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1.
Sugar beet is widely grown throughout the world and represents the second largest crop used to produce sugar. Root rot in sugar beet, caused by Fusarium, significantly reduces yield, juice purity, and sugar concentration. Here, 307 Fusarium isolates were collected from sugar beet roots exhibiting typical root rot symptoms in eight provinces or autonomous regions of China from 2009 to 2012. Based on morphological characteristics and sequence data of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) and the translation elongation factor 1α (EF-1α), Fusarium oxysporum (38.4%) was identified as the most prevalent species, followed by F. solani (20.9%), and F. equiseti (18.9%). These three species were widely distributed in all eight of the provinces and autonomous regions. F. tricinctum (5.9%), F. brachygibbosum (4.6%), F. redolens (3.3%), F. proliferatum (3.3%), F. graminearum (2.3%), F. verticillioides (1.6%), F. nygamai (0.7%), and F. culmorum (0.3%) were less frequently obtained. Of the 307 Fusarium isolates, 117 representing different species and geographic locations were demonstrated to cause tip rot and vascular discoloration in sugar beet roots, with disease incidence ranging from 84.2 to 100.0% and disease index ranging from 41.94 to 75.83. This is the first detailed report of Fusarium species, in particular F. tricinctum, F. brachygibbosum, F. redolens, F. proliferatum, F. nygamai, and F. culmorum, causing sugar beet root rot in China.  相似文献   

2.
Fusarium Head Blight is a major disease of wheat and an important contributor to the reduced cultivation of wheat in South Africa, where the crop often is grown under irrigation. We collected Fusarium isolates from 860 Fusarium Head Blight-infected wheat heads in seven irrigated wheat-growing areas of South Africa. Six Fusarium species, i.e., F. chlamydosporum, F. crookwellense, F. culmorum, F. equiseti, F. graminearum and F. semitectum were recovered, three of which, i.e., F. chlamydosporum, F. equiseti and F. semitectum, were not previously associated with Fusarium Head Blight in South Africa. Fusarium graminearum occurred at high frequencies at all seven locations. Based on polymerase chain reaction (PCR) assays of diagnostic sequences, more isolates were predicted to produce deoxynivalenol than nivalenol. Fusarium graminearum (sensu lato) appears to be the primary causal agent of Fusarium Head Blight in irrigated wheat in South Africa, which may not be the case for wheat cultivated under rain-fed conditions. Rotations of irrigated wheat with other graminaceous crops and maize could increase fungal inoculum and disease pressure. The establishment of Fusarium Head Blight in the irrigated wheat region of the country means that resistant lines and alternative agronomic practices are needed to limit disease severity, yield losses and mycotoxin contamination.  相似文献   

3.
Fusarium head blight (FHB) is one of the most important fungal diseases affecting wheat worldwide and it is caused mainly by species within the Fusarium graminearum species complex (FGSC). This study evaluated the presence of FGSC in durum wheat from the main growing area in Argentina and analyzed the trichothecene genotype and chemotype of the strains isolated. Also, the genetic variability of the strains was assayed using ISSR markers. Molecular analysis revealed that among the strains isolated and identified morphologically as F. graminearum, there were 14 strains identified as F. cerealis. Also, it revealed that durum wheat grains were mostly contaminated by F. graminearum, being this the only species reported so far, within the FGSC, affecting durum wheat in Argentina. Analysis of molecular variance (AMOVA) indicated a high genetic variability within rather than between F. graminearum populations. All F. graminearum strains presented 15ADON genotype and were able to produce DON while all F. cerealis strains presented the NIV genotype and most of them were able to produce this toxin. The finding of F. cerealis in durum wheat grains indicates the need for investigating if this fungus is the responsible for the NIV contamination found in wheat in Argentina.  相似文献   

4.
Two Fusarium strains, isolated from Asparagus in Italy and Musa in Vietnam respectively, proved to be members of an undescribed clade within the Fusarium solani species complex based on phylogenetic species recognition on ITS, partial RPB2 and EF-1α gene fragments. Macro- and micro-morphological investigations followed with physiological studies done on this new species: Fusarium ershadii sp. nov can be distinguished by its conidial morphology. Both isolates of Fusarium ershadii were shown to be pathogenic to the monocot Asparagus officinalis when inoculated on roots and induced hollow root symptoms within two weeks in Asparagus officinalis seedlings. In comparison mild disease symptoms were observed by the same strains on Musa acuminata seedlings.  相似文献   

