Fusarium Species Pathogenic to Barley and Their Associated Mycotoxins

Characterization of Fusarium species causing head blight of highland barley (qingke) in Tibet, China

Most of the research on the characterization of Fusarium species focused on wheat, barley, rice, and maize in China. However, there has been limited research in highland barley (qingke). Recently, Fusarium head blight (FHB) of qingke was recently observed in Tibet, China, especially around the Brahmaputra River. To gain a better understanding of the pathogens involver, 201 Fusarium isolates were obtained from qingke samples in 2020. Among these isolates, the most abundant species was F. avenaceum (45.3 %), followed by F. equiseti (27.8 %), F. verticillioides (13.9 %), F. acuminatum (9.0 %), F. flocciferum (3.5 %), and F. proliferatum (0.5 %). The distribution of Fusarium species varied along the Brahmaputra River, with F. avenaceum being predominant in the midstream and downstream regions, while F. equiseti was more common in the upstream region. Chemical analyses of all the isolates revealed the production of different mycotoxins by various Fusarium species. It was found that enniatins were produced by F. acuminatum, F. avenaceum, and F. flocciferum, beauvericin (BEA) and fumonisins were produced F. proliferatum and F. verticillioides, and zearalenone (ZEN) and nivalenol (NIV) were produced by F. equiseti. Pathogenicity test showed that F. avenaceum was more aggressive in causing FHB compared to F. acuminatum, F. equiseti, and F. flocciferum. The disease severity, measured by the area under the disease progress curve (AUDPC), was significantly positively (P < 0.01) correlated with the concentration of total toxins produced by each species. Furthermore, all the Fusarium strains which were used for pathogenicity test were susceptible to carbendazim, and the 50 % effective concentration (EC50) ranged from 0.406 μg/mL to 0.673 μg/mL with an average EC50 of 0.551 ± 0.012 μg/mL.

Infected grasses as inoculum for Fusarium infestation and mycotoxin accumulation in wheat with and without irrigation

Grasses growing next to agricultural fields influence the Fusarium abundance, the species composition, and the mycotoxin accumulation of wheat plants, especially the field parts directly adjacent to grasses, are highly affected. Grasses are a more attractive and suitable habitat for Fusarium fungi compared to other arable weeds and occur at mostly every semi-natural landscape element (e.g., kettle holes, hedgerows, field-to-field-borders). In our study, we analyzed the ability of a highly Fusarium infected grass stripe (F. graminearum, F. culmorum, F. sporotrichioides) to infect an adjacent wheat field with these species. Results show that the primary inoculated Fusarium species were as well the dominant species isolated from the wheat field. Regarding transects originating from the grass stripe going into the field, the results demonstrate that wheat ears next to the infected grass stripe have a higher Fusarium abundance and furthermore show higher mycotoxin accumulation in the wheat kernels. This effect was highly promoted by irrigation. Therefore, grass stripes next to arable fields must be considered as reservoirs for fungal infections and as a source for a contamination with mycotoxins.

Implications of Crop Rotation and Fungicide on Fusarium and Mycotoxin Spectra in Manitoba Barley, 2017–2019

Fusarium head blight (FHB) is one of the most important diseases of barley in Manitoba province (western Canada), and other major barley producing regions of the world. Little is known about the Fusarium species and mycotoxin spectra associated with FHB of barley in Manitoba. Hence, barley grain samples were collected from 149 commercial fields from 2017 to 2019, along with information on respective cropping history, and analyzed with respect to Fusarium species spectra, abundance, chemotype composition, and mycotoxin profiles. Fusarium poae was the predominant Fusarium species associated with FHB of barley in Manitoba, followed by F. graminearum, and F. sporotrichioides; F. equiseti and F. avenaceum were also detected but at low levels. F. poae strains with the nivalenol (NIV) chemotype and F. graminearum strains with 3-acetyl deoxynivalenol (3-ADON) and 15-acetyl deoxynivalenol (15-ADON) chemotypes were commonly detected in the barley grain samples. Nivalenol (597.7, 219.1, and 412.4 µg kg⁻¹) and deoxynivalenol (DON) (264.7, 56.7, and 65.3 µg kg⁻¹) were the two most prevalent mycotoxins contaminating Manitoba barley in 2017, 2018 and 2019, respectively. A substantially higher DON content was detected in grain samples from barley fields with cereals as a preceding crop compared to canola and flax. Furthermore, F. poae proved less sensitive to four triazole fungicides (metconazole, prothioconazole+tebuconazole, tebuconazole, and prothioconazole) than F. graminearum. Findings from this research will assist barley producers with improved understanding of FHB threat levels and optimizing practices for the best management of FHB in barley.

