Fusarium graminearum, the causative agent of Fusarium head blight, is an economically important pathogen of wheat (Triticum aestivum). Breeding Fusarium head blight (FHB) resistant wheat requires knowledge of the underlying genetic control of FHB resistance. Genetic parameters for FHB resistance and five related traits were estimated in three populations at two locations and in two years. Moderate broad sense heritabilities for FHB severity and Fusarium damaged kernels (FDK) were observed. Incidence of FHB and the toxin deoxynivalenol (DON) accumulation had low to moderate broad sense heritabilities. Correlations between FDK and severity and FDK and DON were moderate to high in the three populations and do support indirect selection for FHB severity or DON based on FDK data alone, but it is important to be cautious in years with a high disease pressure when FHB resistance could be masked. A cycle of among-family and within-family selection cycle was conducted in 2003. Actual selection gain was higher than predicted gain based on variance components in 2003 in the within-family selection study. One population had also a strong response for low DON in the among-family selection study. The observed results suggest that selection for FHB resistant genotypes could be achieved with a recurrent selection scheme. Along with conventional breeding, molecular techniques are being used in breeding for FHB resistance. A first genotypic screening of the three populations showed Population 2 had the presence of a resistance allele form the resistant Chinese cultivar Sumai 3. Although Populations 1 and 3 did not have the resistance allele, the results suggest other sources of resistance might be present in these two populations.

Fusarium graminearum, the causative agent of Fusarium head blight, is an economically important pathogen of wheat (Triticum aestivum). Breeding Fusarium head blight (FHB) resistant wheat requires knowledge of the underlying genetic control of FHB resistance. Two nine-parent diallel analyses were completed in greenhouse and field environments. Combining abilities, variance component ratios, and narrow sense heritabilities for FHB resistance and deoxynivalenol levels were calculated. Significant general and specific combining ability effects were observed. Resistance to FHB seems to be mostly controlled by additive genetic effects with some dominance noted in the field. Resistance noted in the greenhouse environment may not hold up in the field. Genetic parameters for FHB resistance and four related traits were estimated in three populations. Moderate to high broad sense heritabilities for FHB severity and Fusarium damaged kernels (FDK) were observed. Incidence of FHB had low to moderate broad sense heritabilities. Correlations between FDK and severity and FDK and incidence were moderate and low, respectively, and do not support indirect selection for FHB severity or incidence based on FDK data alone. Substantial predicted gains from family selection were observed and therefore selection of FHB resistant wheat lines should be based on family means and not individual selection.

The use of exotic resistance quantitative trait loci (QTL) provides one strategy for breeding wheat cultivars resistant to Fusarium Head Blight (FHB), a devastating disease of wheat. The objective of this study was to evaluate the effectiveness of two QTL, Fhb1 and QFhs.nau-2DL, in diverse genetic backgrounds and to evaluate their effects on agronomic and quality traits. Five populations from crosses between FHB susceptible parents (26R58, KY97C-0574-01, 25R54, KY97C, KY97C-0554-02, 25R78 and KY93C-1238-17-1) and FHB-resistant VA01W-476, were evaluated in the FHB nursery at Lexington, KY in 2010 and 2011. The populations were also grown in yield trials at Lexington (2010 and 2011) and Princeton (2011), KY, to measure agronomic and quality traits. Fhb1 reduced Fusarium damaged kernels (FDK) by 32% and the toxin, deoxynivalenol (DON) by 20%. QFhs.nau-2DL significantly reduced mean FDK by 29% in two of five populations and DON by 24% in four of five populations. While the effects of these QTL on agronomic and quality traits were significant, the impact was small. One cycle of either direct or indirect simulated phenotypic selection was effective at reducing DON levels and the frequency of Fhb1-homozygous resistant lines among the selects was higher than the frequency of QFhs.nau-2DL-homozygous resistant lines.

