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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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TRATAMENTO DE SEMENTES NO ARMAZENAMENTO E PROMOÇÃO DE CRESCIMENTO DE MUDAS DE Parapiptadenia rigida (BENTH.) BRENAN / SEEDS TREATMENT IN STORAGE AND SEEDLING GROWTH PROMOTION OF Parapiptadenia rigida (BENTH.) BRENAN

Missio, Evandro Luiz 15 January 2015 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Parapiptadenia rigida is a forest species that appears in many regions of Brazil, frequently produced in forest nurseries, being the seeds the multiplication form. Usually presents a good germination, however, aspects involving the physiological and health qualities of the lots, still results in lost in the nurseries. In this sense, microorganisms with antagonist characteristics and/or promoters of growth related to many products and coated with polymers, arise as options to improve the growth of the seedlings in the nurseries. This work aimed to evaluate the treatment of Parapiptadenia rigida seeds, for the physiological quality maintenance in the storage and promotion of the seedlings growth in the nursery. The work was split in studies of storage and nursery. In the storage study, the treatments were arranged in completely randomized lineation in trifactorial scheme (4x4x2), represented by storage timing (0, 4, 8, 12 months), products (biological, chemical and witness) and polymers (polymer and witness), with four repetitions. In each time were made evaluations of the germination percentage, vigor tests, seedling length, fresh and dry mass, besides of regular strong and weak seedlings. The nursery studies was subdivided in two experiments: the first using combinations involving Trichoderma sp., polymers and vegetal growth stimulators, and the second involved the use of Bacilus subtilis, polymers and vegetal stimulators. For both of them, the treatments was arranged in completely randomized lineation in trifactorial scheme (3x2x4), represented by fungicide product (biological, chemical e witness), polymers (polymers and witness), micronutrients and biostimulating (micronutrients, biostimulating, micronutrients + biostimulating, witness) with four repetitions. In about 60 to 120 days after the emergency, the height of the plant, the stem diameter, and the number of leaves was evaluated. At the experiment ending was made weighing of the dry mass of the aerial part, root and total, besides the relation dry mass of the root/aerial part. The work results showed that: the treatment of the Parapiptadenia rigida seeds, with Trichoderma sp. is efficient to the physiological quality maintenance during the storage; Parapiptadenia rigida Seedlings have higher growth in the nursery when derived from seeds treated with Trichoderma sp. and polymer; Polymerization of Parapiptadenia rigida seeds is a technique that can be used in the nursery; Treatment of Parapiptadenia rigida seeds with Bacillus subtilis is not effective in maintaining the physiological quality during storage, as well as to promote the growth of seedlings in nursery; The application of micronutrients and biestimulant in Parapiptadenia rigida seeds, does not promote the growth of seedlings in nursery. / Parapiptadenia rigida é uma espécie florestal de ocorrência em várias regiões do Brasil, produzida com freqüência em viveiros florestais, sendo a semente sua forma de multiplicação. Geralmente apresenta boa germinação, porém, aspectos envolvendo a qualidade fisiológica e sanitária dos lotes ainda ocasiona perdas em viveiro. Nesse contexto, microrganismos com características antagônicas e/ou promotoras de crescimento associados a diferentes produtos e revestidos com polímeros surgem como alternativa para melhorar o crescimento de mudas em viveiro. Este trabalho teve como objetivo avaliar o tratamento de sementes de Parapiptadenia rigida visando a manutenção da qualidade fisiológica no armazenamento e promoção de crescimento de mudas no viveiro. O trabalho foi dividido em estudos de armazenamento e viveiro. No estudo de armazenamento, os tratamentos foram arranjados em delineamento inteiramente casualizado em esquema trifatorial (4x4x2), representados por tempo de armazenamento (0, 4, 8, 12 meses), produtos (biológico, químico e testemunha) e polímero (polímero e testemunha), com quatro repetições. Em cada tempo foram efetuadas avaliações do percentual de germinação, teste de vigor, comprimento de plântula, massa fresca e seca, além de plântulas normais fortes e fracas. O estudo em viveiro foi subdividido em dois experimentos: o primeiro utilizou combinações envolvendo Trichoderma sp., polímero e estimulantes de crescimento vegetal, e o segundo envolveu o uso de Bacillus subtilis, polímero e estimulantes vegetais. Para ambos, os tratamentos foram arranjados em delineamento inteiramente casualizado em esquema trifatorial (3x2x4), representados por produto biopromotor/fungicida (biológico, químico e testemunha), polímero (polímero e testemunha), micronutrientes e bioestimulante (micronutrientes, bioestimulante, micronutrientes + bioestimulante, testemunha) com quatro repetições. Aos 60 e 120 dias após a emergência avaliou-se a altura de planta, o diâmetro do coleto e o número de folhas. Ao término do experimento foram efetuadas pesagens de massa seca da parte aérea, raiz e total, além da relação massa seca da raiz/parte aérea. Os resultados do trabalho mostraram que: O tratamento das sementes de Parapiptadenia rigida com Trichoderma sp. é eficiente para a manutenção da qualidade fisiológica durante o armazenamento; Mudas de Parapiptadenia rigida apresentam maior crescimento em viveiro quando provenientes de sementes tratadas com Trichoderma sp. e polímero; A polimerização de sementes de Parapiptadenia rigida é uma técnica que pode ser utilizada em viveiro; O tratamento de sementes de Parapiptadenia rigida com Bacillus subtilis não é eficaz na manutenção da qualidade fisiológica durante o armazenamento, bem como para promover o crescimento de mudas em viveiro; A aplicação de micronutrientes e biestimulante vegetal em sementes de Parapiptadenia rigida, não promove o crescimento das mudas em viveiro.
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Atividade antimicrobiana de Trichoderma viride e Trichoderma stromaticum / Antimicrobial activity of Trichoderma viride and Trichoderma stromaticum

Hurmann, Eliéte Moura de Souza 08 January 2016 (has links)
Made available in DSpace on 2017-07-10T18:01:58Z (GMT). No. of bitstreams: 1 Eliete Moura de Souza Hurmann.pdf: 819870 bytes, checksum: 4302d144fe2194c2bcd5c074b31e3635 (MD5) Previous issue date: 2016-01-08 / Fundação Araucária / Trichoderma spp. is a promising antagonist, the development and use of products based on this organism gives us the opportunity not only to reduce health risks, but also costs and environmental damage. This work aimed to analyze the efficiency of Trichoderma viride extracts and Trichoderma stromaticum against some microorganisms of interest in clinical medicine, agriculture and fish farming. Among them Colletotrichum musae, banana anthracnose causes, Saprolegnia, which affects fish eggs and some bacteria that cause harm to human health. The dichlorometane extracts were tested at various concentrations, and as positive control a commercial antimicrobial. Inhibition of the pathogen was verified directly by paired cultivation technique. The antimicrobial activity of the extracts was evaluated by disk diffusion and the determination of minimum inhibitory concentration (MIC) by microdilution test broth. In situ tests were done in the fruit inoculating the pathogenic fungus and treated with the extracts and the sensory analysis where it was determined the acceptance of the product. In cultivation paired the Trichoderma spp. inhibited the growth of pathogens being 0.05% significance level. In the disk diffusion test results were positive, and for E. coli and Aeromonas hydrophila gave the best results. MIC against microorganisms of the extracts ranged from 50% to 3,125%. Given the results presented, it is concluded that the extracts were effective in in vitro inhibition of the microorganisms as well as their application in the fruits did not alter the organoleptic characteristics. / O Trichoderma spp. é um antagonista promissor, o desenvolvimento e uso de produtos à base deste microrganismo nos oferece a oportunidade, não apenas de reduzir os riscos da saúde, mas também custos e danos ambientais. Assim, este trabalho teve por objetivo analisar a eficiência dos extratos de Trichoderma viride e Trichoderma stromaticum contra alguns microrganismos de interesse na clínica médica, agricultura e piscicultura. Dentre eles o Colletotrichum musae, causador da antracnose da banana, Saprolegnia, que acomete ovas de peixes e algumas bactérias que causam danos à saúde humana. Os extratos diclorometânicos foram testados em várias concentrações, tendo como controle positivo um antimicrobiano comercial. A inibição do patógeno foi verificada, de forma direta pela técnica de cultivo pareado. A atividade antimicrobiana dos extratos foi avaliada por disco-difusão e pela determinação da concentração inibitória mínima (MIC) por teste de microdiluição em caldo. Foram feitos testes in situ no fruto inoculando o fungo patogênico e tratados com os extratos e a análise sensorial onde foi determinada a aceitação do produto. No cultivo pareado os Trichoderma spp. inibiram o crescimento dos patógenos sendo 0,05% de significância. No teste de disco-difusão os resultados foram positivos, sendo que para Aeromonas hydrophila e E. coli obteve-se os melhores resultados. O MIC (concentração inibitória mínima)dos extratos contra os microrganismos variou de 50% a 3,125 %. Diante dos resultados apresentados, evidenciou-se que, os extratos foram eficientes na inibição in vitrodos microrganismos testados, bem como sua aplicação nos frutos não alterou as características organolépticas dos mesmos.
