Open field study of some Zea mays hybrids, lipid compounds and fumonisins accumulation

Lipid molecules are increasingly recognized as signals exchanged by organisms interacting in pathogenic and/or symbiotic ways. Some classes of lipids actively determine the fate of the interactions. Host cuticle/cell wall/membrane components such as sphingolipids and oxylipins may contribute to determining the fate of host–pathogen interactions. In the present field study, we considered the relationship between specific sphingolipids and oxylipins of different hybrids of Zea mays and fumonisin by F. verticillioides, sampling ears at different growth stages from early dough to fully ripe. The amount of total and free fumonisin differed significantly between hybrids and increased significantly with maize ripening. Oxylipins and phytoceramides changed significantly within the hybrids and decreased with kernel maturation, starting from physiological maturity. Although the correlation between fumonisin accumulation and plant lipid profile is certain, the data collected so far cannot define a cause-effect relationship but open up new perspectives. Therefore, the question—“Does fumonisin alter plant lipidome or does plant lipidome modulate fumonisin accumulation?”—is still open

Occurrence of Fusarium mycotoxins in cereal crops and processed products (ogi) from Nigeria

In Nigeria, maize, sorghum, and millet are very important cash crops. They are consumed on a daily basis in different processed forms in diverse cultural backgrounds. These crops are prone to fungi infestation, and subsequently may be contaminated with mycotoxins. A total of 363 samples comprising of maize (136), sorghum (110), millet (87), and ogi (30) were collected from randomly selected markets in four agro-ecological zones in Nigeria. Samples were assessed for Fusarium mycotoxins contamination using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Subsequently, some selected samples were analysed for the occurrence of hidden fumonisins. Overall, 64% of the samples were contaminated with at least one toxin, at the rate of 77%, 44%, 59%, and 97% for maize, sorghum, millet, and ogi, respectively. Fumonisins were the most dominant, especially in maize and ogi, occurring at the rate of 65% and 93% with mean values of 935 and 1128 mu g/kg, respectively. The prevalence of diacetoxyscirpenol was observed in maize (13%), sorghum (18%), and millet (29%), irrespective of the agro-ecological zone. Other mycotoxins detected were deoxynivalenol, zearalenone, and their metabolites, nivalenol, fusarenon-X, HT-2 toxin, and hidden fumonisins. About 43% of the samples were contaminated with more than one toxin. This study suggests that consumption of cereals and cereal-based products, ogi particularly by infants may be a source of exposure to Fusarium mycotoxins

Mycotoxin occurrence in maize silage : a neglected risk for bovine gut health?

Forages are important components of dairy cattle rations but might harbor a plethora of mycotoxins. Ruminants are considered to be less susceptible to the adverse health effects of mycotoxins, mainly because the ruminal microflora degrades certain mycotoxins. Yet, impairment of the ruminal degradation capacity or high ruminal stability of toxins can entail that the intestinal epithelium is exposed to significant mycotoxin amounts. The aims of our study were to assess (i) the mycotoxin occurrence in maize silage and (ii) the cytotoxicity of relevant mycotoxins on bovine intestinal cells. In total, 158 maize silage samples were collected from European dairy cattle farms. LC-MS/MS-based analysis of 61 mycotoxins revealed the presence of emerging mycotoxins (e.g., emodin, culmorin, enniatin B1, enniatin B, and beauvericin) in more than 70% of samples. Among the regulated mycotoxins, deoxynivalenol and zearalenone were most frequently detected (67.7%). Overall, 87% of maize silages contained more than five mycotoxins. Using an in vitro model with calf small intestinal epithelial cells B, the cytotoxicity of deoxynivalenol, nivalenol, fumonisin B1 and enniatin B was evaluated (0-200 mu M). Absolute IC50 values varied in dependence of employed assay and were 1.2-3.6 mu M, 0.8-1.0 mu M, 8.6-18.3 mu M, and 4.0-6.7 mu M for deoxynivalenol, nivalenol, fumonisin B1, and enniatin B, respectively. Results highlight the potential relevance of mycotoxins for bovine gut health, a previously neglected target in ruminants

Free and Hidden Fumonisins in Corn (Zea Mays L.): Occurrence and Masking Mechanism