Host Genotype and Weather Effects on Fusarium Head Blight Severity and Mycotoxin Load in Spring Barley

Epidemiology of Fusarium Head Blight (FHB) of spring barley is relatively little understood. In a five-year study, we assessed quantitative resistance to FHB in an assortment of 17 spring barley genotypes in the field in southern Germany. To this end, we used soil and spray inoculation of plants with F. culmorum and F. avenaceum. This increased disease pressure and provoked genotypic differentiation. To normalize effects of variable weather conditions across consecutive seasons, we used a disease ranking of the genotypes based on quantification of fungal DNA contents and multiple Fusarium toxins in harvested grain. Together, this allowed for assessment of stable quantitative FHB resistance of barley in several genotypes. Fungal DNA contents were positively associated with species-specific Fusarium toxins in single years and over several years in plots with soil inoculation. In those plots, plant height limited FHB; however, this was not observed after spray inoculation. A multiple linear regression model of recorded weather parameter and fungal DNA contents over five years identified time periods during the reproductive phase of barley, in which weather strongly influenced fungal colonization measured in mature barley grain. Environmental conditions before heading and late after anthesis showed strongest associations with F. culmorum DNA in all genotypes, whereas for F. avenaceum, this was less consistent where we observed weather-dependent associations, depending on the genotype. Based on this study, we discuss aspects of practical resistance breeding in barley relevant to improve quantitative resistance to FHB and associated mycotoxin contaminations.

Contamination of Wheat, Barley, and Maize Seeds with Toxigenic Fusarium Species and Their Mycotoxins in Tunisia

Background

Fusarium is a worldwide distributed fungal genus. It includes different species pathogenic to cereals among others crops. Some of these species can also produce toxic compounds toward animals and humans.

Objective

In this work, occurrence of fumonisins B1+B2, zearalenone, type A trichothecenes (T-2 and HT-2 toxins), and type B trichothecenes (deoxynivalenol[DON] and nivalenol[NIV]) was studied in 65 samples of stored and freshly harvested wheat, barley, and maize collected in Tunisia.

Methods

Mycotoxins analyses were performed by using gas chromatography for type B trichothecenes and HPLC for other mycotoxins. Obtained results were compared with the presence of mycotoxigenic species considered responsible for their synthesis by using species-specific polymerase chain reaction (PCR).

Results

Fumonisins occurred in 20.83% of wheat, 40% of barley, and 57.14% of maize samples, at levels exceeding European limits and suggesting a risk in Tunisian cereals, especially maize. Zearalenone, DON, NIV, and T-2+HT-2 toxins were detected at lower values in only wheat and barley samples. PCR protocols showed the predominance of F. verticillioides especially in maize, and occurrence of F. equiseti and F. graminearum in wheat and barley, and F. proliferatum in only two maize samples. A very consistent correlation was found between the detection of F. verticillioides and the contamination by fumonisins, as well as between the presence of F. graminearum and the contamination by zearalenone, DON, and NIV in the analyzed cereals.

Conclusions

Consequently, the detection of Fusarium species with the current PCR assays strategy in wheat, barley, and maize grains may be considered predictive of their potential mycotoxin risk in these matrices.

Highlights

This work is the first to report information on the occurrence of fumonisins, trichothecene, and ZEN, together with their potentially producing Fusarium species in wheat, barley, and maize in Tunisia. The high level of fumonisins in cereals, especially maize, stresses the importance of the control and the regularization of these mycotoxins for food safety.

Multi-(myco)toxins in Malting and Brewing By-Products

Fungi, yeasts, and bacteria are common microorganisms on cereals used in malting and brewing industries. These microorganisms are mostly associated with the safety and quality of malt and beer, but also with the health safety of by-products used in animal nutrition. The real problem is their harmful metabolites-toxins that, due to their thermostable properties, can easily be transferred to malting and brewing by-products. Besides fungal metabolites, other toxins originating from plants can be harmful to animal health. Precise and accurate analytical techniques broadened the spectrum of known toxins originating from microorganisms and plants that can pose a threat to animal health. Multi-(myco)toxin analyses are advanced and useful tools for the assessment of product safety, and legislation should follow up and make some important changes to regulate yet unregulated, but highly occurring, microbial and plant toxins in malting and brewing by-products used for animal feed.

Malting of Fusarium Head Blight-Infected Rye (Secale cereale): Growth of Fusarium graminearum, Trichothecene Production, and the Impact on Malt Quality

This project was initiated with the goal of investigating the malt quality of winter rye cultivars and hybrids grown in the United States in 2014 and 2015, but high levels of deoxynivalenol (DON) were subsequently found in many of the malt samples. DON levels in 75% of the investigated rye samples (n = 117) were actually below 1.0 mg/kg, as quantified by a gas chromatography combined with electron capture detector (GC-ECD). However, 83% of the samples had DON in excess of 1.0 mg/kg following malting, and the average DON level in malted rye was 10.6 mg/kg. In addition, relatively high levels of 3-acetate DON (3-ADON), 15-acetate DON (15-ADON), nivalenol (NIV), and DON-3-glucoside (D3G) were observed in some rye malts. Our results show that rye grain DON is likely a poor predicator of type B trichothecenes in malt in practice, because high levels of malt DON, 15-ADONm and D3G were produced, even when the rye samples with DON levels below 0.50 mg/kg were processed. Fusarium Tri5 DNA content in rye was highly associated with malt DON levels (r = 0.83) in a small subset of samples (n = 55). The impact of Fusarium infection on malt quality was demonstrated by the significant correlations between malt DON levels and wort viscosity, β-glucan content, wort color, wort p-coumaric acid content, and total phenolic content. Additional correlations of rye Fusarium Tri5 DNA contents with malt diastatic power (DP), wort free amino nitrogen (FAN) content, and arabinoxylan content were observed.

