Influence of agronomic conditions on the efficacy of different fungicides applied to wheat at heading: effect on flag leaf senescence, Fusarium head blight attack, grain yield and deoxynivalenol contamination

A series of field experiments has been conducted in North West Italy over a period of 3 years to evaluate the effect of fungicide applications on common wheat yield and safety, combined with different agronomic conditions (high: a susceptible variety to FHB planted in an untilled field; low: a medium tolerant variety to FHB planted in a ploughed field) for Fusarium head blight (FHB) infection risk. A azole mixture (prochloraz + epoxiconazole), applied at heading, was compared in each year and for each agronomic condition with a triazole with high activity against F. graminearum and F. culmorum (metconazole), a strobilurin-azole mixture with elevated action to control leaf diseases and delay leaf senescence (azoxystrobin + prochloraz) and an untreated control. The following parameters were analyzed: flag leaf greenness, grain yield, test weight, thousand kernel weight (TKW), FHB incidence and severity and deoxynivalenol (DON) contamination. The results of this research, conducted over three years with different meteorological conditions, underline the important link between fungicide efficacy and environmental and agronomic conditions that can influence fungal disease pressure. The fungicide effect on the control of FHB and the increase in flag leaf longevity and grain yield were greater with an increase in the disease pressure. On the other hand, the DON contamination was reduced by the fungicide to a greater extent in the low risk agronomic and environmental conditions compared to the high risk ones. Prochloraz + epoxiconazole showed a lower efficacy in reducing DON contamination compared to metconazole, particularly in the higher FHB pressure conditions. No significant differences were observed between the azole mixture and the strobilurin-azole mixture for flag leaf greenness, grain yield, test weight or TKW. This study provides useful information that can be used to evaluate, in naturally-infected field conditions, the effect of a fungicide application at heading on wheat yield and safety in distinct scenarios for FHB and foliar disease pressure

Trichothecenes and zearalenone production by Fusarium equiseti and Fusarium semitectum species isolated from Argentinean soybean

Fusarium equiseti and F. semitectum represent the most abundant species in the Fusarium complex isolated from flowers, soybean pods and seeds in Argentina. The aim of the present study was to assess the production of major type A and type B trichothecenes (diacetoxyscirpenol, neosolaniol, T-2 toxin and HT-2 toxin, nivalenol, deoxynivalenol) and zearalenone by 40 F. equiseti and 22 F. semitectum isolates on rice culture. Mycotoxins were determined by HPLC with fluorescence detection after derivatisation with 1-anthronylnitrile for type A trichothecenes (i.e. diacetoxyscirpenol, neosolaniol, T-2 toxin and HT-2 toxin), by HPLC with UV detection for type B trichothecenes (i.e. nivalenol and deoxynivalenol) and by TLC for zearalenone. Twenty-two of 40 F. equiseti isolates produced diacetoxyscirpenol, nivalenol and ZEA alone or in combination, whereas only 2 of 20 F. semitectum isolates were nivalenol and ZEA producers. Both Fusarium species did not produce any deoxynivalenol, neosolaniol, T-2 toxin and HT-2 toxin. The variable retention in toxigenicity displayed by both fungal species suggests that these species have a saprophytic lifestyle in the soybean agroecosystem in Argentina.Fil: Barros, Germán Gustavo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Alaniz Zanon, Maria Silvina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Palazzini, Juan Manuel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Haidukowski, M.. b Institute of Sciences of Food Production; ItaliaFil: Pascale, M.. b Institute of Sciences of Food Production; ItaliaFil: Chulze, Sofia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentin

Enniatin and Beauvericin Biosynthesis in Fusarium Species: Production Profiles and Structural Determinant Prediction