Nel presente lavoro di tesi sono stati studiati diversi aspetti riguardanti le fumonisine, metaboliti secondari tossici prodotti da funghi del genere Fusarium, focalizzando l’attenzione sulle forme nascoste. In particolare, il meccanismo di mascheramento è stato ampiamente studiato attraverso modelli in vitro, allo scopo di capire qual è la natura delle interazioni che intercorrono tra queste micotossine e le macromolecole del mais. Successivamente, è stato effettuato uno studio allo scopo di individuare quali sono i principali fattori in grado di influenzare positivamente l’infezione fungina, la sintesi e il mascheramento delle fumonisine sulla pianta in fase di maturazione, con particolare attenzione riguardo al ruolo esercitato dal genotipo di mais, dalla sua composizione macromolecolare e dalle interazioni pianta-patogeno nel fenomeno di mascheramento. Infine, è stato sviluppato un metodo LC-ESI-MS/MS per l’analisi multiresiduale di diversi analoghi delle fumonisine appartenenti alle serie minori A e C, allo scopo di monitorarli in brodi di coltura di Fusarium sottoposti a condizioni di crescita diverse, ottenendo nuove informazioni riguardanti il pattern di produzione di tali composti.The work is focused on the study of specific aspects of fumonisins, toxic metabolites produced by a number of Fusarium species in corn, considering especially hidden forms. In particular, masking mechanism has been largely investigated through in vitro experiments, in order to establish which type of interactions occur between such mycotoxins and maize macromolecules. Subsequently, the main factors able to promote fungal infection and fumonisins production and masking in growing maize have been researched, focusing the attention on the role played by the maize genotype and the macromolecular composition as well as by the plant-pathogen interaction in masking phenomenon. Finally, a multiresidual LC-ESI-MS/MS method has been developed to allow the monitoring of several fumonisin analogues produced by Fusarium species under different growing condition, collecting several information concerning the biosynthetic pattern of such compounds

Fusarium verticillioides infection and fumonisin production during maize kernel maturation