Barley RNA viromes in six different geographical regions in Korea

Barley is a kind of cereal grass belonging to the family Poaceae. To examine viruses infecting winter barley in Korea, we carried out a comprehensive study of barley RNA viromes using next-generation sequencing (NGS). A total of 110 barley leaf samples from 17 geographical locations were collected. NGS followed by extensive bioinformatics analyses revealed six different barley viromes: Barley yellow mosaic virus (BaYMV), Barley mild mosaic virus (BaMMV), Barley yellow dwarf virus (BYDV), Hordeum vulgare endornavirus (HvEV), and Barley virus G (BVG). BaYMV and HvEV were identified in all libraries, while other viruses were identified in some specific library. Based on the number of virus-associated reads, BaYMV was a dominant virus infecting winter barley in Korea causing yellow disease symptoms. We obtained nearly complete genomes of six BaYMV isolates and two BaMMV isolates. Phylogenetic analyses indicate that BaYMV and BaMMV were largely grouped based on geographical regions such as Asia and Europe. Single nucleotide polymorphisms analyses suggested that most BaYMV and BaMMV showed strong genetic variations; however, BaYMV isolate Jeonju and BaMMV isolate Gunsan exhibited a few and no SNPs, respectively, suggesting low level of genetic variation. Taken together, this is the first study of barley RNA viromes in Korea.

Fusarium infection and trichothecenes in barley and its comparison with wheat

Barley is a small-grain cereal that can be infected by Fusarium spp. resulting in reduced quality and safety of harvested barley (products). Barley and other small-grain cereals are commonly studied together for Fusarium infection and related mycotoxin contamination, since the infection and its influencing factors are assumed to be the same for all small-grain cereals. Using relevant literature, this study reviewed Fusarium spp. infection and mycotoxin contamination, mainly T-2/HT-2 toxin and deoxynivalenol (DON), in barley specifically. For the first time, review results provide an extensive overview of the influencing factors for Fusarium infection and mycotoxin production in barley, such as weather, agricultural management and processing factors, and includes the comparison of these mechanisms in wheat. Results showed that Fusarium infection in barley is difficult to recognise in the field and mycotoxin levels cannot be estimated based on the symptoms. These factors make it difficult to establish the real severity of Fusarium infection in barley. In addition, most pre-harvest measures to mitigate initial Fusarium infection, such as cultivar use and soil cultivation, are the same for barley and wheat, but due to anatomical differences, some pre-harvest measures have a different effect on Fusarium infection in barley. For example, the effective moment (days after anthesis) of fungicide application in barley and wheat is different. Also, in wheat, there is an additional effect of multiple fungicide applications in reducing Fusarium Head Blight and DON concentrations, whereas in barley, no additional effect of multiple application is seen. Hence, care should be taken to use data from one small-grain cereal to draw conclusions on other small-grain cereals.

Updated survey of Fusarium species and toxins in Finnish cereal grains

The aim of the project was to produce updated information during 2005-14 on the Fusarium species found in Finnish cereal grains, and the toxins produced by them, as the last comprehensive survey study of Fusarium species and their toxins in Finland was carried out at the turn of the 1960s and the 1970s. Another aim was to use the latest molecular and chemical methods to investigate the occurrence and correlation of Fusarium species and their mycotoxins in Finland. The most common Fusarium species found in Finland in the FinMyco project 2005 and 2006 were F. avenaceum, F. culmorum, F. graminearum, F. poae, F. sporotrichioides and F. langsethiae. F. avenaceum was the most dominant species in barley, spring wheat and oat samples. The occurrence of F. culmorum and F. graminearum was high in oats and barley. Infection by Fusarium fungi was the lowest in winter cereal grains. The incidence of Fusarium species in 2005 was much higher than in 2006 due to weather conditions. F. langsethiae has become much more common in Finland since 2001. F. graminearum has also risen in the order of importance. A highly significant correlation was found between Fusarium graminearum DNA and deoxynivalenol (DON) levels in Finnish oats, barley and wheat. When comparing the FinMyco data in 2005-06 with the results of the Finnish safety monitoring programme for 2005-14, spring cereals were noted as being more susceptible to infection by Fusarium fungi and the formation of toxins. The contents of T-2 and HT-2 toxins and the frequency of exceptionally high DON concentrations all increased in Finland during 2005-14. Beauvericin (BEA), enniatins (ENNs) and moniliformin (MON) were also very common contaminants of Finnish grains in 2005-06. Climate change is leading to warmer weather, and this may indicate more changes in Finnish Fusarium mycobiota and toxin contents and profiles in the near future.