5.
The presence of Fusarium temperatum in France was investigated by analyzing 40 Fusarium strains, previously isolated from infected maize ears in 2011 and formerly identified as Fusarium subglutinans based on morphological characteristics. In this study, 26 strains out of the 40 were identified as F. temperatum and 14 as F. subglutinans based on sequencing of the translation elongation factor 1α gene. The phylogenetic analysis showed that the two species represented two clades strongly supported by bootstrap values. The pathogenicity of F. temperatum strains was confirmed on maize ears. This study provides new information about F. temperatum isolated from maize in France.  相似文献   

6.
Fusarium is one of the most destructive fungal genera whose members cause many diseases on plants, animals, and humans. Moreover, many Fusarium species secrete mycotoxins (e.g. trichothecenes and fumonisins) that are toxic to humans and animals. Fusarium isolates from date palm trees showing disease symptoms, e.g. chlorosis, necrosis and whitening, were collected from seven regions across Saudi Arabia. After single-sporing, the fungal strains were morphologically characterized. To confirm the identity of morphologically characterized Fusarium strains, three nuclear loci, two partial genes of translation elongation factor 1 α (tef1α) and β-tubulin (tub2), and the rDNA-ITS region, were amplified and sequenced. Of the 70 Fusarium strains, 70 % were identified as F. proliferatum that were recovered from six regions across Saudi Arabia. Fusarium solani (13 %), as well as one strain each of the following species: F. brachygibbosum, F. oxysporum, and F. verticillioides were also recovered. In addition, five Fusarium-like strains were recognized as Sarocladium kiliense by DNA-based data. The preliminary in vitro pathogenicity results showed that F. proliferatum had the highest colonization abilities on date palm leaflets, followed by F. solani. Although F. oxysporum f. sp. albedinis is the most serious date palm pathogen, F. proliferatum and F. solani are becoming serious pathogens and efforts should be made to restrict and control them. In addition, the potential toxin risks of strains belonging to F. proliferatum should be evaluated.  相似文献   

7.
Soybean root rot is a worldwide soil-borne fungal disease threatening soybean production, causing large loss in yield and quality of soybean. Fusarium species are well recognized as the important causal agent of Fusarium root rot, which are often distinct with respect to various factors in different soybean-producing regions around the world. Recently, Fusarium root rot has been frequently reported in Sichuan Province of China, where is unique in its climate and diverse cropping patterns, but it is still unclear about the predominant Fusarium species and their pathogenicity on soybean. In this study, diseased soybean roots were collected from three regions of Sichuan Province during 2014–2015. Based on morphological characteristics and phylogenetic analysis of nucleotide sequences of the ribosomal internal transcribed spacer region and the translation elongation factor 1-α gene, 78 isolates of Fusarium were identified as nine distinct species. Pathogenicity tests showed that seven species of Fusarium were able to infect soybean, but differed in pathogenicity. F. oxysporum, F. equiseti and F. graminearum were the most aggressive species to soybean, whereas F. fujikuroi and F. verticillioides were not pathogenic to soybean. There was a strong positive correlation of the pathogenicity of Fusarium species with seedling emergence and fresh root weight. In addition, the diversity of Fusarium species varied among soybean-growing regions. To our knowledge, this report on population and pathogenicity of Fusarium species, in particular, F. graminearum, associated with soybean root rot in Sichuan Province of southwest China, will be helpful to provide effective control strategies for the disease.  相似文献   

8.
Competitive effects between Fusarium graminearum, causing Fusarium head blight, and the endophyte Epicoccum nigrum, were performed in in vitro competition assays between the two species. Two E. nigrum isolates were isolated from wheat grains and tested as competitors against two F. graminearum isolates. A dual petri dish assay showed that E. nigrum reduced the mycelial growth of F. graminearum and vice versa. A glass slide assay revealed that E. nigrum crude cultural filtrate also had reducing effect on the growth of F. graminearum comparable to that of E. nigrum spore suspensions. Microscopy showed hyphae of F. graminearum and E. nigrum with many side branches when in close proximity, in contrast to pronounced apical hyphal growth when growing alone. Combinations of F. graminearum and E. nigrum on sterilised wheat grains were studied over time by qPCR. F. graminearum biomass was significantly reduced in inoculations applying E. nigrum three days prior to F. graminearum. In conclusion, these results showed competition and mycelial behaviour effects between F. graminearum and E. nigrum and support that E. nigrum may have potential to reduce F. graminearum infections in wheat. Competition experiments should be carried out in planta to study the interaction further.  相似文献   

9.
Ear rot with white or pink mold was found on corn (Zea mays L.). A species of Fusarium, not registered previously as a pathogen causing Gibberella ear rot of corn in Japan, was isolated from the rotted ear. The isolates, identified as F. asiaticum based on morphological characteristics and nucleotide sequences, caused white or pink mold on corn ear after inoculation. Moreover, the 3-acetyl deoxynivalenol chemotype and the nivalenol chemotype were found in the isolates. We propose to include F. asiaticum as one of the pathogens causing Gibberella ear rot of corn in Japan.  相似文献   

10.
Fusarium species causing maize kernel rot are major threats to maize production, due to reduction in yield as well as contamination of kernels by mycotoxins that poses a health risk to humans and animals. Two-hundred maize kernel samples, collected from 20 major maize growing areas in Ethiopia were analyzed for the identity, species composition and prevalence of Fusarium species and fumonisin contamination. On average, 38 % (range: 16 to 68 %) of maize kernels were found to be contaminated by different fungal species. Total of eleven Fusarium spp. were identified based on morphological characteristics and by sequencing the partial region of translation elongation factor 1-alpha (EF-1α) gene. Fusarium verticillioides was the dominant species associated with maize kernels (42 %), followed by F. graminearum species complex (22.5 %) and F. pseudoanthophilium (13.4 %). The species composition and prevalence of Fusarium species differed among the areas investigated. Fusarium species composition was as many as eight and as few as four in some growing area. The majority of the maize samples (77 %) were found positive for fumonisin, with concentrations ranging from 25 μg kg?1 to 4500 μg kg?1 (mean: 348 μg kg?1 and median: 258 μg kg?1). Slight variation in fumonisin concentration was also observed among areas. Overall results indicate widespread occurrence of several Fusarium species and contamination by fumonisin mycotoxins. These findings are useful for intervention measures to reduce the impact of the main fungal species and their associated mycotoxins, by creating awareness and implementation of good agricultural practices.  相似文献   

11.
We investigated incidences of Fusarium head blight (FHB) and concentrations of six mycotoxins (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, T-2 toxin, HT-2 toxin and zearalenone) in wheat from 2010 to 2013. Field trials were conducted at the Experimental Station of Cultivar Testing in Chrz?stowo, Poland (53o11’N, 17o35’E). We examined the effects of four agronomic factors, including pre-crop type (corn, sugar beets and wheat), date of sowing (late autumn: November 8–December 9 or spring: March 29–April 19), fungicidal application (untreated or treated with two applications) and cultivar (Monsun, Cytra), on FHB index (FHBi) and mycotoxin levels in order to minimize the risk of wheat grain contamination by mycotoxins via integrated pest management methods. The dominant Fusarium species observed on wheat heads were F. culmorum, F. avenaceum (Gibberella avenacea) and F. graminearum (Gibberella zeae), at 21.1%, 17.2% and 7.1%, respectively. A monthly rainfall sum of 113.9 mm and a relatively low air temperature (monthly average 15.5 °C) resulted in the highest FHBi in untreated wheat (25.1%). Agronomic factors crucial for the FHB incidence were the pre-crop, fungicidal treatments and cultivar selection. In wheat planted after wheat or corn, the FHBi was higher compared with a pre-crop of sugar beet. A double application of fungicides at BBCH 30–32 with prothioconazole and spiroxamine and at a BBCH 65 with fluoxastrobin and prothioconazole effectively reduced the FHBi and mycotoxin concentrations, respectively, in grain. The cultivar ‘Cytra’ had a greater FHBi (10.4%) than ‘Monsun’ (4.6%), and grain infestations by Fusarium species were also greater in ‘Cytra’, at 16.5%, than in ‘Monsun’, at 11.2%. Untreated cv. Cytra grown after corn in spring produced grains with the highest amounts of the mycotoxins, deoxynivalenol, 3-acetyldeoxynivalenol, zearalenone and HT-2 (605, 103, 17.5 and 5.53 μg/kg, respectively). Total mycotoxin levels in wheat were correlated with five determinants: duration of the period between the end of flowering and the beginning of kernel abscission, FHBi, F. culmorum isolation, G. zeae isolation and Fusarium ratio (FR) as a % of total mould isolations. Although, the mean concentration of mycotoxins in grain did not exceed the maximum permissible values for unprocessed wheat our study suggests necessity to monitor and mitigate FHB risk for susceptible cultivars, when wheat spring sowing follows corn or wheat.  相似文献   

12.
Fusarium head blight (FHB), mainly caused by Fusarium graminearum species complex (FGSC) and also by other species of this genus, is one of the most destructive cereal diseases with high yield losses and mycotoxin contamination worldwide. The aim of this study was to identify Fusarium species, characterize their virulence factors such as trichothecene genotypes and cell wall degrading enzymes (CWDEs), and also investigate virulence of the isolates obtained from wheat plants with FHB symptoms in Golestan province of Iran. Among 41 isolates tested, 24 were F. graminearum sensu stricto (s.s.), six were F. proliferatum, four were F. culmorum, three isolates belonged to each of F. subglutinans and F. meridionale species and one isolate of F. asiaticum was identified. Among Fusarium isolates, the nivalenol (NIV) genotype could be found more frequently, followed by 3-acetyl deoxynivalenol (3-ADON) and 15-acetyl deoxynivalenol (15-ADON) genotypes. Production of trichothecenes in autoclaved rice cultures was analyzed by gas chromatography (GC) and confirmed by GC–MS. The mean levels of NIV, 3-ADON and 15-ADON produced by Fusarium spp. were 824, 665 and 622 μg kg?1, respectively. All Fusarium isolates were capable of producing CWDEs, mainly cellulase and xylanase. Lipase and pectinase activities appeared later and at less quantities. In overall, the isolates FH1 of F. graminearum and FH8 of F. proliferatum showed the maximum activity of CWDEs, which was correlated with high level of their virulence and aggressiveness on wheat. On the other hand, correlation was observed between the level and type of trichothecene produced by each isolate and its virulence on wheat. Virulence of trichothecene producing isolates was higher than that of non-trichothecene producing isolates. Our results suggested that CWDEs and trichothecenes, as virulence factors, have considerable roles on virulence and aggressiveness of the pathogen. This is the first report on the effect of trichothecenes and CWDEs on virulence and aggressiveness of Fusarium spp. associated with FHB disease in wheat growing regions of Iran.  相似文献   

13.
Streptomyces griseorubens E44G is a chitinolytic bacterium isolated from cultivated soil in Saudi Arabia (a hot, arid climatic region). In vitro, antifungal potential of S. griseorubens E44G was assessed against the phytopathogenic fungus, Fusarium oxysporum f. sp. lycopersici (the causative agent of the Fusarium wilt disease of tomato). An inhibition zone of 24 mm was recorded. The chitinolytic activity of S. griseorubens E44G was proved when the colloidal chitin agar plate method was used. A thermostable chitinase enzyme of 45 kDa molecular weight was purified using gel filtration chromatography. The optimum activity was obtained at 60 °C and pH 5.5. The purified enzyme has shown a very pronounced activity against the phytopathogenic fungus, F. oxysporum. The molecular characterization of the chitinase gene indicated that it consists of 1218 bp encoding 407 amino acids. The phylogentic analysis based on the nucleotide DNA sequence and the deduced amino acids sequence showed high similarity percentages with other chitinases isolated from different Streptomyces species. In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent.  相似文献   

14.
Fusarium species involved in the Fusarium crown rot (FCR) complex affect wheat in every stage of development from seedling to grain fill. This study was designed to compare the aggressiveness of the FCR complex members including F. culmorum, F. pseudograminearum and F. graminearum in causing seedling blight, decreased plant vigour and crown rot. To assess their relative pathogenicity, two hard red spring wheat cultivars and two durum wheat cultivars were inoculated in the field with five isolates from each of the three species for two years. Significant differences in patterns of pathogenicity were identified. In particular, F. culmorum caused greater seedling blight while F. pseudograminearum and F. graminearum caused greater crown rot. Greatest yield reductions were caused by F. pseudograminearum. Cultivar differences were identified with respect to seedling disease and late season crown rot. No interactions were identified between cultivar performance and isolates or species with which they were challenged.  相似文献   

15.
Sorghum [Sorghum bicolor (L.) Moench] has drawn attention as potential feedstock for lignocellulosic biofuels production, and reducing lignin is one way to increase conversion efficiency. Little research has been previously conducted to assess the response of reduced lignin sorghum lines to the Fusarium stalk rot pathogens Fusarium verticillioides and Fusarium proliferatum and the charcoal rot pathogen, Macrophomina phaseolina. Loss of function mutations in either the Brown midrib (Bmr) 6 or 12 gene that both encode a monolignol biosynthetic enzyme in the pathway that produces subunits of the lignin polymer, results in reduced lignin content. Near-isogenic bmr6, bmr12, and bmr6 bmr12 lines had previously been developed, which were shown to have significantly reduced lignin content and increased levels of soluble phenolics. In the current study, these lines in two backgrounds were shown to not be more susceptible to F. verticillioides, F. proliferatum and M. phaseolina inoculations, and some bmr lines exhibited increased resistance to F. proliferatum and M. phaseolina, compared to wild-type lines. When the Fusarium stalk rot pathogen, Fusarium thapsinum, was grown on methanol soluble stalk extracts from bmr6 and wild-type plants, it grew significantly faster on medium with bmr6 extract than on wild-type extract or controls. This result suggested that factors other than soluble phenolics from the extract, such as cell wall bound phenolics or inducible defense compounds, contributed to increased resistance observed in bmr6 plants.  相似文献   

16.
Internal fruit rot in bell pepper (Capsicum annuum L.) is mainly caused by members of the Fusarium lactis species complex (FLASC) and to a lesser extent by Fusarium oxysporum and Fusarium proliferatum. Despite the importance of the disease, there is hardly no information about growth, sporulation and germination dynamics of FLASC. In order to understand the dominance of FLASC as main pathogen of internal fruit rot, the effects of temperature (5 °C – 35 °C), water activity (aw 0.76–0.96), pH (pH 3 - pH 9) and oxygen concentration (2.5% - 20%) on growth and sporulation of all three Fusarium species were compared. In addition, germination kinetics were also investigated. FLASC showed optimal mycelium growth and sporulation in the narrow range of 25 °C, while both other strains were also tolerant for higher temperatures to 30 °C. FLASC was also characterized by a broad pH optimum from pH 3–7 while F. oxysporum (pH 4–7) and F. proliferatum (pH 5–8) were more demanding concerning pH. In addition, optimal sporulation occurred in the acid region for FLASC (pH 3) whilst neutral and alkaline pH were more favourable for the other species. Germination kinetics revealed that FLASC did not benefit from an earlier and/or faster germination process. A thorough understanding of the growth characteristics and dominance of FLASC as main pathogen for internal fruit rot is inevitable to develop sustainable control measures for the disease.  相似文献   

17.
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   

18.
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19.
Fusarium wilt, one of the destructive diseases of cucumber can be effectively controlled by using biocontrol agents such as Trichoderma harzianum. However, the mechanisms controlling T. harzianum-induced enhanced resistance remain largely unknown in cucumber plants. Here we screened the potent T. harzianum isolate TH58 that could effectively control F. oxysporum (FO). Glasshouse efficacy trials also showed that TH58 decreased disease incidence by 69.7 %. FO induced ROS over accumulation, while TH58 inoculation suppressed ROS over accumulation and improved root cell viability under F. oxysporum infection. TH58 inoculation could reverse the FO-induced cell division block and regulate the proportional distribution of nuclear DNA content through inducing 2C fraction. Moreover, the expression levels of cell cycle-related genes such as CDKA, CDKB, CycA, CycB, CycD3;1 and CycD3;2 in TH58 - pre-inoculated seedlings were up-regulated compared with those infected with FO alone. Taken together, these results suggest that T. harzianum improved plant resistance against Fusarium wilt disease via alterations in nuclear DNA content and cell cycle-related genes expression that might maintain a lower ROS accumulation and higher root cell viability in cucumber seedlings.  相似文献   

20.
Sixty two rhizospheric and endophytic bacterial strains were evaluated for their biocontrol effect on two aggressive Fusarium culmorum isolates (Fc2 and Fc3). We observed that 35 % and 23 % of the tested strains inhibited the in vitro growth of Fc2 and Fc3 respectively. The observed antagonism was due to inhibition by contact (13–19 % of the strains) or at distance (10–16 % of the strains) for both fungal isolates. Some of the antagonistic bacteria showed the ability to produce diffuse and/or volatile compounds that inhibit the growth, the sporulation and macroconidia germination of F. culmorum. None of the tested antagonistic bacteria showed chitinase activity on synthetic medium. The sequencing of the 16S rDNA genes of some antagonistic bacteria showed that they belong to the genera Bacillus, Pseudomonas and Microbacterium. The double inoculation of durum wheat seeds by the antagonistic bacterial strains (B13, B18, BSE1, BSE3 and B16E) and the two F. culmorum isolates showed that germination and seedling vigor were generally improved in vitro. The percentage of infected seeds was also reduced. In greenhouse trials, the biocontrol effectiveness of F. culmorum was dependant from the virulence of the fungal strain and the specificity of the antagonistic interaction between bacterial and fungal strains. The bacterial strains B18 and B16E reduced F. culmorum infection on durum wheat plants probably due to their antagonistic and plant growth promoting activities and they may be used in a mixture as seed biopriming inoculum for plant growth bio-promoting and Fusarium wheat diseases biocontrol.  相似文献   

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