Thesis (MScAgric)--Stellenbosch University, 2021.ENGLISH ABSTRACT: Maize (Zea mays. L), a cereal crop readily consumed by humans and animals globally, is subject to infection by fungal pathogens such as Fusarium verticillioides. This pathogen is found wherever maize is grown, causes Fusarium ear rot (FER) and is also capable of producing harmful secondary metabolites known as mycotoxins. Fumonisins are the most important class of mycotoxins. Fumonisin contaminated maize has been associated with irreversible, nocuous effects in humans and animals. For this reason, fumonisins are of great concern to farmers and researchers. More recently, attention has been given to hidden fumonisins. These are fumonisin molecules trapped within the maize kernel that are not detected during mycotoxin screening and are potentially liberated upon ingestion, thus contributing to a greater risk of exposure. Fusarium verticillioides can be managed using cultural practices and controlling maize- feeding insects. However, once conditions that favour the growth of the pathogen occur, these practices are no longer adequate to prevent fungal infection in the field. Not only is the use of chemicals not feasible, but there are also no registered chemicals available for the control of F. verticillioides in South Africa. Incorporating host resistance into locally adapted maize serves as the most environmentally friendly means of managing F. verticillioides. This requires a better understanding of factors that may contribute to disease development and progression. As the physical and biochemical composition of maize contribute to resistance to FER, understanding the relationship between structural and physico-chemical factors and fungal infection as well as fumonisin contamination would provide pivotal knowledge for breeding resistant maize cultivars. In this study, we utilised locally adapted maize inbred lines with known response to FER and/or fumonisin contamination to investigate the role that structural traits, such as husk coverage, silk length, silk detachment and silk browning, may have on FER and/or fumonisin and hidden fumonisin contamination. We also investigated physico-chemical properties of the maize kernel, such as pH, moisture, total carbon and nitrogen, fatty acids and starch in the form of amylopectin. Maize ears were inoculated at 7 days after pollination (dap) while another independent set of maize plants were inoculated 35 dap and grain was subsequently harvested at 7, 28, 42 and 52 days after inoculation (dai). Infection indicators (FER disease severity, F. verticillioides target DNA and fumonisin contamination) as well as hidden fumonisins were correlated with the physico-chemical properties. Fusarium verticillioides growth and fumonisins increased progressively over time after inoculation, reaching a maximum at 52 dai for both inoculation events with significant differences between inoculated and control maize grain. Inoculated grain of resistant lines accumulated lower levels of F. verticillioides target DNA and fumonisins when inoculated 7 dap, however, when inoculated 35 dap resistant lines showed an increase in fumonisin contamination. The susceptible line accumulated high levels of fungal DNA and fumonisins in both inoculation events. Of the physico-chemical properties evaluated, pairwise correlations revealed that carbon and nitrogen had strong significant association with fungal DNA at both inoculation events. Silk browning, carbon, nitrogen and C/N were also significantly correlated with infection indicators. Moisture content had a significant negative association with fungal DNA at both inoculation events. Amylopectin increased over time in Inoculation Event 1 and remained constant in Inoculation Event 2 while no significant associations were observed between amylopectin and infection indicators. The fatty acid profile showed a synchronised increase and decrease over time, however, no significant associations with infection indicators or hidden fumonisins were noted. Hidden fumonisins extracted using alkaline hydrolysis was significantly higher when only free hydrolysed fumonisins was extractedusing a standard fumonisin extraction. Furthermore, hidden fumonisins followed a similar trend as free fumonisins, increasing over time after inoculation and peaking at the mature stages of kernel development. Inoculated resistant maize grain accumulated significantly less hidden fumonisins. Lastly, there were no significant correlations between hidden fumonisins and any of the physico-chemical factors evaluated. This study demonstrated that F. verticillioides growth and fumonisin accumulation in maize grain is dependent on the timing of infection and is not triggered by a specific kernel developmental stage. Response of maize lines should also be assessed by artificially inoculating early stages of kernel maturation to determine accurate plant response in matured grain. Physico-chemical factors, such as carbon, nitrogen and C/N, may serve as indicators of potential resistance to F. verticillioides and/or fumonisins. The maize inbred lines used in this study can now be further classified according to their ability to accumulate both free fumonisins and hidden fumonisins.AFRIKAANSE OPSOMMING: Mielies (Zea mays. L), ‘n graangewas wat grootskaals deur die mens en diere wêreldwyd verbruik word, is onderhewig aan infeksie deur swampatogene soos Fusarium verticillioides. Hierdie patogeen word gevind waar mielies ook al verbou word, veroorsaak Fusarium kop vrot (FER) en is ook in staat om skadelike sekondêre metaboliete, bekend as mikotoksiene, te produseer. Fumonisiene is die belangrikste klas van mikotoksiene. Fumonisien- gekontamineerde mielies is al met onomkeerbare, giftige effekte in mense en diere geassosieer. Om hierdie rede is fumonisiene rede tot groot kommer vir produsente en navorsers. Aandag is meer onlangs aan versteekte fumonisiene gegee. Hierdie is fumonisien molekules wat in die mieliekern vasgevang is en wat nie gedurende mikotoksien toetsing waargeneem word nie, en potensieel gedurende inname vrygestel word, en sodoende tot ʼn groter blootstellingsrisiko bydra. Fusarium verticillioides kan deur verbouingspraktyke en beheer van mielie-vretende insekte bestuur word. Sodra toestande wat die groei van die patogeen bevorder voorkom, is hierdie toestande egter nie meer voldoende om swam-infeksie in die veld te voorkom nie. Nie net is die gebruik van chemikalieë onuitvoerbaar nie, maar daar is ook geen geregistreerde chemikalieë beskikbaar vir die beheer van F. verticillioides in Suid-Afrika nie. Die inkorporering van gasheerweerstand in plaaslik-aangepaste mielies, dien as die mees omgewingsvriendelike wyse van bestuur van F. verticillioides. Dit vereis beter kennis van faktore wat tot siekte-ontwikkeling en -vordering kan bydra. Aangesien die fisiese en biochemiese samestelling van mielies tot weerstand teen FER bydra, kan kennis oor die verhouding tussen strukturele en fisiek-chemiese faktore en swam-infeksie, asook fumonisien kontaminasie, sleutel kennis tot die teel van weerstandbiedende mielie kultivars bydra. In hierdie studie is plaaslik-aangepaste mielie inteellyne met bekende reaksie tot FER en/of fumonisien kontaminasie gebruik om die rol wat strukturele kenmerke, soos mieliekop blaar bedekking, mieliekop baard lengte, baard losmaking en baard verbruining, op FER en/of fumonisien en versteekte fumonisien kontaminasie het, ondersoek. Ons het ook fisiek- chemiese eienskappe van die mieliekern, soos pH, vog, totale koolstof en stikstof, vetsure en stysel in die vorm van amilopektien, ondersoek. Mielie koppe is op 7 dae ná bestuiwing (dap) geïnokuleer, terwyl ʼn ander onafhanklike stel van mielieplante op 35 dap geïnokuleer is, en graan is gevolglik op 7, 28, 42 en 52 dae ná inokulasie (dai) geoes. Infeksie indikators (FER siekte intensiteit, F. verticillioides teiken DNS en fumonisien kontaminasie) asook versteekte fumonisiene is met die fisiek-chemiese eienskappe gekorreleer. Fusarium verticillioides groei en fumonisiene het progressief oor tyd ná inokulasie toegeneem, en het ʼn maksimum op 52 dai vir beide inokulasie gebeurtenisse bereik, met betekenisvolle verskille tussen geïnokuleerde en kontrole mieliegraan. Geïnokuleerde graan van weerstandbiedende lyne het laer vlakke van F. verticillioides teiken DNS en fumonisiene geakkumuleer wanneer geïnokuleer op 7 dap, maar wanneer egter geïnokuleer op 35 dap, het weerstandbiedende lyne ʼn toename in fumonisien kontaminasie getoon. Vatbare lyne het hoë vlakke van swam DNS en fumonisiene in beide inokulasie gebeurtenisse geakkumuleer. Van die fisiek-chemiese eienskappe wat geëvalueer is, het paarsgewys korrelasies getoon dat koolstof en stikstof sterk betekenisvolle assosiasie met swam DNS by beide inokulasie gebeurtenisse gehad het. Mieliekop baard verbruining, koolstof, stikstof en C/N was ook betekenisvol met infeksie indikators gekorreleer. Vog-inhoud het ʼn betekenisvolle negatiewe assosiasie met swam DNS by beide inokulasie gebeurtenisse gehad. Amilopektien het met tyd in Inokulasie Gebeurtenis 1 toegeneem en het konstant gebly in Inokulasie Gebeurtenis 2, terwyl geen betekenisvolle assosiasies tussen amilopektien en infeksie indikators waargeneem is nie. Die vetsuur profiel het ʼn gesinkroniseerde toename en afname oor tyd getoon, maar geen betekenisvolle assosiasies is egter met infeksie indikators of versteekte fumonisiene waargeneem nie. Versteekte fumonisiene wat geëkstraheer is, deur gebruik te maak van alkaliese hidrolise, was betekenisvol hoër as vry gehidroliseerde fumonisiene verkry, deur gebruik te maak van ʼn standaard fumonisien ekstraksie. Versteekte fumonisiene het verder ʼn soortgelyke tendens gevolg as vry fumonisiene, deur oor tyd ná inokulasie toe te neem, en te piek by die volwasse stadia van korrel ontwikkeling. Geïnokuleerde weerstandbiedende mieliegraan het betekenisvol minder versteekte fumonisiene geakkumuleer. Laastens, daar was geen betekenisvolle korrelasies tussen versteekte fumonisiene en enige van die fisiek-chemiese faktore wat geëvalueer is nie. Hierdie studie demonstreer dat F. verticillioides groei en fumonisien akkumulasie in mieliegraan, afhanklik is van die tyd van infeksie en word nie aangeskakel deur ʼn spesifieke korrel ontwikkelingsstadium nie. Reaksie van mielielyne moet ook vasgestel word deur kunsmatige inokulasie van vroeë stadia van korrel rypwording, ten einde akkurate plantreaksie in volwasse graan te bepaal. Fisiek-chemiese faktore, soos koolstof, stikstof en C/N, kan as indikators van potensiële weerstand dien. Die mielie inteellyne wat in hierdie studie gebruik is, kan nou verder geklassifiseer word volgens hul vermoë om beide vry fumonisiene en versteekte fumonisiene te akkumuleer.Master