Fusarium Head Blight (FHB) is a destructive disease caused by Fusarium graminearum that affects wheat (Triticum aestivum L.) worldwide. Breeding for resistance to FHB is arguably the best way to combat this disease. However, FHB resistance is highly complex and phenotypic screening is difficult. Molecular markers are a promising tool but breeding programs face the challenge of allocating resources in such a way that the optimum balance between phenotypic and genotypic selection is reached. An F2:3 population derived from a resistant x susceptible cross was subjected to phenotypic and genotypic selection. For phenotyping, a novel air separation method was used to measure percentage of damaged kernels (FDK). Heritability estimates were remarkably high, which was attributed to the type of cross and the quality of phenotyping. Genotypic selection was done by selecting resistance alleles at quantitative trait loci (QTL) on the 3BS (Fhb1) and the 2DL chromosomes. Fhb1 conferred a moderate but stable FHB resistance while the 2DL QTL conferred a surprisingly high level of resistance but with significant interaction with the environment. Phenotypic selection conferred higher or lower genetic gains than genotypic selection, depending on the selection intensity. Based on these results, different selection strategies are discussed.

Le micotossine sono metaboliti tossici prodotti da funghi in grado di svilupparsi sulle derrate alimentari. Diverse strategie sono state considerate per risolvere questo problema studiando la crescita di funghi/produzione di micotossine. Questa tesi è focalizzata sullo sviluppo/validazione di modelli matematici per prevedere la contaminazione di micotossine (deossinivalenolo, fumonisine e aflatossine) in cereali (mais/grano) sulla base di dati meteorologici. Il primo capitolo fornisce un’introduzione sulla teoria dei modelli e sui pat-sistemi modelizzati. Il secondo si concentra sulla presenza di tricoteceni e zearalenone nel frumento coltivato in Italia. Nel cap.3 sono stati confrontate le differenze predittive di modelli empirici/meccanicistici per la contaminazione di deossinivalenolo nel grano. Nel cap.4 è stata descritta la contaminazione da fumonisine e aflatossine in mais coltivato in Italia. I capitoli 5 e 6 analizzano il pato-sistema mais-Aspergillus flavus, il primo si concentra sulla sporulazione di A. flavus , il secondo sullo sviluppo di un modello per prevedere la contaminazione da aflatossina. Un altro modello meccanicistico per prevedere la presenza di fumonisina nel mais è descritto nel cap.7. L'ultimo capitolo riassume l'attività svolta nel progetto europeo MYCORED in cui sono stati coinvolti diversi paesi in tutto il mondo che hanno fornito i dati necessari per la validazione dei modelli. / Mycotoxin are toxic secondary metabolite produced by fungi able to colonize crops and thus posing a potential menace to human/animal health. Several strategies have been considered to mitigate the problem studying the variables related to mould growth and mycotoxin production. This thesis focuses on the development and validation of mechanistic models to predict mycotoxins (deoxinivalenol, fumonisins and aflatoxins) contamination in cereals (maize/ wheat) based on meteorological data. The first chapter introduce modelling theory, and patho-systems analysed. Chapter 2 focuses on trichothecenes and zearalenone occurrence in wheat produced in Italy. Predictive performance of empirical and mechanistic models for deoxnivalenol contamination in wheat were discussed in chapter 3. Chapter 4 described fumonisins and aflatoxins occurrence in maize grown in Italy. Chapters 5 and 6 analised the patho-system maize-Aspergillus flavus; the former focuses on the dynamics of A. flavus sporulation the lalatter on the development of a mechanistic model to predict aflatoxin produced by A. falvus. Another mechanistic model for Fusarium ear rot and fumosin production in maize (chapter 7). The last chapter summarised the activity done in the European project MYCORED in which several countries worldwide were involved and wheat and/or maize samples collected with data necessary for model validation.

