Influence of water activity and temperature on growth and fumonisin production by Fusarium proliferatum strains on irradiated wheat grains

Prevalence and Concentration of Mycotoxins in Animal Feed in the Middle East and North Africa (MENA): A Systematic Review and Meta-Analysis

This study seeks a comprehensive meta-analysis of mycotoxin contaminants in animal feed consumed in the Middle East and North Africa (MENA) region. The obtained articles were reviewed, and 49 articles that investigated the contamination of mycotoxins including aflatoxins (AFs), deoxynivalenol (DON), zearalenone (ZEA), T-2 toxin, fumonisins (FUM), and ochratoxin A (OTA), in feed samples or components of animal feed in the MENA region were selected. The titles of the final articles included in the study were meta-analyzed. Necessary information was extracted and categorized from the articles, and a meta-analysis was performed using Stata software. The highest contamination was in dry bread (80%), and Algeria was the most contaminated country (87% of animal feed), with the most mycotoxins contaminating AFs (47%) and FUM (47%). The highest concentration of mycotoxins in animal feed is related to FUM (1240.01 μg/kg). Climate change, economic situation, agricultural and processing methods, the nature of the animal feed, and improper use of food waste in animal feed are among the most critical factors that are effective in the occurrence of mycotoxin contamination in animal feed in MENA. Control of influential factors in the occurrence of contaminations and rapid screening with accurate identification methods to prevent the occurrence and spread of mycotoxin contamination of animal feed seem important.

Genomic footprints related with adaptation and fumonisins production in Fusarium proliferatum

Fusarium proliferatum is the principal etiological agent of rice spikelet rot disease (RSRD) in China, causing yield losses and fumonisins contamination in rice. The intraspecific variability and evolution pattern of the pathogen is poorly understood. Here, we performed whole-genome resequencing of 67 F. proliferatum strains collected from major rice-growing regions in China. Population structure indicated that eastern population of F. proliferatum located in Yangtze River with the high genetic diversity and recombinant mode that was predicted as the putative center of origin. Southern population and northeast population were likely been introduced into local populations through gene flow, and genetic differentiation between them might be shaped by rice-driven domestication. A total of 121 distinct genomic loci implicated 85 candidate genes were suggestively associated with variation of fumonisin B1 (FB1) production by genome-wide association study (GWAS). We subsequently tested the function of five candidate genes (gabap, chsD, palA, hxk1, and isw2) mapped in our association study by FB1 quantification of deletion strains, and mutants showed the impact on FB1 production as compared to the wide-type strain. Together, this is the first study to provide insights into the evolution and adaptation in natural populations of F. proliferatum on rice, as well as the complex genetic architecture for fumonisins biosynthesis.

Climate Change and Effects on Molds and Mycotoxins

Earth’s climate is undergoing adverse global changes as an unequivocal result of anthropogenic activity. The occurring environmental changes are slowly shaping the balance between plant growth and related fungal diseases. Climate (temperature, available water, and light quality/quantity; as well as extreme drought, desertification, and fluctuations of humid/dry cycles) represents the most important agroecosystem factor influencing the life cycle stages of fungi and their ability to colonize crops, survive, and produce toxins. The ability of mycotoxigenic fungi to respond to Climate Change (CC) may induce a shift in their geographical distribution and in the pattern of mycotoxin occurrence. The present review examines the available evidence on the impact of CC factors on growth and mycotoxin production by the key mycotoxigenic fungi belonging to the genera Aspergillus, Penicillium, and Fusarium, which include several species producing mycotoxins of the greatest concern worldwide: aflatoxins (AFs), ochratoxins, and fumonisins (FUMs).

A Case Study in Saudi Arabia: Biodiversity of Maize Seed-Borne Pathogenic Fungi in Relation to Biochemical, Physiological, and Molecular Characteristics

