Fusarium langsethiae – a HT‐2 and T‐2 Toxins Producer that Needs More Attention

Fusarium langsethiae is a toxigenic fungus that was formally described as a new species in 2004. This fungus was first detailed in the 1990s but was initially referred to as ‘powdery Fusarium poae’ having a spore morphology similar to F. poae but a mycotoxin profile like that of Fusarium sporotrichioides. The species has been isolated from infected oat, wheat and barley grains but has been reported as more problematic in the former crop rather than the latter two. Whilst the epidemiology of F. langsethiae remains unclear, the fungus has been shown to produce high levels of type‐A trichothecenes HT‐2 and T‐2 toxins in small‐grain cereals. HT‐2 and T‐2 toxins are two of the most potent trichothecenes capable of inhibiting protein synthesis in eukaryotes. In this regard, mycotoxin contamination caused by F. langsethiae is clearly a food and feed safety hazard. With the European Commission considering legislation of HT‐2 and T‐2 toxins, more information is required not only on the producer and conditions favouring mycotoxin production, but also on reliable methods of pathogen detection and reduction of cereal contamination. This review describes recent research concerning the known epidemiology of F. langsethiae and suggestions of what needs to be known about the fungus in order to be able to understand and employ measures for preventing its infection and contamination of cereals with HT‐2 and T‐2 toxins.     

A Survey Investigating the Infection of Fusarium langsethiae and Production of HT‐2 and T‐2 Mycotoxins in UK Oat Fields

Fusarium langsethiae is a toxigenic fungal species that has been reported in European small‐grain cereal crops such as oats, wheat and barley. Although its relative contribution to fusarium head blight (FHB) symptoms is not well understood, it is reported to contaminate these cereals with high levels of HT‐2 and T‐2 trichothecenes mycotoxins that are currently under consideration for legislation by the European Commission. Ten commercial oat fields in Shropshire and Staffordshire (two adjacent counties in the Midlands) in the UK were surveyed in the 2006/2007 growing season. Samples were taken from predetermined field locations at Zadoks growth stages 32/33, 69, 77‐85 and 90‐92 for F. langsethiae biomass and HT‐2 and T‐2 toxins quantification. The results from this study showed that oats can be heavily infected with F. langsethiae and have high concentrations of HT‐2 and T‐2 toxins with no apparent FHB symptoms. The regression of HT‐2 + T‐2 toxins on F. langsethiae DNA concentration was highly significant (P < 0.001, r² = 0.55). The results indicated that although F. langsethiae had no direct effect on crop yield, it may result in indirect economic losses where the grain can be rejected or downgraded as a result of intolerable levels of HT‐2 and T‐2 toxins, which are of human food and animal feed safety concern. The influence of cultural field practices on the infection and HT‐2 and T‐2 toxins accumulation in oats was not clear and warrants further studies to identify the sources of F. langsethiae inoculum and conditions favourable for infection and mycotoxin production.     

Mycotoxin production of <Emphasis Type="Italic">Fusarium langsethiae</Emphasis> and <Emphasis Type="Italic">Fusarium sporotrichioides</Emphasis> on cereal-based substrates

The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cereal-flour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography–tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cereal-based assays but was more predominant on the carbohydrate-rich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000 μg/kg after 7 days’ incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.     

