared to media containing a single PA and the control. Also, average reductions of 40% and 62% in the glucosamine levels and the amylase activity were observed. In general, the LEB-18 extract and the PAs reduced mycotoxin concentration, with an average reduction of 68% for the trichothecene mycotoxins deoxynivalenol and nivalenol.

Advanced hyphenated chromatographic-mass spectrometry in mycotoxin determination: current status and prospects

Mass spectrometric techniques are essential for advanced research in food safety and environmental monitoring. These fields are important for securing the health of humans and animals, and for ensuring environmental security. Mycotoxins, toxic secondary metabolites of filamentous fungi, are major contaminants of agricultural products, food and feed, biological samples, and the environment as a whole. Mycotoxins can cause cancers, nephritic and hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders. Mycotoxin-contaminated food and feed can provoke trade conflicts, resulting in massive economic losses. Risk assessment of mycotoxin contamination for humans and animals generally depends on clear identification and reliable quantitation in diversified matrices. Pioneering work on mycotoxin quantitation using mass spectrometry (MS) was performed in the early 1970s. Now, unambiguous confirmation and quantitation of mycotoxins can be readily achieved with a variety hyphenated techniques that combine chromatographic separation with MS, including liquid chromatography (LC) or gas chromatography (GC). With the advent of atmospheric pressure ionization, LC-MS has become a routine technique. Recently, the co-occurrence of multiple mycotoxins in the same sample has drawn an increasing amount of attention. Thus, modern analyses must be able to detect and quantitate multiple mycotoxins in a single run. Improvements in tandem MS techniques have been made to achieve this purpose. This review describes the advanced research that has been done regarding mycotoxin determination using hyphenated chromatographic-MS techniques, but is not a full-circle survey of all the literature published on this topic. The present work provides an overview of the various hyphenated chromatographic-MS-based strategies that have been applied to mycotoxin analysis, with a focus on recent developments. The use of chromatographic-MS to measure levels of mycotoxins, including aflatoxins, ochratoxins, patulin, trichothecenes, zearalenone, and fumonisins, is discussed in detail. Both free and masked mycotoxins are included in this review due to different methods of sample preparation. Techniques are described in terms of sample preparation, internal standards, LC/ultra performance LC (UPLC) optimization, and applications and survey. Several future hyphenated MS techniques are discussed as well, including multidimensional chromatography-MS, capillary electrophoresis-MS, and surface plasmon resonance array-MS.

Fungicides and the effects of mycotoxins on milling fractions of irrigated rice

This study aimed to evaluate the effect of fungicides on rice cultivation, regarding the occurrence and the distribution of mycotoxins in fractions of the processed grain, by a validated chromatographic method. A method based on extraction with acetonitrile:water, determination by HPLC-DAD, and confirmation by LC-MS was validated before the mycotoxin evaluation. Control samples and samples to which triazole fungicides had been applied were collected from experimental fields for four years. Results showed that 87% of the samples were contaminated with deoxynivalenol or zearalenone, and that all samples treated with fungicide were contaminated with some of these mycotoxins. Aflatoxin B(1) and ochratoxin A were found in 37% of the samples; half of them had been treated with fungicide. Therefore, fungicides tend to be stressors for toxigenic fungi found in the fields.