Mycotoxins in maize: mitigation actions, with a chain management approach

Maize is the principal staple food/feed crop exposed to mycotoxins, and the co-occurrence of multiple mycotoxins and their metabolites has been well documented. This review presents the infection cycle, ecology, and plant-pathogen interactions of Aspergillus and Fusarium species in maize, and current knowledge on maize chain management to mitigate the occurrence of aflatoxins and fumonisins. Preventive actions include at pre-harvest, as part of cropping systems, at harvest, and at postharvest, through storage, processing, and detoxification to minimize consumer exposure. Preventive actions in the field have been recognized as efficient for reducing the entrance of mycotoxins into production chains. Biological control of Aspergillus flavus has been recognized to minimize contamination with aflatoxins. Post-harvest maize grain management is also crucial to complete preventive actions, and has been made mandatory in government food and feed legislation.This review was prepared as part of MYCHIF EFSA project (GP/EFSA/AFSCO/2016/01). Roberta Palumbo carried out this work within the PhD school Agrisystem of Università Cattolica del Sacro Cuore, Italy. This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This paper was critically reviewed in collaboration with MycoKey project (Horizon 2020, Grant Agreement No. 678781).info:eu-repo/semantics/publishedVersio

Free and hidden fumonisins in maize and gluten-free products

Nel presente lavoro di tesi è stato sviluppato un metodo per la valutazione delle Fumonisine nascoste. L’applicazione del metodo a diversi lotti di campioni di mais grezzo e prodotti gluten-free, ha permesso di scoprire una diffusa presenza di Fumonisine nascoste lungo la filiera del mais. Tutti i dati sperimentali successivamente ottenuti nel presente lavoro suggeriscono fortemente una interazione di tipo non covalente tra FB1 e l’α-Zeina (la principale proteina dell’endosperma di mais), per spiegare il fenomeno di mascheramento delle Fumonisine.The work has been focused on the development of a LC-MS/MS method for the evaluation of hidden Fumonisins. The application of the method to several batches of raw maize and gluten free products let us to discover that hidden FBs are widespread along the maize chain. Moreover, further experimental data collected in the work strongly suggest a non-covalent interaction between FB1 and the α-Zein (the principal endosperm protein of maize), with an inclusion-like mechanism, allowing us to partially explain the masking mechanism of Fumonisins