Fusarium diseases of maize associated with mycotoxin contamination of agricultural products intended to be used for food and feed

Protocols to enable fluorescence microscopy of microbial interactions on living maize silks (style tissue)

There is interest in studying microbes that colonize maize silks (style tissue, critical for reproduction) including the fungal pathogen Fusarium graminearum (Fg) and its interactions with the microbiome and biocontrol agents. In planta imaging of these interactions on living silks using confocal fluorescence microscopy would provide key insights. However, newly discovered microbes have unknown effects on human health, and there are regulatory requirements to prevent the release of fluorescently tagged microbes into the environment. Therefore, the microbe infection, colonization, and interaction stages on silks prior to microscopy must be contained. At the same time, silk viability must be maintained and experiments conducted that are biologically relevant (e.g. silks should remain attached to the cob), yet the silk tissue must be accessible to the researcher (i.e. not within husk leaves) and allow for multiple replicates. Here we present methods that meet these five contrasting criteria. We tested these methods using Fg and four silk-derived bacterial endophytes. The endophytes were previously known to have anti-Fg activity in vitro, but in planta observations were lacking. In Method 1, a portion of the tip of a cob was dissected, and silks remained attached to the cob in a Petri dish. The cob was placed on a water agar disc to maintain hydration. DsRed-tagged bacteria and GFP-tagged Fg were inoculated onto the silks and incubated, allowing the two microbes to grow towards one another before staining with propidium iodide for confocal microscopy. A variation of the protocol was presented in Method 2, where detached silk segments were placed directly on water agar where they were inoculated with bacteria and Fg to promote dense colonization, and to allow for many replicates and interventions such as silk wounding. The bacterial endophytes were successfully observed colonizing Fg hyphae, silk trichomes, and entering silks via cut ends and wounds. These protocols can be used to study other silk-associated microbes including several globally important fungal pathogens that enter maize grain through silks.

Unlocking the Potential of Glutinol: Structural Diversification and Antifungal Activity against Phytopathogenic Fusarium Strains

Unlike most common pentacyclic plant triterpenes, glutinol has a methyl group at position C-9 and a Δ5 double bond. At the same time, it lacks a methyl at C-10. These features significantly modify its chemical behavior compared to other triterpenes, particularly under oxidative conditions. Although the isolation of glutinol from various plant species has been documented, its chemistry remains largely unexplored. In this study, glutinol was isolated from the bark of Balfourodendron riedelianum as a starting material for top-down strategies of structural diversification, which included ring fusion, oxidation, aromatization, and ring cleavage reactions. Glutinol, together with a library of 22 derivatives, was evaluated for antifungal activity against three phytopathogenic Fusarium strains, F. solani, F. graminearum, and F. tucumaniae. Some of the derivatives displayed antifungal activity; in particular, compound 12, featuring a triazine ring, displayed the best fungicidal properties against F. solani and F. graminearum, while the ring B cleavage product 23 showed the best activity against F. tucumaniae. This study highlights the potential of glutinol as a scaffold for structural diversification, and these results may contribute to the design of novel fungicidal agents against phytopathogenic strains.

Identification and Aggressiveness of Fusarium Species Associated with Onion Bulb (Allium cepa L.) during Storage

Plant pathogens present a major challenge to crop production, leading to decreased yield and quality during growth and storage. During long-term storage, healthy onions can develop diseases from latent pathogen infections. This poses a challenge for onion growers because infected bulbs without visible symptoms can lead to significant crop losses during the growing season. In this study, we aimed to isolate and identify Fusarium species from yellow onion bulbs (Allium cepa L.) that developed disease symptoms during storage. The aggressiveness of these strains against onion bulbs and seedlings was also evaluated. The isolated strains were further subjected to morphological and molecular differentiation. The results revealed that all 16 isolated strains belonged to the Fusarium complex species incarnatum-equiseti and Fusarium fujikuroi, namely, F. proliferatum (98%), F. oxysporum (1%), and Fusarium sp. (1%). Koch's postulate analysis of isolated strains revealed varying aggressiveness on onion bulbs and plants depending on fungal species. Disease symptoms developed more slowly on plants than on onion bulb plants according to Koch's postulates. Moreover, the results revealed that Fusarium strains that can infect onion plants were less pathogenic to onion bulbs and vice versa. In addition, three isolates were found to be non-pathogenic to onions. Furthermore, the in vitro control of Fusarium species through Bacillus velezensis KS04-AU and Streptomyces albidoflavus MGMM6 showed high potential for controlling the growth of these pathogenic fungi. These results may contribute to the development of environmentally friendly approaches for controlling onion spoilage caused by pathogens during storage.

Magnetic-fluorescent immunosensing platform applying AuNPs heterogeneous MIL-53(Al) composite for efficient detection of zearalenone

Rapid, sensitive, specific and stable detection of mycotoxin in food remains an extremely crucial issue. Herein, a magnetic-fluorescent immunosensing platform for the detection of zearalenone (ZEN) was proposed. The platform utilized Au nanoparticles (AuNPs) heterogeneous fluorescent metal-organic framework (MIL-53(Al)@AuNPs) labeled with ZEN-bovine serum albumin (ZEN-BSA) as signal probe and ZEN mono-antibodies coupled with magnetic NPs (MNPs-mAbs) as capture probe. Specifically, the heterogenization of AuNPs on the MIL-53(Al) surface improved its biocompatibility, and facilitated the loading of ZEN-BSA conjugates. The MNPs-mAbs could rapidly capture the target ZEN, simplify the immunoassay process and further improve the detection efficiency. The established competitive magnetic-fluorescent immunosensing platform had a wider linear response to ZEN in the range of 0.001-100 ng/mL with a lower limit of detection (LOD) at 0.0035 ng/mL, and could finish the whole detection process within 20 min, showing great potential for rapid and sensitive detection of food contaminants.

Virulence factors of the genus Fusarium with targets in plants

Fusarium spp. comprise various species of filamentous fungi that cause severe diseases in plant crops of both agricultural and forestry interest. These plant pathogens produce a wide range of molecules with diverse chemical structures and biological activities. Genetic functional analyses of some of these compounds have shown their role as virulence factors (VF). However, their mode of action and contributions to the infection process for many of these molecules are still unknown. This review aims to analyze the state of the art in Fusarium VF, emphasizing their biological targets on the plant hosts. It also addresses the current experimental approaches to improve our understanding of their role in virulence and suggests relevant research questions that remain to be answered with a greater focus on species of agroeconomic importance. In this review, a total of 37 confirmed VF are described, including 22 proteinaceous and 15 non-proteinaceous molecules, mainly from Fusarium oxysporum and Fusarium graminearum and, to a lesser extent, in Fusarium verticillioides and Fusarium solani.

