Fusarium Community Research Articles

Shifts in Fusarium Communities and Mycotoxins in Maize Residues, Soils, and Wheat Grains throughout the Wheat Cycle: Implications for Fusarium Head Blight Epidemiology.

Fusarium Head Blight (FHB), predominantly caused by Fusarium species, is a devastating cereal disease worldwide. While considerable research has focused on Fusarium communities in grains, less attention has been given to residues and soil, the primary inoculum sources. Knowledge of Fusarium spp. diversity, dynamics, and mycotoxin accumulation in these substrates is crucial for assessing their contribution to wheat head infection and the complex interactions among Fusarium communities throughout the wheat cycle. We monitored six minimum-tillage wheat fields, with maize as the preceding crop, over two years. Soils, maize residues, and wheat grains were sampled at four stages. Fusarium composition was analyzed using a culture-dependent method, species-specific qPCR, and EF1α region metabarcoding sequencing, enabling species-level resolution. The Fusarium communities were primarily influenced by substrate type, accounting for 35.8% of variance, followed by sampling location (8.1%) and sampling stage (3.2%). Among the 32 identified species, F. poae and F. graminearum dominated grains, with mean relative abundances of 47% and 29%, respectively. Conversely, residues were mainly contaminated by F. graminearum, with a low presence of F. poae, as confirmed by species-specific qPCR. Notably, during periods of high FHB pressure, such as in 2021, F. graminearum was the dominant species in grains. However, in the following year, F. poae outcompeted F. graminearum, resulting in reduced disease pressure, consistent with the lower pathogenicity of F. poae. Source Tracker analysis indicated that residues were a more significant source of Fusarium contamination on wheat in 2021 compared to 2022, suggesting that F. graminearum in 2021 primarily originated from residues, whereas F. poae's sources of infection need further investigation. Additionally, multiple mycotoxins were detected and quantified in maize residues during the wheat cycle, raising the question of their ecological role and impact on the soil microbiota.

A diverse Fusarium community is responsible for contamination of rice with a variety of Fusarium toxins

Rice plays an important role in the daily diet in China and therefore its quality and safety have been of great concern. However, few systematic studies have investigated Fusarium community and toxins in rice grains. Here, we collected 1381 rice samples from Jiangsu Province in eastern China and found a higher frequency of zearalenone (ZEN), deoxynivalenol (DON), fumonisins (FBs), and beauvericin (BEA). The positive samples were individually contaminated with a minimum of one and a maximum of ten toxins. Fusarium was isolated and identified as the major fungus, which exhibited temporal and geographical distribution. The most prevalent species complexes within this genus were Fusarium incarnatum-equiseti species complex (FIESC), Fusarium fujikuroi species complex (FFSC), and Fusarium sambucinum species complex (FSAMSC). Nevertheless, the amplicon sequence analysis revealed a low relative abundance of Fusarium in the rice panicles, and the fungal community exhibited an irregular change along with the symptom’s emergence. In vitro toxigenic profiles of Fusarium strains showed significant complexity and specificity depending on the type and content. FIESC strains were non-pathogenic to wheat heads and weakly pathogenic to maize ears, respectively, accumulating lower amounts of toxins than F. asiaticum and F. fujikuroi. There was no significant variation in the ability to cause panicle blight in rice among the various species tested. Our study provides detailed information about the contamination of Fusarium toxins and community in rice after harvest. This information is valuable for understanding the relationship between Fusarium and rice and for developing effective control strategies.

Impact of Fusarium Species Composition and Incidence on Onion Basal Rot in Northeastern Israel

