Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2008. / Härtill 4 uppsatser.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2008. / Härtill 4 uppsatser.

Numerous evidences showed that the resistance to syntenic fungal species Fusarium graminearum and Fusarium virguliforme infection in plants was partial, quantitative, and strongly influenced by environmental conditions. However, the molecular mechanisms underlying the resistance are still not fully understood. The objectives of this dissertation were to investigate the molecular mechanisms underlying the resistance in different plant species (mainly in maize, soybean, and Arabidopsis); identify and clone disease resistance genes; decipher their quantitative responses to Fusarial pathogens and mycotoxin deoxynivalenol (DON); identified genes that were transcriptionally regulated when the plants were treated with the pathogens and toxin. Methods were used to achieve these objectives including mapping, isolation, characterization, and functional analyses of genes implicated in disease resistance; analysis of microsynteny at their encoding loci; and identification of orthologs that might be associated with resistance to pathogen Fusaria across plant species etc. First, a maize gene that encoded a putative guanylyl cyclase-like protein (ZmGC1; EC 4.6.1.2) was characterized and shown to be associated with resistance to Gibberella ear rot caused by F. graminearum. The putative ZmGC1 amino acid sequence was 53% identical and 65% similar to AtGC1, one of the two Arabidopsis proteins known to possess an active and substrate specific guanylyl cyclase enzymatic function. Using a probe derived from the maize guanylyl cyclase-like gene (Zmgc1) to screen a recombinant inbred population developed from `CO387' (a partially resistant variety) X `CG62' (a partially susceptible variety), several polymorphic molecular markers were identified and four of them were significantly associated with Gibberella ear rot resistance in different environments. Polymorphisms were functional since the amount of Zmgc1 transcripts accumulating in ears increased more quickly and to a higher amount in the resistant genotype compared to the susceptible genotype after inoculation with F. graminearum. Furthermore, transcripts were responding to fungicidal activity when the maize seedlings (CO387) were treated with a fungicide, probenazole (3-allyloxy-1,2-benzothiazole-1,1-dioxide, PBZ). The transcript abundance (TA) of the maize Zmgc1 gene was increased more than 10 fold 8 hours after PBZ treatment. In contrast, the TA of Zmnbslrr1 (a NBS-LRR gene) transcript was significantly reduced in the Gibberella ear rot resistant genotype CO387 after the treatment with PBZ in the time-course study. Therefore, natural resistance and fungicide induced resistance may share common transcript abundance changes in maize plants. Second, to examine global effects of Fusarial pathogens on transcript abundance, cDNA microarrays from the model plant Arabidopsis thaliana were used. After Arabidopsis thaliana cv 'Columbia' was infested with Fusarium virguliforme, 168 transcripts were increased, nearly four times more than that of decreased. A. thaliana seedling growth was reduced by the pathogen in a proportional response to increasing spore concentrations. A set of putative resistance pathways involved in responding to the pathogen infection in A. thaliana was identified. Functional analyses of the orthologs of the responding genes between soybean and A. thaliana showed that the resistance responses had both common elements in some pathways (primary metabolism) and species specific differences in others (secondary metabolism). For example, the phenylpropanoid pathway response was different between the two species. In contrast to soybean, the phenylpropanoid pathway was not fully activated during the resistance response in Arabidopsis. Therefore, soybean and Arabidopsis did not share completely overlapping strategies in the specific pathways induced during resistance to F. virguliforme. Resistance to Fusarial toxins is a common mechanism for plant resistance. The mycotoxin deoxynivalenol (DON), produced by Gibberella zeae (the teleomorph of F. graminearum), was known to be both a virulence factor in the pathogenesis of wheat and an inhibitor of Arabidopsis seed germination. A. thaliana seedling growth was reduced by the toxin in a proportional response to increasing concentrations. A parallel comparison with a set of resistance pathways involved in response to the DON toxicity in A. thaliana was performed. The alterations of transcript abundances in the Arabidopsis plants treated with the toxin suggest that DON plays a significant role affecting the key primary metabolisms in Arabidopsis plants. The alterations ranged from the protein metabolism to redox production. New putative resistance pathways involved in responding to both pathogen and DON infestation in soybean and A. thaliana were described.