Genomic Insights into the Microbial Agent Streptomyces albidoflavus MGMM6 for Various Biotechnology Applications

Microbial biotechnology plays a crucial role in improving industrial processes, particularly in the production of compounds with diverse applications. In this study, we used bioinformatic approaches to analyze the genomic architecture of Streptomyces albidoflavus MGMM6 and identify genes involved in various metabolic pathways that have significant biotechnological potential. Genome mining revealed that MGMM6 consists of a linear chromosome of 6,932,303 bp, with a high G+C content of 73.5%, lacking any plasmid contigs. Among the annotated genes, several are predicted to encode enzymes such as dye peroxidase, aromatic ring-opening dioxygenase, multicopper oxidase, cytochrome P450 monooxygenase, and aromatic ring hydroxylating dioxygenases which are responsible for the biodegradation of numerous endogenous and xenobiotic pollutants. In addition, we identified genes associated with heavy metal resistance, such as arsenic, cadmium, mercury, chromium, tellurium, antimony, and bismuth, suggesting the potential of MGMM6 for environmental remediation purposes. The analysis of secondary metabolites revealed the presence of multiple biosynthesis gene clusters responsible for producing compounds with potent antimicrobial and metal-chelating activities. Furthermore, laboratory tests conducted under controlled conditions demonstrated the effectiveness of MGMM6 in inhibiting phytopathogenic microbes, decolorizing and degrading aromatic triphenylmethane dyes, particularly Blue Brilliant G250, from wastewater by up to 98 ± 0.15%. Overall, the results of our study highlight the promising biotechnological potential of S. albidoflavus MGMM6.

Identification and Analysis of Candidate Genes Associated with Maize Fusarium Cob Resistance Using Next-Generation Sequencing Technology

The pressure to reduce mineral fertilization and the amount of pesticides used has become a factor limiting production growth, as has the elimination of many crop protection chemicals from the market. A key condition for this to be an effective form of protection is the use of varieties with higher levels of resistance. The most effective and fastest way to assist in the selection and control of pathogens is the conducting of genome-wide association studies. These are useful tools for identifying candidate genes, especially when combined with QTL mapping to map and validate loci for quantitative traits. The aim of this study was to identify new markers coupled to genes that determine maize plant resistance to fusarium head blight through the use of next-generation sequencing, association and physical mapping, and to optimize diagnostic procedures to identify selected molecular markers coupled to plant resistance to this fungal disease. As a result of field experiments and molecular analyses, molecular markers coupled to potential genes for resistance to maize ear fusariosis were selected. The newly selected markers were tested against reference genotypes. As a result of the analyses, it was found that two markers (11801 and 20607) out of the ten that were tested differentiated between susceptible and resistant genotypes. Marker number 11801 proved to be the most effective, with a specious product of 237 bp appearing for genotypes 1, 3, 5, 9 and 10. These genotypes were characterized by a field resistance of 4-6 on the 9° scale (1 being susceptible, 9 being resistant) and for all genotypes except 16 and 20, which were characterized by a field resistance of 9. In the next step, this marker will be tested on a wider population of extreme genotypes in order to use it for the preliminary selection of fusarium-resistant genotypes, and the phosphoenolpyruvate carboxylase kinase 1 gene coupled to it will be subjected to expression analysis.

Diversity and Pathogenicity of Fusarium Species Associated with Stalk and Crown Rot in Maize in Northern Italy

The genus Fusarium includes several agronomically important and toxin-producing species that are distributed worldwide and can cause a wide range of diseases. Crown and stalk rot and grain infections are among the most severe symptoms that Fusarium spp. can cause in maize. Disease development usually occurs during germination, but it may also affect the later phases of plant growth. The purpose of this study was to investigate the diversity and pathogenicity of 41 isolates recovered from symptomatic seedlings collected in Northern Italy and seeds of five different geographical origins in 2019 and 2020. The pathogenicity was tested and confirmed in 23 isolates causing rotting in maize seedlings, with disease indexes from 20% to 90%. A multilocus phylogeny analysis based on four genomic loci (tef1-α, rpb2, calm and tub2) was performed on 23 representative isolates. Representative isolates were identified as species belonging to three species complexes (SC), including Fusarium verticillioides and F. annulatum in the F. fujikuroi SC. Fusarium commune was identified in the F. nisikadoi SC, and three different lineages were found in the Fusarium oxysporum SC. This study reports F. annulatum and two lineages of the Fusarium oxysporum SC as maize pathogens for the first time in Italy.

Effects of maize genotypes, nitrogen rates and sources in yield, nutritional status, and fumonisins incidence

The maize yield, nutritional status, and grain fumonisins concentration were evaluated in different genotypes, doses, and nitrogen sources (N) in two years and three locations. Two experiments were carried out in each area and year in an experimental design of a subdivided plot with four replications. One experiment involved a 4x2 factorial treatment: four nitrogen (N) doses (0, 80, 160, and 240 kg ha-1) in coverage and having urea as a source of N and two genotypes. Another experiment involved a 4x2 factorial treatment: four N sources: urea, urea covered with polymer, ammonium nitrate, and ammonium nitrate + urea (UAN), at a dose of 160 kg ha-1, in two genotypes. The genotype generally influenced maize yield more than N doses and sources, mainly due to the bushy stunt/corn stunt tolerance of AG7098 PRO2 and AG8677 PRO2. The N doses linearly increased the N leaf content. However, the N sources did not affect the N leaf content. The N doses and sources had no significant effect on the content of fumonisins, which was affected only by the genotypes in Sete Lagoas in 2016 (N doses experiment) and 2017 (N sources experiment). The hybrids, P3630H and AG8677PRO2 (Sete Lagoas, 2016, N doses experiment and 2017, N sources experiment, respectively) exceeded the Brazilian legislation for Maximum Tolerance Limit for fumonisins in corn grains, which is 5,000 µg kg-1. The best result was obtained with AG7098 PRO2, with yields (above 10,000 kg ha-1) and fumonisins consistently below 5,000 µg kg-1. Therefore, the selection of corn hybrids is a strategy to reduce the occurrence of fumonisins in the grains.

Maize plant expresses SWEET transporters differently when interacting with Trichoderma asperellum and Fusarium verticillioides, two fungi with different lifestyles

Most Trichoderma species are beneficial fungi that promote plant growth and resistance, while Fusarium genera cause several crop damages. During the plant-fungi interaction there is a competition for sugars in both lifestyles. Here we analyzed the plant growth promotion and biocontrol activity of T. asperellum against F. verticillioides and the effect of both fungi on the expression of the maize diffusional sugar transporters, the SWEETs. The biocontrol activity was done in two ways, the first was by observing the growth capacity of both fungus in a dual culture. The second one by analyzing the infection symptoms, the chlorophyl content and the transcript levels of defense genes determined by qPCR in plants with different developmental stages primed with T. asperellum conidia and challenged with F. verticillioides. In a dual culture, T. asperellum showed antagonist activity against F. verticillioides. In the primed plants a delay in the infection disease was observed, they sustained chlorophyll content even after the infection, and displayed upregulated defense-related genes. Additionally, the T. asperellum primed plants had longer stems than the nonprimed plants. SWEETs transcript levels were analyzed by qPCR in plants primed with either fungus. Both fungi affect the transcript levels of several maize sugar transporters differently. T. asperellum increases the expression of six SWEETs on leaves and two at the roots and causes a higher exudation of sucrose, glucose, and fructose at the roots. On the contrary, F. verticillioides reduces the expression of the SWEETs on the leaves, and more severely when a more aggressive strain is in the plant. Our results suggest that the plant is able to recognize the lifestyle of the fungi and respond accordingly by changing the expression of several genes, including the SWEETs, to establish a new sugar flux.