Influence of inoculum and climatic factors on the severity of Fusarium head blight in German spring and winter barley

Fusarium head blight (FHB) of small cereals is a disease of global importance with regard to economic losses and mycotoxin contamination harmful to human and animal health. In Germany, FHB is predominantly associated with wheat and F. graminearum is recognised as the major causal agent of the disease, but little is known about FHB of barley. Monitoring of the natural occurrence of FHB on Bavarian barley revealed differences for individual Fusarium spp. in incidence and severity of grain infection between years and between spring and winter barley. Parallel measurement of fungal DNA content in grain and mycotoxin content suggested the importance of F. graminearum in winter barley and of F. langsethiae in spring barley for FHB. The infection success of these two species was associated with certain weather conditions and barley flowering time. Inoculation experiments in the field revealed different effects of five Fusarium spp. on symptom formation, grain yield and mycotoxin production. A significant association between fungal infection of grain and mycotoxin content was observed following natural or artificial infection with the type B trichothecene producer F. culmorum, but not with the type A trichothecene-producing species F. langsethiae and F. sporotrichioides. Trichothecene type A toxin contamination also occurred in the absence of significant damage to grain and did not necessarily promote fungal colonisation.

Breeding healthy cereals: genetic improvement of Fusarium resistance and consequences for mycotoxins

Although it is generally agreed that increased genetic resistance to fungal colonisation by Fusarium head blight (FHB) should lead to reduced damage and particularly to reduced contamination due to mycotoxins, this review aims to highlight on this relation based on published literature in comparison to our own results. We focus here on the major cereal crop plants wheat and barley. Generally, correlations between measures for disease severity on the plants or the seeds and toxin content were found positive and significant. Breeding of new cultivars with reduced Fusarium disease severity will therefore lead to a correlated selection response in the direction of reduced toxin contamination, for the prevalent toxins such as deoxynivalenol, but also for less abundant mycotoxins and masked mycotoxins. Choosing resistant cultivars is possibly the best option for mycotoxin reduction right at the beginning of the cereal production chain: on the farmer’s field. Therefore, investment in breeding FHB resistant cultivars will contribute to sustainable reduction of the mycotoxin problems in the cereal production chain, and increase food and feed safety.

Survey of mycotoxins in corn distillers' dried grains with solubles from seventy-eight ethanol plants in twelve States in the U.S. In 2011

Fuel ethanol co-products known as distillers' dried grains with solubles (DDGS) are a significant source of energy, protein, and phosphorous in animal feed. Fuel ethanol production may concentrate mycotoxins present in corn into DDGS. One hundred and forty one corn DDGS lots collected in 2011 from 78 ethanol plants located in 12 states were screened for the mycotoxins deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), 3-acetyldeoxynivalenol (3-ADON), nivalenol (NIV), and zearalenone (ZON). DON ranged from <0.50 to 14.62 μg g-1, 15-ADON ranged from <0.10 to 7.55 μg g-1, and ZON ranged from <0.10 to 2.12 μg g-1. None of the DDGS lots contained 3-ADON or NIV. Plants in OH had the highest levels of DON overall (mean of 9.51 μg g-1), and plants in NY, MI, IN, NE, and WI had mean DON levels >1 and <4 μg g-1. Twenty six percent (36/141) of the DDGS lots contained 1.0 to 5.0 μg g-1 DON, 2% (3/141) contained >5.0 and <10.0 μg g-1 DON, and 3% (4/141) contained >10.0 μg g-1 DON. All DDGS lots contaminated with unacceptable levels of DON evaded detection prior to their commercial distribution and were likely sold as feed products.

Contamination of barley seeds with Fusarium species and their toxins in Spain: an integrated approach

Fusarium is a globally distributed fungal genus that includes different species pathogenic to cereals among others crops. Some of these Fusarium species can also produce toxic compounds towards animals and humans. In this work, the presence of the most important Fusarium toxins was determined in barley seeds from Spain, sampled according to European Union requirements. The results obtained were compared with the presence of mycotoxigenic species considered responsible for their synthesis by using species-specific polymerase chain reaction protocols. Fumonisins B(1) and B(2), zearalenone, trichothecenes type A (T-2 and HT-2) and trichothecenes type B (deoxynivalenol and nivalenol) were analysed by using high-performance liquid chromatography. Deoxynivalenol and zearalenone were detected in 72% and 38% of the barley samples, respectively, at levels below European Union limits in all cases. However, the co-occurrence of both toxins in 34% of the samples suggested that synergistic activity of these two mycotoxins should be evaluated. Nivalenol and HT-2/T-2 were detected at low levels in 17% and 10% of the samples, respectively. Fumonisins occurred in 34% of the samples at levels up to 300 µg/kg. This suggested that they might represent a risk in Spanish barley, and to our knowledge, this is the first report on the presence of fumonisins in barley in this country. The species-specific polymerase chain reaction assays to detect mycotoxin-producing Fusarium species showed a very consistent correlation between F. verticillioides detection and fumonisin contamination as well as F. graminearum presence and zearalenone, deoxynivalenol and nivalenol contamination in barley samples. The approach used in this study provided information of mycotoxin contamination of barley together with the identification of the fungal species responsible for their production. Detection of the species with the current polymerase chain reaction assay strategy may be considered predictive of the potential mycotoxin risk in this matrix.

