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1.
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.  相似文献   

2.
A field survey was performed to study the infection and development of Fusarium langsethiae in the growing season of wheat, barley, oats and triticale under commercial (2009 – 2011) production. Sampling was completed over three years from fields within the counties of Shropshire and Staffordshire in the UK. Plants sampled (from tillering to harvest) were divided into roots, leaves, lower stem, upper stem and inflorescence/head sub-samples depending on the growth stage of the cereal. DNA was extracted and F. langsethiae DNA quantified using real-time PCR. Fusarium mycotoxins HT-2 and T-2 were quantified from head samples at harvest. Three years of data showed oat to contain the highest levels of both F. langsethiae biomass and HT-2?+?T-2 mycotoxins in harvested heads of the cereals studied. The development of F. langsethiae in all three cereals appeared to be similar. Fusarium langsethiae DNA was not detected in the roots and seedlings of all three cereals suggesting F. langsethiae is not a seedling pathogen of cereals. Head infection if it occurs, is at head emergence but before flowering. Seemingly symptomless heads had high levels of F. langsethiae DNA and HT-2?+?T-2, confirming previous suggestions that F. langsethiae is a symptomless pathogen of oats.  相似文献   

3.
In the western part of Japan, two wheat cultivars, Nishinokaori and Minaminokaori, are currently cultivated for breadmaking. Breadmaking wheat requires a higher protein content compared to the Japanese noodle wheat (the major type of wheat in Japan). This high protein level in the grain is obtained by top-dressing with nitrogen (N) near anthesis. Because such N applications may increase levels of Fusarium head blight (FHB) and consequent mycotoxin [deoxynivalenol (DON) and nivalenol (NIV)] accumulation in the grain, the effect of N application (0, 4, and 8 g/m2) at anthesis on FHB and mycotoxin accumulation in Nishinokaori and Minaminokaori was tested in the greenhouse in 2004 and 2005 and in two fields in 2006. In the greenhouse, plants were spray inoculated at 3, 10, and 20 days after N treatment. In field experiments, colonized maize kernels, which generate ascospores during the testing season, served as inoculum. In all experiments for both cultivars, N application at anthesis significantly increased grain protein as expected, but had no significant effect on FHB and DON and NIV levels in grain. These results suggest that, at least in these cultivars, N can be applied close to anthesis without increasing the risk of FHB and mycotoxin (DON and NIV) accumulation.  相似文献   

4.
Quantitative real-time polymerase chain reaction differentiating 10 Fusarium spp. and Microdochium nivale or M. majus was applied to a total of 396 grain samples of wheat, barley, triticale, oat, and rye sampled across Denmark from 2003 to 2007, along with selected samples of wheat and barley from 1957 to 2000, to determine incidence and abundance of individual Fusarium spp. The mycotoxins deoxynivalenol (DON), nivalenol, zearalenone, T-2, and HT-2 were quantified using liquid chromatography-double mass spectrometry. Major differences in the Fusarium species complex among the five cereals as well as great yearly variation were seen. Fusarium graminearum, F. culmorum, and F. avenaceum were dominant in wheat, with DON as the dominant mycotoxin. F. langsethiae, F. culmorum, and F. avenaceum were dominant in barley and oat, leading to relatively high levels of the mycotoxins T-2 and HT-2. F. graminearum, F. culmorum, and F. avenaceum dominated in triticale and rye. The nontoxigenic M. nivale/majus were present in significant amounts in all cereal species. Wheat and barley samples from 1957 to 1996 exhibited no or very low amounts of F. graminearum, indicating a recent increase of this pathogen. Biomass and mycotoxin data exhibited good correlations between Fusarium spp. and their corresponding mycotoxins under field conditions.  相似文献   

5.
Experiments were conducted to determine the extent of Fusarium langsethiae infection in wheat, barley and oats grown under identical experimental conditions. In total, four experiments were conducted with both winter and spring sown experiments at two locations. The amount of F. langsethiae infection was determined by quantifying F. langsethiae DNA and quantifying the combined concentration of the trichothecene mycotoxins HT-2 and T-2 (HT-2 + T-2) in cereal head fractions (grain and rest of the head) after threshing at harvest. Results of the study showed that under identical experimental conditions, oats had the highest F. langsethiae DNA and HT-2 + T-2 concentrations compared to wheat and barley. This indicates that the high levels detected on UK oats compared to wheat and barley from surveys of commercial crops is a consequence of genetic differences rather than differences in agronomy applied to the cereal species. The concentration of HT-2 and T-2 per unit of F. langsethiae DNA in oats compared to wheat and barley was also significantly higher indicating host differences in either the stimulation of HT-2 and T-2 production or in the metabolism of HT-2 and T-2. The study also showed that the proportion of F. langsethiae DNA in threshed grains was significantly lower than that in the rest of the cereal head.  相似文献   