Mycotoxigenic fungal growth inhibition and multi-mycotoxin reduction of potential biological control agents indigenous to grain maize

The present work investigated the potential of fungal species from grain maize farms in Malaysia as antagonists against the indigenous mycotoxigenic fungal species and their subsequent mycotoxin production. Dual-culture assay was conducted on grain maize agar (GMA) with 12 strains of potential fungal antagonists namely Bjerkandra adusta, Penicillium janthinellum, Schizophyllum commune, Trametes cubensis, Trichoderma asperelloides, Trichoderma asperellum, Trichoderma harzianum, and Trichoderma yunnanense against seven mycotoxigenic strains namely Aspergillus flavus, Aspergillus niger, Fusarium verticillioides, and Fusarium proliferatum producing aflatoxins, ochratoxin A, and fumonisins, respectively. Based on fungal growth inhibition, Trichoderma spp. showed the highest inhibitory activity (73-100% PIRG, Percentage Inhibition of Radial Growth; 28/0 I_D, Index of Dominance) against the tested mycotoxigenic strains. Besides, B. adusta and Tra. cubensis showed inhibitory activity against some of the tested mycotoxigenic strains. All fungal antagonists showed varying degrees of mycotoxin reduction. Aflatoxin B₁ produced by A. flavus was mainly reduced by P. janthinellum, Tra. cubensis, and B. adusta to 0 ng/g. Ochratoxin A produced by A. niger was mainly reduced by Tri. harzianum and Tri. asperellum to 0 ng/g. Fumonisin B₁ and FB₂ produced by F. verticillioides was mainly reduced by Tri. harzianum, Tri. asperelloides, and Tri. asperellum to 59.4 and 0 µg/g, respectively. Fumonisin B₁ and FB₂ produced by F. proliferatum were mainly reduced by Tri. asperelloides and Tri. harzianum to 244.2 and 0 µg/g, respectively. This is the first study that reports on the efficacy of Tri. asperelloides against FB₁, FB₂, and OTA, P. janthinellum against AFB₁, and Tra. cubensis against AFB₁.

A secondary function of trehalose-6-phosphate synthase is required for resistance to oxidative and desiccation stress in Fusarium verticillioides

The disaccharide trehalose has long been recognized for its role as a stress solute, but in recent years some of the protective effects previously ascribed to trehalose have been suggested to arise from a function of the trehalose biosynthesis enzyme trehalose-6-phosphate (T6P) synthase that is distinct from its catalytic activity. In this study, we use the maize pathogenic fungus Fusarium verticillioides as a model to explore the relative contributions of trehalose itself and a putative secondary function of T6P synthase in protection against stress as well as to understand why, as shown in a previous study, deletion of the TPS1 gene coding for T6P synthase reduces pathogenicity against maize. We report that a TPS1-deletion mutant of F. verticillioides is compromised in its ability to withstand exposure to oxidative stress meant to simulate the oxidative burst phase of maize defense and experiences more ROS-induced lipid damage than the wild-type strain. Eliminating T6P synthase expression also reduces resistance to desiccation, but not resistance to phenolic acids. Expression of catalytically-inactive T6P synthase in the TPS1-deletion mutant leads to a partial rescue of the oxidative and desiccation stress-sensitive phenotypes, suggesting the importance of a T6P synthase function that is independent of its role in trehalose synthesis.

Fusarium verticillioides of maize plant: Potentials of propitious phytomicrobiome as biocontrol agents

Disease outbreaks have been recorded due to exposure to Fusarium verticillioides and fumonisin, a mycotoxin produced by this fungus. F. verticillioides is a fungal pathogen of maize that causes infections, such as wilting and rotting, while contact with its fumonisin derivative manifests in the form of mild to severe illnesses in humans and animals. Maize infection by F. verticillioides causes loss or reduction in expected crop yield, thereby influencing households and nations' economies. While several efforts have been made to control the pathogenic fungus and its occurrence in the environment, it remains a challenge in agriculture, particularly in maize production. Several microorganisms which are plant-associated, especially those associated with the rhizosphere niche have been noted to possess antagonistic effects against F. verticillioides. They can inhibit the pathogen and tackle its debilitating effects on plants. Hence this study reviews the use of rhizosphere-associated biocontrol agents, such as Bacillus spp., Pseudomonas, Enterobacter, and Microbacterium oleivorans which forms part of the phytomicrobiome in other to prevent and control this toxicogenic fungus. These microorganisms were found to not only be effective in controlling its occurrence on maize plants but are environmentally safe and promote crop yield.

A review of the potential of lichen substances as antifungal agents: the effects of extracts and lichen secondary metabolites on Fusarium fungi

The present meta-analysis provides literature data on the effect of lichen extracts and single secondary metabolites used against Fusarium spp. moulds. Lichen extracts were obtained from 51 corticolous, 17 terricolous and 18 saxicolous lichen species and 37 secondary compounds were tested against eight fungal species, i.e., Fusarium acuminatum, F. avenaceum, F. culmorum, F. fujikuroi, F. oxysporum, F. roseum, F. solani and F. udum. The researchers used several test methods, mostly to determine MIC and IZ. Extracts were obtained using several solvents, mainly organic ones with use of the Soxhlet apparatus. The most frequently tested species was F. oxysporum, against which lichen substances from Alectoria sarmentosa, Cladonia mitis, C. rangiferina, Flavoparmelia caperata, Hypotrachyna cirrhata, Leucodermia leucomelos, Parmotrema austrosinense, P. reticulatum, Physcia aipolia, Pseudevernia furfuracea, Roccella montagnei and Umbilicaria nylanderiana and secondary metabolites such as 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid, atranorin, lecanoric and (+)-usnic acids showed the highest antifungal potential. These agencies could compete with the potential of fungicides, such as flucytosine and fluconazole. Other species have been poorly investigated. Statistical analysis of literature data showed that the fungistatic potential of lichen extracts is significantly different from individual secondary metabolites. Similarly, the potential of secondary metabolites often differs significantly from that of non-lichen substances. This meta-analysis indicates the potential of lichen substances as future anti-fusarial agents.

