Fusarium head blight (FHB) is one of the most economically important diseases of small grains and continues to impact crops when environmental conditions are favorable to Gibberella zeae (Fusarium graminearum), the causal agent of the disease. Corn residues are considered to be primary sources of inoculum for epidemics of FHB. Therefore, knowledge of the movement of Gibberella zeae from a local source of infested corn residue is critical to the management of FHB in wheat and barley. Previous research made significant progress in defining the spatial dissemination of inoculum sources of G. zeae within agricultural fields, but was unable to clearly distinguish between within-field and background sources. Using amplified fragment length polymorphism, released clones of G. zeae were tracked within wheat and barley fields. This strategy allowed the distinction between the contributions of released clones to FHB, compared to that of background inocula. Corn residue infested with clones of G. zeae was placed into small replicated plots in winter wheat fields in New York and Virginia in 2007 and 2008 and wheat spikes were collected at 0, 3, 6, and ≥24 m from the inoculum sources. Recovery of released clones decreased an average of 90% between 3 and 6 m from inoculum sources. Various amounts of corn residue infested with a single clone of G. zeae were placed into small replicated plots in winter wheat and barley fields in Virginia from 2008 to 2010. The use of minimal or conventional tillage and a moderately resistant cultivar of wheat or barley may reduce the contribution of within-field inocula to FHB; however, environmental conditions play an important role in the effectiveness of these management strategies. With the increase of corn production due to incentives for ethanol-based fuel, overwintering sites for G. zeae on corn residue are likely to increase. Our work contributes to an increased understanding of the influence of overwintered corn residue to FHB which will also direct future research on how to reduce the inoculum potential from within-field sources. / Ph. D.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The gibberellic acid (GA3) is a natural hormone found in some plants, this hormone has been used in agricultural formulations, as growth regulator, highly relevance both economic and industrial. Currently, its industrial scale production is achieved by Submerged Fermentation (SF) using the fungus Gibberella fujikuroi. The main problem in the industrial process is related to the low yield of GA3, causing the purification process presents high costs. An alternative to this process is the Solid- State Fermentation (SSF) that allows to obtain higher concentrations of this product. The greatest advantage of the SSF front SF is related to increased production of GA3 using low cost substrates such as waste and by-products of agroindustry. Given the fact that Brazil is highlighted as one of the most prosperous countries in terms of agricultural production, and the Rio Grande do Sul accounts for about 30-40% of rice and barley production in the country, this research evaluated the use of Raw Rice Bran (RRB) and Wet Brewery Waste (WBW), rice processing and brewing industry residues, as substrates for GA3 production by the fungus Gibberella fujikuroi. Two experimental designs, a linear type 2n and CCRD, both for two variables were performed. The first design evaluated, on three levels, evaluated the effect of moisture content in the range of 50 to 70%, and the composition of the medium, with RRB content ranging from 30 to 70% of the total substrate mass (RRB and WBW mass). In turn, the second planning in 5 levels, evaluated the effect of the addition of glucose, the carbon source over the range 0 to 80 g/L, and ammonium nitrate (NH4NO3), the nitrogen source, in the range 0 - 5 g/L, by making use of the best conditions of the first planning. It was found that, for seven days of fermentation, the greater yield for the first research proposed, was at the test carried out with medium composition of 30% RRB and 70% WBW and moisture content equals 70%. At the second design It was observed that the highest concentration of NH4NO3 favored the formation of GA3 by the fungus, towards intermediate value to the glucose content. Finally, investigation of the kinetic behavior showed an increase in production of GA3, with the peak on the seventh day with maximal production of 10,10 g/kg of substrate, and subsequent tendency for stabilization. / O ácido giberélico (GA3) é um hormônio natural presente em algumas plantas, sendo empregado em formulações agrícolas como regulador de crescimento, apresentando grande importância econômica e industrial. Atualmente, sua produção em escala industrial é realizada por fermentação submersa (FSub) empregando o fungo Gibberella fujikuroi. O maior problema no processo submerso está relacionado aos baixos rendimentos de GA3, fazendo com que o processo de purificação apresente elevados custos. Uma alternativa a este processo é a fermentação em estado sólido (FES) que permite a obtenção deste produto em concentrações maiores. A maior vantagem da FES frente à FSub está relacionada à maior produção de GA3 empregando substratos de baixo custo, como por exemplo, resíduos e subprodutos da agroindústria. Dado o fato de que o Brasil é destacado como um dos mais prósperos países em termos da produção agrícola, e que o Rio Grande do Sul é responsável por cerca de 30 a 40% da produção de arroz e cevada, no país, avaliou-se a utilização de Farelo de Arroz Bruto (FAB) e Resíduo de Cervejaria Úmido (RCU), resíduos do processamento de arroz e da indústria cervejeira, como substratos para a produção de GA3 pelo fungo Gibberella fujikuroi. Foram realizados dois planejamentos experimentais, linear do tipo 2n e DCCR, ambos para duas variáveis. O primeiro planejamento, em três níveis, avaliou o efeito da umidade, na faixa de 50 a 70%, e a composição do meio, com o teor de FAB variando entre 30 e 70% do total de massa do substrato (massa de FAB e de RCU). Por sua vez, o segundo planejamento, em 5 níveis, avaliou o efeito da adição de glicose, fonte de carbono na faixa de 0 a 80 g/L, e do Nitrato de Amônio (NH4NO3), fonte de nitrogênio, na faixa entre 0 a 5 g/L, na produtividade de GA3, fazendo uso das melhores condições do primeiro planejamento. Foi verificado que, para sete dias de fermentação, o maior rendimento obtido, para a primeira investigação proposta, foi no ensaio realizado com composição do meio 30% FAB e 70% RCU e umidade do meio de 70%. No segundo planejamento constatou-se que a maior concentração de NH4NO3 favoreceu a formação de GA3 pelo fungo, para um valor intermediário do teor de glicose. Por fim, a investigação da cinética demonstrou um comportamento de crescimento na produção de GA3, com o pico no sétimo dia, com produção máxima de 10,10 g/Kg de substrato, e posterior tendência à estabilização.