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La Fusariosis de la Espiga de Trigo (FET) causada por Fusarium graminearum genera pérdidas en rendimiento y contaminación de granos con micotoxinas. Existe escasa variabilidad genética a la resistencia en el germoplasma de trigo candeal. La línea recombinante cromosómica endocriada LDN(Dic-3A), presenta promisorios niveles de resistencia. Los objetivos de esta Tesis comprenden: i)- identificar genes implicados en la resistencia a FET en LDN(Dic-3A); ii)- transferir el QTL de resistencia de LDN(Dic-3A) a variedades susceptibles de trigo candeal; iii)- desarrollar un ensayo in vitro en plántula para identificar genotipos resistentes y su relación con la severidad de la enfermedad. La identificación de la expresión diferencial de genes inducida en diferentes tiempos postinoculación con F. graminearum entre LDN(Dic-3A) y el parental susceptible LDN se basó principalmente en la técnica de cDNA-AFLP. De ~500 fragmentos derivados de transcripción (TDF) identificados con las distintas combinaciones de cebadores utilizados, 85 mostraron expresión diferencial: el 36% y el 19% fueron identificados en LDN(Dic-3A) y LDN, respectivamente, mientras que el 45% se indujeron en ambos genotipos. Los patrones de TDFs obtenidos mediante cDNA-AFLP demostraron ser reproducibles mediante la técnica de RT-PCR, dando validez a nuestro sistema experimental. La comparación con secuencias depositadas en bases de datos mostró que entre los TDFs identificados se hallan proteínas asociadas a la respuesta temprana a la infección, receptores NBS-LRR y receptores quinasa involucrados en el reconocimiento específico del determinante de avirulencia del patógeno. Fueron identificados además TDFs que, aunque no pudo asignárseles una proteína o función, resultaron específicos de la respuesta a la inoculación. La identidad de TDFs con ESTs de genotecas de espiga de materiales de T. aestivum inoculadas con F. graminearum constituye un sustento adicional para esta afirmación. El mapeo in silico permitió localizar 28 TDFs en el genoma de T. aestivum, siendo el brazo cromosómico 5BL el más representado, además de obtener las regiones genómicas y regulatorias de varios genes. A partir de estas regiones, pudo determinarse la existencia de mecanismos de regulación de la transcripción en común entre algunos genes asociados a los TDFs, entre ellas las proteínas WRKY implicadas en la regulación de los genes asociados con la defensa ante patógenos. La integración de la información obtenida sugiere que la interacción trigo - F. graminearum no sería una interacción compatible como generalmente se cree sino que se trataría de una interacción “gen a gen” que finalmente lleva a la expresión de genes asociados a la defensa. Hemos asumido además el desafío de desarrollar cultivares de trigo candeal resistentes. La compleja herencia de la resistencia y los efectos ambientales, son los responsables del escaso éxito obtenido hasta el momento por los mejoradores en la incorporación al mercado de cultivares resistentes. En este trabajo, por medio de cruzamientos se incorporó el QTL de resistencia Qfhs.ndsu-3AS de LDN(Dic-3A) en los cultivares BESM y BCAN. El microsatélite Xgwm2, ligado al QTL de resistencia permitió reducir la cantidad de individuos que continuaron en el programa de mejoramiento. En la generación F3, se seleccionaron los individuos homocigotos para el alelo de resistencia, y en F4, se evaluó la severidad en espiga identificando individuos con niveles de resistencia similares o mejores que el parental resistente. El programa de mejoramiento continuará con autofecundaciones de genotipos resistentes hasta alcanzar estabilidad en la resistencia junto con la presencia de caracteres agronómicos de interés. La evaluación del comportamiento ante F. graminearum de nuevos materiales requiere de la existencia de ensayos rápidos y confiables. Hemos desarrollado un ensayo in vitro a través de la evaluación de las variables Germinación, Largo de coleoptilo, Peso de coleoptilo, Peso de raíces, utilizando siete variedades comerciales de trigo candeal, el trigo