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-04-24T18:48:59Z No. of bitstreams: 1 texto completo.pdf: 3493058 bytes, checksum: 1aa65a58b68661df0465f55d054a91ab (MD5) / Made available in DSpace on 2017-04-24T18:48:59Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3493058 bytes, checksum: 1aa65a58b68661df0465f55d054a91ab (MD5) Previous issue date: 2003-03-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Visando entender os mecanismos envolvidos na resistência de quatro cultivares de batata à pinta preta, esse trabalho teve por objetivos: 1) quantificar os componentes epidemiológicos da resistência dos cultivares Aracy, Delta, Desirée e Bintje que apresentam diferentes níveis de resistência à pinta preta, e estudar o efeito da idade dos tecidos nesses componentes; 2) realizar a análise histológica do processo infeccioso nesses cultivares, visando identificar possíveis mecanismos estruturais e relacionados com os níveis de resistência dos cultivares, e com a resistência de tecidos jovens; 3) verificar se a expressão diferencial de genes homólogos aos genes que codificam as proteínas PR gluB (glucanase básica de tabaco) e chiB (quitinase básica de feijão) respectivamente, se correlaciona com os níveis de resistência dos cultivares analisadas, e com a maior resistência dos tecidos jovens. Os componentes epidemiológicos da resistência, período de incubação (PI), número de lesões (NL), a severidade, taxa de expansão das lesões (TEL), período latente (PL) e o número de esporos por área foliar afetada (NEAA) foram quantificados nos terços inferior, médio e superior de plantas dos cultivares Aracy (resistente), Delta (resistência intermediária), Desirée(suscetível) e Bintje (suscetível) inoculadas com Alternaria solani numa concentração de 10 3 conídios.mL -1 . No cultivar Aracy constatou-se maior PI, redução do NL, da TEL e conseqüentemente da severidade em todos os terços avaliados. Já o menor NL, TEL, e severidade no terço médio explicam a resistência moderada do cultivar Delta. O cultivar Desirée, classificado como suscetível, apresentou, no terço superior, NL e severidade similar ao cultivar Aracy. O PL e o NEAA não foram adequados para a avaliação da resistência em condições de casa de vegetação e, provavelmente, foram influenciados pela falta de molhamento foliar. Todos os componentes foram influenciados pela idade dos tecidos. Maior PI e menores valores de NL, TEL, severidade e AACPD foram observados no terço superior, comprovando a menor suscetibilidade desses tecidos. Foram efetuados estudos histológicos do processo infeccioso de A. solani nas diferentes cultivares e terços usando a técnica de diafanização de tecidos. Foi quantificado o número de conídios germinados, número de apressórios, número de penetrações diretas e número de sítios de penetração exibindo células com reação de hipersensibilidade (HR). Não se constatou mecanismos de resistência que pudessem ser associados com os níveis de resistência dos cultivares estudados, nem com a maior resistência dos tecidos jovens. Constatou-se uma relação positiva entre o número de sítios de penetração mostrando HR e a resistência do cultivar Aracy. Houve associação desse componente com a resistência dos tecidos jovens. A expressão de genes homólogos à glucanase básica de tabaco (gluB) e à chitinase básica de feijão (chiB) como resposta a infecção de A. solani, foi analisada nos terços inferior e superior dos cultivares Bintje e Aracy, mediante a técnica de "Northern Blotting". Um aumento na expressão de transcritos a gluB e chiB foi constatado no terço inferior do cultivar Aracy, mas não em Bintje. Esse padrão de expressão sugere um possível envolvimento de isoformas destes genes com a resistência de Aracy a A. solani. Essa expressão diferenciada, não foi observada em folhas do terço superior desse cultivar sugerindo um padrão de regulação gênica dependente da idade dos tecidos, e o envolvimento de outros mecanismos bioquímicos na resistência dos tecidos jovens. / The resistance components of four potato cultivars to Alternaria solani were studied in three different levels: 1) quantification of epidemiological components related to resistance in cultivars Aracy, Delta, Desirée, and Bintje, and the effect of age-related resistance in these components; 2) histological analysis of the infectious process in these cultivars, aiming at identifying possible structural mechanisms related to resistance; 3) differential expression of genes homologous to gluB (basic glucanase of tobacco) and chiB (basic chitinase of bean) that encode pathogenesis-related proteins (PR) and the correlation between gene expression levels and cultivar/tissue age resistance levels. The epidemiological components related to resistance, incubation period (PI), number of lesions (NL), early blight severity, lesion expansion rate (TEL), latent period (PL), and the number of spores produced by lesion area (NEAA) were quantified in the lower, middle, and upper parts of cultivars Aracy (resistant), Delta (intermediate resistance), Desirée (susceptible), and Bintje (susceptible) inoculated with a suspension of 103 conidia of A. solani.mL-1. Longer PI, reduced NL, low TEL, and low severity were recorded in Aracy in all parts of the plant. For 'Delta', the reduced NL, low TEL and severity on the middle part of the plant corroborates its intermediate resistance level. Desirée is a susceptible cultivar, but NL and severity on the upper part did not differ from Aracy. The PL and NEAA were not informative when assessing resistance under greenhouse conditions. Probably, PL and NEAA were influenced by the shortage or lack of leaf wetness. All components were influenced by