2,4-Diacetylphloroglucinol producing Pseudomonas fluorescens JM-1 for management of ear rot disease caused by Fusarium moniliforme in Zea mays L

Maize (Zea mays L.) is a major cereal crop grown in a large number of countries. Loss in maize yield due to biotic stresses including fungal phytopathogens is a matter of immense concern. Control measures applied for eradication of fungal phytopathogens in maize are not up to the mark and more often involve harsh chemical(s)/pesticide(s) that cause deleterious effects both in humans and soil biota. Greener alternatives, such as the use of rhizosphere microbes in the form of bioinoculants, have proven to be very successful in terms of enhancing crop yield and suppressing fungal phytopathogens. In the present study, fluorescent pseudomonads were isolated from the maize rhizosphere and monitored for their plant growth-promoting (PGP) and biocontrol activities against Fusarium moniliforme. Based on various PGP traits and biocontrol potential, isolate JM-1 was found to be most effective and as per 16S rRNA gene sequencing analysis was identified as Pseudomonas fluorescens. Further experiments showed that the biocontrol potential of JM-1 against ear rot fungus involved the production of antifungal compound 2,4-diacetylphloroglucinol (DAPG). When examined for antagonistic interaction under scanning electron microscopy (SEM), structural abnormality, hyphal lysis, and deformity in fungal mycelium were observed. In the pot experiment, application of talc-based JM-1 containing bioformulation (in pot trials) showed significant enhancement in maize growth parameters (including the seed number and weight) in comparison to control even in presence of the phytopathogen. Ear fresh weight, dry weight, number of seeds per plant, and 100-grain weight were found to increase significantly by 34, 34, 52, and 18% respectively, in comparison to control. P. fluorescens JM-1 can therefore be used as a bioinoculant for ear rot disease control and sustainably enhancing maize yield.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03201-7.

Associative and Physical Mapping of Markers Related to Fusarium in Maize Resistance, Obtained by Next-Generation Sequencing (NGS)

On the basis of studies carried out in the last few years, it is estimated that maize diseases cause yield losses of up to 30% each year. The most dangerous diseases are currently considered to be caused by fungi of the genus Fusarium, which are the main culprits of root rot, ear rots, and stalk rot. Early plant infection causes grain diminution, as well as a significant deterioration in nutritional value and fodder quality due to the presence of harmful mycotoxins. Therefore, the aim of the research was to identify new markers of the SilicoDArT and SNP type, which could be used for the mass selection of varieties resistant to fusarium. The plant material consisted of 186 inbred maize lines. The lines came from experimental plots belonging to two Polish breeding companies: Plant Breeding Smolice Ltd., (Co., Kobylin, Poland). Plant Breeding and Acclimatization Institute-National Research Institute Group (51°41'23.16″ N, 17°4'18.241″ E), and Małopolska Plant Breeding Kobierzyce, Poland Ltd., (Co., Kobierzyce, Poland) (50°58'19.411″ N, 16°55'47.323″ E). As a result of next-generation sequencing, a total of 81,602 molecular markers were obtained, of which, as a result of the associative mapping, 2962 (321 SilicoDArT and 2641 SNP) significantly related to plant resistance to fusarium were selected. Out of 2962 markers significantly related to plant resistance in the fusarium, seven markers (SilicoDArT, SNP) were selected, which were significant at the level of 0.001. They were used for physical mapping. As a result of the analysis, it was found that two out of seven selected markers (15,097-SilicoDArT and 58,771-SNP) are located inside genes, on chromosomes 2 and 3, respectively. Marker 15,097 is anchored to the gene encoding putrescine N-hydroxycinnamoyltransferase while marker 58,771 is anchored to the gene encoding the peroxidase precursor 72. Based on the literature data, both of these genes may be associated with plant resistance to fusarium. Therefore, the markers 15,097 (SilicoDArT) and 58,771 (SNP) can be used in breeding programs to select lines resistant to fusarium.

2-Methoxy-1,4-naphthoquinone regulated molecular alternation of Fusarium proliferatum revealed by high-dimensional biological data

Fungi Fusarium proliferatum and the toxins it produces are hazardous to agricultural plants, animals, and human health. However, there is a lack of more effective and environment-friendly natural anti-F. proliferatum agents. In the search for natural anti-fungal agents, we found that naturally originated 2-methoxy-1,4-naphthoquinone (MNQ) with a minimal inhibitory dose of 8.0 mg L^-1 possessed a potential inhibitory effect on F. proliferatum. The results of transcriptomic, proteomic, and metabolomic reveal a total of 1314 differential expression genes (DEGs, 873 up-regulated and 441 down-regulated), 259 differential expression proteins (DEPs, 104 up-regulated and 155 down-regulated), and 86 differential accumulation metabolites (DAMs, 49 up-regulated and 37 down-regulated) in MNQ-induced F. proliferatum. Further, the correlation analysis of transcriptomic, proteomic, and metabolomic indicated that these DEGs, DEPs, and DAMs were co-mapped in the pathways of glyoxylate and dicarboxylate metabolism, glycine, serine, and threonine metabolism, and pyruvate metabolism that linked to the TCA cycle. Furthermore, the key DEGs of the significantly co-mapped pathways were verified with qPCR analysis, which was related to the permeability of the cell membrane of F. proliferatum. Thus, these findings will provide fundamental scientific data on the molecular shifts of MNQ-induced F. proliferatum.

Aggressiveness and Mycotoxin Production by Fusarium meridionale Compared with F. graminearum on Maize Ears and Stalks in the Field

Fusarium meridionale and F. graminearum both cause Gibberella ear rot (GER) and Gibberella stalk rot (GSR) of maize in Brazil, but the former is much more common. Recent work with two isolates of each from maize suggested this dominance could be caused by greater aggressiveness and competitiveness of F. meridionale on maize. We evaluated pathogenicity and toxigenicity of 16 isolates of F. graminearum and 24 isolates of F. meridionale recovered from both wheat and maize. Strains were individually inoculated into ears of four maize hybrids in field trials. GER severity varied significantly between isolates within each species. Although ranges overlapped, the average GER severity induced by F. meridionale (25.2%) was two times as high overall as that induced by F. graminearum (12.8%) for isolates obtained from maize but was similar for those isolated from wheat (19.9 and 21.4%, respectively). In contrast, severity of GSR was slightly higher for F. graminearum (22.2%) than for F. meridionale (19.8%), with no effect of the host of origin. Deoxynivalenol and its acetylated form 15ADON were the main mycotoxins produced by F. graminearum (7/16 strains), and nivalenol toxin was produced by F. meridionale (17/24 strains). Six isolates of F. graminearum and three of F. meridionale also produced zearalenone. Results confirmed that F. meridionale from maize is, on average, more aggressive on maize but also suggested greater complexity related to diversity among the isolates within each species and their interactions with different hybrids. Further studies involving other components of the disease cycle are needed to more fully explain observed patterns of host dominance.