Citation: Liuzzi, V. C., Mirabelli, V., Cimmarusti, M. T., Haidukowski, M., Leslie, J. F., Logrieco, A. F., . . . Mule, G. (2017). Enniatin and Beauvericin Biosynthesis in Fusarium Species: Production Profiles and Structural Determinant Prediction. Toxins, 9(2), 17. doi:10.3390/toxins9020045Members of the fungal genus Fusarium can produce numerous secondary metabolites, including the nonribosomal mycotoxins beauvericin (BEA) and enniatins (ENNs). Both mycotoxins are synthesized by the multifunctional enzyme enniatin synthetase (ESYN1) that contains both peptide synthetase and S-adenosyl-L-methionine-dependent N-methyltransferase activities. Several Fusarium species can produce ENNs, BEA or both, but the mechanism(s) enabling these differential metabolic profiles is unknown. In this study, we analyzed the primary structure of ESYN1 by sequencing esyn1 transcripts from different Fusarium species. We measured ENNs and BEA production by ultra-performance liquid chromatography coupled with photodiode array and Acquity QDa mass detector (UPLC-PDA-QDa) analyses. We predicted protein structures, compared the predictions by multivariate analysis methods and found a striking correlation between BEA/ENN-producing profiles and ESYN1 three-dimensional structures. Structural differences in the beta strand's Asn789-Ala793 and His797-Asp802 portions of the amino acid adenylation domain can be used to distinguish BEA/ENN-producing Fusarium isolates from those that produce only ENN

Fusariosi e grano tenero:quali sono le varietà più resistenti

L’esperienza condotta ha fornito informazioni di interesse per le diverse figure professionali coinvolte nel gruppo di lavoro e più in generale per i diversi operatori della filiera cerealicola. Per quanto concerne in particolare i costitutori, si sono potute evidenziare valide fonti di resistenza da affiancarea quelle più note. Sarà quindi possibile inserire scientemente nei programmi di incrocio ulteriore germoplasma dotato di maggiori potenzialità agronomiche, rispetto a varietà esotiche (ad esempio Sumai 3) che associano ai pregi gati alla resistenza a FHB molteplici altre caratteristiche negative (ad esempio sensibilità ad altre fitopatie). La metodica messa a punto ha inoltre confermato la possibilitàdi effettuare uno screening per resistenza a FHB su di un elevato numero di genotipi, con adeguata riproducibilità dei risultati negli anni. Ne deriva l’opportunità di lavorare con continuità a un’attivitàdi selezione che trova nella discontinuità dell’infezione naturale un fattore limitante l’efficacia del breeding. Per la ricerca di base si rendono disponibili ulteriori genotipi, le cui caratteristiche di resistenza attiva potranno essere indagate in studi di metabolomica e genomica, allo scopo di cquisire conoscenze fruibili in programmi di selezione assistita (MAS), per l’ accumulo di fattori utili in germoplasma coltivabile. La caratterizzazione effettuata su varietà di interesse commerciale offre agli operatori di filiera indicazioni per integrare le conoscenze disponibili, in particolare laddove la scelta varietale assume una valenza strategica nel piano colturale. In tal senso si pensi agli agricoltori che si trovano a produrre in condizioni di elevato rischio d’infezione (ad esempio dopo mais, semina su sodo e ambienti a elevata frequenza di FHB) o che devono comunque puntare all’ottenimento di livelli particolarmente contenuti della contaminazione da DON (ad esempio prodotti per l’infanzia). In conclusione, va rimarcato che le positive sinergie create all’interno del gruppo di lavoro consentiranno la prosecuzione dell’iniziativa, con l’intento di fornire utili contributi e aggiornamenti alla filiera cerealicola nazionale

DON on wheat crop residues: effects on mycobiota as a source of potential antagonists of Fusarium culmorum

