Antonio Logrieco

Toxigenic Fusarium species and mycotoxins associated with maize ear rot in Europe

Several Fusarium species occurring worldwide on maize as causal agents of ear rot, are capable of producing mycotoxins in infected kernels, some of which have a notable impact on human and animal health. The main groups of Fusarium toxins commonly found are: trichothecenes, zearalenones, fumonisins, and moniliformin. In addition, beauvericin and fusaproliferin have been found in Fusarium-infected maize ears. Zearalenone and deoxynivalenol are commonly found in maize red ear rot, which is essentially caused by species of the Discolour section, particularly F. graminearum. Moreover, nivalenol and fusarenone-X were often found associated with the occasional occurrence of F. cerealis, and diacetoxyscirpenol and T-2 toxin with the occurrence of F. poae and F. sporotrichioides, respectively. In addition, the occurrence of F. avenaceum and F. subglutinans usually led to the accumulation of moniliformin. In maize pink ear rot, which is mainly caused by F. verticillioides, there is increasing evidence of the wide occurrence of fumonisin B1. This carcinogenic toxin is usually found in association with moniliformin, beauvericin, and fusaproliferin, both in central Europe due to the co-occurrence of F. subglutinans, and in southern Europe where the spread of F. verticillioides is reinforced by the widespread presence of F. proliferatum capable of producing fumonisin B1, moniliformin, beauvericin, and fusaproliferin.

Epidemiology of toxigenic fungi and their associated mycotoxins for some Mediterranean crops

Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.

A European Database of Fusarium graminearum and F. culmorum Trichothecene Genotypes

Fusarium species, particularly Fusarium graminearum and F. culmorum, are the main cause of trichothecene type B contamination in cereals. Data on the distribution of Fusarium trichothecene genotypes in cereals in Europe are scattered in time and space. Furthermore, a common core set of related variables (sampling method, host cultivar, previous crop, etc.) that would allow more effective analysis of factors influencing the spatial and temporal population distribution, is lacking. Consequently, based on the available data, it is difficult to identify factors influencing chemotype distribution and spread at the European level. Here we describe the results of a collaborative integrated work which aims (1) to characterize the trichothecene genotypes of strains from three Fusarium species, collected over the period 2000–2013 and (2) to enhance the standardization of epidemiological data collection. Information on host plant, country of origin, sampling location, year of sampling and previous crop of 1147 F. graminearum, 479 F. culmorum, and 3 F. cortaderiae strains obtained from 17 European countries was compiled and a map of trichothecene type B genotype distribution was plotted for each species. All information on the strains was collected in a freely accessible and updatable database (www.catalogueeu.luxmcc.lu), which will serve as a starting point for epidemiological analysis of potential spatial and temporal trichothecene genotype shifts in Europe. The analysis of the currently available European dataset showed that in F. graminearum, the predominant genotype was 15-acetyldeoxynivalenol (15-ADON) (82.9%), followed by 3-acetyldeoxynivalenol (3-ADON) (13.6%), and nivalenol (NIV) (3.5%). In F. culmorum, the prevalent genotype was 3-ADON (59.9%), while the NIV genotype accounted for the remaining 40.1%. Both, geographical and temporal patterns of trichothecene genotypes distribution were identified.

Occurrence of Beauvericin and Enniatins in Wheat Affected by Fusarium avenaceum Head Blight

ABSTRACT We evaluated Fusarium contamination and the levels of hexadepsipeptide mycotoxins in 13 wheat samples affected by head blight in Finland. Fusarium avenaceum was the dominant species (91%) isolated from all samples, but isolates of F. culmorum (4%), F. tricinctum (3%), and F. poae (2%) also were recovered. Beauvericin (0.64 to 3.5 μg/g) was detected in all 13 samples. Enniatin B (trace to 4.8 μg/g) was detected in 12 samples, enniatin B1 (trace to 1.9 μg/g) was detected in 8 samples, and enniatin A1 (trace to 6.9 μg/g) was detected in 10 samples. Ten of 13 strains of F. avenaceum and 2 strains of F. poae and F. tricinctum produced beauvericin in culture on rice (trace to 70, 9.4, and 33 μg/g, respectively). All strains also produced enniatins (trace to 2,700 μg/g). This is the first report on the natural cooccurence of beauvericin and enniatins in wheat infected predominantly by F. avenaceum.