Study of the Vapor Phase Over Fusarium Fungi Cultured on Various Substrates

The compositions of volatile organic compounds (VOCs) emitted by Fusarium fungi (F. langsethiae, F. sibiricum, F. poae, and F. sporotrichioides) grown on two nutritive substrates: potato sucrose agar (PSA) and autoclaved wheat kernels (WK) were investigated. The culturing of fungi and study of their VOC emissions were performed in chromatographic vials at room temperature (23 – 24 °C) and the VOCs were sampled by a solid‐phase microextraction on a 85 μm carboxen/polydimethylsiloxane fiber. GC/MS was performed using a 60‐m HP‐5 capillary column. Components of the VOC mixture were identified by electron impact mass spectra and chromatographic retention indices (RIs). The most abundant components of the VOC mixture emitted by Fusarium fungi are EtOH, AcOH, ⁱBuOH, 3‐methylbutan‐1‐ol, 2‐methylbutan‐1‐ol, ethyl 3‐methylbutanoate, terpenes with M 136, sesquiterpenes with M 204 (a total of about 25), and trichodiene. It was found that the strains grown on PSA emit a wider spectrum and larger amount of VOCs compared with those grown on wheat kernels. F. langsethiae strain is the most active VOC producer on both substrates. The use of SPME and GC/MS also offers the potential for differentiation of fungal species and strains.     

Identification and Genetic Division of Fusarium graminearum and Fusarium asiaticum by Species‐Specific SCAR Markers

Fusarium head blight (FHB), also called scab, is a devastating and insidious disease of cereals including wheat (Triticum spp.) and barley (Hordeum vulgare L.) worldwide. Apart from direct yield losses, the most serious concern about FHB is the contamination of the crop with mycotoxins, which pose a health risk to human and livestock. Recent research reported that phylogenetic species F. asiaticum (Fa) and F. graminearum (Fg) were the major causal agents of FHB from infected wheat heads in China. To investigate the population structure of Fusarium species in China by species‐specific as well as the chemotype‐specific markers, sequence‐related amplified polymorphism (SRAP) markers were screened on representative isolates of F. asiaticum‐NIV, F. asiaticum‐ 3ADON and F. graminearum‐15ADON to find amplification products characteristic of either species or chemotypes. Selected amplified fragments were cloned and sequenced so that sequence‐characterized amplified region (SCAR) primer pairs could be developed which permit specific detection of Fusarium species using conventional PCR. Primer pairs SCAR‐Fa1 and SCAR‐Fg1 were confirmed to be able to amplify specific products only in F. asiaticum and F. graminearum isolates, respectively. These species‐specific primers were applied to determine genetic division of F. asiaticum and F. graminearum isolates collected in Yangtze–Huaihe valley. The results indicated that F. asiaticum was the predominant species causing FHB in this wheat production area. It is the first report that SRAP markers were adapted for species characterization in Fusarium isolates.     

SRAP as an Informative Molecular Marker to Study the Fusarium poae Genetic Variability

Fusarium poae is one of the Fusarium species isolated from grains associated with Fusarium head blight (FHB), whose occurrence has increased in the last years. In this study, a total of 105 F. poae isolates from Argentina, Belgium, Canada, England, Finland, France, Germany, Hungary, Italy, Luxembourg, Poland, Switzerland and Uruguay were evaluated using sequence‐related amplified polymorphism (SRAP) to analyse the capacity of this molecular marker to evaluate the F. poae genetic variability. The molecular analysis showed high intraspecific variability within F. poae isolates, and a partial relationship was revealed between variability and the host/geographic origin. Analysis of molecular variance (amova ) indicated a high genetic variability in the F. poae collection, with most of the genetic variability resulting from differences within, rather than between American and European populations. The analysis of sequenced SRAP fragments targets into hypothetical proteins from different Fusarium species showing that the SRAP technique not only allows studying F. poae genetic variability, but also targets coding regions into the F. poae genome. To our knowledge, this is the first report on genetic variability of F. poae using SRAP technique and also demonstrates the efficacy of this molecular marker to amplify open reading frames in fungus.     