6.
Measurements of local environmental conditions, intensity of Fusarium head blight (FHB) in wheat spikes, biomass of Fusarium graminearum, F. culmorum, and F. poae (pathogens causing FHB) and concentration of the mycotoxins deoxynivalenol (DON) and nivalenol (NIV) in harvested wheat grain were obtained in a total of 150 location-years, originating in three European countries (Hungary, Ireland, United Kingdom) from 2001 to 2004. Through window-pane methodology, the length and starting time of temporal windows where the environmental variables were significantly associated with the biological variables were identified. Window lengths of 5 to 30?days were evaluated, with starting times from 18?days before anthesis to harvest. Associations were quantified with nonparametric Spearman correlation coefficients. All biological variables were significantly associated with at least one evaluated environmental variable (P?≤?0.05). Moisture-related variables (e.g., average relative humidity, hours of relative humidity above 80%) had the highest positive correlations with the biological variables, but there also was a significant negative correlation between average temperature and several biological variables. When significant correlations were found, they were generally for all window lengths, but for a limited number of window start times (generally before anthesis for disease index and after anthesis for the toxins and late-season fungal biomasses). Semi-partial Spearman correlation coefficients were used to evaluate the relationship between the environmental variables and the concentration of DON and NIV after the effects of FHB intensity and fungal biomass on the mycotoxins were removed. Significant semi-partial correlations were found between relative humidity variables and DON, and between temperature and relative humidity variables and NIV for time windows that started after anthesis (and not for any earlier time windows). Results confirm that the environment influences disease, fungal biomass, and mycotoxin production, and help refine the time windows where the association is greatest. However, variability in the relationships was high, indicating that no single environmental variable is sufficient for prediction of disease or mycotoxin contamination.  相似文献   

7.
Combined analyses of the natural occurrence of fusarium head blight (FHB), mycotoxins and mycotoxin‐producing isolates of Fusarium spp. in fields of wheat revealed FHB epidemics in 12 of 14 regions in Hubei in 2009. Mycotoxin contamination ranged from 0·59 to 15·28 μg g?1 in grains. Of the causal agents associated with symptoms of FHB, 84% were Fusarium asiaticum and 9·5% were Fusarium graminearum, while the remaining 6·5% were other Fusarium species. Genetic chemotyping demonstrated that F. asiaticum comprised deoxynivalenol (DON), 3‐acetyldeoxynivalenol (3‐AcDON), 15‐acetyldeoxynivalenol (15‐AcDON) and nivalenol (NIV) producers, whereas F. graminearum only included DON and 15‐AcDON producers. Compared with the chemotype patterns in 1999, there appeared to be a modest shift towards 3‐AcDON chemotypes in field populations during the following decade. However, isolates genetically chemotyped as 3‐AcDON were present in all regions, whereas the chemical 3‐AcDON was only detected in three of the 14 regions where 3‐AcDON accounted for 15–20% of the DON and acetylated forms. NIV mycotoxins were detected in seven regions, six of which also yielded NIV chemotypes. The number of genetic 3‐AcDON producers was positively correlated with amounts of total mycotoxins (DON, NIV and acetylated forms) or DON in wheat grains. Chemical analyses of wheat grains and rice cultures inoculated with different isolates from the fields confirmed their genetic chemotypes and revealed a preferential biosynthesis of 3‐AcDON and 4‐AcNIV in rice. These findings suggest the importance of chemotyping coupled with species identification for improved prediction of mycotoxin contamination in wheat.  相似文献   