Ochratoxin A Production and Amplified Fragment Length Polymorphism Analysis of Aspergillus carbonarius, Aspergillus tubingensis, and Aspergillus niger Strains Isolated from Grapes in Italy

ABSTRACT Ochratoxin A is a potent nephrotoxin and a possible human carcinogen that can contaminate various agricultural products, including grapes and wine. The capabilities of species other than Aspergillus carbonarius within Aspergillus section Nigri to produce ochratoxin A from grapes are uncertain, since strain identification is based primarily on morphological traits. We used amplified fragment length polymorphisms (AFLPs) and genomic DNA sequences (rRNA, calmodulin, and β-tubulin genes) to identify 77 black aspergilli isolated from grape berries collected in a 2-year survey in 16 vineyards throughout Italy. Four main clusters were distinguished, and they shared an AFLP similarity of <25%. Twenty-two of 23 strains of A. carbonarius produced ochratoxin A (6 to 7,500 μg/liter), 5 of 20 strains of A. tubingensis produced ochratoxin A (4 to 130 μg/liter), 3 of 15 strains of A. niger produced ochratoxin A (250 to 360 μg/liter), and none of the 19 strains of Aspergillus “uniseriate” produced ochratoxin A above the level of detection (4 μg/liter). These findings indicate that A. tubingensis is able to produce ochratoxin and that, together with A. carbonarius and A. niger, it may be responsible for the ochratoxin contamination of wine in Italy.

Alternaria toxins and plant diseases: an overview of origin, occurrence and risks

The genus Alternaria includes both plant-pathogenic and saprophytic species, which may affect crops in the field or cause harvest and postharvest decay of plant products. The taxonomy of the genus Alternaria is not well-defined yet. A polyphasic approach based on morphological features, phylogeny and toxin profiles could be the key to a correct identification at species level and the evaluation of mycotoxin risks associated with fungal contamination. Species of Alternaria are known to produce many metabolites, mostly phytotoxins, which play an important role in the pathogenesis of plants. However, certain species, in particular the most common one A. alternata, are capable of producing several mycotoxins in infected plants and/or in agricultural commodities. The major Alternaria mycotoxins belong to three structural classes: the tetramic acid derivative, tenuazonic acid; the dibenzopyrone derivatives, alternariol, alternariol monomethyl ether and altenuene; and the perylene derivatives, the altertoxins. T...

Occurrence and toxigenicity of Fusarium proliferatum from preharvest maize ear rot, and associated mycotoxins, in Italy.

Forty-two samples of preharvest maize ear rot, collected in 1992-1993 from different maize fields throughout Italy, were examined for the relative incidence of Fusarium proliferatum and its toxigenicity. F. proliferatum (34%), together with F. moniliforme (54%), were the predominant species in infected ear kernels. Less frequently isolated were F. equiseti (8%) and F. graminearum (2%), and to a much lesser extent, F. chlamydosporum, F. culmorum, F. oxysporum, F. semitectum, F. solani, F. sporotrichioides, and F. subglutinans. When cultured on autoclaved maize kernels for 4 wk in the dark at 25 C, mycotoxin production by strains of F. proliferatum was as follows: all of the 26 assayed strains (100%) produced fumonisin B 1 (up to 2,250 mg/kg); 22 strains (85%) also produced beauvericin (up to 200 mg/ kg); and 12 (46%) produced fumonisin B 1 , beauvericin, and moniliformin (up to 5,300 mg/kg). Cultural extracts of almost all F. proliferatum strains revealed a high level of toxicity towards Artemia salina larvae. Selected infected maize ears, mostly colonized by F. proliferatum, were found to be contaminated by fumonisin B 1 (up to 250 mg/kg), beauvericin (up to 40 mg/kg), and moniliformin (200 mg/kg). This is the first investigation of the relative incidence of toxigenic F. proliferatum strains as causal agents of maize ear rot, as well as of the natural occurrence of mycotoxins in preharvest F. proliferatum-colonized maize ears. The results strongly suggest a more significant role of F. proliferatum in maize ear rot and in the associated mycotoxicoses. Moreover, these results show that a potential exists for the production of beauvericin, fumonisin B 1 , and moniliformin in maize grown in Italy.