Diversity of Fusarium Species Isolated from Weeds and Plant Debris in Croatia

Weeds are alternative hosts of plant pathogens and when colonized may not exhibit disease symptoms. In 2008 and 2009, samples of weeds and plant debris were collected from 12 locations in eastern Croatia, and 300 Fusarium isolates colonizing them were identified. Strains were grouped and identified based on morphology and amplified fragment length polymorphism (AFLP) patterns. Portions of the β‐tubulin and translocation elongation factor 1‐α genes were sequenced from representative strains of each group to confirm the identifications. Fourteen Fusarium species were identified with F. graminearum (20%), F. verticillioides (18%), F. oxysporum (16%), F. subglutinans (13%) and F. proliferatum (11%) all present as more than 10% of the population. Fusarium acuminatum, F. avenaceum, F. concolor, F. crookwellense (F. cerealis), F. equiseti, F. semitectum, F. solani, F. sporotrichioides and F. venenatum, were all present at frequencies < 8%. Our results indicate that economically important Fusarium spp. may be isolated from numerous alternative hosts during the off season and that weeds and plant debris can serve as a reservoir of genetically diverse inoculum.     

Competitive Aggressiveness in Binary Mixtures of Fusarium graminearum and F. culmorum Isolates Inoculated on Spring Wheat with Highly Effective Resistance QTL

Fusarium head blight (FHB) caused by Fusarium graminearum and F. culmorum is a devastating disease with high effects on grain yield and quality. We developed spring wheat lines incorporating the highly effective FHB resistance quantitative trait loci (QTL) Fhb1 and Qfhs.ifa‐5A. Whether these QTL lead to competition within Fusarium populations in the field resulting in isolates with higher aggressiveness has not been analysed. The aims of this study were to determine (i) the aggressiveness potential of F. graminearum and F. culmorum isolates, (ii) competition effects of these isolates in binary mixtures and (iii) the stability of resistant hosts. Six F. graminearum, two F. culmorum isolates and seven binary mixtures containing these isolates were tested for their aggressiveness and mycotoxin production at two locations in South Germany in 2007 and 2008. Host lines were four spring wheat lines containing the resistance QTL Fhb1 and/or Qfhs.ifa‐5A or none of them and one standard variety. Re‐isolates were sampled from plots inoculated with the binary mixtures to identify the percentage of each isolate in the mixture by simple sequence repeat markers. Resistant host lines reacted as expected and had a high stability to all isolates and mixtures. Only less important host × mixture interactions were detected. Aggressiveness among isolates and mixtures was significantly different. Type and amount of mycotoxin and high single isolate aggressiveness were not necessarily advantageous in the mixture. However, both F. culmorum isolates outcompeted F. graminearum isolates. Significant deviations from the inoculated 1 : 1 proportions occurred in 34 of 49 cases, illustrating that competition effects appeared in the mixtures. These differences depended mainly on the year and not on the level of host resistance. We conclude that resistance should not be affected by the Fusarium isolates and mixtures.     

Characterization of Fusarium spp. associated with pineapple fruit rot and leaf spot in Peninsular Malaysia

Pineapple (Ananas comosus) is one the important fruit crops planted in Malaysia, and this study was conducted to determine Fusarium spp. associated with diseases of the fruit crop as Fusarium is prevalent in tropical countries. Our objective was to identify and characterize Fusarium spp. associated with pineapple fruit rot and leaf spot mainly found on the fruits and leaves in Peninsular Malaysia. Fusarium isolates (n = 108) associated with pineapple fruit rot and leaf spot were characterized by morphological, molecular and phylogenetic analyses, a mating study and pathogenicity testing. TEF‐1α sequence analysis identified Fusarium proliferatum, Fusarium verticillioides, Fusarium sacchari and Fusarium sp. Mating was successful only between tester strains of F. proliferatum and F. verticillioides. Sexual crosses with standard tester strains showed that 82 isolates of F. proliferatum produced fertile crosses with mating population D (Gibberella intermedia) and three isolates of F. verticillioides were fertile with the tester strain of mating population A (Gibberella moniliformis). All isolates were pathogenic, causing pineapple fruit rot and leaf spot, thus fulfilling Koch's postulates.     