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-10-03T17:35:05Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Taiane_Viana.pdf: 904492 bytes, checksum: 30037558592bcb3fdf60ab01d643c574 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-10-06T20:46:17Z (GMT) No. of bitstreams: 2 Dissertacao_Taiane_Viana.pdf: 904492 bytes, checksum: 30037558592bcb3fdf60ab01d643c574 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-06T20:46:17Z (GMT). No. of bitstreams: 2 Dissertacao_Taiane_Viana.pdf: 904492 bytes, checksum: 30037558592bcb3fdf60ab01d643c574 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2013-12-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O cultivo do trigo no Brasil é marcado pelo elevado número de doenças capazes de causar danos à produção. Entre as principais doenças que afetam o trigo está a giberela ou fusariose da espiga, causada pelo agente etiológico Gibberella zeae (Schw.) Petch, (anamorfo Fusarium graminearum Schwabe) que causa impacto negativos não somente à produtividade mas também a qualidade dos grãos produzidos. As condições ambientais para que a infecção ocorra carac terizam-se com temperaturas de 20-25°C e duração do molhamento foliar de, no mínimo, 48 horas consecutivas. O controle químico é realizado via aplicação de fungicidas a partir do inicio da floração estendendo-se até o final do florescimento, sendo que este tipo de controle caracteriza-se pela sua menor eficiência quando comparado com o controle de doenças foliares. Caso as condições climáticas impeçam a realização das aplicações de fungicidas no período indicado, o controle fica muito dificultado, por outro lado, se não ocorrer clima favorável à infecção, não se justifica o tratamento. A ineficiência dos tratos culturais no controle de giberela, associado à natureza quantitativa da característica de resistência, e o fato de sofrer alta influência do ambiente resultam na necessidade de identificar fontes efetivas de resistência que possam ser utilizadas em programas de melhoramento de trigo. De fato, existem culturas onde o controle das doenças mais importantes ocorre, quase que exclusivamente, por meio da resistência sendo que a identificação de genotipos que contenham resistência é um dos primeiros passos para selicioná-los. Desta forma, é fundamental o conhecimento de cultivares que apresentem níveis de resistência a giberela e métodos que possam identificar estas cultivares. Frente ao exposto o objetivo deste trabalho foi: i) separar genótipos suscetíveis e que contenham diferentes níveis de resistência utilizando avaliações morfológicas e moleculares; ii) verificar a resistência à giberela nas cultivares Frontana e Pampeano. Para isso foram utilizadas avaliações de características morfológicas citadas na literatura e associadas a resistência à giberela, assim como, o meprego de primers descritos na literatura significativamente associados à QTL de resistência à giberela. Como resultado do estudo espera-se auxiliar no desenvolvimento de ferramentas que possam ser utilizadas em programas de melhoramento de trigo visando facilitar a identificação de fontes de resistência. / The cultivation of wheat in Brazil is marked by the large number of diseases that can damage the production. Among the major diseases affecting wheat is wheat scab or Fusarium head blight (FHB), caused by the agent Gibberella zeae (Schw.) Petch (anamorph Fusarium graminearum Schwabe ) that causes negative impact not only on productivity but also the quality of the grain produced. The environmental conditions for infection are temperatures between 20-25°C and 48 consecutive hours of leaf wetness. Chemical control is performed via application of fungicides from the start extending until the end of flowering, and this type of control is characterized by its low efficiency when compared to the disease control. If the weather conditions prevent the aplication of fungicide applications within this period, there is no possibility control, on the other hand, if it does not favorable environment for infec tion treatment is not justified. The inefficiency of cultural control of FHB, associated with the quantitative trait (QTL- Quantitative traits loci)of resistance, and the fact of suffering high influence of the environment results in the need to identify effective sources of resistance that can be used in wheat breeding programs. In fact, there are cultures where control of major diseases occurs almost exclusively through resistance where the identification of genotypes containing resist ance is one of the first steps in their selection. Thus it is crucial to understand cultivar present levels of resistance to FHB and methods that can identify these cultivars.The objective of this study was: i) separate susceptible and containing different levels of resistance using molecular and morphological evaluations; ii) determine FHB resistance using cultivars Frontana and Pampeano as a source of resistance. Using morphological assessments cited in the literature and associated with resistance to FHB, as, primers as described in the literature as significantly associated with QTL for resistance to FHB. As a result of the study one expects to develop tools that can be used to facilitate the identification of sources of resistance.