Microbiodiversity is usually correlated with environmental conditions. This investigation is a case study to cover the lack of knowledge on the correlation of biochemical, physiological, and molecular attributes with the distribution of seed-borne pathogenic fungi of maize under the environmental conditions of the Kingdom of Saudi Arabia to help forecast any destructive epidemics. Forty-one fungal species belonging to 24 genera were detected using standard moist blotter (SMB), deep freezing blotter (DFB), and agar plate (AP) techniques. SMB was superior in detecting the maximum numbers (36 species) of seed-borne mycoflora. The pathogenicity assay revealed that, among 18 seed-borne fungal pathogens used, 12 isolates caused high percentages of rotted seeds and seedling mortality symptoms, which were identified molecularly using an internal transcribed spacer sequence. Two Curvularia spp. and Sarocladium zeae were reported for the first time in KSA. The strains showed various enzymatic activities and amino acid profiles under different environmental setups. Temperature and humidity were the environmental variables influencing the fungal pathogenicity. The highest pathogenicity was correlated with the presence and concentration of threonine, alanine, glutamic, aspartic acids, and protein. The study concluded with the discovery of four new phytopathogens in KSA and, further, evidenced a marked correlation among the investigated variables. Nevertheless, more studies are encouraged to include additional physiological properties of the phytopathogens, such as toxigenic activity, as well as extend the fungal biodiversity study to other plants.

Biodiversity of Pathogenic and Toxigenic Seed-Borne Mycoflora of Wheat in Egypt and Their Correlations with Weather Variables

Surveillance investigations for pathogenic and toxigenic fungi are important to refine our understanding of their epidemiology and help in predicting their outbreaks. During 2019, 198 samples of wheat grains were collected from 25 wheat-growing governorates in Egypt to detect and identify seed-borne mycoflora in vitro. Forty-four fungal species belonging to 20 genera were identified. Molecular data for these fungi were analyzed to construct a phylogenetic tree. Occurrence and biodiversity indicators were calculated. Two prevalent pathogens (average incidence > 40%) were Alternaria alternata and Cladosporium spp. Ustilago tritici was present in only seven of the 25 governorates, and less abundant than Tilletia tritici, the causal agent of stinking smut. Sinai governorate recorded the greatest species diversity, while the greatest species richness was in Qena and Sohag governorates. Canonical correspondence analysis of data for 20 fungal genera with temperature, relative humidity, precipitation, wind speed or solar radiation revealed that relative humidity was the most influential weather variable. It showed that occurrence and distribution of the 20 genera corresponded well with three out of four Egyptian climatic regions: Mediterranean, semi-arid, and arid. Knowing pathogen occurrence and distribution in Egypt is the first step to developing future disease management strategies to limit yield losses and improve food security. Despite this study being conducted on the wheat-growing areas in Egypt, our findings are useful for other wheat-growing countries that share the same climatic conditions. The correlation between a given fungus and the climatic variables can be useful in other ecosystems.

Influence of H2O2-Induced Oxidative Stress on In Vitro Growth and Moniliformin and Fumonisins Accumulation by Fusarium proliferatum and Fusarium subglutinans

Fusarium proliferatum and Fusarium subglutinans are common pathogens of maize which are known to produce mycotoxins, including moniliformin (MON) and fumonisins (FBs). Fungal secondary metabolism and response to oxidative stress are interlaced, where hydrogen peroxide (H₂O₂) plays a pivotal role in the modulation of mycotoxin production. The objective of this study is to examine the effect of H₂O₂-induced oxidative stress on fungal growth, as well as MON and FBs production, in different isolates of these fungi. When these isolates were cultured in the presence of 1, 2, 5, and 10 mM H₂O₂, the fungal biomass of F. subglutinans isolates showed a strong sensitivity to increasing oxidative conditions (27–58% reduction), whereas F. proliferatum isolates were not affected or even slightly improved (45% increase). H₂O₂ treatment at the lower concentration of 1 mM caused an almost total disappearance of MON and a strong reduction of FBs content in the two fungal species and isolates tested. The catalase activity, surveyed due to its crucial role as an H₂O₂ scavenger, showed no significant changes at 1 mM H₂O₂ treatment, thus indicating a lack of correlation with MON and FB changes. H₂O₂ treatment was also able to reduce MON and FB content in certified maize material, and the same behavior was observed in the presence and absence of these fungi, highlighting a direct effect of H₂O₂ on the stability of these mycotoxins. Taken together, these data provide insights into the role of H₂O₂ which, when increased under stress conditions, could affect the vegetative response and mycotoxin production (and degradation) of these fungi.