Structural and functional characterization of TRI3 trichothecene 15‐O‐acetyltransferase from Fusarium sporotrichioides

Fusarium head blight is a devastating disease of cereal crops whose worldwide incidence is increasing and at present there is no satisfactory way of combating this pathogen or its associated toxins. There is a wide variety of trichothecene mycotoxins and they all contain a 12,13‐epoxytrichothecene skeleton but differ in their substitutions. Indeed, there is considerable variation in the toxin profile across the numerous Fusarium species that has been ascribed to differences in the presence or absence of biosynthetic enzymes and their relative activity. This article addresses the source of differences in acetylation at the C15 position of the trichothecene molecule. Here, we present the in vitro structural and biochemical characterization of TRI3, a 15‐O‐trichothecene acetyltransferase isolated from F. sporotrichioides and the “in vivo” characterization of Δtri3 mutants of deoxynivalenol (DON) producing F. graminearum strains. A kinetic analysis shows that TRI3 is an efficient enzyme with the native substrate, 15‐decalonectrin, but is inactive with either DON or nivalenol. The structure of TRI3 complexed with 15‐decalonectrin provides an explanation for this specificity and shows that Tri3 and Tri101 (3‐O‐trichothecene acetyltransferase) are evolutionarily related. The active site residues are conserved across all sequences for TRI3 orthologs, suggesting that differences in acetylation at C15 are not due to differences in Tri3. The tri3 deletion mutant shows that acetylation at C15 is required for DON biosynthesis even though DON lacks a C15 acetyl group. The enzyme(s) responsible for deacetylation at the 15 position of the trichothecene mycotoxins have not been identified.     

Seasonal variations of Fusarium species in wheat fields in Upper Egypt

Abstract

Populations of the genus Fusarium in wheat fields were studied within the crop-growing season at Qena area (Upper Egypt) using two different types of media (DCPA and DRBA) at 25°C. Fourteen Fusarium species were isolated during this study, namely F. anthophilum, F. aquaeductuum, F. chlamdosporum, F. dimerum, F. merismoides, F. moniliforme, F. oxysporum, F. poae, F. proliferatum, F. sambucinum, F. scripi, F. solani, F. sporotrichioides and F. subglutinans. Fusarium merismoides, F. oxysporum and F. sambucinum were the most common Fusarium species isolated from different wheat plant parts (rhizosphere and rhizoplane) as well as from the wheat fields (soil and air). Fusarium spp. rarely appeared at the beginning of the season and increased sharply between January to March and decreased slightly or sharply at the end of the season according to the type of media and isolation source.     

Production of T-2 toxin by a Fusarium resembling Fusarium poae

A Fusarium species with a micro morphology similar to F. poae and a metabolite profile resembling that of F. sporotrichioides has been identified. Like typical F. poae, the microconidia have a globose to pyriform shape, but the powdery appearance, especially on Czapek-Dox Iprodione Dichloran agar (CZID), less aerial mycelium and the lack of fruity odour on Potato Sucrose Agar (PSA) make it different from F. poae. The lack of macroconidia, polyphialides and chlamydospores differentiates it from F. sporotrichioides. All 18 isolates investigated, 15 Norwegian, two Austrian and one Dutch, produced T-2 toxin (25–400 μg/g) on PSA or Yeast Extract Sucrose agar (YES). In addition, neosolaniol, iso-neosolaniol, HT-2 toxin, 4- and 15-acetyl T-2 tetraol, T-2 triol and T-2 tetraol and4,15-diacetoxyscirpenol were formed in variable amounts. Neither nivalenol, 4- or 15-acetylnivalenolor 4,15-diacetylnivalenol were detected in any of the cultures, while these toxins were produced at least in small amounts by all the 12 typical F. poae isolates studied. The question of whether this Fusarium should be classified as F. poae or F. sporotrichioides or a separate taxon should be addressed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Guava Decline: A Complex Disease Involving Meloidogyne mayaguensis and Fusarium solani