candeal LDN y las líneas resistentes LDN(Dic-3A) y LDN-DGE1 y dos genotipos de trigo pan A601 y A601S3. Las variables de plántula explicaron entre el 51 y el 74% de la severidad de la enfermedad, siendo Largo y Peso de coleoptilo las más eficaces para predecir la resistencia a FET. Los genotipos introgresados mostraron un buen comportamiento en el ensayo en plántula y menor daño en espiga comparados con los susceptibles, sugiriendo que la prueba in vitro es efectiva para la determinación de la resistencia a FET en diferentes fondos genéticos. Entonces, se propone un ensayo in vitro basado en las variables de coleoptilo para evaluar de manera eficaz, rápida y económica el nivel de resistencia a FET, definiendo el Índice de Resistencia en Plántula, altamente correlacionado con severidad, para cada genotipo. Los principales hallazgos de esta Tesis pueden compendiarse indicando que se ha establecido que la interacción trigo - F. graminearum sería una interacción “gen a gen” que lleva a la expresión de genes asociados a la defensa, la obtención de genotipos de trigo candeal resistente a fusariosis de la espiga y el dearrollo de un ensayo in vitro predictor del comportamiento de los genotipos ante la infección. / Fusarium head blight (FHB) caused by Fusarium graminearum produce yield losses and contamination of grain with mycotoxins. Scarce genetic variability for resistance exists in durum wheat germplasm. The LDN(Dic-3A) recombinant inbred chromosome line showed to be resistant to FBH. The goals of this Thesis include: i)- identification of genes involved in FHB resistance in LDN(Dic-3A); ii)- transference from LDN(Dic-3A) to susceptible durum varieties of the resistance QTL; iii)- development of an in vitro seedling assay to identify wheat resistant genotypes and their relationship with disease severity. Analysis of differential gene expression induced at different time points post- inoculation with F. graminearum between LDN(Dic-3A) and the susceptible parental LDN was performed by cDNA-AFLP technique. A total 85 out of the ~500 transcript-derived fragments (TDFs) identified with the diverse primer combination used showed to be differentially expressed: 36% and 19% were identified in LDN(Dic-3A) and LDN, respectively, whereas 45% were induced in both genotypes. The TDF patterns obtained though cDNA-AFLP showed to be reproducible by RT-PCR, supporting the reliability of our experimental system to identify differentially expressed transcripts. Comparison with protein databases revealed that among the cloned TDFs, several showed identity to proteins associated with early response to infection, to NBS-LRR and kinases receptors involved in specific recognition of avirulence pathogen determinant. However, there was a group of TDFs that, in spite of being specific of the inoculation response, could not be assigned to characterized proteins. The identity of these TDFs with ESTs from libraries from T. aestivum inoculated with Fusarium graminearum additionally supports this affirmation. The availability of T. aestivum genome sequences allowed the in silico mapping of 28 TDFs and the identification of several genes and regulatory regions, being the 5BL chromosome arm where most TDFs were located. The analysis of the regulatory regions revealed the existence of transcription regulation mechanisms shared by some TDFs associated genes, such as WRKY proteins, implied in the regulation of genes associated to pathogen defence. The present results suggest that wheat – F. graminearum interaction is governed by gene-for-gene relationships. The development of resistant cultivars has been a difficult task due to the complex inheritance of resistance and the influence of environmental factors. The resistance QTL Qfhs.ndsu-3AS from LDN(Dic-3A) was incorporated in the cultivars Buck Emeralda and Buck Candisur through crosses. F3 homozygous individuals for the resistance allele were subjected to marker assisted selection using the Xgwm2 microsatellite, linked to the mentioned QTL, allowing a reduction in the number of individuals included in the following steps of the breeding