Fusarium cerealis is a causal agent of Fusarium Head Blight in wheat, and it produces both deoxynivalenol (DON) and nivalenol (NIV). Nevertheless, the effect of environmental factors on the growth and mycotoxin production of this species has not been studied so far. The objective of this study was to investigate the impact of environmental factors on the growth and mycotoxin production of F. cerealis strains. All strains were able to grow in a wide range of water activity (a(W)) and temperatures, but their mycotoxin production was influenced by strain and environmental factors. NIV was produced at high a(W) and temperatures, while optimal conditions for DON production were observed at low a(W). Interestingly, some strains were able to simultaneously produce both toxins, which could pose a more significant risk for grain contamination.

Chickpeas are a very important legume due to their nutritional richness and high protein content and they are used as food for humans and as fodder for livestock. However, they are susceptible to fungal infections and mycotoxin contamination. The Alternaria genus was among the main fungi isolated from chickpea samples in Argentina. The species within this genus are able to produce several mycotoxins such as alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TA). So, the objectives of this study were to identify the Alternaria spp. found in the chickpea samples and to determine their toxigenic potential in vitro. A phylogenetic analysis of 32 Alternaria strains was carried out based on the combined sequences of the tef1, gpd, and Alt a1 genes. All Alternaria strains clustered into the section Alternaria and were identified as A. alternata and A. arborescens. Further, the toxigenic profile of each strain was determined in a ground rice–corn steep liquor medium and analysed by HPLC. Most strains were able to co-produce AOH, AME, and TA. These results indicate a potential risk for human health when consuming chickpeas since this legume could be contaminated with Alternaria and its mycotoxins, which are not yet regulated in food.

Fusarium Head Blight (FHB) is a very important fungal disease that affects small grain cereals worldwide. This disease not only causes yield loses but also crops contamination with mycotoxins such as deoxynivalenol (DON) and nivalenol (NIV). Species within the Fusarium graminearum species complex have been described as the main causal agents of this disease, however lately there have been few reports of Fusarium cerealis causing the disease in wheat and barley in different parts of the world. This study evaluated the aggressiveness of F. cerealis to durum wheat cultivars and also mycotoxin production in planta. Moreover, the mycotoxin profile of F. cerealis strains was characterized molecularly and chemically. All durum wheat cultivars showed typical FHB symptoms but the disease severity varied among them in levels up to 66%. In addition, seventeen different compounds were detected in the infected heads including DON, NIV and nivalenol-3-β-d-glucose (NIV3G). NIV was detected in all cultivars and was the most produced mycotoxin with levels ranging from 1.04 to 6.8 mg/kg. On the other hand, the molecular analysis of F. cerealis strains showed that all of them possessed NIV genotype while the chemical assessment showed that the strains were able to produce not only this toxin in vitro but also DON, zearalenone and other twenty-one secondary metabolites. The increasing incidence of F. cerealis and the possible contamination of crops with the mycotoxins that it produces are of great concern for food security and world cereal trade since it has been reported that NIV is more toxic for humans and animals than DON.

The Chaco wetland is among the most biologically diverse regions in Argentina. In collections of fungi from asymptomatic native grasses (Poaceae) from the wetlands, we identified isolates of Fusarium that were morphologically similar to F. armeniacum, but distinct from it by their production of abundant microconidia. All the isolates had identical, or nearly identical, partial sequences of TEF1 and RPB2. But they were distinct from reference sequences from F. armeniacum and Fusarium species closely related to it. Phylogenetic analysis of 34 full-length housekeeping gene sequences retrieved from whole genome sequences of three Chaco wetland isolates, 29 genes resolved the isolates as an exclusive clade within the F. sambucinum species complex. Based on results of the morphological and phylogenetic analysis, we concluded that the Chaco wetland isolates are a distinct and novel species, herein described as Fusarium chaquense, sp. nov., which is closely related to F. armeniacum. F. chaquense in culture can produce the trichothecenes T-2 and HT-2 toxin, neosolaniol, diacetoxyscirpenol, and monoacetoxyscirpenol, as well as beauvericin and the pigment aurofusarin. Genome sequence analysis also revealed the presence of three previously described loci required for trichothecene biosynthesis. This research represents the first study of Fusarium in a natural ecosystem in Argentina.