Šio darbo tikslas: Nustatyti, įvertinti ir palyginti ekologiškoje ir įprastinėje grūdinėje žaliavoje mikologinį ir mikotoksikologinį užterštumą, panaudojant pienarūgštes bakterijas deoksinivalenolio detoksikacijai. Darbo uždaviniai: Ištirti, įvertinti ir palyginti ekologiniuose ir įpratiniuose ūkiuose surinktų grūdų mikologinį ir mikotoksikologinį užterštumą. Įvertinti ir palyginti kvietinių ir ruginių miltų mikotoksikologinį užretštumą. Įvertinti fermentacinių procesų įtaką DON kiekiui duonos gamybos grandinėje Naudota metodika: Mikromicetų skaičius įvertintas pagal LST ISO 6611:2004. Mikromicetų rūšys identifikuotos vadovaujantis apibūdintojais (Samson et al., 2000; Lugauskas ir kt., 2002). Mikotoksinų koncentracija nustatyta imunofermentinės analizės metodu (IFA), panaudojus komercinius VERATOX® DON 5/5, (Neogen, JAV) rinkinį. Fermentacija atlikta panaudojus pieno rūgšties bakterijų kultūrą L. sakei. Tyrimų rezultatai pateikti panaudojus R statistinį paketą. Išvados: Ištyrūs kviečius ir rugius surinktus iš ekologinių ir iprastinių ūkių daugiausia dominavo Fusarium spp. genties mikromicetai. Potencialūs deoksinivalenolio producentai. Gyvybingų sporų skaičius 33 proc. didesnis nustatytas kviečiuose surinktuose iš ekologinių ūkių (p<0,05). Lyginant rugių mėginius, gyvybingų sporų skaičius 29,5 proc. didesnis nustatytas taip pat ekologiniuose ūkiuose surinktuose rugiuose 44±2,1x102 KSV/g (p<0,05). Palyginus gyvybingų sporų skaičių kvietiniuose ir ruginiuose miltuose 5... [toliau žr. visą tekstą] / Objective of the thesis: To identify, evaluate and compare mycological and mycotoxicological contamination in ecological and standard grains by using lactic acid bacteria for deoxynivalenol detoxification. Tasks: Investigate, evaluate and compare mycological and mycotoxicological contamination of grains collected in ecological and standard farms. Evaluate and compare mycotoxicological contamination of wheat and rye flour. Evaluate influence of fermentation processes on DON level in bread production chain. Research methodology: The total count of microorganisms (CFU/g-1) in the analysed sample was determined by way of dilution using the nutrient agar. LST ISO 6611:2004. Micromycete content was determined according to the method of enzyme-linked immunosorbent assay (ELISA) by using the commercial VERATOX® DON 5/5, (Neogen, JAV). Fermentation processes using latic acid bacteria L. sakei. The results of the data analysis and research presented using the R statistical package. Results and discussion: After examining wheat and rye that were collected from ecological and standard farms, it was noticed that mycromycetes of Fusarium spp. genus dominated mostly. Potential Deoxynivalenol Prudecents. Wheat that was collected from ecological farms had 33 proc. higher number of viable spores, i.e. (p<0,05). Similarly, the number of viable spores of rye was 29.5 proc. higher in the rye that was collected in the ecological farms, i.e. 44±2,1x102 CFU/g (p<0,05). (CFU-Colony forming... [to full text]

Several Fusarium species can cause Fusarium head blight (FHB) and Fusarium crown rot (FCR) diseases in wheat and these are of economic importance in wheat production systems globally. Fusarium graminearum represents a model pathogen species to study these diseases because it has a sequenced genome, commercially available gene expression arrays and an growing collection of mutants impaired in pathogenicity and virulence, at least for FHB. FCR occurs at the stem base of the wheat plant, causing major reductions in grain yield. FCR has been much less intensively researched than FHB and the infection process of F. graminearum during crown rot disease in wheat has not been studied previously at the molecular level. Fungal biomass estimations by real-time quantitative PCR analysis of DNA from inoculated plants identified three distinct phases of infection during FCR, an initial increase in fungal mass in phase 1 up to 2 days post inoculation (dpi), then a reduction during phase 2 until 14 dpi followed by a large increase thereon in phase 3 that corresponded to symptom