program. In F4, there were selected the individuals that showed equal or better resistance performances compared to the resistant parent, evaluated through the spike severity at 21 days post-inoculation. The breeding program will continue by selfing resistant genotypes to obtain plant materials that possess both stable resistance and suitable agronomic traits. Rapid and trustable assays are required for the evaluation of germoplasm response to F. graminearum infection. In this Thesis, it was developed an in vitro assay through the evaluation of the variables Germination, Coleoptile length, Coleoptile weight and Root weight using seven varieties of commercial durum, durum wheat cv. LDN and the derived resistant lines LDN(Dic- 3A) and LDN-DGE1 and two common wheat genotypes, A601 and A601S3. The seedling variables explained between 51 and 74% of the disease severity, being Coleoptile length and weight the ones that more effectively predicted the resistance to FHB. The introgressed genotypes showed better performance in the seedling assay and relatively lower damage in the spikes in relation to susceptible ones, suggesting that this in vitro test can detect FHB resistance in different genetic backgrouds. Thus, we propose an in vitro assay based on coleoptile variables to perform quick, qualified and cost-effective evaluation of the FHB resistance level, defining the Seedling Resistance Index, highly related to severity, for each genotype. Thus, the present Thesis allowed us to postulate that the interaction wheat – F. graminearum could be classified as “gen-for-gen” leading to the expression of defense-related genes. Concurrently, there were obtained genotypes resistant to F. graminearum and it was developed an in vitro assay that predicts the genotypes reponse to infection.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Orientador: Wagner Bettiol / Banca: Marcelo Augusto Boechat Morandi / Banca: Eugenio Alfredo Sanfuentes Von Stowasser / Banca: Miguel Angel Dita Rodriguez / Banca: Carlos Gilberto Raetano / Resumo: Os resíduos orgânicos e agentes de biocontrole podem constituir em alternativas no controle dos fitopatógenos habitantes do solo. O trabalho teve por objetivo estudar o controle de Fusarium spp. com resíduos orgânicos e agentes de biocontrole. Inicialmente foi avaliado o efeito de hidrolisado e emulsão de peixe, nas concentrações de 0, 10, 20, 30, 40 e 50% do volume de água para atingir a capacidade de campo do solo; e de alga, casca de camarão, concha de marisco e caroço de abacate moídos, nas concentrações de 0, 1, 2, 3, 4 e 5% v/v, na germinação de microconídios de Fusarium oxysporum f. sp. lactucae, em casa de vegetação. Enquanto a emulsão e o hidrolisado de peixe reduziram a germinação de microconídios do patógeno, os demais resíduos não apresentaram efeito. Também foi avaliado o efeito de resíduos de alga, concha de marisco, casca de caranguejo e repolho triturado fresco, nas concentrações de 0, 1, 2 e 4% v/v, sobre a germinação de microconídios de Fusarium circinatum em condições controladas, e associado ou não, a Trichoderma harzianum, no controle da fusariose (F. circinatum) em plantas de Pinus radiata mantidas em casa de vegetação. Nenhum resíduo reduziu a germinação de microconídios de F. circinatum ou a doença em casa de vegetação. No terceiro estudo foi avaliado o efeito de hidrolisado de peixe nas concentrações de 0, 5, 10, 15 e 20% do volume de água necessário para atingir a capacidade de campo, a partir do solo seco, associados ou não a T. harzianum (Iblf 006) ... / Abstract: The organic residues and biocontrol agent might be alternative in the control of soilborne plant pathogens. This work aimed to study the control of Fusarium species with organic residues and biocontrol agents. First, the effect of fish hydrolyzed and fish emulsion was evaluated, at concentrations of 0, 10, 20, 30, 40 and 50% of volume of water required to reach the water retention capacity of the soil; and the seaweed, shrimp shells, clamshell and grounded avocado seeds at concentration of 0, 1, 2, 3, 4 and 5% v/v in the microconidia germination of Fusarium