Fusarium diseases of small grain cereals and maize cause significant yield losses worldwide. Fusarium infections result in reduced grain yield and contamination with mycotoxins, some of which have a notable impact on human and animal health. Regulations on maximum limits have been established in various countries to protect consumers from the harmful effects of these mycotoxins. Several factors are involved in Fusarium disease and mycotoxin occurrence and among them environmental factors and the agronomic practices have been shown to deeply affect mycotoxin contamination in the field. In the present review particular emphasis will be placed on how environmental conditions and stress factors for the crops can affect Fusarium infection and mycotoxin production, with the aim to provide useful knowledge to develop strategies to prevent mycotoxin accumulation in cereals.Keywords: Fusarium toxins; Fusarium disease; mycotoxin regulation; mycotoxin management Mycotoxigenic Fusarium and Fusarium-Related DiseasesFusarium is one of the most economically important genera of phytopathogenic fungi. Several Fusarium species can infect small grain cereals (wheat, barley and oat) and maize; the predominant species can vary according to crop species involved, geographic region and environmental conditions [1,2]. Fusarium toxins are secondary metabolites produced by toxigenic fungi that naturally contaminate cereals, they represent a source of grave concern in cereals and cereal-based products, resulting in harmful contamination of foods and feedstuffs [3].Fusarium diseases that affect cereal crops are caused by several individual Fusarium or more commonly, co-occurring species. Fusarium spp. can cause indirect losses resulting from seedling blight or reduced seed germination, or direct losses such as seedling foot and stalk rots; however, the most important diseases in cereals due to a severe reduction in yield and quality are head blight of small cereals as wheat, barley and oat, and ear rot of maize [4,5]. The coexistence of different Fusarium spp. in the field is a normal situation and although the number of detectable species can be high [6], only some of them are pathogenic, especially under suitable climatic conditions. The composition of species involved in the Fusarium disease complex is dynamic [7]. The species comprising a Fusarium community associate with each other and this cohabitation is particularly affected by climatic factors such as temperature and moisture. Moreover, evidences indicates that the environmental conditions that favour the infection process can differ from those that affect colonization [8]; therefore, the relationship among Fusarium species may change over time during the infection process.

The effects of oxidative stress induced by H2O2 were tested in liquid cultures in the fumonisin-producing fungus Fusarium verticillioides. The quantitative analysis of fumonisins B1, B2, B3, and B4 was achieved by means of liquid chromatography coupled to high-resolution mass spectrometry. Two effects in F. verticillioides, consisting of different abilities to produce fumonisins in response to oxidative stress, were identified. Following H2O2 addition, two F. verticillioides strains produced significantly more fumonisin (>300%) while three other strains produced significantly less (<20%) in comparison to control cultures. Transcriptional studies with seven biosynthetic genes showed a significant increase in transcript levels in the strain that made more fumonisin and either no or minimal changes in the strain that made less fumonisin. Our data indicate the important role of oxidative stress toward the modulation of the fumonisin biosynthesis and suggest the necessity to verify the presence of such divergent behavior in F. verticillioides populations under natural conditions.

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Microalgae provide one of the more promising strategies for the production of renewable biodiesel and liquid fuels. Coupling biodiesel production and wastewater treatment based on the use of microalgae can be an effective approach for achieving sustainable production. Several pilot programs aimed at lipid production are currently working with Acutodesmus obliquus, and companies offering algal inocula are increasing in number. A. obliquus strain RL01 was isolated from a pretreated leachate, and preliminary analyses indicated a high growth rate, a final biomass concentration of 1.9 g∙L-1 and a lipid content of 47% DW. With the aim of strictly differentiating and unequivocally identifying the new strain in comparison with other A. obliquus lipid producers available in culture collections, we employed a DNA barcoding approach, targeting conventional and non-conventional genome regions. Genomic analyses were performed using two internal transcribed spacers (nuclear ITS1 and ITS2 sequences) and three selected chloroplast regions (the trnL genic intron and the rpl20-psbA and psbM-psbZ intergenic spacers). Our findings raise some concerns about the discriminant power of the ITS2 nuclear target and place particular emphasis on the psbM-psbZ plastid DNA barcode, which is characterized by high polymorphism, for use in studies addressing intraspecific genetic diversity

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Fusarium verticillioides, one of the most common pathogens in maize, is responsible for yield losses and reduced kernel quality due to contamination by fumonisins (FBs). Two F. verticillioides isolates that differed in their ability to produce FBs were treated with a selection of eight natural phenolic compounds with the aim of identifying those that were able to decrease toxin production at concentrations that had a limited effect on fungal growth. Among the tested compounds, ellagic acid and isoeugenol, which turned out to be the most effective molecules against fungal growth, were assayed at lower concentrations, while the first retained its ability to inhibit toxin production in vitro, the latter improved both the fungal growth and FB accumulation. The effect of the most effective phenolic compounds on FB accumulation was also tested on maize kernels to highlight the importance of appropriate dosages in order to avoid conditions that are able to promote mycotoxin biosynthesis. An expression analysis of genes involved in FB production allowed more detailed insights into the mechanisms underlying the inhibition of FBs by phenolic compounds. The expression of the fum gene was generally down-regulated by the treatments; however, some treatments in the low-producing F. verticillioides strain up-regulated fum gene expression without improving FB production. This study showed that although different phenolic compounds are effective for FB reduction, they can modulate biosynthesis at the transcription level in opposite manners depending on strain. In conclusion, on the basis of in vitro and in vivo screening, two out of the eight tested phenols (ellagic acid and carvacrol) appear to be promising alternative molecules for the control of FB occurrence in maize.