development. Histological characterisation of F. graminearum colonisation during these three phases of infection showed that initially the spores germinated on the stem surface at the point of inoculation forming a superficial hyphal mat. This occurred within the first two days of infection. The second phase was characterised by a period of low amounts of fungal tissue present in the infected plants and 14 days following infection hyphae were only observed below the point of inoculation at the stem base of the wheat seedling and had penetrated and colonised the adaxial epidermis of the outer leaf sheath. Following this, the third phase was characterised by a major colonisation of the internal tissues of the crown which corresponded to visible symptom development around 35 days after inoculation. Fungal gene expression during all three phases of infection were examined using the Affymetrix GeneChip system comprised of 22,000 F. graminearum gene probe sets. This analysis showed 1,839 genes were significantly up regulated in planta compared to axenic vegetative mycelia, including some known FHB virulence genes (e.g. those involved in the biosynthesis of trichothecene toxins). Fungal genes differentially regulated between the phases were identified indicating that FCR disease development requires a coordinated process involving distinct fungal gene expression programs. A bioinformatic comparison of global F. graminearum gene expression during FCR of wheat with published data for FHB of barley indicated similarities at very early stages of infection but divergence thereafter. It was decided to functionally test whether F. graminearum utilises the same virulence genes in FCR and FHB diseases. Because no virulence genes have been previously identified from FCR studies a small group of genes were initially selected from the FCR gene expression studies for further functional analysis using gene knock-out technology. Only two of these genes showed a changed phenotype during Fusarium infection of wheat plants and they encoded a probable ABC transporter (FgABC1) and a probable superoxide dismutase (FgSOD1). It was interesting to note that even though both FgABC1 and FgSOD1 exhibited similar transcription profiles during both FCR of wheat and FHB of barley it was found that FgABC1 was specifically required for full FCR disease development on the wheat cultivar Kennedy whereas FgSOD1 was specifically required for FHB disease on the same cultivar. This indicated that F. graminearum virulence genes can show specificity to the infection of different plant tissues and that these types of genes cannot be predicted based only on their transcription profiles. It is suggested that F. graminearum induces a global set of virulence factors but only some of these may be effective in particular tissues. To test further whether there was tissue specialisation for specific tissues and FCR & FHB diseases, a group of F. graminearum genes that were known virulence factors during FHB were tested to see if they were also virulence factors for FCR. This analysis showed that two genes displayed specificity only for FHB and five were virulence factors for both FHB and FCR. One of the genes that was a virulence factor for both diseases was the Tri5 gene that is necessary for the biosynthesis of trichothecene mycotoxins. This gene and these toxins did not appear to be necessary for symptom development and the induction of host defence responses but were necessary for fungal colonisation of the crown and stem in later stages of infection. Interestingly there were parallels in the role played by the Tri5 gene in FCR and that reported for FHB where it is necessary for colonisation for the spike. This study is the first molecular analysis of any Fusarium species during crown rot of wheat. Importantly, it shows that there may be specialisation towards host tissues for some virulence genes but also suggests that some factors may be non-specifically required for infection and it is these factors that will represent attractive targets for future control measures of both diseases.