oxysporum f. sp. lactucae in greenhouse. Fish emulsion and fish hydrolyzed reduced the microconidia germination and none of the other residues presented effect. Also, it was evaluated the effect of seaweed, clamshell, crab shell and fresh triturated cabbage, at concentrations of 0, 1, 2 and 4% v/v, in the germination of Fusarium circinatum microconidia under controlled conditions and associated or not with Trichoderma harzianum in Pinus radiata to control the disease caused by F. circinatum in greenhouse. Neither residue reduced the F. circinatum microconidia germination or the disease in greenhouse. In the third study the effect of fish hydrolyzed was evaluated at concentration of 0, 5, 10, 15 and 20% of volume of water to required to reach the water retention capacity of the soil, from dry soil, associated or not with T. harzianum (Iblf 006) and Bacillus subtilis + Bacillus licheniformis in the control of F. oxysporum ... / Doutor

Thesis (Ph.D. (Chemistry)) -- University of Limpopo, 2021 / Fusarium species are among pathogenic organisms responsible for massive yield and quality losses in crop production. They cause crop diseases in the field and during storage, and some species are capable of producing mycotoxins which contaminate products and threaten consumer s’ health. Conventional synthetic fungicides are available for the control of Fusarium pathogens, however, their applications have been restricted or discouraged due to their harmful effect on the environment, livestocks and human health. There are also reports about fungal-resistance to available fungicides. Moreover, the synthetic chemicals are not affordable to smallholder farmers and to some extent, they are not recommended for applications in organic farming. As an alternative to these fungicides, selected medicinal plant species were investigated as sources of natural chemicals or compounds with potential to be developed into plant-based fungicides to control Fusarium pathogens. This study aimed to identify antifungal extracts among the selected medicinal plant species which could be used to develop plant-based fungicides to control Fusarium diseases. It also focused on isolation and characterization of antifungal compounds from selected medicinal plant species. Thirteen medicinal plant species (Combretum erythrophyllum (Burch.) Sond , Melia azedarach L, Solanum mauritianum Scop, Nicotiana glauca Graham, Schotia brachypetala Sond, Lantana camara L, Combretum molle R. Br. ex G. Don, Quercus acutissima Carruth, Olea europaea L, Vangueria infausta Burch, Withania somnifera (L.) Dunal, Harpephyllum caffrum Bernh and Senna didymobotrya (Fresen.) H.S. Irwin & Barneby) were selected from literature based on their reported strong antimicrobial activity against human and/or animal pathogens. The leaves of these plant species were collected, shade-dried and extracted with water, petroleum ether, ethyl acetate and acetone. Extractant yield was recorded and each extract was evaluated for antifungal activity using a micro-dilution assay against nine Fusarium pathogens (Fusarium verticillioides, Fusarium proliferatum, Fusarium subglutinans, Fusarium graminearum, Fusarium solani, xxvii Fusarium oxysporum, Fusarium semitectum, Fusarium chlamydosporum and Fusarium equiseti). Similar solvent extracts from different plant species that demonstrated MIC value of less than 0.1 mg/ml against the same pathogen were combined and evaluated for antifungal activity. The interation effect of combined extracts was determined by calculating their fractional inhibitory concentration index (FICI) in order to determine their possible synergistic, additive, indifference or antagonistic antifungal activity against tested pathogens. Plant extracts demonstrating synergistic and or additive interaction were further evaluated in combination and individually for in vivo antifungal activity against maize seed Fusarium pathogens. At least, one of the extracts obtained from these medicinal plant species showed strong antifungal activity with minimum inhibitory concentration (MIC) of less than 0.1 mg/ml against at least one of the