8.
Fusarium head blight and mycotoxin contamination of wheat,a review   总被引：9，自引：0，他引：9  
Summary An infection of bread wheat by fusarium head blight contaminates the crop with mycotoxins, particularly deoxynivalenol (DON) and nivalenol (NIV). The toxicity and natural occurrence of these mycotoxins in wheat are reviewed. Based on 8 years data of fusarium head blight epidemics of wheat in the Netherlands, DON contamination of the grain was estimated. Fusarium head blight ratings averaged an infection of 1.7% of all spikelets; estimates for DON contamination averaged 0.9 mg kg–1. Taking a guideline level for DON in uncleaned bread wheat of 2 mg kg–1, in 1979 and 1982 a wheat crop was produced with estimated DON concentrations above the limit of tolerance. Human and animal exposure to mycotoxins in the Netherlands appears to be small but chronic. The information presented in this paper illustrates the need for an annual evaluation of the crop for fusarium head blight incidence and mycotoxin content, and the necessity of fusarium head blight resistant wheat cultivars.Samenvatting Aaraantasting van tarwe doorFusarium culmorum enFusarium graminearum leidt tot vorming van mycotoxinen in het graan, waarvan deoxynivalenol (DON) en nivalenol (NIV) de belangrijkste toxinen zijn. In dit artikel wordt een overzicht gegeven van de toxicologische aspecten, en het voorkomen van deze toxinen in tarwe. Informatie over DON en NIV in tarwe in West-Europa is schaars. Gebaseerd op gegevens vanFusarium epidemieën in de jaren 1979–1986 wordt een schatting gegeven van de concentratie DON in Nederlandse tarwe. Rekening houdend met de herkomst en verwerking van tarwe, blijken zowel in dierlijk als menselijk voedsel lage concentraties DON chronisch voor te komen. Op basis van een maximaal toelaatbare dagelijkse dosis DON van 3 g kg–1 lichaamsgewicht is de schatting van de dagelijkse opname van DON in het jaar volgend op de oogst van 1982 net op de grens. Zowel een jaarlijkse inventarisatie vanFusarium aantasting en DON besmetting van het graan, als de ontwikkeling vanFusarium-resistente rassen zijn noodzakelijk.  相似文献   

9.
Fusarium langsethiae is a recently characterized fungus within the genus Fusarium. It is found as a grain contaminant of small grain cereals such as oats and barley, and to a lesser extent wheat. Fusarium langsethiae is particularly widespread in the Nordic countries and the UK where it poses a serious problem as the main producer of T-2 and HT-2 mycotoxins. The biology of F. langsethiae and its interaction with the plant remains poorly understood, partly hampered by difficulties reproducing a natural level of infection under controlled conditions. The reported study was designed as a series of glasshouse experiments to advance our understanding of F. langsethiae biology by investigating alternative infection routes and its proliferation in oats, Avena sativa. Various methods of seed, soil, and seedling inoculation, boot injection and spray inoculation, were tested. The results clearly show a strong preference of F. langsethiae for the panicle, ruling out alternative infection routes. At relatively low temperatures spray infection, accompanied by prolonged humidity, ensured a thorough establishment of the fungus both at flowering and at early dough stage. Boot injection proved to be a reliable working tool for production of an even and predictable grain infection. Apart from in the panicle, considerable fungal proliferation was only detected in flag leaf nodes, and was a direct consequence of the boot injection method. Fungal presence in the node tissue also correlated with significant stunting of infected shoots. In light of the results the pathogenic and endophytic abilities of F. langsethiae are discussed.  相似文献   

10.
Grain samples of 15 naturally contaminated barley cultivars, collected after harvest in southeastern Poland, were analysed for occurrence of Fusarium trichothecenes and zearalenone (ZEA). Barley kernels were contaminated with the following toxic metabolites: deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), nivalenol (NIV), HT-2 toxin (HT-2), T-2 toxin (T-2), diacetoxyscirpenol (DAS), T-2 tetraol and ZEA. Significant correlations between concentrations of individual toxins and the dominant Fusarium species were found. Moreover, significant differences in toxin concentrations between cultivars were detected. Distribution of these mycotoxins was studied in two fractions of kernels (diameter > 2.5 mm and < 2.5 mm). A two-factor analysis of variance revealed significant differences between the two fractions, and between the analysed cultivars. Most of the interactions between fractions and cultivars were also significant. The highest concentration of the analysed toxins was in the fraction of small kernels. Kernel fraction <2.5 mm, although accounting for only 12.8% of sample weight, contained high proportions of the total toxin content: 80% of DON, 94% of NIV, 85% of ZEA, 83% of T-2 tetraol, 80% of DAS, 68% of HT-2 toxin and 81% of T-2 toxin. The results indicate that the level of contamination with Fusarium trichothecenes and ZEA, can be reduced by rejection of small kernels.  相似文献   