One fungus, one name

In this letter, we advocate recognizing the genus Fusarium as the sole name for a group that includes virtually all Fusarium species of importance in plant pathology, mycotoxicology, medicine, and basic research. This phylogenetically guided circumscription will free scientists from any obligation to use other genus names, including teleomorphs, for species nested within this clade, and preserve the application of the name Fusarium in the way it has been used for almost a century. Due to recent changes in the International Code of Nomenclature for algae, fungi, and plants, this is an urgent matter that requires community attention. The alternative is to break the longstanding concept of Fusarium into nine or more genera, and remove important taxa such as those in the F. solani species complex from the genus, a move we believe is unnecessary. Here we present taxonomic and nomenclatural proposals that will preserve established research connections and facilitate communication within and between research communities, and at the same time support strong scientific principles and good taxonomic practice.

One fungus, one name: defining the genus Fusarium in a scientifically robust way that preserves longstanding use.

In this letter, we advocate recognizing the genus Fusarium as the sole name for a group that includes virtually all Fusarium species of importance in plant pathology, mycotoxicology, medicine, and basic research. This phylogenetically guided circumscription will free scientists from any obligation to use other genus names, including teleomorphs, for species nested within this clade, and preserve the application of the name Fusarium in the way it has been used for almost a century. Due to recent changes in the International Code of Nomenclature for algae, fungi, and plants, this is an urgent matter that requires community attention. The alternative is to break the longstanding concept of Fusarium into nine or more genera, and remove important taxa such as those in the F. solani species complex from the genus, a move we believe is unnecessary. Here we present taxonomic and nomenclatural proposals that will preserve established research connections and facilitate communication within and between research communities, and at the same time support strong scientific principles and good taxonomic practice.

Natural occurrence ofAlternaria mycotoxins in olives—their production and possible transfer into the oil

A limited survey of the natural occurrence of the major Alternaria mycotoxins, i.e. alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT), altertoxin-I (ATX-I), and tenuazonic acid (TA) has been carried out on olives and related processing products (oil and husks). The toxigenicity of Alternaria strains isolated from olives and the possible mycotoxin transfer into the oil have also been investigated. Four out of 13 olive samples were contaminated by 2 to 4 Alternaria mycotoxins. The highest contamination was found in a badly damaged sample containing 2.9, 2.3, 1.4 and 0.3 mg/kg of AME, AOH, ALT and TA, respectively. No mycotoxins were detected in olive-oil destined for human consumption (6 samples) or olive-husks (3 samples) collected from oil-mills after the first pressing of olives. An oil sample produced in our laboratory by processing the most contaminated olive sample contained AME (0.79 mg/kg) and AOH (0.29 mg/kg). The estimated mycotoxin amount transferred into the oil was 4% for AME, 1.8% for AOH, and zero for ALT and TA (considering 15% the oil yield). Although Alternaria species, mostly A. alternata (Fr.) Keissler, were present at various extent on all the examined olive samples, mycotoxins were only detected in samples of physically damaged olives. The production of mycotoxins by A. alternata isolated from olives was much higher (up to 3 order of magnitude for TA) on rice cultures than on olive cultures.