Hohenheim, Univ., Diss., 2004.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Two studies were performed in order to evaluate, through meta-analysis, the relationship of mycotoxins with performance and organ weights in pigs and broilers. The databases totaled 13,196 pigs (85 articles published between 1968 and 2010) and 37,371 broilers (98 articles, between 1980 and 2009). Meta-analysis followed three sequential analyses: graphical, correlation and variance-covariance. Pigs challenged by mycotoxins reduced feed intake by 18% and weight gain by 21% in relation to the control group. Challenged broilers presented a reduction of 12% in feed intake and 14% in weight gain. Mycotoxins with the greatest impact on performance were deoxynivalenol and aflatoxins in pigs, and ochratoxins and aflatoxins in broilers. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination in equations for estimating the mycotoxin effect on weight gain. The mycotoxin effect on growth was greater in younger animals. In addition, the residual analysis demonstrated that the greater part of the variation in weight gain was explained by the variation in the feed intake (87% in pigs and 65% in broilers). The variation in weight gain in challenged animals was also influenced by nutrient ingestion, such as protein and methionine. The mycotoxin effect on growth was greater in male pigs (-19%) compared to females (-15%). Mortality rate and some hematological parameters were also influenced by mycotoxins in broilers. Relative weight of organs increased in challenged pigs (liver, kidneys and heart) and broilers (liver, kidneys, lungs and gizzard). Mycotoxins influence on performance, productive indexes and organ weight in pigs and broilers. However, the magnitude of the effects varies with the type and concentration of mycotoxin, sex and age of the animal, as well as nutritional factors. / Dois trabalhos foram desenvolvidos com o objetivo de estudar, através de meta-análise, a relação das micotoxinas com o desempenho e o peso de órgãos de suínos e frangos de corte. As bases de dados totalizaram 13.196 suínos (85 artigos publicados entre 1968 e 2010) e 37.371 frangos de corte (98 artigos, entre 1980 e 2009). A meta-análise foi realizada através de três análises sequenciais: estudos gráficos, de correlação e de variância-covariância. Suínos desafiados por micotoxinas apresentaram redução de 18% no consumo de ração e de 21% no ganho de peso. Frangos de corte desafiados apresentaram redução de 12% no consumo de ração e 14% no ganho de peso. As micotoxinas com maior impacto sobre o desempenho foram deoxinivalenol e aflatoxinas para os suínos, e ocratoxinas e aflatoxinas para as aves. A concentração de micotoxinas nas dietas e a idade dos animais ao desafio foram as variáveis que mais ajustaram o coeficiente de determinação nas equações para estimar o efeito das micotoxinas sobre o ganho de peso. O efeito das micotoxinas sobre o crescimento foi maior nos animais jovens. Além disso, a análise de resíduos mostrou que a maior parte da variação no ganho de peso foi explicada pela variação no consumo de ração (87% nos suínos e 65% nas aves). A variação no ganho de peso em animais desafiados também foi influenciada pela ingestão de nutrientes, como proteína e metionina. O efeito das micotoxinas sobre o ganho de peso foi maior nos suínos machos (-19%) que nas fêmeas (-15%). A taxa de mortalidade e alguns parâmetros hematológicos também foram influenciados pelas micotoxinas nos frangos de corte. O peso relativo dos órgãos aumentou nos suínos (fígado, rins e coração) e nas aves (fígado, rins, pulmões e moela) desafiadas. As micotoxinas influenciam o desempenho, os índices produtivos e o peso dos órgãos em suínos e frangos de corte. No entanto, a magnitude destes efeitos varia com o tipo e a concentração de micotoxinas, o sexo e a idade do animal, bem como com fatores nutricionais.