11.
Lodging is one possible risk factor that leads to increased cereal mycotoxin contamination, but few reports have been published on the subject. We examined the effects of lodging on the level of deoxynivalenol (DON) and nivalenol (NIV) contamination in wheat, barley, and rice infected with the Fusarium graminearum species complex. Case-control and intervention studies were applied to test the hypothesis that lodging increases the level of mycotoxin contamination. A total of 66 grain samples were collected from each field in 12 Japanese prefectures from 2002 to 2006. Each sample set consisted of grains from lodged and nonlodged plants. The concentration of DON + NIV in lodged plants was significantly higher than in nonlodged plants. All samples of wheat and barley were contaminated with DON and NIV; however, most of the lodged rice samples were contaminated only with NIV. In intervention trials to investigate the effects of lodging duration, a small area of wheat inoculated with the pathogen was completely lodged by trampling. Even with 5 days of lodging, the levels of DON + NIV in wheat grain at harvest increased by 27–51% compared to nonlodged control plots. For rice, half of each plot area was completely lodged by trampling 20 days before harvest. The level of NIV in lodged rice grain was significantly higher than that in nonlodged rice at optimum and delayed harvests, because lodging significantly increased the level of Fusarium mycotoxins in the three crops. Thus, practices (e.g., rational use of fertilizers) to avoid lodging should reduce the risk of mycotoxin contamination. This is the first epidemiological study on the effect of lodging on mycotoxin production by the F. graminearum species complex in wheat, barley, and rice.  相似文献   

12.
徐哲  刘太国  刘博  高利  陈万权 《植物保护》2021,47(3):200-205
为明确自然发病条件下我国小麦主产区小麦籽粒镰刀菌毒素污染情况,用超高效液相色谱-串联质谱仪(UPLC-MS/MS)测定了长江中下游冬麦组(CZX)、黄淮冬麦区南片冬水组(HNS)、黄淮冬麦区北片水地组(HBS)、北部冬麦区水地组(BBS)180份小麦样品中DON、3ADON、15ADON、T-2、HT-2和ZEN共6种镰刀菌毒素含量并对其进行比较分析。结果显示:来自CZX小麦籽粒中的DON、3ADON与ZEN毒素含量显著高于其他麦区;T-2毒素在CZX小麦籽粒中含量显著低于其他麦区;15ADON毒素含量在HNS与CZX、HBS与BBS以及CZX与BBS差异不显著,其他麦区间该毒素含量差异显著,15ADON在HNS含量最高;检出率方面,HT-2毒素均未检出;ZEN、3ADON检出率较低,DON、15ADON和T-2毒素的检出率较高。  相似文献   

13.
The objective of this study was to evaluate the potential role of gramineous weeds present near paddy fields as alternative hosts for the Fusarium graminearum species complex (FGSC) that causes fusarium head blight (FHB) in rice. A total of 142 weed samples were collected from 10 gramineous weed species near paddy fields from August to October 2018 in Jiangsu Province, China. Of the 145 isolates of seven Fusarium species isolated from the weed samples, F. asiaticum was the most abundant (86.9%), followed by F. fujikuroi (5.5%), F. proliferatum (2.8%), F. graminearum (2.1%), F. tricinctum (1.4%), F. acuminatum (0.7%), and F. sporotrichioides (0.7%). Genotype and mycotoxin analyses confirmed that 72.2% of F. asiaticum isolates were producers of deoxynivalenol (DON) with 3-acetyl deoxynivalenol (3ADON), and the remainder were nivalenol (NIV) producers. Pathogenicity assays showed that both 3ADON and NIV chemotypes of F. asiaticum could cause FHB in rice, but NIV chemotypes were significantly (p < .05) more aggressive than 3ADON chemotypes. Three Fusarium mycotoxins, DON, NIV, and zearalenone, occurred naturally at low concentrations in the weed samples. Taken together, this study provides insight into the mycotoxin production and aggressiveness of F. asiaticum isolates from gramineous weeds in China.  相似文献   