Fusarium basal rot (FBR) places a significant limitation on Allium production worldwide. The damage caused by the disease can be observed throughout the entire crop cycle. This research aimed to further our understanding of the impact of FBR on the cultivation of onions (Allium cepa) in northeast Israel. It focused on studying the composition and incidence of Fusarium species involved in disease outbursts in two representative fields, one in Galilee (Hula Valley) and the second in the Golan Heights, where the disease incidences reached 8%. Using colony morphology, microscopic taxonomic keys, and molecular methods, a new, unreported Neocosmospora (previously Fusarium solani) species complex (SC, mostly N. falciformis) was discovered as a wildly spread member of the Fusarium pathobiome community. This species complex appeared more generalist in its nature since it was found in all three onion cultivars’ samples. It was also less virulent in seed germination (42–52% higher sprout biomass, p < 0.05) and bulb pathogenicity tests (41–45% less necrotic) than Fusarium acutatum. Whereas the Galilee yellow Orlando (Riverside) onion cultivar bulbs sampled were colonized by Neocosmospora SC (70%) and two other, less abundant species, F. oxysporum f. sp. cepae and F. acutatum (15% each), the Golan Heights field’s Fusarium community showed host specificity. In the Golan Heights field, F. oxysporum f. sp. cepae inhabited the red Ha2 onion cultivar bulbs, whereas F. acutatum colonized the yellow Ha1 cultivar (40% and 50% prevalence along with Neocosmospora SC). A better understanding of the complexity of this disease caused by different Fusarium species and with a divergence in host susceptibility and virulence is critical for developing disease management strategies. Since each Fusarium species reacts differently to pest control treatments, changes in the species composition may require specifically adapted management solutions.

Maize–Fusarium associations and their mycotoxins: Insights from South Africa

For maize, a staple food in South Africa, there is a lack of comprehensive knowledge on the mycotoxin-producing fungal diversity. In this study, a fungal community profile was established using culture-dependent methods for 56 maize seed samples that were also analysed for 13 mycotoxins. The fungal isolates were identified by morphology and DNA sequencing. A total of 723 fungal isolates from 21 genera and 99 species were obtained and characterised. Fusarium was the most common genus (isolated from 52 samples), followed by Cladosporium (n = 45), Aspergillus (n = 41), Talaromyces (n = 40), and Penicillium (n = 38). Fusarium communities were dominated by the Fusarium fujikuroi species complex, which includes species such as Fusarium verticillioides and Fusarium temperatum, while Fusarium awaxy and Fusarium mirum are reported here for the first time from South Africa. As for the deoxynivalenol (DON) producing species, only Fusarium boothii and Fusarium graminearum were isolated to a lesser extent. DON (n = 37), fumonisins (FUM) (n = 32), and zearalenone (ZEA) (n = 6) were detected. The presence of a particular species did not guarantee the presence of the corresponding mycotoxins, while the inverse was also true. The occurrence of DON and/or FUM in South African maize remains a health concern, so continuous monitoring of both fungal species and their mycotoxins is important.

Short-term soil amendment by sewage sludge anaerobic digestate in a tomato monoculture suppresses Fusarium vascular wilt disease by changing the taxonomic characteristics of soil microbiota

Digestate incorporation into topsoil determines soil fertility improvement by changing composition and structure of soil microbiota. However, how microbiota responds to short-term soil amendment by sewage sludge anaerobic digestate (SSD) for suppressing Fusarium vascular wilt disease is unknown. This study compares the effects of three SSD-based treatments to suppress Fusarium oxysporum f. sp. lycopersici (Fol) in a long-term cherry tomato monoculture under field condition in a 3-year trial. Three sampling sites with two application times (two bulk soils at 3–12 weeks after amendment and one tomato rhizosphere soil at 12 weeks post-amendment) were chosen. Three digestate typologies (liquid, centrifuged, and dried) having physicochemical features and heavy metals content below the legal limits were tested at 50 l, 3.5 kg and 2.5 kg m−2y−1 dose, respectively. Fusarium wilt disease was measured for three consecutive years by severity index and Fol abundance in tomato vascular tissue was assessed by ITS rDNA gene sequencing. Fol abundance and taxonomic structure of Fusarium community in the rhizosphere were determined at specie level at the end of the trial by ITS rDNA and EF1α rDNA genes sequencing, respectively. The taxonomic structure (α-, β-diversity) of soil bacterial community (SBC) was characterized from phylum up to genus level at the end of the trial in all the sites by 16S rRNA gene sequencing. The results showed that dry SSD reduced disease severity in field up to 18 % and Fol abundance in tomato up to 0.9 ITS copies g−1 tissue. Fol abundance was decreased in the rhizosphere up to 0.0027 ng μl−1 DNA, while the Fusarium community shifted between treated-soils and un-amended. The SBC composition (α-diversity) changed in the rhizosphere by applying dry digestate, while the SBC structure (β-diversity) shifted either among treatments or sites. Bacterial members related to Fol suppression (Bacillus, Chitinophaga, Flavihumibacter, Flavobacterium, Pseudomonas and Terrimonas) increased in the rhizosphere (P < 0.01, P < 0.001) more than in the bulk soils by applying both dewatered-SSDs. Thus, digestate soil amendment carried out for three consecutive years has affected tomato Fusarium wilt severity by changing the taxonomic characteristics of fusaria and bacteria communities of the amended soil.