Machine learning approach for predicting the antifungal effect of gilaburu (Viburnum opulus) fruit extracts on Fusarium spp. isolated from diseased potato tubers

This work addresses the mathematical model building to detect the diameter of the inhibition zone of gilaburu (Viburnum opulus L.) extract against eight different Fusarium strains isolated from diseased potato tubers. Gilaburu extracts were obtained with acetone, ethanol or methanol. The isolated Fusarium strains were: F. solani, F. oxysporum, F. sambucinum, F. graminearum, F. coeruleum, F. sulphureum, F. auneaceum and F. culmorum. In general, it was observed that ethanolic extracts showed highest antifungal activity. The antifungal activity of extracts was evaluated with machine learning (ML) methods. Several ML methods (classification and regression trees (CART), support vector machines (SVM), k-Nearest Neighbors (k-NN), artificial neural network (ANN), ensemble algorithms (EA), AdaBoost (AB) algorithm, gradient boosting (GBM) algorithm, random forests (RF) bagging algorithm and extra trees (ET)) were applied and compared for modeling fungal growth. From this research, it is clear that ML methods have the lowest error level. As a result, ML methods are reliable, fast, and cheap tools for predicting the antifungal activity of gilaburu extracts. These encouraging results will attract more research efforts to implement ML into the field of food microbiology instead of traditional methods.

Lipid Signaling Modulates the Response to Fumonisin Contamination and Its Source, Fusarium verticillioides, in Maize

Fumonisin-contaminated maize (Zea mays L.) products are a major health concern because of their toxic effects in humans and animals. Breeding maize for increased mycotoxin resistance is one of the key sustainable strategies for mitigating the effects of fumonisin contamination. Recent studies suggest a link between fumonisin accumulation and plant lipid and oxylipin profiles. However, the data collected so far do not reveal a cause-and-effect relationship. In this study, to decipher the multifactorial nature of mycotoxin resistance and plant-pathogen interaction mechanisms, we examined the oxylipin and complex lipid profiles of two maize hybrids (H21 and H22, the latter showing significantly lower FBs content) grown in the open field in two locations over 3years. Untargeted ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight (UHPLC-Q-TOF), together with chemometrics analysis, successfully distinguished between the two hybrids as having low- and high-level fumonisin contamination. Considering that H21 and H22 were exposed to the same environmental factors, the higher activation of lipid signaling systems in H22 suggests that other routes are enabled in the less susceptible hybrids to limit fumonisin B (FB) accumulation. Our results highlighted the crucial role played by oxylipin and sphingolipid signaling in modulating the complex maize response to F. verticillioides infection. Overall, our results returned a global view on the changes in lipid metabolites related to fumonisin accumulation under open field conditions, and revealed a strong activation of the lipid signaling cascade in maize in the presence of FB₁.

Updated Review of the Toxicity of Selected Fusarium Toxins and Their Modified Forms

Mycotoxins are one of the most dangerous food and feed contaminants, hence they have significant influence on human and animal health. This study reviews the information reported over the last few years on the toxic effects of the most relevant and studied Fusarium toxins and their modified forms. Deoxynivalenol (DON) and its metabolites can induce intracellular oxidative stress, resulting in DNA damage. Recent studies have also revealed the capability of DON and its metabolites to disturb the cell cycle and alter amino acid expression. Several studies have attempted to explore the mechanism of action of T-2 and HT-2 toxins in anorexia induction. Among other findings, two neurotransmitters associated with this process have been identified, namely substance P and serotonin (5-hydroxytryptamine). For zearalenone (ZEN) and its metabolites, the literature points out that, in addition to their generally acknowledged estrogenic and oxidative potentials, they can also modify DNA by altering methylation patterns and histone acetylation. The ability of the compounds to induce alterations in the expression of major metabolic genes suggests that these compounds can contribute to the development of numerous metabolic diseases, including type 2 diabetes.

The Dominance of Fusarium meridionale Over F. graminearum Causing Gibberella Ear Rot in Brazil May Be Due to Increased Aggressiveness and Competitiveness

In Brazil, Gibberella ear rot (GER) of maize is caused mainly by Fusarium meridionale, whereas F. graminearum is a minor contributor. To test the hypothesis that F. meridionale is more aggressive than F. graminearum on maize, six experiments were conducted in the south (summer) and one in the central-south (winter), totaling seven conditions (year × location × hybrid). Treatments consisted of F. graminearum or F. meridionale (two isolates of each) inoculated once 4 days after silk, inoculated sequentially and alternately (F. graminearum → F. meridionale or F. meridionale → F. graminearum) 6 days apart, or (in the central-south) inoculated sequentially without alternating species (F. meridionale → F. meridionale or F. graminearum → F. graminearum). Overall, severity was two times greater in the south (37.0%), where summer temperatures were warmer (20 to 25°C) than in central-south. In the south, severity was greatest in F. meridionale treatments (67.8%); followed by F. meridionale → F. graminearum (41.1%), then F. graminearum → F. meridionale (19.4%), and lowest in F. graminearum (2.1%), suggesting an antagonistic relationship. In the central-south (15 to 20°C), severity was generally higher in the sequential nonalternating inoculation treatments (F. meridionale → F. meridionale or F. graminearum → F. graminearum) than when either species was inoculated only once. Only nivalenol (NIV) or deoxynivalenol was detected when F. meridionale or F. graminearum, respectively, was inoculated singly, or sequentially with no alternation. Both toxins were found in grains harvested from the F. meridionale → F. graminearum treatment, whereas only NIV was found in kernels from the F. graminearum → F. meridionale treatment, suggesting that F. meridionale was more competitive than F. graminearum in coinoculations. The dominance of F. meridionale as a cause of GER in Brazil may be due in part to its higher aggressiveness and competitiveness compared with F. graminearum.

Metabolic Footprints of Burkholderia Sensu Lato Rhizosphere Bacteria Active against Maize Fusarium Pathogens

Consistent with their reported abundance in soils, several Burkholderia sensu lato strains were isolated from the rhizosphere of maize plants cultivated at different sites in central México. Comparative analysis of their 16S rRNA gene sequences permitted their separation into three distinctive clades, which were further subdivided into six other clusters by their close resemblance to (1) Trinickia dinghuensis; (2) Paraburkholderia kirstenboschensis, P. graminis, P. dilworthii and P. rhynchosiae; (3) B. gladioli; (4) B. arboris; (5) B. contaminans, or (6) B. metallica representative species. Direct confrontation assays revealed that these strains inhibited the growth of pathogenic Fusarium oxysporum f. sp. radicis-lycopersici, and F. verticillioides within a roughly 3-55% inhibition range. The use of a DIESI-based non-targeted mass spectroscopy experimental strategy further indicated that this method is an option for rapid determination of the pathogen inhibitory capacity of Burkholderia sensu lato strains based solely on the analysis of their exometabolome. Furthermore, it showed that the highest anti-fungal activity observed in B. contaminans and B. arboris was associated with a distinctive abundance of certain m/z ions, some of which were identified as components of the ornbactin and pyochelin siderophores. These results highlight the chemical diversity of Burkholderia sensu lato bacteria and suggest that their capacity to inhibit the Fusarium-related infection of maize in suppressive soils is associated with siderophore synthesis.