In Brazil, Meloidogyne mayaguensis has become a threat to guava production. Approximately a third of the cultivated area is infested, leading almost inevitably to the decimation of the orchards. Because parasitized trees develop rotten roots as the disease progresses, the possibility that a soil‐borne pathogen could be involved was investigated. From several nematode‐free or nematode‐infested orchards, nearly 2000 root fragments were tested for bacteria and fungi. Positive isolations were obtained from nematode‐infested areas only and were predominantly identified as Fusarium sp. In a 5‐month microplot experiment, guava seedlings were uninoculated (control) or were inoculated with M. mayaguensis only or with this nematode and 21 days later with one of 11 Fusarium sp. isolates. A Scott–Knot analysis of several vegetative variables and of the extent of root rot allowed the generation of a dissimilarity dendrogram that indicated that four Fusarium sp. isolates were particularly associated with damage to the seedlings. Upon identification of these isolates as Fusarium solani, a 6‐month microplot experiment was set up, in which guava seedlings were uninoculated or were inoculated with one of the following: (i) M. mayaguensis only, (ii) four F. solani isolates, separately, (iii) four F. solani isolates separately, combined with physical injury of the roots with a knife, (iv) M. mayaguensis, and 21 days later with four F. solani isolates, separately. No root rot and virtually no effect on all variables were observed in the seedlings inoculated with the fungus isolates, with or without physical injury. Major root rot and a negative effect on all variables were observed in the seedlings inoculated with M. mayaguensis and all four F. solani isolates. This characterizes guava decline as a complex disease caused by the synergistic effect of these organisms, in which parasitism by the nematode predisposes the plants to root decay caused by the fungus.     

Coconut malformation: An emerging disease caused by Fusarium proliferatum in southern Iran

Symptoms of vegetative malformation were observed on coconut palms (Cocos nucifera L.) in the Qeshm Island, Bandar Abbas and Minab, in Hormozgan province, southern Iran. The symptoms included misshapen and dwarfed leaves with shortened, thickened and tightened leaflets in wavy and zigzag form. The aim of this study was to identify the causal pathogen of coconut palm malformation and complete Koch's postulates for putative pathogen. Small pieces of surface‐disinfested malformed vegetative tissues of coconut palms were cultured on potato dextrose agar (PDA) medium. Fusarium isolates were permanently obtained from the symptomatic tissues. Sequence data from the internal transcribed spacer region (ITS1–5.8S‐ITS2) and translation elongation factor 1 alpha (TEF‐1α) gene were used for molecular identification of the isolates. BLAST search of the sequences showed 99%–100% identity to several Fusarium proliferatum strains in the GenBank, FUSARIUM‐ID and Fusarium MLST databases. A phylogeny inferred using individual sequence data from ITS region and TEF‐1α gene placed our isolates together with the other F. proliferatum sequences retrieved from the GenBank. Pathogenicity tests were carried out using one‐year‐old healthy coconut palm seedlings and conidial suspensions (10⁶ conidia/ml) of the F. proliferatum isolates. The first visible symptoms appeared on newly produced leaves of the inoculated seedlings during the 16th week after inoculation, wherease no disease symptoms were observed on the control plants until the end of the experiment. Reisolation from symptomatic tissues of the inoculated seedlings yielded isolates of F. proliferatum with morphological and molecular characteristics identical to those of the isolates used for inoculations. This is the first report of coconut palm malformation caused by F. proliferatum worldwide.     

Morphological and Molecular Characterization of Fusarium Isolated From Maize in Syria

Maize is the third most important cereal after wheat and barley in Syria. Maize plants are attacked by several Fusarium species causing mainly stalk and ear rot of maize which poses a major impact worldwide. Identification of Fusarium species is important for disease control and for assessment of exposure risk to mycotoxines. To identify Fusarium species attacking maize in Syria, a total of 32 Fusarium isolates were recovered from maize ears collected from four different geographical regions, mainly from Ghouta surrounding Damascus. Fusarium isolates were identified based on morphology and on partial DNA sequencing of the TEF1‐α and rDNA/ITS genes. The majority (26 of 32) of these isolates was identified as F. verticillioides (subdivided into four groups), whereas three isolates turned out to be F. thapsinum, F. equiseti and F. andiyazi. The remaining three isolates were close to F. andiyazi, although further investigation is needed to confirm whether they represent a yet undescribed species. Furthermore, our results showed that sequencing the TEF1‐α gene is much more informative than sequencing of the rDNA/ITS region for Fusarium identification at the species level. PCR analysis showed that only F. verticillioides isolates were potentially fumonisin producers and that only the F. equiseti isolate was potentially trichotecene producer. This is the first report on Fusarium thapsinum, F. equiseti and F. andiyazi attacking maize in Syria.     