Fusarium culmorum, a pathogenic fungal species associated with Fusarium Head Blight (FHB) of wheat, can produce the mycotoxin deoxynivalenol (DON) that is frequently found as contaminant in cereals. Wheat haulms, as decomposing plant material, are an important inoculum source of F. culmorum for subsequent crops. In the present work we exploited the mycobiota of haulms buried in natural soil as a source of potential antagonists of F. culmorum and evaluated the role played by DON in determining the composition of such mycobiota. DON was added to wheat haulm pieces that were incubated in three natural soils, namely sandy, clayey and mixed, all with a previous history of wheat cultivation. Composition of mycobiota associated with DON-treated cultural debris was evaluated and compared with mycobiota from control haulms, in order to evaluate the effect of soil type and of the presence of the mycotoxin. Our results showed that DON affected neither the number nor species profile of fungal isolates. Among fungi associated with cultural debris, thirty-nine Pythium spp. isolates were collected and five of them, both from treated and not treated haulms, were tested for their antagonistic ability against F. culmorum. The two strains showing the highest antagonistic activity were further tested against F. oxysporum, a species considered a major competitor of F. culmorum for wheat residues, and frequently recovered from haulms in our experiments. The two Pythium spp. isolates showed a positive antagonistic and mycoparasitic activity against F. culmorum, without affecting the growth of F. oxysporum. Mycobiota of haulms buried in soil represents an interesting source of potential antagonists and competitors for future exploitation in a multitrophic approach for biocontrol of FHB

Effect of prothioconazole-based fungicides against Fusarium Head Blight and deoxynivalenol accumulation in wheat under field conditions

Fusarium head blight (FHB) of wheat is a disease caused mainly from fungi of the genus Fusarium and Microdochium nivale that, under favourable environmental conditions, can colonize plants during the production cycle and cause serious damages in terms of yields and quality of harvested grains. Deoxynivalenol (DON), a trichothecene mycotoxin produced by Fusarium culmorum and F. graminearum that can contaminate wheat causing haematic and anorexic syndromes and neurotoxic and immunotoxic effects in mammals, is often associated with FHB disesase. Strategies for FHB control include the use of good agronomic practices (GAP), resistant varieties and effective fungicides. Prothioconazole is a triazolinthione fungicide with ideal systemic properties providing protective, curative and long lasting activity. In order to evaluate the effectiveness of prothioconazole-based treatments against FHB disease severity, grain yields and the consequent accumulation of DON in wheat kernels, several field experiments have been performed during four consecutive growing seasons (from 2004 to 2008) in the North of Italy. Fungicide treatments were carried out on different cultivars of soft wheat (Blasco and Serio) and durum wheat (Saragolla and San Carlo) after artificial inoculation with a mixture of toxigenic F. graminearum and F. culmorum strains. The application of fungicides containing prothioconazole at the beginning of anthesis (BBCH 61) resulted in a consistent reduction of FHB disease severity (by between 50 and 70%), a strong reduction of DON levels in wheat kernels (by between 40 and 90%), and an increasing of wheat yields ranging from 0.5 to 6.0 t ha-1 (average value 2.0 t ha-1), as compared to the untreated/inoculated control and to treatments with fungicides containing tebuconazole and cyproconazole plus prochloraz. These results show that the application of fungicides containing prothioconazole provide a strong reduction of the FHB disease, allowing both an increase in grain yields and a considerable reduction of DON content in the wheat kernels

Efficacia di fungicidi sulla " fusariosi della spiga" ed effetto sul contenuto di deossinivalenolo nel frumento

\uc9 stata valutata l\u2019azione preventiva di alcuni fungicidi sullo sviluppo della \u201cfusariosi della spiga\u201d del frumento dopo inoculazione artificiale in campo con isolati di Fusarium graminearum e F. culmorum, noti agenti causali della malattia. Sono stati inoltre valutati gli effetti dei trattamenti sulla produzione in granella e sul contenuto di deossinivalenolo (DON) nelle cariossidi. L\u2019impiego di ciproconazolo + prochloraz e della miscela tebuconazolo e azoxystrobin hanno ridotto significativamente sia la gravit\ue0 della malattia (fino al 77%) sia il contenuto di DON (fino all\u201989%), rispetto al testimone inoculato e non trattato con fungicidi. Anche tetraconazolo si \ue8 dimostrato efficace nel ridurre sia la malattia sia i livelli di DON, sebbene con risultati inferiori rispetto agli altri fungicidi. La produzione di granella \ue8 risultata pi\uf9 elevata in tutte le tesi trattate con i fungicidi