Plasma Technology Increases the Efficacy of Prothioconazole against Fusarium graminearum and Fusarium proliferatum Contamination of Maize (Zea mays) Seedlings

The contamination of maize by Fusarium species able to produce mycotoxins raises great concern worldwide since they can accumulate these toxic metabolites in field crop products. Furthermore, little information exists today on the ability of Fusarium proliferatum and Fusarium graminearum, two well know mycotoxigenic species, to translocate from the seeds to the plants up to the kernels. Marketing seeds coated with fungicide molecules is a common practice; however, since there is a growing need for reducing chemicals in agriculture, new eco-friendly strategies are increasingly tested. Technologies based on ionized gases, known as plasmas, have been used for decades, with newer material surfaces, products, and approaches developed continuously. In this research, we tested a plasma-generated bilayer coating for encapsulating prothioconazole at the surface of maize seeds, to protect them from F. graminearum and F. proliferatum infection. A minimum amount of chemical was used, in direct contact with the seeds, with no dispersion in the soil. The ability of F. graminearum and F. proliferatum species to translocate from seeds to seedlings of maize has been clearly proven in our in vitro experiments. As for the use of plasma technology, the combined use of the plasma-generated coating with embedded prothioconazole was the most efficient approach, with a higher reduction of the infection of the maize seminal root system and stems. The debated capability of the two Fusarium species to translocate from seeds to seedlings has been demonstrated. The plasma-generated coating with embedded prothioconazole resulted in a promising sustainable approach for the protection of maize seedlings.

Mycotoxins Biocontrol Methods for Healthier Crops and Stored Products

Contamination of crops with phytopathogenic genera such as Fusarium, Aspergillus, Alternaria, and Penicillium usually results in mycotoxins in the stored crops or the final products (bread, beer, etc.). To reduce the damage and suppress the fungal growth, it is common to add antifungal substances during growth in the field or storage. Many of these antifungal substances are also harmful to human health and the reduction of their concentration would be of immense importance to food safety. Many eminent researchers are seeking a way to reduce the use of synthetic antifungal compounds and to implement more eco-friendly and healthier bioweapons against fungal proliferation and mycotoxin synthesis. This paper aims to address the recent advances in the effectiveness of biological antifungal compounds application against the aforementioned fungal genera and their species to enhance the protection of ecological and environmental systems involved in crop growing (water, soil, air) and to reduce fungicide contamination of food derived from these commodities.

The Effect of Fusarium verticillioides Fumonisins on Fatty Acids, Sphingolipids, and Oxylipins in Maize Germlings

Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.

Occurrence of Fusarium Mycotoxins and Their Modified Forms in Forage Maize Cultivars

Forage maize is often infected by mycotoxin-producing Fusarium fungi during plant growth, which represent a serious health risk to exposed animals. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important Fusarium mycotoxins, but little is known about the occurrence of their modified forms in forage maize. To assess the mycotoxin contamination in Northern Germany, 120 natural contaminated forage maize samples of four cultivars from several locations were analysed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) for DON and ZEN and their modified forms deoxynivalenol-3-glucoside (DON3G), the sum of 3- and 15-acetyl-deoxynivalenol (3+15-AcDON), α- and β-zearalenol (α-ZEL, β-ZEL). DON and ZEN occurred with high incidences (100 and 96%) and a wide range of concentrations, reaching levels up to 10,972 and 3910 µg/kg, respectively. Almost half of the samples (46%) exceeded the guidance value in complementary and complete feeding stuffs for ZEN (500 µg/kg), and 9% for DON (5000 µg/kg). The DON related mycotoxins DON3G and 3+15-AcDON were also present in almost all samples (100 and 97%) with amounts of up to 3038 and 2237 µg/kg and a wide range of concentrations. For the ZEN metabolites α- and β-ZEL lower incidences were detected (59 and 32%) with concentrations of up to 423 and 203 µg/kg, respectively. Forage maize samples were contaminated with at least three co-occurring mycotoxins, whereby 95% of all samples contained four or more mycotoxins with DON, DON3G, 3+15-AcDON, and ZEN co-occurring in 93%, together with α-ZEL in 57% of all samples. Positive correlations were established between concentrations of the co-occurring mycotoxins, especially between DON and its modified forms. Averaged over all samples, ratios of DON3G/DON and 3+15-AcDON/DON were similar, 20.2 and 20.5 mol%; cultivar-specific mean ratios ranged from 14.6 to 24.3 mol% and 15.8 to 24.0 mol%, respectively. In total, 40.7 mol% of the measured DON concentration was present in the modified forms DON3G and 3+15-AcDON. The α-ZEL/ZEN ratio was 6.2 mol%, ranging from 5.2 to 8.6 mol% between cultivars. These results demonstrate that modified mycotoxins contribute substantially to the overall mycotoxin contamination in forage maize. To avoid a considerable underestimation, it is necessary to analyse modified mycotoxins in future mycotoxin monitoring programs together with their parent forms.

Effect of Selected Cooking Ingredients for Nixtamalization on the Reduction of Fusarium Mycotoxins in Maize and Sorghum

Although previous studies have reported the use of nixtamalization for mycotoxins reduction in maize, the efficacy of calcium hydroxide and other nixtamalization cooking ingredients for mycotoxin reduction/decontamination in sorghum and other cereals still need to be determined. The current study investigated the effect of five nixtamalization cooking ingredients (wood ashes, calcium hydroxide, sodium hydroxide, potassium hydroxide, and calcium chloride) on the reduction of Fusarium mycotoxins in artificially contaminated maize and sorghum using liquid chromatography-tandem mass spectrometry. All tested cooking ingredients effectively reduced levels of mycotoxins in the contaminated samples with reduction initiated immediately after the washing step. Except for the calcium chloride nixtamal, levels of fumonisin B₁, B_2, and B₃ in the processed sorghum nixtamal samples were below the limit of detection. Meanwhile, the lowest pH values were obtained from the maize (4.84; 4.99), as well as sorghum (4.83; 4.81) nejayote and nixtamal samples obtained via calcium chloride treatment. Overall, the results revealed that the tested cooking ingredients were effective in reducing the target mycotoxins. In addition, it pointed out the potential of calcium chloride, though with reduced effectiveness, as a possible greener alternative cooking ingredient (ecological nixtamalization) when there are environmental concerns caused by alkaline nejayote.