Master of Science / Department of Plant Pathology / Robert L. Bowden / John F. Leslie / Fusarium graminearum Schwabe sensu lato (teleomorph: Gibberella zeae (Schwein.) Petch), a homothallic ascomycete fungus, is the causal agent of Fusarium head blight (FHB) of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and other small grains. FHB occurs worldwide and serious outbreaks have been reported in North America, South America, Asia, and Europe. According to the phylogenetic species concept (PSC), F. graminearum is composed of at least 15 phylogenetic lineages known as the Fusarium graminearum species complex. Although F. graminearum is homothallic, some members of different phylogenetic lineages are known to intercross in the laboratory. It has been suggested that F. graminearum sensu lato fits the biological species concept (BSC). According to the BSC, “species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups”. Previous reports of intercrossing were qualitative, so the degree of reproductive isolation, if any, is not clear. Since intrinsic reproductive isolation is the key criterion to identify species by the BSC, more detailed quantitative information is needed. Chromosome rearrangements between fungal strains may reduce fertility in sexual crosses through the production of genetically inviable recombinant progeny. As such, rearrangements can be important postzygotic reproductive barriers between species. Following methods used in Neurospora crassa, ascospore tetrads were analyzed for patterns of ascospore viability. Crosses were made with three lineage 7 (F. graminearum sensu stricto according to PSC) strains as female. Each female was a MAT1-2 knockout mutant that rendered it obligately heterothallic. Males were several members of lineages 6 (F. asiaticum according to PSC) and lineage 7. Crosses with lineage 7 males formed complete asci with 8 ascospores indicating that their genomes are isosequential with the testers. Crosses with one strain from lineage 6 with two known inversions produced asci containing 8, 6, and 4 ascospores, consistent with it not being isosequential. However, three other strains of lineage 6 appeared to be isosequential with the testers. Therefore, chromosome rearrangements did not appear to be common to strains of lineage 6 and probably do not contribute significantly to reproductive isolation of lineage 6 and lineage 7. Interlineage fertility studies with the three lineage 7 tester strains were performed to quantify interlineage fertility parameters including the total number of ascospores produced, perithecial density, and perithecium internal development scores. All lineage 7 female testers successfully crossed to all 23 male strains from lineages 1 to 9. For total ascospore production, one female tester crossed equally well with all lineages and the other two testers showed statistically significant differences for a few lineages. For perithecial density, there was a significantly lower density with all three testers when crossed with lineage 6, but the other lineages were not statistically different from lineage 7. For perithecial development, there was large variation for every lineage. Therefore, in the crosses with reduced fertility, the reduction can be attributed to a postzygotic effect since mature perithecia and asci developed. All of the tested lineages of the Fusarium graminearum species complex can produce viable progeny with F. graminearum lineage 7, which was the taxonomic type of the original species before it was split into phylogenetic species. There are a few examples of reduced fertility with two lineage 7 testers, the remaining tester crossed equally well with all lineages. Therefore members of lineages 1-9 all should be considered members of Fusarium graminearum according to the BSC. The existing female testers could be used to identify members of the F. graminearum clade by performing test crosses in the laboratory. The PSC and BSC species concepts do not agree for this group of fungi. This disagreement indicates that the F. graminearum species complex is in the early stages of speciation. The lack of intrinsic reproductive barriers supports the hypothesis that these lineages have developed in geographic isolation. As the lineages have apparently been brought together through global trade, interlineage hybrids have been reported in the field. The discrepancy between PSC and BSC will eventually be resolved by whether the lineages fuse or remain separate in nature. Even if the lineages remain separate, this study demonstrates the potential for gene flow between lineage 7 and lineages 1 through 9.

Gibberella zeae (anamorph: Fusarium graminearum) is the causal agent of fusarium head blight (FHB) and maize ear rot, two major diseases of wheat and corn in Eastern Canada. / In Quebec, Microsphaeropsis sp., an antagonist of Venturia inaequalis, the causal agent of apple scab, was isolated from the apple leaf litter. This fungus, well adapted to Quebec climate, can reduce the initial inoculum of V. inaequalis. FHB and Gibberella ear rot are similar to apple scab because the major inoculum source comes from melanized structures produced on crop residues. Consequently, we evaluated the potential of Microsphaeropsis sp. (isolate P130A) to inhibit ascospore production of G. zeae when applied to crop residues as post harvest or pre-planting applications. Under in vitro conditions, the antagonist significantly reduced ascospore production on wheat and corn residues, when applied prior to (82% and 92% respectively) or at the same time as the pathogen (36% and 58% respectively). Under field conditions, the antagonist had no effect on the pattern of perithecia maturation but significantly reduced the number of ascospores produced on two sampling dates, May 1998 and July 1999. (Abstract shortened by UMI.)

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