tested pathogens. Of the four solvent extracts evaluated, acetone and ethyl acetate extracts showed stronger antifungal activity compared to petroleum ether and water extracts. Of the nine pathogens tested, F. proliferatum was the most susceptible and was strongly inhibited (MIC < 0.1 mg/ml) by 41 plant extracts whilst F. equisite was found to be resistant with MIC < 0.1 mg/ml by only three plant extracts. In total, each pathogen was tested against 52 plant extracts. There were 17, 16 and 15 extracts from C. erythrophyllum, S. mauritianum and Q. acutissima, respectively, with MIC values less than 0.1 mg/ml. These species were the most active when tested individually. Schotia brachypetala was found to be the least active medicinal plant with only seven extracts demonstrating very strong activity (MIC < 0.1 mg/ml) against the tested pathogens. Minimum inhibitory dilution (MID) or total activity was also calculated and it was found that water and acetone extracts had the highest MID, followed by ethyl acetate extracts while petroleum ether extracts recorded the lowest. Of all plant extracts tested against the nine pathogens, 59 plant extracts demonstrated MID values of more than 1000 ml/g. Out of the 348 extract combinations evaluated, 116 and 87 extract combinations demonstrated synergistic and additive antifungal activity, respectively. The strongest activity xxviii recorded for the combined extracts resulted from synergistic interaction with MIC value of 0.001 mg/ml against F. proliferatum and F. verticilloides. Combined acetone extract of C. erythrophyllum and Q. acutissima was very active (95.75% inhibition) against F. verticilloides inoculated on maize seeds while individual preparation from M. azedarach acetone extract demonstrated 97.10% inhibition against F. proliferatum. The extracts showing good antifungal activity (≥ 50% inhibition) were further tested for phytotoxicity on maize seed germination and the lowest recorded seed germination was 86.25%, resulting from Q. acutissima ethyl acetate extract. Combined acetone extract of C. erythrophyllum and Q. acutissima did not significantly affect maize seedling growth when compared to negative control (water treatment). All plant extracts that showed strong activity (MIC < 0.1 mg/ml) when tested using micro-dilution assay were spotted on thin layer chromatography (TLC) bioautographic assay to establish and determine the number of active compounds or bands. The white spots observed on the chromatograms indicated the presence of antifungal compounds. Combretum erythrophyllum, W. somnifera and L. camara exhibited the presence of antifungal compounds against 7, 5 and 4 pathogens, respectively. Hence, these plant species were selected for isolation of antifungal compounds where open column chromatography and preparative TLC were used for compound purification. At least, three isolated fractions from the three plant species were found to be active (MIC values ranging from 0.0098 to 0.625 mg/ml) against more than five pathogens. The fractions were also found to contain different levels of phytochemicals such as glycosides, flavonoids, steroids, and terpernoids. The structures of isolated compounds or fractions were determined using nuclear magnetic resonance (NMR) and mass spectroscopic (MS) techniques. A mixture of apeginin (4′,5,7-trihydroxyflavone) and salvigenin (5-hydroxy-6,7,4'-trimethoxyflavone) isolated from the leaves of C. erythrophyllum showed strong antifungal activity (MIC values ranging from 0.01 mg/ml to 0.63 mg.ml) against 5 tested Fusarium pathogens. Also isolated from C. erythrophyllum was a derivative of maslinic acid and it has xxix shown antifungal activity with MIC values ranging from 0.08 mg/ml to 0.63 mg/ml against 6 tested pathogens. On the other hand, lantadene A (22- angeloyloxy-9-hydroxy-3-oxo-olean-12-en-28-oic acid), boswellic acid (11-keto-β-boswellic acid) and boswellic acid glycoside isolated from the leaves of Lantana camara showed good activity (MIC values ≤ 0.63 mg/ml) against one or more Fusarium pathogens. Withaferin A (4β,27-dihydroxy-1-oxo-5β,6β-epoxywitha-2-24-dienolide) glycoside