Production of Microsclerotia From Entomopathogenic Fungi and Use in Maize Seed Coating as Delivery for Biocontrol Against Fusarium graminearum

The commercial use of the entomopathogenic fungi Metarhizium spp. in biopesticides has gained more interest since the discovery that several species of this genus are able to colonize roots. In general, commercial products with Metarhizium are formulated based on conidia for insect pest control. The process of mass production, harvesting, and formulation of infective conidia can be detrimental for conidial viability. Entomopathogenic fungi such as Metarhizium spp. are able to produce high concentrations of resistant structures, known as microsclerotia, when grown in liquid media. Microsclerotia are desiccation tolerant, with excellent storage stability, and are capable of producing high quantities of infective conidia after rehydration. The aim of this study was to evaluate microsclerotia production by different isolates of Metarhizium spp. and determine the effect of microsclerotia coated onto maize seeds on plant growth in the presence of soil-borne pathogen Fusarium graminearum. On average, ~1 × 105 microsclerotia/mL were produced by selected isolates of M. anisopliae (A1080 and F672) and Metarhizium robertsii (F447). Microsclerotia were formulated as granules with diatomaceous earth and used for seed coating, after which propagules produced around 5 × 106 CFU/g of seeds. In the presence of the plant pathogen, maize plants grown from untreated seeds had the lowest growth, while plants treated with the Metarhizium microsclerotia had significantly greater growth than the control plants. Hyphae were observed growing on and in root tissues in all the Metarhizium spp. treatments but not in samples from control plants. Metarhizium hyphal penetration points' on roots were observed 1 month after sowing, indicating the fungi were colonizing roots as endophytes. The results obtained indicate that microsclerotia can be coated onto seeds, providing plant protection against soil plant pathogens and a method to establish Metarhizium in the ecto- and endo-rhizosphere of maize roots, allowing the persistence of this biocontrol agent.

The fate of mycotoxins during secondary food processing of maize for human consumption

Mycotoxins are naturally occurring fungal metabolites that are associated with health hazards and are widespread in cereals including maize. The most common mycotoxins in maize that occur at relatively high levels are fumonisins (FBs), zearalenone, and aflatoxins; furthermore, other mycotoxins such as deoxynivalenol and ochratoxin A are frequently present in maize. For these toxins, maximum levels are laid down in the European Union (EU) for maize raw materials and maize-based foods. The current review article gives a comprehensive overview on the different mycotoxins (including mycotoxins not regulated by EU law) and their fate during secondary processing of maize, based on the data published in the scientific literature. Furthermore, potential compliance with the EU maximum levels is discussed where appropriate. In general, secondary processing can impact mycotoxins in various ways. Besides changes in mycotoxin levels due to fractionation, dilution, and/or concentration, mycotoxins can be affected in their chemical structure (causing degradation or modification) or be released from or bound to matrix components. In the current review, a special focus is set on the effect on mycotoxins caused by different heat treatments, namely, baking, roasting, frying, (pressure) cooking, and extrusion cooking. Production processes involving multiple heat treatments are exemplified with the cornflakes production. For that, potential compliance with FB maximum levels was assessed. Moreover, effects of fermentation of maize matrices and production of maize germ oil are covered by this review.

Methanolic Extracts from Cultivated Mushrooms Affect the Production of Fumonisins B and Fusaric Acid by Fusarium verticillioides

The maize pathogen Fusarium verticillioides and their mycotoxins cause damage to plants, animals, and human health. This work aimed to evaluate the effect of crude extracts (CEs) from Agaricus subrufescens, Lentinula edodes, and Pleurotus ostreatus fruiting bodies on in vitro production of biomass and mycotoxins by two strains of F. verticillioides. Stipes and pilei were separated before extraction for A. subrufescens and L. edodes. Comparative metabolomics and dereplication of phenolic compounds were used to analyze all CEs. Mushroom CEs did not significantly inhibit the production of mycelial biomass at concentrations of 2 mg mL⁻1. CEs from A. subrufescens (stipes and pilei) and L. edodes pilei inhibited the production of fumonisins B1 + B2 + B3 by 54% to 80%, whereas CE from P. ostreatus had no effect. In contrast, CE from L. edodes stipes dramatically increased the concentration of fumonisins in culture media. Fusaric acid concentration was decreased in cultures by all CEs except L. edodes stipes. Differences in phenolic composition of the extracts may explain the different effects of the CE treatments on the production of mycotoxins. The opposing activities of stipes and pilei from L. edodes offer an opportunity to search for active compounds to control the mycotoxin production by F. verticillioides.

Physiological and biochemical insights into the basal level of resistance of two maize hybrids in response to Fusarium verticillioides infection

Fusarium stalk rot (FSR), caused by Fusarium verticillioides, is one of the most destructive diseases impacting maize yield worldwide. In this study, net carbon assimilation rate (A), stomatal conductance to water vapor (gs), transpiration rate (E), and internal CO2 concentration (Ci) were evaluated on leaves and the activities of enzymes (chitinase (CHI), β-1-3-glucanase (GLU), phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POX)) as well the concentrations of total soluble phenolics (TSP), lignin-thioglycolic acid (LTGA) derivatives, and malondialdehyde (MDA) were evaluated in the internodes and nodes of plants from maize hybrids moderately resistant (BRS 1035) and susceptible (30F35Y) to FSR. The upward relative lesion length (URLL) and radial fungal colonization (RFC) were 46 and 29% lower for the BRS 1035 hybrid in comparison to 30F35Y hybrid, respectively, at 30 after inoculation (dai). For both hybrids, A, gs, and E values significantly decreased while the Ci values increased on infected leaves compared to noninoculated plants. Inoculated plants from BRS 1035 hybrid showed an increase in A compared to inoculated plants from 30F35Y hybrid, and the increase in Ci values was greater for plants from 30F35Y hybrid at 30 dai compared to plants from BRS 1035 hybrid. The CHI, GLU, PPO, CAT, APX, and POX activities increased for inoculated plants from both hybrids compared to the noninoculated plants. In the internodes region, the increase in the activities of CHI (during the infection process of F. verticillioides) and GLU (at earlier stages of F. verticillioides infection) was more pronounced for plants from BRS 1035 hybrid than for plants from 30F35Y hybrid. In the region of the nodes, activities of CHI (during the infection process of F. verticillioides), PAL (at 20 dai), PPO (at 30 dai), and CAT and POX (both at three dai) were more pronounced for plants from BRS 1035 hybrid than for plants from 30F35Y hybrid. In the internodes region, the lower TSP concentration at 30 dai was linked to a high concentration of LTGA derivatives for inoculated plants from BRS 1035 hybrid compared to inoculated plants from 30F35Y hybrid. Taking together, the results of the present study allowed to conclude that the infection by F. verticillioides triggered physiological and biochemical changes on the stalk of maize plants influencing photosynthesis on leaves. A more robust antioxidative metabolism for reactive oxygen species removal in association with an efficient and strong activity of defense enzymes helped to minimize the cellular damage caused by F. verticillioides infection resulting, therefore, in an increase in maize resistance to FSR.