Peanut brown root rot is a rhizoplane disease caused by the soil-borne pathogen Fusarium solani. The objective of this study was to determine the genetic and physiological mechanisms of T. harzianum ITEM 3636 involved in the antagonism against the phytopathogenic fungi F. solani, and to evaluate its biocontrol effect on peanut brown root rot in greenhouse assays. The in vitro tests showed that T. harzianum ITEM 3636 exert its antagonistic activity against F. solani RC386 through the synthesis of secondary metabolites, high enzymatic activity (chitinases 0.054 U ml- 1, N-Acetyl-beta-D-glucosaminidases 0.21 U ml-1, proteases 0.063 U ml-1 and glucanases 0.139 U ml-1) and important modifications in the pathogen hyphae. In the gene expression analysis of biocontrolassociated genes (prb1, chit33, bgn13.1) an upregulation was detected when T. harzianum ITEM 3636 interacted with F. solani RC386 mycelia. The greenhouse assays showed that the previous application of T. harzianum ITEM 3636 on peanut seeds generated a protective effect in peanut plants which were then affected by F. solani, since it reduced both the incidence and the severity of peanut brown root rot, by 3.8% and 63.98% respectively. In conclusion, T. harzianum ITEM 3636 strain could be considered as a biofungicide against F. solani in microbial formulations intended for peanut plants.

With 744 million metric tons produced in 2017/2018, bread wheat (Triticum aestivum) and durum wheat (Triticum durum) are the second most widely produced cereal on a global basis. Prevention or control of wheat diseases may have an enormous impact on global food security and safety. Fusarium head blight is an economically debilitating disease of wheat that reduces the quantity and quality of grain harvested, and may lead to contamination with the mycotoxin deoxynivalenol, which affects the health of humans and domesticated animals. Current climate change scenarios predict an increase in the number of epidemics caused by this disease. Multiple strategies are available for managing the disease including cultural practices, planting less-susceptible cultivars, crop rotation, and chemical and biological controls. None of these strategies, however, is completely effective by itself, and an integrated approach incorporating multiple controls simultaneously is the only effective strategy to limit the disease and reduce deoxynivalenol contamination in human food and animal feed chains. This review identifies the available tools and strategies for mitigating the damage that can result from Fusarium head blight.

Fusarium head blight (FHB) is a devastating disease that causes extensive yield and quality losses to wheat and other small cereal grains worldwide. Species within the Fusarium graminearum complex are the main pathogens associated with the disease, F. graminearumsensu stricto being the main pathogen in Argentina. Biocontrol can be used as part of an integrated pest management strategy. Phytohormones play a key role in the plant defense system and their production can be induced by antagonistic microorganisms. The aims of this study were to evaluate the effect of the inoculation of Bacillus velezensis RC 218, F. graminearum and their co-inoculation on the production of salicylic acid (SA) and jasmonic acid (JA) in wheat spikes at different periods of time under greenhouse conditions, and to evaluate the effect of B. velezensis RC 218 and Streptomyces albidoflavus RC 87B on FHB disease incidence, severity and deoxynivalenol accumulation on Triticum turgidum L. var. durum under field conditions. Under greenhouse conditions the production of JA was induced after F. graminearum inoculation at 48 and 72 h, but JA levels were reduced in the co-inoculated treatments. No differences in JA or SA levels were observed between the B. velezensis treatment and the water control. In the spikes inoculated with F. graminearum, SA production was induced early (12 h), as it was shown for initial FHB basal resistance, while JA was induced at a later stage (48 h), revealing different defense strategies at different stages of infection by the hemibiotrophic pathogen F. graminearum. Both B. velezensis RC 218 and S. albidoflavus RC 87B effectively reduced FHB incidence (up to 30%), severity (up to 25%) and deoxynivalenol accumulation (up to 51%) on durum wheat under field conditions.