Different diagnostic approaches for the characterization of the fungal community and Fusarium species complex composition of Italian durum wheat grain and correlation with secondary metabolite accumulation.

The evolution of the fungal communities associated with durum wheat was assessed using different diagnostic approaches. Durum wheat grain samples were collected in three different Italian cultivation macro-areas (north, center and south). Fungal isolation was realized by potato dextrose agar (PDA) and by deep-freezing blotter (DFB). Identification of Fusarium isolates obtained from PDA was achieved by partial tef1α sequencing (PDA + tef1α), while those obtained from DFB were identified from their morphological characteristics (DFB + mc). The fungal biomass of eight Fusarium species was quantified in grains by quantitative polymerase chain reaction (qPCR). Fungal secondary metabolites were analyzed in grains by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Correlations between Fusarium detection techniques (PDA + tef1α; DFB + mc and qPCR) and mycotoxins in grains were assessed. Alternaria and Fusarium showed the highest incidence among the fungal genera developed from grains. Within the Fusarium community, PDA + tef1α highlighted that F. avenaceum and F. graminearum were the most represented members, while, DFB + mc detected a high presence of F. proliferatum. Alternaria and Fusarium mycotoxins, principally enniatins, were particularly present in the grain harvested in central Italy. Deoxynivalenol was mainly detected in northern-central Italy. The adoption of the different diagnostic techniques of Fusarium detection highlighted that, for some species, qPCR was the best method of predicting their mycotoxin contamination in grains. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Diversity of Fusarium community assembly shapes mycotoxin accumulation of diseased wheat heads.

Fusarium head blight (FHB) is a major disease worldwide on cultivated cereals, caused by several Fusarium species. FHB can cause not only yield reduction but also accumulation of mycotoxins in the grain contaminating the food supply. Much of the earlier research has focused on Fusarium pathogenesis, conditions required for disease development and toxin accumulation, and FHB management. However, the Fusarium community composition within the micro-habitat of a single diseased wheat head in the field has had limited investigation. Similarly, the relationship between the Fusarium community structure and mycotoxin accumulation within diseased heads remains unclear. In the present study, we investigated the Fusarium community in diseased heads sampled from different geographical sites in China. Several sites in Shandong province formed a transitional region which contained highly variable profiles of Fusarium OTUs, where a single diseased head could contain more than 10 Fusarium OTUs. Mycotoxin accumulation was independent of geographical properties, however, deoxynivalenol, 15-acetyldeoxynivalenol and zearalenone concentrations showed a significant negative correlation with Fusarium diversity on diseased heads while a significant positive correlation between nivalenol concentration and Fusarium diversity was observed. Taken together, the Fusarium OTU diversity within diseased heads in the field significantly influences mycotoxin accumulation, providing an important point to consider in FHB disease management and mycotoxin research.

Amplicon Sequencing ofFusariumTranslation Elongation Factor 1α Reveals that Soil Communities ofFusariumSpecies Are Resilient to Disturbances Caused by Crop and Tillage Practices