Development of Weather-Based Predictive Models for Fusarium Head Blight and Deoxynivalenol Accumulation for Spring Malting Barley

The associations between Fusarium head blight (FHB), caused by Gibberella zeae, and deoxynivalenol (DON) accumulation in spring malting barley (Hordeum vulgare) and hourly weather conditions predictive of DON accumulation were examined using data from six growing seasons in the U.S. Northern Great Plains. Three commonly grown cultivars were planted throughout the region, and FHB disease and DON concentration were recorded. Nine predictor variables were calculated using hourly temperature and relative humidity during the 10 days preceding full head spike emergence. Simple logistic regression models were developed using these predictor variables based on a binary threshold for DON of 0.5 mg/kg. Four of the nine models had sensitivity greater than 80%, and specificity of these models ranged from 67 to 84% (n = 150). The most useful predictor was the joint effect of average hourly temperature and a weighted duration of uninterrupted hours (h) with relative humidity greater than or equal to 90%. The results of this study confirm that FHB incidence is significantly associated with DON accumulation in the grain and that weather conditions prior to full head emergence could be used to accurately predict the risk of economically significant DON accumulation for spring malting barley.

Within-field variation of Fusarium graminearum isolates for aggressiveness and deoxynivalenol production in wheat head blight

Fusarium head blight (FHB), caused by Fusarium graminearum sensu stricto (s.s.), causes tremendous annual yield losses in wheat worldwide. Variation of aggressiveness of isolates from individual field populations in terms of FHB infection and deoxynivalenol (DON) concentration in the host are important population parameters reflecting parasitic ability. Our main objective was to estimate the variation of both traits within three populations of F. graminearum s.s., each consisting of 30 single-spore isolates collected from small wheat fields in Germany, and to compare it with 11 isolates of a collection (F. graminearum collection) from four countries. The same isolates were characterized using 19 single-sequence repeat markers. All isolates were spray inoculated on a moderately resistant spring wheat cultivar at two field locations over 2 years (i.e., in four environments). The genotypic proportion of phenotypic variance (σ(2)(G)) within populations was significant (P < 0.01) for both traits, and the σ(2)(G) × environment interaction was even more important for mean FHB severity. Ranges in mean FHB severity and DON concentration in the host were only slightly smaller for the field populations than for the F. graminearum collection. Both traits were significantly (P < 0.05) correlated within and across populations. A further partitioning of σ(2)(G) revealed 72% of σ(2)(G) within and 28% of σ(2)(G) across populations for both traits. Molecular variance of the three populations was similarly distributed (73.6% within versus 26.4% between populations). In view of this high within-field variation for traits of parasitic ability and selection, neutral molecular markers, multiple resistance genes of different origin should be employed in wheat breeding programs to obtain a long-term stable FHB resistance.

Effect of ozone treatment on the safety and quality of malting barley

Molds and their mycotoxins are an expensive problem for the malting and brewing industries. Deoxynivalenol (DON) is a mycotoxin that is associated with Fusarium spp. These fungi frequently cause Fusarium head blight in wheat and barley in the midwestern region of the United States; Manitoba, Canada; Europe; and China. Barley growers and malt producers would benefit from a postharvest control method for mold growth and DON production. We evaluated the use of gaseous ozone (O(3)) for preventing Fusarium growth and mycotoxin production while maintaining malt quality characteristics. Micromalting was performed in three replications under standard conditions. Ozone treatment was applied to malting barley during steeping via a submerged gas sparger. Ozone treatment conditions were 26 mg/cm(3) for 120 min after 2 and 6 h of steeping. The effects of gaseous ozone on DON, aerobic plate counts, Fusarium infection, and mold and yeast counts of barley throughout the malting process were measured. Various quality parameters of the malt were measured after kilning. Statistical tools were used to determine the significance of all results. Ozonation of malting barley during steeping did not lead to significant reductions in aerobic plate counts but did lead to a 1.5-log reduction in mold and yeast counts in the final malt. The influence of gaseous ozone on DON concentration was inconclusive because of the low initial concentrations of DON in the barley. Ozone significantly reduced Fusarium infection in germinated barley. Gaseous ozone did not negatively influence any aspect of malt quality and may have subtle beneficial effects on diastatic power and β-glucan concentrations.