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Populações de fungos fitopatogênicos e concentrações de nutrientes no solo em pomares de fruteiras temperadas adubados com Dejeto suíno compostado / Pathogenic fungi populations and nutrient concentrations in soil in orchards of temperate fruit trees fertilized with swine manure composted

Costa Junior, Avanor Cidral da 31 July 2014 (has links)
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 ≤ 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 ≤ 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
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Uso de reguladores de crescimento e controle biológico de fungos no feijoeiro cultivado em sucessão à dife-rentes culturas de cobertura / Use of growth regulators and biological control of fungi in the common bean cultivated in succession to different cover crops

BERNARDES, Tatiely Gomes 25 February 2008 (has links)
Made available in DSpace on 2014-07-29T16:24:14Z (GMT). No. of bitstreams: 1 DISSERTACAO TATIELY GOMES BERNARDES 2008.pdf: 436182 bytes, checksum: ed86a8aa78f5feb99af31d615243e746 (MD5) Previous issue date: 2008-02-25 / In order to increase the productivity of the common bean crop several technologies are offered, but there is lack of studies to verify their efficiency. The objective of this work was to evaluate the effect of growth regulator and the biological control of fungi of the soil through Trichoderma sp., seeking larger productivity of the commom bean plant irrigated in succession to different cover crops. The experiments were conducted in Fazenda Capivara - Embrapa Arroz e Feijão, in the municipality of Santo Antônio de Goiás, GO, in a Dystrophic Red Latosol. The experimental design was a randomized complete block on split-plot, with four replications. The plots of the two experiments consisted of cultures used as soil cover, as the leguminous: pigeon pea (Cajanus cajan L. Millisp), Stylosanthes guianensis cv. Campo Grande, and Crotalária spectabilis Roth., and the grasses: millet (Pennisetum glaucum L. R. Br.), Panicum maximum cv. Mombaça, Brachiaria brizantha cv. Marandu, B. brizantha associated with corn (Zea mays L.) and sorghum (Sorghum bicolor L. Moench). To the 84 days after the cut of the cover crops common bean cultivar BRS Valente was sown under central pivot. Experiment 1: the subplot treatments were: a) control; b) 500 ml of growth regulator (RC - commercial product Stimulate) in 100 kg of seeds; c) 1250 ml of biological fungicide (FB - commercial product Trichodermil) in 100 kg of seeds; and, d) 500 ml of RC plus 1250 ml FB in 100 kg of seeds. They were evaluated severity of root rot, incidence of fusarium wilt, grain yield, mass of 100 grains, number of beans for plant, number of grains for bean and initial and final stand of the commom bean. Experiment 2: the subplots consisted of the following treatments: a) control; b) 500 ml of growth regulator (RC - commercial product Stimulate) in 100 kg of seeds; c) 250 ml of RC for hectare in the V4 development stage, foliar treatment; and, d) 500 ml RC in 100 kg of seeds and 250 ml of RC for hectare via foliar, in the V4 development stage. They were evaluated the grain yield, mass of 100 grains, number of beans for plant, number of grains for bean and initial and final stand of the commom bean. The obtained data of the studied variables were submitted to the variance analyses being applied the F test, and when there were differences among the averages, these were compared by the Tukey test at 5% of probability. Experiment 1: The treatments with Trichoderma sp. and growth regulators applied via seeds did not showed significant effect