The fungal genus Fusarium contains plant pathogens, mutualists, and commensalists. Because nonpathogenic Fusarium strains can contribute to disease suppression in soil by competition or induced plant resistance, identifying factors that influence the abundance of nonpathogenic strains could lead to strategies that enhance plant-beneficial interactions and deter pathogen invasion. We developed a Fusarium-specific high-throughput translation elongation factor 1α (EF-1α) amplicon-sequencing method with subspecies resolution. Newly designed primers enabled reads to be joined for improved quality metrics after Illumina MiSeq sequencing. By including the ‘oligotyping’ program in our bioinformatic workflow, we reconstructed Fusarium EF-1α haplotypes with 100% accuracy. We conducted simulated crop rotation experiments in soil infested with the strawberry pathogen Fusarium oxysporum f. sp. fragariae ( Fof) and the following treatments: strawberry, blackberry, raspberry, lettuce, broccoli, and fallow. We profiled root Fusarium communities with EF-1α amplicons and observed that nonpathogenic strains of F. oxysporum did not colonize crops uniformly; some strains exhibited asymptomatic host preferences. In susceptible strawberry roots, &gt;90% of sequences corresponded to Fof. Bulk soil communities of Fusarium were remarkably stable and had minimal treatment-dependent effects after 1 year. Similarly, in a long-term agricultural research experiment, 18 years of conservation tillage and cover cropping did not lead to bulk soil Fusarium communities that were significantly different than controls. Although the roots of rotation crops can augment the abundance of nonpathogenic F. oxysporum strains, their abundance in bulk soil is unlikely to be altered after a single year. Climate and soil physicochemical properties may have a greater effect on Fusarium community structure.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Occurrence and Distribution of Fusarium Communities in the Root Zone in a Post-Bog Permanent Meadow in Relation to Mineral Fertilization and Growing Seasons.

The present study is the first report of a detailed analysis of the frequency of Fusarium and genera related to Fusarium colonizing the root zone of clovers and grasses growing in a permanent meadow established on peat-muck soil in a post-bog habitat. The isolation of fungi was carried out on the Nash and Snyder medium with the plate dilution method. The taxonomic identification of the collection of pure fungal cultures was based on morphological features revealed by macroscopic and microscopic observations. The species dominance coefficients, Marczewski–Steinhaus and Simpson species diversity index were calculated. Eight Fusarium complexes were distinguished. The distribution of the Fusarium population was uneven, which was generally reflected in a higher frequency of the F. oxysporum species complex in the clover root zone and M. nivale, F. avenaceum from the Fusarium tricinctum species complex, and F. culmorum from the F. sambucinum species complex in the grass root zone. The highest similarity of fungi was determined in the rhizoplane and the endorhizosphere. The highest species diversity and the highest population size were determined in the rhizosphere soil. The fertilization treatment reduced the growth rates in the Fusarium sensu lato and in genera related to Fusarium, as evidenced by the decrease in the total abundance and species richness. The root colonization by the Fusarium, especially the F. oxysporum species complex, was not accompanied by plant pathologies, which suggests a saprotrophic and endophytic rather than parasitic character of the relationships with the plant host.

Unselective Transport of Phytopathogenic Fusarium Fungi from Litter and Soil by Ground-Dwelling Arthropods Links Semi-Natural and Agricultural Habitats.

The dispersal of propagules, such as fungal spores or seeds by actively moving animals, connects and shapes communities. The dispersal of plant pathogens by arthropods might be a crucial mechanism in the spread of several crop diseases. Ground-dwelling arthropods are potential linkers between fungal communities in semi-natural and agricultural habitats by transporting propagules of Fusarium fungi. We compared the Fusarium communities on the body surface of ground-dwelling arthropods with litter in semi-natural and soil in agricultural habitats with a focus on the Fusarium community. We found three relatively distinct Fusarium communities with moderate overlap. We detected a higher richness of Fusarium species on the body surface of arthropods compared to litter and soil communities. The results suggest that the Fusarium community on the body surface of arthropods relates to the composition observed in litter and soil with limited filtering mechanisms between communities. Ground-dwelling arthropods are relevant agents for the distribution of Fusarium and therefore link fungal communities in adjacent habitats.