isolated from the leaves of Withania somnifera showed antifungal activity with MIC value of 0.16 mg/ml against F. verticilloides. This study demonstrated potential applications of medicinal plant extracts as cheap, accessible and sustainable source of eco-friendly pesticides for fighting crop diseases in organic and smallholder farming. The extracts can be used as treatment agents to control maize seed spoilage during post-harvest storage. Additionally, characterised antifungals may serve as scaffold compounds during commercial synthesis of plant-based fungicides. / Agricultural Research Council (ARC) and National Research Foundation (NRF)

Stink bugs, including native brown stink bug (Euschistus servus) and invasive brown marmorated stink bug (Halyomorpha halys), cause damage to a variety of crops including field corn (Zea mays). Frequency and size of stink bug infestations have increased in corn fields in the Mid-Atlantic U.S., and there are growing concerns that these infestations may contribute to reductions in grain quality including increased mycotoxin concentrations. Prior research on native and invasive stink bugs has focused on understanding their biology, the damage they cause, and elucidating effective and economic management strategies. However, few studies examined the potential for stink bugs to facilitate fungal infection and mycotoxin contamination of corn grain. Thus, the objectives of this research were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxigenic Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. A correlation between H. halys feeding injury and fumonisin concentrations was identified, and the ability of H. halys to increase F. verticillioides infection and fumonisin concentrations in corn was demonstrated in field experiments. Fusarium species including fumonisin-producing F. verticillioides and F. proliferatum were isolated from field-collected stink bugs, and in laboratory experiments, E. servus was able to transmit F. verticillioides to non-infected corn ears after feeding on F. verticillioides-infected corn. In field studies, both fungicide and insecticide reduced stink bug-associated mycotoxin concentrations in corn, but levels of control were inconsistent. Thus, additional tactics that target both the stink bug and Fusarium should be implemented to mitigate risks of mycotoxin contamination in corn. / Doctor of Philosophy / Native and invasive stink bugs can severely damage crops including field corn. Frequency and size of stink bug infestations in Mid-Atlantic U.S. corn fields have increased, and there is growing concern that this may contribute to reductions in grain quality. Insect feeding injury is a risk factor for fungal infection and mycotoxin contamination in corn. Mycotoxins are toxic chemicals produced by certain fungi that have detrimental health effects on animals including livestock and humans. The relationship between stink bug feeding injuries and mycotoxin contamination in corn grain is not well understood, and management strategies to minimize the risk of mycotoxin contamination in corn need to be identified. The main goal of this research was to characterize interactions between stink bugs and mycotoxin-producing fungi and identify tactics for controlling both the insect pest and pathogen. Specific objectives were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxin-producing Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. Results from this work indicated that stink bugs have the ability to cause feeding injuries which facilitate invasion of mycotoxin-producing Fusarium species, leading to increases in mycotoxin concentrations in corn grain. Studies also demonstrated that stink bugs can vector Fusarium species during feeding and increase Fusarium infection of corn resulting in subsequent mycotoxin contamination. Field studies indicated that pesticide applications targeting both the stink bugs and mycotoxigenic fungi may be needed to minimize risk of mycotoxin contamination in corn. However, under low pest pressure, application of pesticides is unlikely to be profitable.