Trichothecene profiling and population genetic analysis of Gibberella zeae from barley in North Dakota and Minnesota

Gibberella zeae, the principal cause of Fusarium head blight (FHB) of barley, contaminates grains with several mycotoxins, which creates a serious problem for the malting barley industry in the United States, China, and Europe. However, limited studies have been conducted on the trichothecene profiles and population genetic structure of G. zeae isolates collected from barley in the United States. Trichothecene biosynthesis gene (TRI)-based polymerase chain reaction (PCR) assays and 10 variable number tandem repeat (VNTR) markers were used to determine the genetic diversity and compare the trichothecene profiles of an older population (n = 115 isolates) of G. zeae collected in 1997 to 2000 with a newer population (n = 147 isolates) collected in 2008. Samples were from across the major barley-growing regions in North Dakota and Minnesota. The results of TRI-based PCR assays were further validated using a subset of 32 and 28 isolates of G. zeae by sequence analysis and gas chromatography, respectively. TRI-based PCR assays revealed that all the G. zeae isolates in both populations had markers for deoxynivalenol (DON), and the frequencies of isolates with a 3-acetyldeoxynivalenol (3-ADON) marker in the newer population were ≈11-fold higher than those among isolates in the older population. G. zeae populations from barley in the Midwest of the United States showed no spatial structure, and all the isolates were solidly in clade 7 of G. zeae, which is quite different from other barley-growing areas of world, where multiple species of G. zeae are commonly found in close proximity and display spatial structure. VNTR analysis showed high gene diversity (H = 0.82 to 0.83) and genotypic diversity but low linkage disequilibrium (LD = 0.02 to 0.07) in both populations. Low genetic differentiation (F(ST) = 0.013) and high gene flow (Nm = 36.84) was observed between the two populations and among subpopulations within the same population (Nm = 12.77 to 29.97), suggesting that temporal and spatial variations had little influence on population differentiation in the Upper Midwest. Similarly, low F(ST) (0.02) was observed between 3-ADON and 15-acetyldeoxynivalenol populations, indicating minor influence of the chemotype of G. zeae isolates on population subdivision, although there was a rapid increase in the frequencies of isolates with the 3-ADON marker in the Upper Midwest between the older collection made in 1997 to 2000 and the newer collection made in 2008. This study provides information to barley-breeding programs for their selection of isolates of G. zeae for evaluating barley genotypes for resistance to FHB and DON accumulation.

Advances in electronic-nose technologies developed for biomedical applications

The research and development of new electronic-nose applications in the biomedical field has accelerated at a phenomenal rate over the past 25 years. Many innovative e-nose technologies have provided solutions and applications to a wide variety of complex biomedical and healthcare problems. The purposes of this review are to present a comprehensive analysis of past and recent biomedical research findings and developments of electronic-nose sensor technologies, and to identify current and future potential e-nose applications that will continue to advance the effectiveness and efficiency of biomedical treatments and healthcare services for many years. An abundance of electronic-nose applications has been developed for a variety of healthcare sectors including diagnostics, immunology, pathology, patient recovery, pharmacology, physical therapy, physiology, preventative medicine, remote healthcare, and wound and graft healing. Specific biomedical e-nose applications range from uses in biochemical testing, blood-compatibility evaluations, disease diagnoses, and drug delivery to monitoring of metabolic levels, organ dysfunctions, and patient conditions through telemedicine. This paper summarizes the major electronic-nose technologies developed for healthcare and biomedical applications since the late 1980s when electronic aroma detection technologies were first recognized to be potentially useful in providing effective solutions to problems in the healthcare industry.

A native QTL for Fusarium head blight resistance in North American barley (Hordeum vulgare L.) independent of height, maturity, and spike type loci

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe (teleomorph Gibberella zeae (Schwein.) Petch), is one of the major diseases of barley (Hordeum vulgare L.) in eastern China, the Upper Midwest of the USA, and the eastern Prairie Provinces of Canada. To identify quantitative trait loci (QTL) controlling FHB resistance, a recombinant inbred line population (F6:7) was developed from the cross Zhenongda 7/PI 643302. The population was phenotyped for resistance to FHB in two experiments in China and four experiments in North Dakota. Accumulation of the mycotoxin deoxynivalenol was determined in one experiment in China and two in North Dakota. Simplified composite interval mapping was performed on the whole genome level using the software MQTL. The QTL FHB-2 from PI 643302 for FHB resistance was found on the distal portion of chromosome 2HL in all six FHB screening environments. This QTL accounted for 14% of phenotypic variation over six environments and was not associated with heading date or plant height. The FHB resistance QTL FHB-2 detected near the end of chromosome 2HL is in a different location from those found previously and is therefore probably unique. Because the QTL was not contributed by the Chinese cultivar Zhenongda 7, it is likely a native QTL present in North American barley. The QTL FHB-2 represents the first reported QTL for native FHB resistance in North American germ plasm and has been given the provisional name Qrgz-2H-14. This QTL should be considered for pyramiding with other FHB QTL previously mapped.