Effects of ferulic and p-hydroxybenzoic acids on Fusarium community structure and abundance in cucumber seedling rhizosphere

Soil microorganisms play an important role in agricultural ecosystem. However, there is little information about the effects of putative allelochemicals on specific soil microorganisms in vivo. Cucumber seedlings were treated with four concentrations of ferulic and p-hydroxybenzoic acids (0–1.0 μmol·g−1 soil) in soil. Effects of ferulic and p-hydroxybenzoic acids on rhizosphere Fusarium community structures and abundance were analyzed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR techniques, respectively. The results showed that ferulic acid at concentrations of 0.25, 0.5, and 1.0 μmol·g−1 soil significantly reduced the number of bands of Fusarium, and ferulic acid at concentrations of 0.5 and 1.0 μmol·g−1 soil significantly reduced Shannon–Wiener and evenness index of Fusarium community. All concentrations of p-hydroxybenzoic acid changed the community structure of Fusarium, including decreasing the number of bands, Shannon–Wiener, and evenness index. Ferulic and p-hydroxybenzoic acids at all concentrations significantly promoted the abundance of Fusarium. Ferulic and p-hydroxybenzoic acids at 0.5 μmol·g−1 soil had the highest Fusarium abundance among all treatments. These results indicate that four concentrations of ferulic acid had various effects on Fusarium, which was different from p-hydroxybenzoic acid, and this may be related to the cucumber autotoxicity, giving us a further understanding of soil sickness.

Taqman qPCR Quantification and Fusarium Community Analysis to Evaluate Toxigenic Fungi in Cereals

Fusarium head blight (FHB) is an economically important plant disease. Some Fusarium species produce mycotoxins that cause food safety concerns for both humans and animals. One especially important mycotoxin-producing fungus causing FHB is Fusarium graminearum. However, Fusarium species form a disease complex where different Fusarium species co-occur in the infected cereals. Effective management strategies for FHB are needed. Development of the management tools requires information about the diversity and abundance of the whole Fusarium community. Molecular quantification assays for detecting individual Fusarium species and subgroups exist, but a method for the detection and quantification of the whole Fusarium group is still lacking. In this study, a new TaqMan-based qPCR method (FusE) targeting the Fusarium-specific elongation factor region (EF1α) was developed for the detection and quantification of Fusarium spp. The FusE method was proven as a sensitive method with a detection limit of 1 pg of Fusarium DNA. Fusarium abundance results from oat samples correlated significantly with deoxynivalenol (DON) toxin content. In addition, the whole Fusarium community in Finnish oat samples was characterized with a new metabarcoding method. A shift from F. culmorum to F. graminearum in FHB-infected oats has been detected in Europe, and the results of this study confirm that. These new molecular methods can be applied in the assessment of the Fusarium community and mycotoxin risk in cereals. Knowledge gained from the Fusarium community analyses can be applied in developing and selecting effective management strategies for FHB.

Phylogenomic Analysis of a 55.1-kb 19-Gene Dataset Resolves a Monophyletic Fusarium that Includes the Fusarium solani Species Complex.

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option available.

Structure and Abundance of Fusarium Communities Inhabiting the Litter of Beech Forests in Central Europe

Members of the genus Fusarium and related genera are important components of many ecosystems worldwide and are responsible for many plant diseases. However, the structure of beech litter-inhabiting Fusarium communities and their potential role in reducing the natural regeneration of European beech are not well understood. To address this issue, we examined Fusarium communities in the litter of uneven-aged, old-growth beech-dominated forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand (Poland). The fungi inhabiting beech litter were investigated using beechnuts and pine seedlings as bait. The pathogenicity of the most common species was investigated by inoculating beech germinants. Fusarium spp. were identified based on morphology and DNA sequence comparisons of RPB2 and TEF1-α genes, combined with phylogenetic analyses. Twelve fungal species were identified from 402 isolates, including nine known and three currently undescribed species. The isolates resided in three species complexes within the genus Fusarium. These were the F. oxysporum (one taxon), F. sambucinum (three taxa), and F. tricinctum (six taxa) species complexes. In addition, one isolate was assigned to the genus Neocosmospora, and one isolate could be placed within the genus Fusicolla. The most frequently isolated fungi from beechnuts and beech germinants were F. avenaceum (Fr.) Sacc., F. sporotrichioides Sherb. and Fusarium sp. B. The structure and abundance of species within Fusarium communities varied by beech forest type. The species richness of Fusarium spp. was greatest in old-growth beech-dominated stands, while abundances of Fusarium spp. were higher in managed beech-dominated stands. Pathogenicity tests showed that all four Fusarium species isolated from beechnuts and beech germinants could cause germinants to rot beech, suggesting that these fungi may play a negative role in the natural beech regeneration.