14.
The development of new maize hybrids with resistance to Fusarium infection is an effective means of minimizing the risk of mycotoxin contamination. Several maize hybrids have been investigated for Fusarium ear rot and accumulation of fumonisin B1 (FB1), fumonisin B2 (FB2), beauvericin (BEA) and fusaproliferin (FP) after artificial inoculation in the field with toxigenic strains of Fusarium verticillioides and Fusarium proliferatum. The year of inoculation had a significant influence on the disease severity and mycotoxin accumulation in maize kernels. Of all the hybrids tested, only Mona exhibited resistance to ear rot caused by F. verticillioides and produced low levels of fumonisins during three years of experiments. In Fusarium-damaged kernels (FDK), fumonisin B1, fumonisin B2, beauvericin and fusaproliferin were detected at concentrations much higher (up to 10–20 times) than in healthy-looking kernels (HLK). Animal and human exposure to these mycotoxins can be drastically reduced by removing mouldy and visibly damaged kernels from the commodity.  相似文献   

15.
We screened 188 isolates of Fusarium graminearum, which originated from northwest Europe, the USA and Nepal, for genetic diversity using a sequence-characterised amplified region polymorphism (SCAR). On the basis of this analysis, 42 of the 118 isolates were selected for random amplified polymorphic DNA (RAPD) analysis. Three groups were identified, two of which, A and B, contained the isolates from Nepal, and a third, group C, contained the isolates from Europe and the USA. In pathogenicity tests on wheat and maize seedlings, group C isolates were more pathogenic than the group A and B isolates. The isolates were assigned chemotypes based on their ability to produce the trichothecene mycotoxins nivalenol (NIV) and deoxynivalenol (DON). Isolates from group A were equally likely to produce NIV or DON while group B isolates produced predominantly NIV, and group C isolates produced predominantly DON. Within group A, isolates of the two chemotypes were equally pathogenic to wheat but isolates with the NIV chemotype were significantly more pathogenic to maize. The results confirm that distinct genetic groups exist within F. graminearum and demonstrate that these groups have different biological properties, especially with respect to their pathogenicity to two of the most economically important hosts of this pathogen.  相似文献   

16.
Within-field variability in the Fusarium head blight (FHB) and its associated mycotoxins was studied in four European countries. At each of 14 sites, each FHB pathogen and associated mycotoxins were quantified in 16 quadrat samples at harvest. Overall, the incidence of quadrat samples with detectable and quantifiable pathogen DNA was significantly lower in the grain than in the corresponding chaff. Deoxynivalenol (DON) was the most frequently detected toxin in the samples and its accumulation was most strongly associated with the presence of Fusarium graminearum. Nivalenol (NIV) accumulation was significantly associated only with the presence of F. culmorum. Zearalenone (ZON) accumulation was strongly associated with the presence of all three pathogens (F. graminearum, F. culmorum and F. poae). The levels of both DON and ZON concentrations were positively related to the amount of F. graminearum DNA in the grain or in the chaff. The presence/absence of FHB pathogens within a single quadrat appeared to be independent of each other. The presence of a particular FHB pathogen and the amount of its DNA, as well as the associated mycotoxin(s), varied greatly among samples at each site. This study demonstrated the large extent of within-field variability of FHB and its associated mycotoxins, and the importance of representative sampling in FHB studies.  相似文献   

17.
Fusarium head blight (FHB) in small grain cereals is primarily caused by the members of the Fusarium graminearum species complex. These produce mycotoxins in infected grains, primarily deoxynivalenol (DON); acetylated derivatives of DON, 3‐acetyl‐DON (3‐ADON) and 15‐acetyl‐DON (15‐ADON); and nivalenol (NIV). This study reports the isolation of Fusarium cerealis in infected winter wheat heads for the first time in Canada. A phylogenetic analysis based on the TRI101 gene and F. graminearum species‐specific primers revealed two species of Fusarium: F. graminearum sensu stricto (127 isolates) and F. cerealis (five isolates). Chemotype determination based on the TRI3 gene revealed that 65% of the isolates were 3‐ADON, 31% were 15‐ADON and 4% were NIV producers. All the F. cerealis isolates were of NIV chemotype. Fusarium cerealis isolates can often be misidentified as F. graminearum as the morphological characteristics are similar. Although the cultural and macroconidial characteristics of F. graminearum and F. cerealis isolates were similar, the aggressiveness of these isolates on susceptible wheat cultivar Roblin and moderately resistant cultivar Carberry differed significantly. The F. graminearum 3‐ADON isolates were most aggressive, followed by F. graminearum 15‐ADON and F. cerealis NIV isolates. The findings from this study confirm the continuous shift of chemotypes from 15‐ADON to 3‐ADON in North America. In Canada, the presence of NIV is limited to barley samples and the discovery of NIV‐producing F. cerealis species in Canadian wheat fields may pose a serious concern to the Canadian wheat industry in the future.  相似文献   