Doehlert matrix design for optimization of the determination of bound deoxynivalenol in barley grain with trifluoroacetic acid (TFA)

Fusarium head blight (FHB) is an impediment to barley production in many regions of the world. Tricothecene toxins, associated with FHB-infected grain, particularly, deoxynivalenol (DON), pose a serious threat to human and animal health. Recent research has suggested that a portion of the DON present on grain is bound and escapes detection through conventional determination. The objective of this study was to optimize a method for determination of nonextractable DON in barley grain using trifluoroacetic acid (TFA). A Doehlert matrix design was performed to determine the optimal conditions for time, temperature, and TFA concentration. These conditions were treated with 1.25 N TFA in 86:14 acetontrile/water for 54 min at 133 degrees C. Cleanup, derivatization, and determination of DON by a gas chromatography electron capture detector (GC-ECD) was as normal. Treatment of the test sample resulted in the release of an additional 58% DON under the optimized conditions and an increase of 9-88% in a set of verification samples.

Effect of Extended Irrigation and Host Resistance on Deoxynivalenol Accumulation in Fusarium-Infected Wheat

Deoxynivalenol (DON) levels are not easily predicted from visual disease assessment, and it is thought likely that environmental conditions such as temperature and moisture influence DON accumulation. This field study examined the influence of environmental moisture on DON accumulation in Fusarium-infected wheat (Triticum aestivum). The effect of extended mist irrigation applied from inoculation (at anthesis) until harvest was compared with mist irrigation applied from inoculation until disease assessment (at early dough), as is generally applied in screening nurseries used for germplasm selection and cultivar improvement. DON concentrations were quantified in kernels at early dough, hard dough, kernel hard, and maturity. Kernels from plots with extended mist irrigation generally had lower DON concentrations than those from plots where mist irrigation was not applied following disease assessment. DON concentrations tended to decrease from disease assessment until harvest, regardless of the irrigation treatment. DON concentrations in the cultivars moderately resistant to Fusarium head blight were lower than those in the susceptible cultivar. Environmental moisture is an important factor determining the DON content of Fusarium-infected wheat.

Population Subdivision of Fusarium graminearum Sensu Stricto in the Upper Midwestern United States

ABSTRACT A collection of 712 Fusarium graminearum sensu stricto (s.s.) strains, predominantly gathered between 1999 and 2000 from nine states within the United States, was examined for population structure and polymerase chain reaction-based trichothecene type. Most strains belonged to a cohesive genetic population characterized by a 15-acetyldeoxynivalenol (15ADON) trichothecene type. However, using a Bayesian model-based clustering method, we also identified genetically divergent groups of strains in some sampled locations of Minnesota and North Dakota. Strains of the major group of divergent populations were of a 3ADON trichothecene type and formed a distinct cluster with a collection of previously gathered strains from Italy, which displayed all three trichothecene types (15ADON, 3ADON, and nivalenol). The co-existence of genetically divergent populations of F. graminearum s.s. in the Upper Midwest allows for the rejection of the hypothesis that F. graminearum s.s. in the United States consists of a single population. These results also suggest that recombination has been insufficiently frequent in this homothallic (selfing) fungal species to homogenize the divergent populations observed in the Upper Midwest.

Effect of infection timing on fusarium head blight and mycotoxin accumulation in open- and closed-flowering barley

ABSTRACT Barley has two flowering types, chasmogamous (open-flowering) and cleistogamous (closed-flowering). We examined the effect of the timing of Fusarium graminearum infection on Fusarium head blight (FHB) and mycotoxin accumulation in barley cultivars with different flowering types using greenhouse experiments. In the first experiment, 13 cultivars were spray inoculated at two different developmental stages, and the severity of FHB was evaluated. The effect of the timing of infection differed among cultivars. Cleistogamous cultivars were resistant at anthesis but susceptible at 10 days after anthesis, whereas chasmogamous cultivars were already susceptible at anthesis. In the second experiment, five cultivars were inoculated at three different developmental stages and the concentrations of deoxynivalenol (DON) and nivalenol (NIV) in mature grain were analyzed. Cleistogamous cultivars accumulated more mycotoxins (DON and NIV) when inoculated 10 or 20 days after anthesis than when inoculated at anthesis, whereas chasmogamous cultivars accumulated more mycotoxins when inoculated at anthesis. Thus, the most critical time for F. graminearum infection and mycotoxin accumulation in barley differs with cultivar, and likely is associated with the flowering type. Late infection, even without accompanied FHB symptoms, was also significant in terms of the risk of mycotoxin contamination.

Changes in fungi and mycotoxins in pearl millet under controlled storage conditions