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

The occurrence of deoxynivalenol, 3- and 15-deoxynivalenol and deoxynivalenol-3-glucoside in 84 durum wheat samples, from the Argentinean main growing area, was investigated during 2012/13 and 2013/14 using LC-MS/MS. Deoxynivalenol was found in all samples at concentrations varying between <LOQ (50μg/kg) and 9480μg/kg. Deoxynivalenol-3-glucoside was detected in 94% of the samples at concentrations ranging from <LOQ (50μg/kg) to 850μg/kg. Moreover, the acetylated derivatives were also detected but at lower frequency (49%). To the best of our knowledge, this is the first report of deoxynivalenol-3-glucoside in wheat in Argentina. All the commercial cultivars transformed deoxynivalenol to its glucosylated form at conversion rates between 6 and 22%. The results obtained alert of the potential risk present in durum wheat for Argentinean consumers but also show that some of the commercial cultivars currently on used could be promising candidates for breeding programs intended to obtained Fusarium head blight resistance.

The aim of this study was to evaluate the occurrence of several fungal metabolites, including mycotoxins in natural grasses (Poaceae) intended for grazing cattle. A total number of 72 and 77 different metabolites were detected on 106 and 69 grass samples collected during 2011 and 2014, respectively. A total of 60 metabolites were found across both years. Among the few mycotoxins considered toxic for ruminants, no samples of natural grasses were contaminated with aflatoxins, ochratoxin A, ergot alkaloids, and gliotoxin, among others. However, we were able to detect important metabolites (toxic to ruminants) such as type A trichothecenes, mainly T-2 toxin and HT-2 toxin (up to 5000 µg/kg each), and zearalenone (up to 2000 µg/kg), all at very high frequencies and levels. Other fungal metabolites that were found to be prevalent were other Fusarium metabolites like beauvericin, equisetin and aurofusarin, metabolites produced by Alternaria spp., sterigmatocystin and its precursors and anthrachinone derivatives. It is important to point out that the profile of common metabolites was shared during both years of sampling, and also that the occurrence of important metabolites is not a sporadic event. Considering that this area of temperate grassland is used for grazing cattle all year long due to the richness in palatable grasses (Poaceae), the present work represents a starting point for further studies on the occurrence of multi-mycotoxins in natural grasses in order to have a complete picture of the extent of cattle exposure. Also, the present study shows that the presence of zeranol in urine of beef cattle may not be a consequence of illegal use of this banned substance, but the product of the natural occurrence of zearalenone and α-zearalenol in natural grasses intended for cattle feeding.

Fusarium proliferatum is a member of the Fusarium fujikuroi species complex (FFSC) involved in the maize ear rot together with Fusarium verticillioides, which is a very closely related species. Recently, different studies have detected natural fumonisin contamination in wheat kernels and most of them have shown that the main species isolated was F. proliferatum. Fusarium strains obtained from freshly harvested durum wheat samples (2008 to 2011 harvest seasons) from Argentina were characterized through a phylogenetic analysis based on translation elongation factor-1 alpha (EF-1α) and calmodulin (CaM) genes, determination of mating type alleles, and evaluation of fumonisin production capability. The strains were identified as F. proliferatum (72%), F. verticillioides (24%) and other Fusarium species. The ratio of mating type alleles (MAT-1 and MAT-2) obtained for both main populations suggests possible occurrence of sexual reproduction in the wheat fields, although this seems more frequent in F. proliferatum. Phylogenetic analysis revealed greater nucleotide variability in F. proliferatum strains than in F. verticillioides, however this was not related to origin, host or harvest year. The fumonisin-producing ability was detected in 92% of the strains isolated from durum wheat grains. These results indicate that F. proliferatum and F. verticillioides, among the fumonisin producing species, frequently contaminate durum wheat grains in Argentina, presenting a high risk for human and animal health.