18.
Fusarium graminearum species complexes (FGSCs), such as Fusarium asiaticum and F. graminearum, are important pathogens that cause Fusarium head blight (FHB) in several cereal crops worldwide. In this study, we collected 342 gramineous weed samples in the proximity of rice fields from May to June 2018 in Korea. Among the 500 Fusarium isolates from the weed samples, 13 species of Fusarium were identified, and F. asiaticum (41.2%), F. avenaceum (18.0%), F. acuminatum (16.4%) and F. graminearum (14.8%) were the most frequently isolated. The trichothecene genotype analysis showed that 206 F. asiaticum strains consisted of the nivalenol (NIV) genotype (n = 195, 94.7%) and 3-acetyldeoxynivalenol (3ADON) genotype (n = 11, 5.3%), whereas 74 F. graminearum strains consisted of the 15-acetyldeoxynivalenol (15ADON) genotype (n = 58, 78.4%) and 3ADON genotype (n = 16, 21.6%). Geographical differences were observed in the FGSC and trichothecene genotype compositions, which appeared host-dependent between the southern provinces and mid-eastern provinces. The aggressiveness assessment of FHB showed that the 3ADON chemotype was most aggressive followed by the 15ADON and NIV chemotypes in wheat, while the NIV chemotype was most aggressive followed by the 3ADON and 15ADON chemotypes in rice. The F. asiaticum strains grew slowly and produced fewer conidia and perithecia than the F. graminearum strains, regardless of their chemotypes. The results of this study suggest that F. asiaticum with the NIV chemotype has a host preference for rice, and FHB-causing pathogens can be harboured in gramineous weeds, which play a role in the dispersal of FHB pathogens to rice and other cereal crops.  相似文献   

19.
A total of 82 fungal isolates was obtained from wheat kernel samples affected by fusarium head blight collected from 20 locations in southern Brazil. Polymerase chain reaction (PCR) assays were used to characterize trichothecene mycotoxin genotypes [deoxynivalenol (DON), nivalenol (NIV) and two acetylated derivatives of DON]. To identify isolates that producing DON and NIV, portions of the Tri13 gene were amplified. To identify 3-acetyl-deoxynivalenol (3-ADON) and 15-acetyl-deoxynivalenol (15-ADON) genotypes, portions of Tri3 and Tri12 were amplified. Nearly all of the isolates studied (76/82) were of the DON/15-ADON genotype. Six of the isolates were of the NIV genotype. The DON/3-ADON genotype was not observed. Portions of three genes were sequenced from representative isolates of the NIV and DON/15-ADON genotypes and compared with sequences from curated reference isolates of Fusarium in GenBank. blast queries for individual gene sequences and pairwise comparisons of percentage identity and percentage divergence based on 1676 bp of concatenated DNA sequence suggested that the isolates representing the DON/15-ADON genotype were Fusarium graminearum sensu stricto and the isolates representing the NIV genotype were Fusarium meridionale . This is the first detailed report of trichothecene mycotoxin genotypes of F. graminearum and F. meridionale in Brazil.  相似文献   

20.
Goswami RS  Kistler HC 《Phytopathology》2005,95(12):1397-1404
ABSTRACT Fusarium head blight (FHB), or scab, is a destructive disease of small grains caused by members of the Fusarium graminearum species complex, comprised of at least nine distinct, cryptic species. Members of this complex are known to produce mycotoxins including the trichothecenes deoxynivalenol (DON) along with its acetylated derivatives and nivalenol (NIV). In this study, 31 strains, belonging to eight species of this complex and originating from diverse hosts or substrates, were tested for differences in aggressiveness and mycotoxin production. Large variation among strains, both in terms of their aggressiveness and the ability to produce trichothecenes on a susceptible cultivar of wheat was found; variation appears to be a strain-specific rather than species-specific characteristic. While pathogenicity was not influenced by the type of mycotoxin produced, a significant correlation was observed between the amount of the dominant trichothecene (DON and its acetylated forms or NIV) produced by each strain and its level of aggressiveness on wheat. Some isolates also were tested for their ability to infect rice cv. M201, commonly grown in the United States. While tested strains were capable of infecting rice under greenhouse conditions and causing significant amount of disease, no trichothecenes could be detected from the infected rice florets.  相似文献   

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