in the analyzed variables. The sorghum straw favored the increase of the severity of the root rot and of the fusarium wilt in the common bean crop, causing a lower grain yield. The highest grain yield was obtained in the millet straw. Experiment 2: The treatments with growth regulator applied via seeds and foliar did not significantly influenced the common bean grain yield. The predecessor cover crops influenced the common bean grain yield, and the millet was that provided the largest common bean grain yield. / Visando aumentar a produtividade do feijoeiro várias tecnologias são oferecidas, mas faltam estudos para verificar a eficiência destas. O objetivo deste trabalho foi avaliar o efeito de regulador de crescimento e o controle biológico de fungos do solo por meio de Trichoderma sp., visando maior produtividade do feijoeiro irrigado em sucessão à diferentes culturas de cobertura. Os experimentos foram conduzidos na Fazenda Capivara Embrapa Arroz e Feijão, no município de Santo Antônio de Goiás, GO, em Latossolo Vermelho distrófico. O delineamento experimental foi em parcelas subdivididas, em blocos completos ao acaso com quatro repetições. Na parcela dos dois experimentos constaram às culturas utilizadas como coberturas do solo, as leguminosas: guandu, estilosante e crotalária, e as gramíneas: milheto, mombaça, braquiária, braquiária consorciada com milho e sorgo. Aos 84 dias após o corte das culturas de cobertura foi realizado a semeadura do feijoeiro, cultivar BRS Valente, sob pivô central. Experimento 1: nas subparcelas os tratamentos foram: a) testemunha; b) 500 ml de regulador crescimento (RC produto comercial Stimulate) em 100 kg de sementes; c) 1250 ml de fungicida biológico (FB produto comercial Trichodermil) em 100 kg de sementes; e, d) 500 ml de RC com mais 1250 ml FB em 100 kg de sementes. Foram avaliadas a severidade de podridão radicular, incidência de murcha-de-fusário, rendimento de grãos, massa de 100 grãos, número de vagens por planta, número de grãos por vagem e estande inicial e final do feijoeiro. Experimento 2: nas subparcelas constaram os seguintes tratamentos: a) testemunha; b) 500 ml de regulador de crescimento (RC - produto comercial Stimulate) em 100 kg de sementes; c) 250 ml de RC por hectare no estágio de desenvolvimento V4, tratamento foliar; e, d) 500 ml RC em 100 kg de sementes e 250 ml de RC por hectare via foliar, no estágio de desenvolvimento V4. Foram avaliados o rendimento de grãos, massa de 100 grãos, número de vagens por planta, número de grãos por vagem e estande inicial e final.do feijoeiro. Os dados obtidos das variáveis estudadas foram submetidos às análises de variância aplicando-se o teste de F, e quando houve diferença entre as médias, estas foram comparadas pelo teste de Tukey a 5% de probabilidade. Experimento 1: Os tratamentos com Trichoderma sp. e reguladores de crescimento aplicados via sementes não apresentaram efeito significativo em relação as variáveis analisadas. A palhada de sorgo favoreceu o aumento da severidade das podridões radiculares e da murcha-de-fusário no feijoeiro, causando um menor rendimento do feijoeiro. O maior rendimento do feijoeiro foi obtido na palhada de milheto. Experimento 2: Os tratamentos com reguladores de crescimento aplicado via sementes e foliar não influenciaram significativamente no rendimento do feijoeiro. As plantas de cobertura antecessoras influenciaram no rendimento do feijoeiro, sendo que o milheto foi a cobertura que proporcionou maior rendimento do feijoeiro.
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EVALUATION DU RISQUE FONGIQUE EN ZONES CONCHYLICOLES : SUBSTANCES TOXIQUES DE SOUCHES MARINES DU GENRE Trichoderma.