tissue age. Longer PI and smaller values of NL, TEL, and severity were observed in the upper leaves, indicating higher resistance of these tissues. Histological analyses of the infectious process of A. solani in different cultivars were carried out by tissue discoloration. The number of germinated conidia, number of apressoria, number of direct penetrations, and number of penetration sites with cells exhibiting hypersensitive reaction (HR) were quantified. No mechanisms of resistance were associated with cultivar resistance levels or with tissue age. For cultivar Aracy there was a direct relationship between number of penetration sites showing HR and cultivar resistance. The number of sites with HR was also associated with resistance of young tissues. The expression of gluB and chiB in response to A. solani infection was analyzed in the lower and upper parts of 'Bintje' and 'Aracy' plants by Northern blotting analysis. An increase in the level of transcripts related to gluB and chiB was recorded in the lower part of Aracy, but not in Bintje. Differential expression suggests the involvement of isoforms of these genes in Aracy resistance. Differential expression was not observed in leaves of the upper part of Aracy suggesting an age-dependent gene regulation process and/or the involvement of other biochemical mechanisms associated with young tissue high resistance level. / Tese importada do Alexandria

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-17Bitstream added on 2014-06-13T21:03:51Z : No. of bitstreams: 1 catelli_ll_dr_jabo.pdf: 365148 bytes, checksum: 08d9d16fd7bd7a58dff2a344f86ecfe6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os fungos patogênicos Phakopsora pachyrhizi e Erysiphe diffusa causam a ferrugem asiática e oídio, respectivamente, em soja, e são responsáveis por grandes perdas nas áreas sojícolas de muitos países. O objetivo deste trabalho foi estudar a herança de caracteres qualitativos e quantitativos e mapear genes de resistência dessas doenças, utilizando populações de plantas F2 e F2:3 derivados dos cruzamentos entre os genótipos resistentes à ferrugem asiática PI 200487 e PI 200526 com o genótipo suscetível BRI98-641. Ambos os genótipos apresentaram um gene dominante para a resistência, os quais foram mapeados no mesmo grupo de ligação da soja (GL-N). Adicionalmente, as análises quantitativas demonstraram que o modelo aditivo-dominante foi suficiente para explicar a herança dos dois caracteres, número de urédias e severidade, mostrando que alguns genes adicionais de efeito menores podem contribuir para a resposta da severidade da ferrugem asiática nas duas populações. No entanto, o número de urédias demonstrou ser menos influenciado pelas condições ambientais, indicando que os genes podem estar concentrados apenas nos parentais resistentes, evidenciando o caráter de resistência. A severidade continua sendo importante na seleção, pois demonstra melhor o caráter seletivo e pela facilidade de avaliação. Para oídio da soja o gene de resistência foi mapeado em uma população F2:3, derivada do cruzamento entre os genótipos BR01-22106 (resistente) e PI 200487 (suscetível). A resistência ao oídio nesta população foi determinada por um único gene dominante e permitiu o mapeamento de um loco red no grupo de ligação C2 da soja. Os marcadores associados ao Rpp e Red identificados neste trabalho mostraram-se potencialmente úteis na seleção assistida de plantas resistência para o desenvolvimento de cultivares elites carregando estes genes e para manter... / The pathogenic fungi Phakopsora pachyrhizi and Erysiphe diffusa cause the Asian rust and powdery mildew diseases, respectively, in soybean and are responsible for severe yield reduction around the world. The aim of this work was to study the inheritance of qualitative and quantitative resistance characters and to map disease resistance genes in F2 e F2:3 soybean populations, derived from the crosses between Asian rust resistance genotypes, PI 200487 and PI 200526, with the susceptible genotype BRI98-641. Both genotypes revealed a dominant resistance gene that was mapped in the same soybean linkage group (LG-N). In addition, quantitative analysis demonstrated that the additivedominant model was sufficient to explain the inheritance of both characters, number of uredinia and severity, showing that some additional genes can contributed to soybean response to Asian rust severity in the two populations. However, the number of uredinia showed to be less influenced by environmental conditions, demonstrating that gene could be concentrated the in PI 200487 and PI 200526 and be evidence for resistance character. The severity remains important in the selection process because showing the best selective character and the available to evaluation. For powdery mildew, the resistance gene was mapped on linkage group C2 in a F2:3 populations derived from the cross between BR01-22106 (resistant) and PI 200487 (susceptible) genotypes. The powdery mildew resistance was determined by one dominant gene, mapped on linkage group C2 of soybean. The associate markers to Rpp and Red genes will be very useful to assist the selection of resistant plants on the development of elite cultivars carrying these genes and keep the competitiveness and sustainability of soybean Brazilian agribusiness.