Fusarium Head Blight From a Microbiome Perspective.

The fungal genus Fusarium causes several diseases in cereals, including Fusarium head blight (FHB). A number of Fusarium species are involved in disease development and mycotoxin contamination. Lately, the importance of interactions between plant pathogens and the plant microbiome has been increasingly recognized. In this review, we address the significance of the cereal microbiome for the development of Fusarium-related diseases. Fusarium fungi may interact with the host microbiome at multiple stages during their life cycles and in different plant organs including roots, stems, leaves, heads, and crop residues. There are interactions between Fusarium and other fungi and bacteria as well as among Fusarium species. Recent studies have provided a map of the cereal microbiome and revealed how different biotic and abiotic factors drive microbiome assembly. This review synthesizes the current understanding of the cereal microbiome and the implications for Fusarium infection, FHB development, disease control, and mycotoxin contamination. Although annual and regional variations in predominant species are significant, much research has focused on Fusarium graminearum. Surveying the total Fusarium community in environmental samples is now facilitated with novel metabarcoding methods. Further, infection with multiple Fusarium species has been shown to affect disease severity and mycotoxin contamination. A better mechanistic understanding of such multiple infections is necessary to be able to predict the outcome in terms of disease development and mycotoxin production. The knowledge on the composition of the cereal microbiome under different environmental and agricultural conditions is growing. Future studies are needed to clearly link microbiome structure to Fusarium suppression in order to develop novel disease management strategies for example based on conservation biological control approaches.

Morpho-molecular identification and first report of Fusarium equiseti in causing chilli wilt from Kashmir (Northern Himalayas)

Chilli (Capsicum annuum L.) is one of the most significant vegetable and spice crop. Wilt caused by Fusarium Sp. has emerged as a serious problem in chilli production. Internal transcribed spacer (ITS) region is widely used as a DNA barcoding marker to characterize the diversity and composition of Fusarium communities. ITS regions are heavily used in both molecular methods and ecological studies of fungi, because of its high degree of interspecific variability, conserved primer sites and multiple copy nature in the genome. In the present study we focused on morphological and molecular characterization of pathogen causing chilli wilt. Chilli plants were collected from four districts of Kashmir valley of Himalayan region. Pathogens were isolated from infected root and stem of the plants. Isolated pathogens were subjected to DNA extraction and PCR amplification. The amplified product was sequenced and three different wilt causing fungal isolates were obtained which are reported in the current investigation. In addition to Fusarium oxysporum and Fusarium solani, a new fungal species was found in association with the chilli wilt in Kashmir valley viz., Fusarium equiseti that has never been reported before from this region. The studies were confirmed by pathogenicity test and re-confirmation by DNA barcoding.

Structure and diversity of Fusarium communities inhabiting non-cultivated grass inflorescences in New York State

The structure and diversity of wild grass spike-inhabiting Fusarium communities are not well understood. Fifteen common, non-cultivated grasses were surveyed across two years, regions, and land uses for spike-dwelling Fusarium spp. Eleven fungal species were identified from 857 isolates, including two, F. camptoceras and F. lactis, not recorded previously in New York state or on grass hosts. Species diversity and community structure varied by year and region. Land use and host community did not influence Fusarium communities, and no species-specific grass-Fusarium associations were detected. Fusarium communities were divided into two categories, those dominated by F. graminearum and those dominated by F. sporotrichioides. The community formation process is relevant to disease prediction and toxin monitoring in cropping systems as well as to land management practices at the intersection of agricultural and natural spaces.

Composition and Predominance of Fusarium Species Causing Fusarium Head Blight in Winter Wheat Grain Depending on Cultivar Susceptibility and Meteorological Factors.