Peanut or groundnut (Arachis hypogaea L.) is cultivated in the tropical and warm temperate regions of the world. Its production reaches approximately 39.9millionmetrictonsperyear. The major producers/exporters of peanuts are the United States, Argentina, Sudan, Senegal, and Brazil. One of the major problems in peanut production worldwide is the contamination with Aspergillus section Flavi and aflatoxins, being these mycotoxins of great concern due to their toxicological effects to human and animals. Different strategies both at pre-harvest and post-harvest stages have been applied to reduce the entry of aflatoxins to the food and feed chains. Nowadays, no single strategy is enough to solve this problem. An integrate management from the field until food or feed processing is necessary to reduce the impact of aflatoxins. This review summarizes the advance in reducing the impact of aflatoxins in different countries where peanuts are cultivated.

A survey was carried out to determine fumonisin contamination in 135 common and 40 durum wheat samples collected during 2011 harvest season (non-FHB epidemic year) in the main wheat production area of Argentina using LC-MS/MS. A 93% of total samples showed fumonisin contamination, with levels ranging from 0.16 to 680.44 ng/g in common and from 0.15 to 1304.39 ng/g in durum wheat samples, respectively. FB1 was the fumonisin most frequently found during the evaluated year. Twenty five wheat samples (15 common and 10 durum) were selected for a deoxynivalenol (DON) analysis among all the samples analyzed for fumonisin content using different contamination levels as selection criteria. DON contamination was present in 24 out of 25 wheat samples, the levels ranging from 50.60 to 28650 ng/g. Nine out of 25 wheat samples reached values higher than 1000 ng/g. However there was no correlation between fumonisin and DON contamination. This is the first report of natural fumonisin presence in common wheat grains in Argentina, as well as of DON co-occurrence in both types of wheat. (C) 2013 Elsevier Ltd. All rights reserved.

Studies were conducted to determine the effect of osmotic and matric stress on germination and growth of two Fusarium solani strains, the etiological agent responsible of peanut brown root rot. Both strains had similar osmotic and matric potential ranges that allowed growth, being the latter one narrower. F. solani showed the ability to grow down to -14 MPa at 25 °C in non-ionic modified osmotic medium, while under matric stress this was limited to -8.4 MPa at 25 °C. However, both strains were seen to respond differently to decreasing osmotic and matric potentials, during early stages of germination. One strain (RC 338) showed to be more sensitive to matric than osmotic (non ionic) and the other one (RC 386) showed to be more sensitive to osmotic than matric imposed water stress. After 24 h of incubation, both isolates behaved similarly. The minimum water potential for germination was -8.4 MPa on glycerol amended media and -5.6 MPa for NaCl and PEG amended media, respectively. The knowledge of the water potential range which allow mycelia growth and spore germination of F. solani provides an inside to the likely behaviour of this devastating soilborne plant pathogen in nature and has important practical implications.

Fil: Ramirez, Maria Laura. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas, Fisicoquimicas y Naturales. Departamento de Microbiologia e Inmunologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba; Argentina

A survey was carried out to determine Fusarium species and fumonisin contamination in 55 durum wheat (Triticum turgidum L. var. durum) samples collected during two harvest seasons (2007 and 2008) using HPLC and further LC-MS/MS confirmation. All samples showed Fusarium contamination with infection levels ranging from 8 to 66%, F. proliferatum being the species most frequently isolated during 2007 and the second most frequently isolated one during the 2008 harvest season, respectively. Natural contamination with fumonisins was found in both harvest seasons. In 2007, 97% of the samples showed total fumonisin (FB(1) + FB(2)) levels ranging from 10.5 to 1245.7 ng/g, while very low levels of fumonisins were detected in samples collected during 2008. These results could be explained by differences in the amount of rainfall during both periods evaluated. A selected number (n = 48) of F. proliferatum isolates showed fumonisin production capability on autoclaved rice. This is the first report of the presence of natural fumonisins in durum wheat grains.