Made available in DSpace on 2017-07-10T19:23:54Z (GMT). No. of bitstreams: 1 Tania_ Claudia Pintro.pdf: 1091369 bytes, checksum: f8c1d3904413167a06cca540a4fcaa7a (MD5) Previous issue date: 2015-02-12 / The objective of this study was to evaluate the effect of insect infestation Sitophilus zeamais on the physicochemical and microbiological quality in wheat grains, during storage in times of 0, 45, 90 and 135 days, in three temperatures: 20, 25 and 30 ºC. For the conduct of the experiment, wheat grain samples were collected (Triticum aestivum L.) of the cultivar BRS Tanager, produced in Western Paraná, from the harvest of 2013. For storage, the grains had water contents below 13%, being stored about 400 g in sealed glass containers with fabric type voil in order to facilitate gas exchange, totaling 72 containers stored in incubator BOD the temperature of 20, 25 and 30 ° C for 135 days. Of the total of containers, 36 were infested with 20 adults of Sitophilus zeamais and the other 36 were kept without infestation. Every 45 days, were samples for subsequent chemical-physical analysis (moisture, ash, and total protein population variation of insects), microbiological (filamentous fungi count and identification of fungi producing of deoxynivalenol) and quantifying of deoxynivalenol for the three temperatures at baseline and 135 days with and without infestation. The samples were evaluated by the use of analysis of variance (ANOVA) and for test of comparison of means the Tukey test was applied, with 5% level of significance. It was observed that, with increased storage time, increased population of insects, mainly at temperatures of 20 and 25° C, reducing the value of the weight of the hectolitre at both temperatures. In general, the water content was reduced with increasing temperature and time of the storage. The contents of protein, in the treatments with and without infestation, increased with storage time. In general, the ash content increased with time of storage in grain, with and without infestation in the three temperatures evaluated. The total count of CFU of filamentous fungi was greater for grains of wheat infested. The results obtained indicate that all samples of grain stored, analyzed in the initial time and 135 days, with and without infestation, for use at temperatures of 20, 25 and 30 &#7506;C, are within the maximum tolerable limit of 3000 &#956;g of deoxynivalenol per kg of wheat. / O objetivo deste trabalho foi avaliar o efeito da infestação de insetos Sitophilus zeamais sobre a qualidade físico-química e microbiológica de grãos de trigo, durante o armazenamento nos tempos de 0, 45, 90 e 135 dias e em três, temperaturas: 20, 25 e 30 ºC. Para a condução do experimento, foram coletadas amostras de grãos de trigo (Triticum aestivum L.) do cultivar BRS Tangará, produzido na região Oeste do Paraná e provenientes da safra de 2013. Para o armazenamento, os grãos apresentaram teores de água abaixo de 13%, sendo armazenados cerca de 400 g em recipientes de vidros, fechados com tecido tipo voil a fim de facilitar as trocas gasosas, totalizando 72 recipientes armazenados em câmara incubadora B.O.D. nas temperaturas de 20, 25 e 30 °C, no tempo de 135 dias. Do total de recipientes, 36 foram infestados com 20 insetos adultos de Sitophilus zeamais e os outros 36 foram mantidos sem infestação. A cada 45 dias, foram retiradas amostras, para posterior análise físico-química, (teor de água, cinzas, proteína total e variação populacional de insetos), microbiológicas (contagem de fungos filamentosos e identificação dos fungos produtores de desoxinivalenol) e de quantificação de desoxinivalenol, para as três temperaturas no tempo inicial e de 135 dias com e sem infestação. As amostras foram avaliadas pelo emprego da análise de variância (ANOVA) e para o teste de comparação de médias foi aplicado o teste de Tukey, com nível de 5% de significância. Observou-se que conforme aumentava o tempo de armazenamento aumentava também a população de insetos, principalmente para as temperaturas de 20 e 25 °C, reduzindo o valor do peso hectolitro em ambas as temperaturas. Em geral, o teor de água diminuiu quando ocorreu aumento de temperatura e tempo de armazenamento. Os teores de proteínas, nos tratamentos com e sem infestação, aumentaram com o tempo de armazenamento. Em geral, o teor de cinzas aumentou com o tempo de armazenamento nos grãos com e sem infestação, nas três temperaturas avaliadas. A contagem total de UFC de fungos filamentosos foi maior para grãos de trigo infestados. Os resultados obtidos mostram que todas as amostras de grãos armazenados, analisadas no tempo inicial e de 135 dias, com e sem infestação para as temperaturas de 20 25 e 30 &#7506;C, estão dentro do limite máximo tolerável de 3000 &#956;g de desoxinivalenol por kg de trigo