Research Progress on Fumonisin B1 Contamination and Toxicity: A Review

Fumonisin B1 (FB1), belonging to the member of fumonisins, is one of the most toxic mycotoxins produced mainly by Fusarium proliferatum and Fusarium verticillioide. FB1 has caused extensive contamination worldwide, mainly in corn, rice, wheat, and their products, while it also poses a health risk and is toxic to animals and human. It has been shown to cause oxidative stress, endoplasmic reticulum stress, cellular autophagy, and apoptosis. This review focuses on the current stage of FB1 contamination, its toxic effects of acute toxicity, immunotoxicity, organ toxicity, and reproductive toxicity on animals and humans. The potential toxic mechanisms of FB1 are discussed. One of the main aims of the work is to provide a reliable reference strategy for understanding the occurrence and toxicity of FB1.

Prevalence and concentration of fumonisins in cereal-based foods: a global systematic review and meta-analysis study

Cereal-based foods are utilized as an essential food segment worldwide. Nevertheless, their contamination by mycotoxins, also fumonisins, could pose a critical health risk. The present research provides the first systematic review regarding the prevalence and concentration of fumonisins in cereal-based food with the aid of a meta-analysis. In this regard, some international databases PubMed, Web of Science, Google Scholar, and Scopus were explored during the last 30 years. Among 9729 screened articles, 73 articles (which meet the proposed inclusion criteria), including 11,132 data, were incorporated in the performed meta-analysis. The overall rank order regarding the concentration of fumonisins in cereal-based foods was corn-based foods > wheat-based foods > other cereal foods > barley-based foods > rice-based foods > oat-based foods. Based on the prevalence of fumonisins, the overall rank order was other cereal foods > corn-based foods > rice-based foods > wheat-based foods > oat-based foods > barley-based food. The present meta-analysis results can be a beneficial database for risk assessment model progress, which can help industries and organizations decrease the presence of fumonisins in cereal-based food.

Further data on the levels of emerging Fusarium mycotoxins in cereals collected from Tianjin, China

A number of 344 samples were collected from Tianjin, China and were analysed for the occurrence of emerging Fusarium mycotoxins including enniatin A (ENN A), enniatin A₁ (ENN A₁), enniatin B (ENN B), enniatin B₁ (ENN B₁) and beauvericin (BEA) by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The frequencies of mycotoxins studied were 69.0% (40/58), 69.8% (37/53), 85.9% (67/78), 78.9% (75/95), and 30.0% (18/60) for rice, wheat, corn, wheat flour, and corn flour, respectively. BEA was the predominant toxin in rice (average = 37.2 μg/kg) and wheat (average = 58.4 μg/kg), followed by ENN B and ENN B₁, while less ENN A and ENN A₁ were detected. ENN A was most common in corns with an average level of 28.1 μg/kg, while BEA had a higher average of 62.8 μg/kg. The levels of ENNs and BEA significantly decreased in wheat flours and corn flours, presumably due to the production process. The co-occurrences of ENNs and BEA in cereal samples were common in the combination of two and three mycotoxins and the significant positive correlations in concentrations were also obtained among them. Besides, agroclimate was considered as an important factor for Fusarium production and the mycotoxin contamination was found more serious in Jizhou district, which had more rainfall and less sunshine, than the other agriculture regions. These results suggested the necessity of carrying out in-depth and large-scale monitoring of mycotoxins in cereals and their products nationwide.

Effect of fungicides commonly used for Fusarium head blight management on growth and fumonisin production by Fusarium proliferatum

Fumonisin occurrence was reported in wheat grains and F. proliferatum has been suggested to be the main contributor to its presence in wheat. Thus, a survey was performed in order to study the impact of four commercial fungicides used in Argentina for controlling Fusarium head blight disease (epoxiconazole+metconazole, tebuconazole, pyraclostrobin+epoxiconazole, and prothioconazole) on growth and fumonisin production of two F. proliferatum strains in relation to water activity (a_W; 0.99, 0.97, 0.95) and temperature (15°C and 25°C). Most fungicides reduced growth rates when compared to the control (reduction increased as fungicide concentration increased), and reduced fumonisin production when they were used at high doses; however, most fungicides enhanced fumonisin production at sublethal doses, with the exception of prothioconazole. Thus, fungicides used for FHB management could enhance fumonisin production by F. proliferatum strains present in wheat grains.