In Vitro Fumonisin Biosynthesis and Genetic Structure of Fusarium verticillioides Strains from Five Mediterranean Countries

Investigating the in vitro fumonisin biosynthesis and the genetic structure of Fusarium verticillioides populations can provide important insights into the relationships between strains originating from various world regions. In this study, 90 F. verticillioides strains isolated from maize in five Mediterranean countries (Italy, Spain, Tunisia, Egypt and Iran) were analyzed to investigate their ability to in vitro biosynthesize fumonisin B₁, fumonisin B₂ and fumonisin B₃ and to characterize their genetic profile. In general, 80% of the analyzed strains were able to biosynthesize fumonisins (range 0.03–69.84 μg/g). Populations from Italy, Spain, Tunisia and Iran showed a similar percentage of fumonisin producing strains (>90%); conversely, the Egyptian population showed a lower level of producing strains (46%). Significant differences in fumonisin biosynthesis were detected among strains isolated in the same country and among strains isolated from different countries. A portion of the divergent FUM1 gene and of intergenic regions FUM6-FUM7 and FUM7-FUM8 were sequenced to evaluate strain diversity among populations. A high level of genetic uniformity inside the populations analyzed was detected. Apparently, neither geographical origin nor fumonisin production ability were correlated to the genetic diversity of the strain set. However, four strains from Egypt differed from the remaining strains.

Mycotoxins in Flanders' Fields: Occurrence and Correlations with Fusarium Species in Whole-Plant Harvested Maize

Mycotoxins are well-known contaminants of several food- and feedstuffs, including silage maize for dairy cattle. Climate change and year-to-year variations in climatic conditions may cause a shift in the fungal populations infecting maize, and therefore alter the mycotoxin load. In this research, 257 maize samples were taken from fields across Flanders, Belgium, over the course of three years (2016-2018) and analyzed for 22 different mycotoxins using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. DNA of Fusarium graminearum, F. culmorum and F. verticillioides was quantified using the quantitative polymerase chain reaction (qPCR). Multi-mycotoxin contamination occurred frequently, with 47% of samples containing five or more mycotoxins. Nivalenol (NIV) was the most prevalent mycotoxin, being present in 99% of the samples, followed by deoxynivalenol (DON) in 86% and zearalenone (ZEN) in 50% of the samples. Fumonisins (FUMs) were found in only 2% of the samples in the wet, cold year of 2016, but in 61% in the extremely hot and dry year of 2018. Positive correlations were found between DON and NIV and between F. graminearum and F. culmorum, among others. FUM concentrations were not correlated with any other mycotoxin, nor with any Fusarium sp., except F. verticillioides. These results show that changing weather conditions can influence fungal populations and the corresponding mycotoxin contamination of maize significantly, and that multi-mycotoxin contamination increases the risk of mycotoxicosis in dairy cattle.

Effect of ensiling duration on the fate of deoxynivalenol, zearalenone and their derivatives in maize silage

Fusarium mycotoxins and their derivatives are frequently detected in freshly harvested forage maize. This study assessed the time course effects during ensiling of forage maize on the fate of Fusarium mycotoxins, using laboratory-scale silos and artificially contaminated raw material. A multi-mycotoxin liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method was used to determine the levels of deoxynivalenol (DON), zearalenone (ZEN) and their derivatives DON-3-glucoside, 3-acetyl-DON, 15-acetyl-DON, deepoxy-DON, α-zearalenol and β-zearalenol. A significant increase of DON was observed during ensiling, whereas the levels of DON-3-glucoside and its acetylated forms proportionally decreased. In contrast, levels of ZEN, α-zearalenol and β-zearalenol were not affected by the ensiling process. Based on these findings, ensiling is not a practical method for reducing the total amount of Fusarium mycotoxins present at harvest.

Mycotoxins Contaminant in Kelp: A Neglected Dietary Exposure Pathway

In order to investigated current occurrence of major mycotoxins in dietary kelp in Shandong Province in Northern China, a reliable, sensitive, and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of the 7 most frequent mycotoxins, including 3-acetoxy deoxynivalenol (3AcDON), 15-acetoxy deoxynivalenol (15AcDON), Deoxynivalenol (DON), Fusarenon-X (F-X), Nivalenol (NIV), T-2 toxin (T-2), and Zearalenone (ZEA). Based on optimized pretreatment and chromatographic and mass spectrometry conditions, these target analytes could be monitored with mean recoveries from 72.59~107.34%, with intra⁻day RSD < 9.21%, inter⁻day RSD < 9.09%, LOD < 5.55 μg kg-1, and LOQ < 18.5 μg kg-1. Approximately 43 kelp samples were detected, 3AcDON/15AcDON ranged from 15.3 to 162.5 μg kg-1 with positive rate of 86% in Shandong Province in Northern China. Considering there were no related investigations about mycotoxin contamination in kelp, the high contamination rate of 3AcDON/15AcDON in kelp showed a neglected mycotoxin exposure pathway, which might lead to high dietary exposure risk to consumers.

Fungal Pathogens of Maize Gaining Free Passage Along the Silk Road

Silks are the long threads at the tips of maize ears onto which pollen land and sperm nuclei travel long distances to fertilize egg cells, giving rise to embryos and seeds; however fungal pathogens also use this route to invade developing grain, causing damaging ear rots with dangerous mycotoxins. This review highlights the importance of silks as the direct highways by which globally important fungal pathogens enter maize kernels. First, the most important silk-entering fungal pathogens in maize are reviewed, including Fusarium graminearum, Fusarium verticillioides, and Aspergillus flavus, and their mycotoxins. Next, we compare the different modes used by each fungal pathogen to invade the silks, including susceptible time intervals and the effects of pollination. Innate silk defences and current strategies to protect silks from ear rot pathogens are reviewed, and future protective strategies and silk-based research are proposed. There is a particular gap in knowledge of how to improve silk health and defences around the time of pollination, and a need for protective silk sprays or other technologies. It is hoped that this review will stimulate innovations in breeding, inputs, and techniques to help growers protect silks, which are expected to become more vulnerable to pathogens due to climate change.

Fusarium toxins in corn food products: a survey of the Serbian retail market

This paper presents data on the occurrence of Fusarium toxins - zearalenone (ZEA), deoxynivalenol (DON) and fumonisins (FUMs) B1 and B2 - in corn flours and corn flakes marketed in Serbia. A total of 71 samples were collected over 2013-2016 and analysed using HPLC with UV or fluorescence detection. In the case of corn flours, none of the samples taken in 2013 exhibited the presence of ZEA or DON, whereas 90% were positive for FUMs. In 2015, occurrence was very high: ZEA 93%, DON 86% and FUMs 100% (mean 43.3, 322.6 and 323.0 μg kg^-1, respectively), with 21% of the samples exceeding the maximum level for ZEA and 7% for DON and FUMs. In 2016, a lower occurrence was recorded in the case of ZEA (75%) and DON (38%), with drastically lower mean contamination levels (six- and 10-fold, respectively), while FUMs stayed at 97%, with twofold lower mean. The maximum level was exceeded only for ZEA (3%). The frequency of ZEA-DON-FB1 co-occurrence was 86% in 2015 and 25% in 2016. Regarding corn flakes, occurrence summarised for the study period was 87% ZEA, 73% FUMs and 40% DON. One sample (7%) exceeded the maximum levels for both ZEA and DON. Observed occurrence changes were in agreement with the climatic conditions during corn growing seasons preceding the market release of the processed products.