Pearl millet is increasingly being grown as a premium-value grain for the recreational wildlife and poultry industries in the southern US. We conducted three experiments to assess grain mold development in storage conditions typically encountered in the region of production. Variables included production year, temperature, relative humidity, atmosphere, and grain moisture content. In the first experiment, grain was stored for 9 weeks at 20 or 25 degrees C and maintained at 86% or 91% relative humidity (r.h.). In the second experiment, grain was stored for 9 weeks at 20 or 25 degrees C in either air (aerobic) or N2 (anaerobic), and maintained at 100% r.h. In the third experiment, high-moisture grain was stored for 3 weeks at 20 or 25 degrees C and maintained at 100% r.h. Grain was sampled at weekly intervals and plated to determine changes in fungal frequency. Fungi isolated included Fusarium chlamydosporum (19% of grain), Curvularia spp. (14%), F. semitectum (16%), Alternaria spp. (9%), Aspergillus flavus (8%), "Helminthosporium"-type spp. (6%), and F. moniliforme sensu lato (3%). Year of grain production significantly affected isolation frequency of fungi. Isolation frequencies from low-moisture grain were rarely affected by temperature, relative humidity, or atmosphere treatments, but was affected by storage duration for some fungi. Changes in isolation of toxigenic fungi occurred in high-moisture grain. Isolation frequency of F. chlamydosporum increased in grain stored at 86% and 91% r.h. Incidence of A. flavus increased in high-moisture grain treatments, particularly at 25 degrees C. Incidence of deoxynivalenol was not affected by storage treatment. Low concentrations of nivalenol were detected in most grain incubated at 100% r.h. Zearalenone was detected only when grain moisture content was 20-22%. Aflatoxin contamination averaged 174 ng g(-1) over all treatments, and increased up to 798 ng g(-1) in high-moisture grain at stored at 25 degrees C.

Resistance of Sharon Goatgrass (Aegilops sharonensis) to Fungal Diseases of Wheat

Sharon goatgrass (Aegilops sharonensis) is a wild relative of wheat that is native to Israel and Lebanon. The importance of A. sharonensis as a source of new resistance genes for wheat warrants additional research on the characterization of accessions for economically important genes. Thus, the objectives of this study were to evaluate a collection of A. sharonensis accessions for resistance to seven important fungal diseases of wheat and assess the phenotypic diversity of the germplasm for disease reaction. The frequency of resistance in A. sharonensis was highest to powdery mildew (79 to 83%) and leaf rust (60 to 77%). Resistance to stem rust also was common, although the percentage of resistant accessions varied markedly depending on the pathogen race-from 13% to race TTTT to 72% to race QCCJ. The frequency of resistance was intermediate to stripe rust (45%) and low to tan spot (15 to 29%) and spot blotch (0 to 34%). None of the A. sharonensis accessions was resistant to Fusarium head blight. Many of the accessions tested exhibited heterogeneous reactions (i.e., had both resistant and susceptible plants) to one or more of the diseases, suggesting that heterozygosity may be present at some resistance loci. Substantial variation was observed in the level of diversity to individual diseases because Shannon's Equitability index ranged from 0.116 (for Fusarium head blight) to 0.994 (for tan spot). A high level of diversity was found both between and within collection sites. Moreover, differences in the geographic distribution of resistant accessions were observed. For example, accessions from northern Israel generally were less diverse and less resistant to leaf rust and stripe rust than accessions from more southern locations. Four A. sharonensis accessions were highly resistant to most of the diseases evaluated and may provide a source of unique resistance genes for introgression into cultivated wheat.

Epidemiology of Fusarium head blight on small-grain cereals

Fusarium head blight (FHB) is one of the most serious diseases affecting wheat and barley worldwide. It is caused by Fusarium graminearum along with F. culmorum, F. avenaceum and other related fungi. These fungi also produce several mycotoxins. Though the disease results in reduced seed quality and yield, the toxins which may accompany the disease are often a more serious problem. Pathogen inoculum is usually very abundant, however production and dispersal of inoculum are weather-sensitive processes. An abundance of colonized substrate (i.e. maize or cereal debris) in a region contributes to airborne inoculum throughout the area. Local residues beneath the cereal crop (i.e. from previous crop) may have a less obvious effect, particularly in regions where long-distance dispersal is likely due to wind conditions. The host is most susceptible to infection at anthesis and shortly thereafter. A warm, moist environment characterized by frequent precipitation or heavy dew is highly favorable to fungal growth, infection and development of disease in head tissues. As the fungus grows, it produces mycotoxins which are water-soluble and may be translocated between tissues or leeched from source tissues. Important epidemiological issues have arisen recently and include an apparent shift in prevalence of Fusarium species on infected heads in Europe toward F. graminearum; and the presence of multiple chemotypes and aggressiveness variants within a species in a region.

Fusarium toxins of the scirpentriol subgroup: a review

Scirpentriol and its seven acetylated derivatives comprise a family of type-A trichothecene toxins produced by several species of Fusarium fungi. Out of this group 4,15-diacetoxyscirpenol has attracted most attention. It elicits toxic responses in several species and was detected in a variety of substrates. Out of the three possible monoacetylated derivatives 15-monoacetoxyscirpenol and the parent alcohol scirpentriol received some attention, whereas the remaining members of the family were mentioned in few reports. The present review deals with the structure, biosynthesis, analysis and toxicity of scirpentriol toxins. Formation by Fusarium species as well as culture conditions used for toxigenicity studies are reviewed; data about the natural occurrence of scirpentriol toxins in different cereal types, cereal associated products as well as in non-grain matrices including potato and soya bean are reported. Basing on literature reports about the toxicity of scirpentriol toxins an attempt is made to summarise the state of knowledge for risk evaluation for human and animal health.