Mohamed-Benkada, Mustapha 23 June 2006 (has links) (PDF)
Ce travail est consacré à l'étude chimique des peptaïbols sécrétés par des souches de Trichoderma endémiques des zones conchylicoles de Loire-Atlantique. La stratégie adoptée a permis de réaliser :<br /> Un échantillonnage, à partir de la mycothèque du SMAB (Substances Marines à Activité Biologique), de souches de Trichoderma productrices de peptaïbols dans l'estuaire de la Loire. Neuf souches représentatives ont été sélectionnées. En fonction de leurs contenus en peptaïbols, elles ont été réparties en 4 ensembles, puis une « souche représentative » de chaque ensemble a été choisie pour la suite du travail.<br /> Une optimisation des protocoles nécessaires à la production in vitro des peptaïbols. La mise au point d'un mode de fermentation sur milieu gélosé a permis d'augmenter le rendement de cette biosynthèse.<br /> Une optimisation des conditions de purification des peptaïbols. Des protocoles simplifiés de pré-purification, de purification par chromatographie en phase liquide (CLHP) ont permis la préparation d'échantillons analysable par spectrométrie de masse.<br /> Une identification structurale des peptaïbols produits, grâce au séquençage par spectrométrie de masse, l'ionisation étant réalisée par électronébulisation ou electrospay (ESI) et l'analyseur étant constitué par une trappe d'ions permettant une analyse SMn. Cette analyse a pu être conduite sur des mélanges de peptaïbols de structure très proche (phénomène de microhétérogénéité). Une analyse par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC-MS-EI) a permis de préciser la nature des acides aminés (AA) de même masse (Valine ou Isovaline ; Leucine ou Isoleucine).<br /><br />Pour les quatre souches de Trichoderma étudiées, 30 peptaïbols ont été mis en évidence dont 24 sont de nouvelles molécules. Ils appartiennent à 5 familles de peptaïbols déjà décrites : les trichokonines, les trichosporines, les hypomurocines, les trichorovines et les suzukacillines. Vingt et un sont à longue séquence (18 à 20 AA) dont 16 sont nouveaux. Neuf sont à courte séquence (11 AA) dont 8 présentent des structures assez originales pour nous permettre de proposer une nouvelle famille, celle des trichobrachines.
6

CHARACTERIZING CYST MYCOBIOME AND BIOLOGICAL CONTROL OF THE POTATO AND SOYBEAN CYST NEMATODES

Blaise Jumbam (13175475) 29 July 2022 (has links)
<p>  </p> <p>Plant-parasitic nematodes are amongst the most important pathogens impacting crops. Potatoes and soybean are vital crops for rural livelihoods and essential for food security, but their cyst nematode parasites remain a significant constraint globally. <em>Globodera</em> and <em>Heterodera </em>species are amongst the most damaging and internationally recognized quarantine pests of these crops, causing up to 80% yield loss. Their second stage juveniles (J2s) penetrate the host plant root tips and establish a residence close to the vascular bundle from where they extract nutrients as they complete their life cycle. Restrictions of control chemicals have led to an urgent need for alternative control strategies for cyst nematodes. Biological control is a promising alternative control measure, and fungi possess many characteristics that could make them great biological control agents of cyst nematodes. Most nematode populations are thought to be regulated by their natural enemy community. It is unclear which fungi are best adapted as natural enemies of these parasites and how they might do this. This project aimed to (a) characterize and compare the mycobiome diversity of cyst nematode species; (b) isolate and characterize fungi associated with potato and soybean cyst nematodes (c) screen isolated fungi for their efficacy as biocontrol agents against cyst nematodes; and (d) describe any isolated fungi identified as new and having potential for cyst nematode antagonism. Cyst populations were collected from different regions and screened for fungi using culture-based methods. For our next-generation sequence data analysis, we found differences in fungal community assemblages between center of origin of the potato cyst nematode (Peru; South America) and the regions where these nematodes were introduced such as Europe and North America.  There was no significant difference in fungal community assemblages of cysts collected between the years 2019 and 2020. We characterized fungi associated with the cyst nematodes and found that the most frequently isolated genera were <em>Fusarium, Penicillium, Cylindrocarpon, Phoma, Aspergillus </em>and<em> Verticillium</em>. Filtrates from <em>Trichoderma</em> sp. 2, <em>Alternaria alternata, </em>and <em>Fusarium acaciae-mearnsii </em>were toxic on SCN eggs while <em>Purpureucillium lilacinum, Fusarium proliferatum</em> and <em>Aureobasidium</em> <em>ellingtonae </em>sp. nov. were toxic on PCN eggs and juveniles. A new species of <em>Aureobasidium</em> isolated from the potato cyst nematode (<em>Globodera ellingtonae</em>) for the first time, and having biocontrol potentials against this nematode, was also identified, and described. </p>

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