Isolates of Fusarium graminearum collected 40–320?meters above ground level cause Fusarium head blight in wheat and produce trichothecene mycotoxins

The aerobiology of fungi in the genus Fusarium is poorly understood. Many species of Fusarium are important pathogens of plants and animals and some produce dangerous secondary metabolites known as mycotoxins. In 2006 and 2007, autonomous unmanned aerial vehicles (UAVs) were used to collect Fusarium 40–320 m above the ground at the Kentland Farm in Blacksburg, Virginia. Eleven single-spored isolates of Fusarium graminearum (sexual stage Gibberella zeae) collected with autonomous UAVs during fall, winter, spring, and summer months caused Fusarium head blight on a susceptible cultivar of spring wheat. Trichothecene genotypes were determined for all 11 of the isolates; nine isolates were DON/15ADON, one isolate was DON/3ADON, and one isolate was NIV. All of the isolates produced trichothecene mycotoxins in planta consistent with their trichothecene genotypes. To our knowledge, this is the first report of a NIV isolate of F. graminearum in Virginia, and DON/3ADON genotypes are rare in populations of the fungus recovered from infected wheat plants in the eastern United States. Our data are considered in the context of a new aerobiological framework based on atmospheric transport barriers, which are Lagrangian coherent structures present in the mesoscale atmospheric flow. This framework aims to improve our understanding of population shifts of F. graminearum and develop new paradigms that may link field and atmospheric populations of toxigenic Fusarium spp. in the future.     

The effect of toxin-producing Fusarium fungi on behavior of the rice weevil Sitophilus oryzae (Coleoptera,Dryophthoridae)

The paper describes laboratory tests in which the behavior response of adult rice weevils Sitophilus oryzae L. to the presence of seven species of micromycetes of the genus Fusarium (F. graminearum, F. culmorum, F. cerealis, F. poae, F. sporotrichioides, F. langsethiae, and F. sibiricum; 3 strains for each species) infecting cereals was characterized. The chemicals of unkown structure, released by the fungi, can have both attractive and repellent effects on the weevils; in some cases a neutral response was observed. The strains of Fusarium species characterized as weak pathogens (F. langsethiae, F. poae, and F. sibiricum) in most cases stimulated attractive and neutral responses. Relatively strong pathogens (F. cerealis, F. culmorum, F. graminearum, and F. sporotrichioides) generally had a repellent effect. The results obtained are discussed in the context of possible relationships between Fusarium fungi and the rice weevil during their utilization of cereals as a shared food substrate.     

Molecular Identification,Mycotoxin Production and Comparative Pathogenicity of Fusarium temperatum Isolated from Maize in China

A recently isolated Fusarium population from maize in Belgium was identified as a new species, Fusarium temperatum. From a survey of Fusarium species associated with maize ear rot in nineteen provinces in 2009 in China, ten strains isolated from Guizhou and Hubei provinces were identified as F. temperatum. Morphological and molecular phylogenetic analyses based on the DNA sequences of individual translation elongation factor 1‐alpha and β‐tubulin genes revealed that the recovered isolates produced macroconidia typical of four‐septate with a foot‐shaped basal cell and belonged to F. temperatum that is distinctly different from its most closely related species F. subglutinans and others within Gibberella fujikuroi complex species from maize. All the strains from this newly isolated species were able to infect maize and wheat in field, with higher pathogenicity on maize. Mycotoxin determination of maize grains infected by the strains under natural field condition by ultra‐high‐performance liquid chromatography–tandem mass spectrometry and gas chromatography–mass spectrometry analyses showed that among fifteen mycotoxins assayed, two mycotoxins fumonisin B₁ and B₂ ranging from 9.26 to 166.89 μg/g were detected, with massively more FB₂ mycotoxin (2.8‐ to 108.8‐fold) than FB₁. This mycotoxin production profile is different from that of the Belgian population in which only fumonisin B₁ was barely detected in one of eleven strains assayed. Comparative analyses of the F. temperatum and F. subglutinans strains showed that the highest fumonisin producers were present among the F. temperatum population, which were also the most pathogenic to maize. These results suggested a need for proper monitoring and controlling this species in the relevant maize‐growing regions.     