Fusarium head blight (FHB) is one of the most important diseases of wheat, causing yield losses and mycotoxin contamination of harvested grain. A complex of different toxigenic Fusarium species is responsible for FHB and the composition and predominance of species within the FHB complex are determined by meteorological and agronomic factors. In this study, grain of three different susceptible winter wheat cultivars from seven locations in northern Germany were analysed within a five-year survey from 2013 to 2017 by quantifying DNA amounts of different species within the Fusarium community as well as deoxynivalenol (DON) and zearalenone (ZEA) concentrations. Several Fusarium species co-occur in wheat grain samples in all years and cultivars. F. graminearum was the most prevalent species, followed by F. culmorum, F. avenaceum and F. poae, while F. tricinctum and F. langsethiae played only a subordinate role in the FHB complex in terms of DNA amounts. In all cultivars, a comparable year-specific quantitative occurrence of the six detected species and mycotoxin concentrations were found, but with decreased DNA amounts and mycotoxin concentrations in the more tolerant cultivars, especially in years with higher disease pressure. In all years, similar percentages of DNA amounts of the six species to the total Fusarium DNA amount of all detected species were found between the three cultivars for each species, with F. graminearum being the most dominant species. Differences in DNA amounts and DON and ZEA concentrations between growing seasons depended mainly on moisture factors during flowering of wheat, while high precipitation and relative humidity were the crucial meteorological factors for infection of wheat grain by Fusarium. Highly positive correlations were found between the meteorological variables precipitation and relative humidity and DNA amounts of F. graminearum, DON and ZEA concentrations during flowering, whereas the corresponding correlations were much weaker several days before (heading) and after flowering (early and late milk stage).

Flavonoid levels rather than soil nutrients is linked with Fusarium community in the soybean [Glycine max(L.) Merr.] rhizosphere under consecutive monoculture

As potent allelochemicals, flavonoids are believed to be associated with the development of soil-borne diseases. Fusarium species infection is responsible for soybean [Glycine max(L.) Merr.] root rot. However, it is uncertain if and how flavonoids influence rhizosphere Fusarium communities under consecutive soybean monoculture. Quantitative real-time PCR and pyrosequencing were used to study the Fusarium community. Spectrophotometric techniques and ultra-performance liquid chromatography (UPLC) were used to quantify flavonoids and daidzein and genistein levels, respectively. In field soil, the sizes of Fusarium community were higher from 6 to 13 years monoculture than from 1 to 3 years. The abundance of Fusarium community was significantly positively correlated with rhizosphere concentrations of the flavonoids and isoflavonoids daidzein and genistein levels. Consecutive monocultured soil selectively inhibited or stimulated certain Fusarium species, F. oxysporum remaining the most abundant. The application of daidzein and a mixture of daidzein and genistein to soil affected the Fusarium community depending on the incubation time and ranging from inhibition to promotion over time. Consecutive soybean monoculture results in shifts in the composition and size of rhizosphere Fusarium community. The Fusarium community was strongly influenced by total flavonoids, in particular daidzein and genistein, rather than soil properties.

Impact of long-term chemical fertilizer and organic amendment to Fusarium root rot of soybean

Soil suppressiveness to Fusarium root rot of soybean had been observed in a black soil field after a long-term fertilization with nitrogen (N) and phosphorus (P) fertilizer combined with pig manure as organic amendment (NPM), rather than that with only nitrogen and phosphorus fertilizer (NP) or no fertilizer (NF). To determine the microbial role on this suppressiveness, fungal and bacterial community characteristics in NPM, NP and NF treatments were investigated by qPCR and DGGE. Compared with the similar bacterial community characteristics among 3 treatments, fungal community, especially Fusarium population size and community composition in NPM treatment were different with those of NP and NF groups. Based on the isolation and pathogenicity test, pathogenic F. oxysporum, F. graminearum, F. verticillioide and F. lateritium absolutely dominated Fusarium community in NF and NP groups. Nonpathogenic F. avenaceum, F. equiseti, F. culmorum, F. redolens, F. solani and F. tricinctum dominated Fusarium community in NPM group. Isolation rate of pathogenic Fusarium in NPM reduced from 100% to 38% in NF. These results suggested that the dominance of soil non-pathogenic Fusarium population induced by organic amendment might play an important role on suppressing Fusarium root rot in the tested field.