Made available in DSpace on 2016-12-08T16:44:49Z (GMT). No. of bitstreams: 1 PGPV14MA158.pdf: 622907 bytes, checksum: 4bef911008ae5cffa26706180f710db4 (MD5) Previous issue date: 2014-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The addition and incorporation of organic matter to the soil, besides favoring crops by improving soil physical, can increase nutrients and add specific biochemicals capable of renewing the native microflora and microfauna. These compounds may, depending on the organic material to act as a suppressant effect and biocontrol. The aim of this study was to evaluate the effect of swine manure compost (DSC) in an orchard of apple, pear and grape vines on the population dynamics of Verticillium dahliae, Fusarium solani, Fusarium oxysporum, Fusarium verticillioides and Trichoderma sp. Soil samples for quantification of fungal colonies and nutrient analysis were collected at a depth of 0-10 cm soil of the orchard with apple, pear and grape vines. The population of pathogenic soil fungi and Trichoderma sp. were obtained by dilution and plating of 10 g of soil samples from soil orchard who received two doses of DSC (50 to 100%) compost and two (50 and 100%), using two culture media (BDA potato-dextrose-agar) and Sabouraud-ágar-chloramphenicol. The application of different doses of DSC and chemical fertilizer began in December 2012, repeated at intervals of 60 days until the 2014 harvest analysis of macronutrients (nitrogen, phosphorus, potassium, calcium and magnesium) and micronutrients (iron, copper, zinc and Manganese) DSC and chemical fertilizer were run using Mehlich-1, spectrophotometry, acid-base titration and Kjeldahl method, all described by Tedesco et al. (1995). Results in the concentration of nutrients was related to the population of Verticillium dahliae, Fusarium solani, Fusarium oxysporum, Fusarium verticillioides and Trichoderma sp. The experimental design was completely randomized, factorial 2 x 5, repeated in time (months). The data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC, v.9.2) and mean comparisons using Tukey least significant difference p &#8804; 0.05. In the apple orchard, Fusarium oxysporum and Fusarium solani showed higher populations in Q100 treatments (0-110 x 103 CFU / g of soil) and Q50 (0-70 x 103 CFU/g of soil) respectively. There were differences in the population periods. Phosphorus, Potassium and Sodium showed significant differences among the treatments tested. In the orchard of pear trees the largest population of Fusarium solani was the S100 treatment (0-50 x 103 CFU/ g of soil). Treatments Q50 and Q100 had higher populations of Verticillium dahliae, Fusarium oxysporum and Fusarium verticillioides in different periods. Concentrations of Nitrogen and Potassium differ between treatments tested. In vineyards the largest populations of Fusarium solani and Fusarium oxysporum were found in December-2012 periods (0-70 x 103 CFU / g of soil) and August 2013 (0-60 x 103 CFU / g of soil) respectively. Concentrations of potassium, phosphorus and sodium were higher in treatment S50 and S100. The orchard of apple, pear and grape vines have different response to chemical and organic fertilization. The intensity of response to fertilization has little influence population dynamics of plant pathogens in soil and Trichoderma / A adição e incorporação de matéria orgânica ao solo, além de favorecer as culturas pela melhoria física do solo, podem potencializar nutrientes e adicionar compostos bioquímicos específicos capazes de renovar a microfauna e microflora nativas. Estes compostos podem, dependendo do material orgânico, agir como efeito supressor e como biocontrole. O objetivo deste trabalho foi avaliar o efeito da aplicação de dejeto suíno compostado (DSC) em pomar de macieiras, pereiras e videiras, sobre a dinâmica populacional de Verticillium dahliae, Fusarium solani, Fusarium oxysporum, Fusarium verticillioides e Trichoderma sp. Amostras de solo para quantificação de colônias fúngicas e análise de nutrientes foram retiradas na profundidade 0-10 cm de solo do pomar de macieiras, pereiras e videiras. A população de fungos fitopatogênicos de solo e Trichoderma sp. foram obtidas pela diluição e plaqueamento de 10 g de amostras de solo provenientes do solo do pomar que receberam duas doses de DSC (50 e 100%) e duas de adubo químico (50 e 100%), utilizando dois meios de cultura, BDA (batata-dextrose-agar) e Sabouraud ágar-cloranfenicol. A aplicação das diferentes doses de DSC e adubo químico tiveram início