Investigation of stored wheat mycoflora,reporting the<Emphasis Type="Italic">Fusarium</Emphasis> cf.<Emphasis Type="Italic">langsethiae</Emphasis> in three provinces of Iran during 2007

Wheat is the most important cereal produced in Iran. A mycological survey was carried out for the first time, on the stored wheat samples in Tehran, East Azarbayejan and Mazandaran provinces in 2007. Exogenous and endogenous fungi, were isolated by the method of flotation with Malachite green agar (MGA 0.25) and Freeze blotter techniques respectively. In this study, 46 species belonging to 23 different genera were isolated.Cladosporium spp. (57.1–89.2%) andAlternaria spp. (82.4–100%) species were the predominant fungal species identified as endogenous mycoflora. The predominant exogenous fungi werePenicillium spp. (78.4–92.8%) andAspergillus spp. (71.4–85.7%) species.Fusarium proliferatum was the most prevalent species ofFusarium isolates.Aspergillus niger (39.4%) andAspergillus flavus (36.7%) were the predominantAspergillus species identified as exogenous mycoflora.Aspergillus flavus (26.6%) was the predominantAspergillus species identified as endogenous mycoflora. Flotation method with MGA 0.25 recommended for isolating of hyaline fungi from wheat cereals. In this study one isolate fromFusarium species was isolated on the basis of morphology and ribosomal internal transcribed spacer classified asFusarium langsethiae but on the basis of partial translation elongation factor-1alpha gene grouped withFusarium sporotrichioides. To our knowledge, this is the first report aboutF. cf.langsethiae in Iran and Asia.     

Nivalenol and 15‐acetyldeoxynivalenol Chemotypes of Fusarium graminearum Clade Species are Prevalent on Maize throughout China

Fusarium graminearum clade species are among the main causative agents of Gibberella ear rot (GER) in maize and responsible for the various trichothecene mycotoxins accumulated in contaminated maize grains. In this study, a total of 620 isolates from diseased maize ears collected from 59 districts in 19 provinces throughout China, previously identified morphologically as Fusarium graminearum clade, was genetically characterized at the species level based on SCAR (Sequence Characterized Amplified Region) and for their potential capability of mycotoxin production using the genetic chemotyping assay. The results showed that 359 isolates were F. asiaticum (SCAR 5), which consisted of 97% nivalenol (NIV)‐chemotypes, 0.8% 3‐acetyldeoxynivalenol (3‐ADON)‐producing isolates and 2.2% 15‐acetyldeoxynivalenol (15‐ADON) producers, whereas the remaining 261 isolates were identified as F. graminearum sensu stricto (SCAR 1), all of which produced 15‐ADON mycotoxins. This high proportion of NIV producers present in F. asiaticum is different from the chemotype patterns in F. asiaticum populations isolated from wheat and barley, where DON and its acetylated chemotypes were the predominant mycotoxins. Moreover, the majority of NIV producers (59.1%) and all the 3‐ADON‐producing strains were derived from the warmer regions in southern China, whereas most of the 15‐ADON‐producing strains (78.4%) were isolated from the colder regions in northern China. Our study is the first report of NIV chemotypes of F. asiaticum and 15‐ADON chemotypes of F. graminearum sensu stricto that were associated with the GER of maize in China.