Fusarium-Produced Mycotoxins in Plant-Pathogen Interactions

Pathogens belonging to the Fusarium genus are causal agents of the most significant crop diseases worldwide. Virtually all Fusarium species synthesize toxic secondary metabolites, known as mycotoxins; however, the roles of mycotoxins are not yet fully understood. To understand how a fungal partner alters its lifestyle to assimilate with the plant host remains a challenge. The review presented the mechanisms of mycotoxin biosynthesis in the Fusarium genus under various environmental conditions, such as pH, temperature, moisture content, and nitrogen source. It also concentrated on plant metabolic pathways and cytogenetic changes that are influenced as a consequence of mycotoxin confrontations. Moreover, we looked through special secondary metabolite production and mycotoxins specific for some significant fungal pathogens-plant host models. Plant strategies of avoiding the Fusarium mycotoxins were also discussed. Finally, we outlined the studies on the potential of plant secondary metabolites in defense reaction to Fusarium infection.

Fumonisins: Impact on Agriculture, Food, and Human Health and their Management Strategies

The fumonisins producing fungi, Fusarium spp., are ubiquitous in nature and contaminate several food matrices that pose detrimental health hazards on humans as well as on animals. This has necessitated profound research for the control and management of the toxins to guarantee better health of consumers. This review highlights the chemistry and biosynthesis process of the fumonisins, their occurrence, effect on agriculture and food, along with their associated health issues. In addition, the focus has been put on the detection and management of fumonisins to ensure safe and healthy food. The main focus of the review is to provide insights to the readers regarding their health-associated food consumption and possible outbreaks. Furthermore, the consumers' knowledge and an attempt will ensure food safety and security and the farmers' knowledge for healthy agricultural practices, processing, and management, important to reduce the mycotoxin outbreaks due to fumonisins.

Visual detection of Fusarium proliferatum based on asymmetric recombinase polymerase amplification and hemin/G-quadruplex DNAzyme

A one-step and instrument-free visual method was established based on asymmetric recombinase polymerase amplification coupled with hemin/G-quadruplex DNAzyme for the detection of Fusarium proliferatum.

Asymmetric recombinase polymerase amplification and hemin/G-quadruplex DNAzyme-based visual detection of F. proliferatum is demonstrated.

Effect of Tebuconazole Enantiomers and Environmental Factors on Fumonisin Accumulation and FUM Gene Expression in Fusarium verticillioides

Fusarium verticillioides is an important corn pathogen that can produce fumonisins (FBs) under certain environmental conditions. In this study, we evaluated the enantioselective impact of tebuconazole enantiomers on the growth and FB production of F. verticillioides on maize-based media at different abiotic factors. The expression of FB biosynthetic genes ( FUM1 and FUM6) was quantified by real-time reverse transcription polymerase chain reaction. The results showed that water activity ( a_w), temperature, and types of tebuconazole significantly affected the growth of F. verticillioides. The order of fungicidal activity was (-)-tebuconazole > rac-tebuconazole > (+)-tebuconazole. (-)-tebuconazole exhibited the maximal selective fungicidal activity (242-fold) against F. verticillioides at 0.95 a_w and 35 °C. Production of fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) by F. verticillioides was influenced by a_w, temperature, types of tebuconazole, and dose. Under most conditions, (-)-tebuconazole showed stronger inhibition for FB₁ and FB₂ production than (+)-tebuconazole (1.87-2.85-fold reduction in FBs) and rac-tebuconazole. The optimal environmental condition for FB production was at 0.99 a_w and 25 °C. Tebuconazole enantiomers differently affected FB biosynthetic gene ( FUM1 and FUM6) expression, but the effects on FB production and gene expression showed no positive correlation. The present study provides a better understanding on ways to minimize FB production in corn treated with fungicides.

Fumonisin occurrence in wheat-based products from Argentina

In Argentina, wheat is the most consumed cereal by the human population. Since fumonisins occurence in wheat grains and wheat-based products have been reported worldwide, a survey was conducted in order to determine fumonisin contamination in 91 wheat-based products (white wheat flour samples, wheat flour used at bakery products and whole-wheat flour samples) collected from different retail stores of Rio Cuarto city in Argentina using HPLC-MS/MS. Sixty-seven samples (74%) showed contamination by fumonisins. From these samples, 16 showed fumonisin levels between LOD and LOQ (between 0.01 to 0.05 ng/g), while fumonisins (FB₁ + FB₂) in quantifiable samples ranged from 0.05 ng/g to 18.9 ng/g. Although FB₁ was more prevalent, FB₂ was foun3d in higher levels than FB₁. Overall, fumonisin prevalence was high, but concentrations were far below EU or USA limits set for maize and maize-based products.