em dezembro-2012, repetidas em intervalos de 60 dias até a safra 2014. A análise dos macronutrientes (nitrogênio, fósforo, potássio, cálcio e magnésio) e micronutrientes (ferro,cobre,zinco e Manganês) do DSC e da adubação química foram realizados pelos métodos de Mehlich -1, espectrofotometria, titulação ácido-base e método Kjeldahl, todas descritas por Tedesco et al. (1995). Resultados da concentração de nutrientes foi relacionado à população de Verticillium dahliae, Fusarium solani, Fusarium oxysporum, Fusarium verticillioides e Trichoderma sp. O delineamento experimental foi inteiramente casualisado, em arranjo fatorial 2 x 5, repetidos no tempo (meses). Os dados foram analisados pelo procedimento MIXED do SAS (SAS Inst. Inc., Cary, NC, v.9.2) e as comparações de médias usando a diferença mínima significativa de Tukey p &#8804; 0,05. No pomar de macieiras, Fusarium oxysporum e Fusarium solani apresentaram maiores populações nos tratamentos Q100 (0-110 x 103 UFC/g de solo) e Q50 (0-70 x 103 UFC/g de solo) respectivamente. Houve diferenças da população nos períodos avaliados. Fósforo, Potássio e Sódio apresentaram diferenças significativas entre os tratamentos testados. No pomar de pereiras a maior população de Fusarium solani foi ao tratamento S100 (0-50 x 103 UFC/g de solo). Os tratamentos Q50 e Q100 apresentaram maiores populações de Verticillium dahliae, Fusarium oxysporum e Fusarium verticillioides em diferentes períodos de avaliação. Concentrações de Potássio e Nitrogênio apresentaram diferenças nos tratamentos testados. Na cultura da videira as maiores populações de Fusarium solani e Fusarium oxysporum foram encontradas nos períodos dezembro-2012 (0-70 x 103 UFC/g de solo) e agosto-2013 (0-60 x 103 UFC/g de solo) respectivamente. Concentrações de Potássio, Fósforo e Sódio foram superiores nos tratamento S50 e S100. O pomar de macieiras, pereiras e videiras apresentam diferentes resposta a adubação química e orgânica. A intensidade de resposta da adubação pouco influencia a flutuação da população de fitopatógenos de solo e Trichoderma

Abscisic acid (ABA) has been well defined as an important stress hormone in plants. The signaling pathway of ABA involves a family of pyrabactin resistant-like-1 PYR/PYL/RCAR receptors (PYL receptors) that bind ABA and form a complex with a protein phosphatase 2C (PP2C) family member resulting in downstream signaling events. The ABA receptor family has been well characterized in the model dicot Arabidopsis thaliana and more recently this characterization has branched out into cereals Oryza sativa (rice) and Hordeum vulgare (barley), as well as the monocot model plant Brachypodium distachyon and Fragaria vesca (strawberry). The analysis of these characterized ABA receptors and the use of online databases has allowed the identification of multiple putative ABA receptors in Triticum aestivum (wheat). ABA has been historically called a positive effector. Overexpression of proteins in the ABA signalling pathway or exogenous application of ABA is known to cause an increase in drought, cold, and salt tolerance. More recently ABA has been linked to increased fungal susceptibility in several plants. The role ABA plays in the biotic stress response is still largely unexplored. The focus of this project was to identify and characterize a putative wheat ABA receptor through bioinformatics and an in vitro enzyme activity assay, and use virus induced gene silencing (VIGS) to test what role this receptor plays in fugal susceptibility. A total of 13 putative ABA receptors were located, nine of which are unique between the wheat subgenomes. One receptor TaPYL5.1 was recombinantly expressed, purified, and confirmed as an ABA receptor through a phosphatase based enzyme activity assay. A receptor with high sequence identity to TaPYL5.1, TaPYL5.2A, was targeted for plant trials because the TaPYL5.1 plasmid sequence was codon optimized. A VIGS approach was used to knock down TaPYL5.2A in planta. The TaPYL5.2A knockdown plants were found to have an increased resistance to Fusarium Head Blight progression in the early stages of the disease. In conclusion, wheat ABA receptors were successfully identified and an important correlation between decreased receptor levels and increased early Fusarium Head Blight resistance was found. This correlation however was not easily reproducible due to the severity of coupling VIGS with Fusarium Head Blight, and should be followed up with additional studies looking at the broader family of wheat ABA receptors.