Made available in DSpace on 2014-10-09T12:43:22Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:27Z (GMT). No. of bitstreams: 1 06436.pdf: 5207504 bytes, checksum: 448669fe7724cf2f7548e2d2f1dfda65 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-11-03T13:18:16Z No. of bitstreams: 1 Ana Maria Maciel dos Santos.pdf: 471720 bytes, checksum: 32b4d609ca8e3d32c3cac3a4c0d50531 (MD5) / Made available in DSpace on 2016-11-03T13:18:16Z (GMT). No. of bitstreams: 1 Ana Maria Maciel dos Santos.pdf: 471720 bytes, checksum: 32b4d609ca8e3d32c3cac3a4c0d50531 (MD5) Previous issue date: 2014-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / There is no genetic studies in the culture of cilantro to identify genotypes resistant to diseases. Cultivar Verdão is the most used by the farmers of the North and Northeast of Brazil, however, is a good host of Meloidogyne incognita. An alternative for population control of this pathogen in the soil is the use of resistant cultivars, by providing reduced nematode inoculum and spread to other areas. The study of correlations is an option that allows a better understanding of the genetic control of the trait in the breeding population, which allows greater efficiency in the selection. The objective of the study was to evaluate a population of coriander as resistance to Meloidogyne incognita race 1 and propose a strategy for driving improvement coriander program to obtain resistant genotypes. 46 half-sib progenies were evaluated in randomized blocks, with three replications, and the experimental plot consisted of eight plants. After fifteen days of sowing the inoculation of eggs in 1500 the pathogen was performed with plants harvested forty-five days after inoculation. The variables evaluated were number of galls in clod, number of root galls washed and the number of eggs per plant. There was no significant difference between the progenies. There was positive genetic correlation between characters in clod number of galls and egg number. The coincidence of individuals with fewer galls in clod and eggs was approximately 50%. Considering the study population, 51.97% of the plants showed lower number of galls on the root ball truncation point set and 55.38% endorsed the guys are tough. / Há ausência de estudos genéticos na cultura do coentro que identifiquem genótipos resistentes a doenças. A cultivar Verdão é a mais utilizada pelos agricultores do Norte e Nordeste do Brasil, porém, é uma boa hospedeira do Meloidogyne incognita. Uma alternativa para o controle da população deste patógeno no solo é a utilização de cultivares resistentes, por proporcionar redução do inoculo do nematoide e disseminação para outras áreas. O estudo de correlações é uma opção que possibilita uma melhor compreensão do controle genético do caráter na população em melhoramento, o que permite maior eficiência na seleção. Assim, o objetivo do trabalho foi avaliar uma população de coentro quanto a resistência à Meloidogyne incognita raça 1 e propor uma estratégia de condução de programa de melhoramento do coentro para obtenção de genótipos resistentes. Foram avaliadas 46 progênies de meios-irmãos em delineamento em blocos ao acaso, com três repetições, sendo a parcela experimental, constituída por oito plantas. Após quinze dias da semeadura foi realizada a inoculação de 1500 ovos do patógeno, cujas plantas colhidas quarenta e cinco dias após a inoculação. As variáveis avaliadas foram número de galhas no torrão, número de galhas no sistema radicular lavado e o número de ovos por planta. Não houve diferença significativa entre as progênies avaliadas. Obteve-se correlação genética positiva entre os caracteres número de galhas no torrão e o número de ovos. A coincidência de indivíduos com menor número de galhas no torrão e de ovos foi de aproximadamente 50%. Considerando a população em estudo, 51,97% das plantas, apresentaram número de galhas no torrão inferior ao ponto de truncagem estabelecido e 55,38% dos indivíduos avalizados são resistentes.

Made available in DSpace on 2014-10-09T12:43:22Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:27Z (GMT). No. of bitstreams: 1 06436.pdf: 5207504 bytes, checksum: 448669fe7724cf2f7548e2d2f1dfda65 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP