Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 91-107).

Thesis (Ph.D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 91-107) Also available in print.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Mar., 24, 2009). Includes bibliographical references.

Zugl.: Göttingen, Univ., Diss., 2009

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-08-31T16:43:51Z No. of bitstreams: 1 texto completo.pdf: 1571624 bytes, checksum: 532bd28b48be76bfcc011401faf8fee6 (MD5) / Made available in DSpace on 2017-08-31T16:43:51Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1571624 bytes, checksum: 532bd28b48be76bfcc011401faf8fee6 (MD5) Previous issue date: 2017-07-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O cultivo do tomateiro possui relevante importância sócio-econômica na agricultura brasileira. Mesmo diante deste cenário favorável, a tomaticultura é considerada uma atividade de elevado risco econômico e de grande complexidade agronômica. Dentre os principais problemas, destaca-se a requeima, causada pelo oomiceto Phytophthora infestans (Mont.) de Bary. O controle da doença é altamente dependente do uso de agrotóxicos, pois a maioria dos cultivares de tomateiro não são resistentes. Na tentativa de reverter esse quadro, a principal alternativa é a transferência de genes de resistência presentes em acessos de tomateiro conservados em Bancos de Germoplasma. Assim, após oito anos de pesquisas foi selecionado o acesso BGH-2127 (Solanum lycopersicum), como fontes de resistência a requeima, dentre os 870 acessos de tomateiro do Banco de Germoplama de Hortaliças da Universidade Federal de Viçosa (BGH-UFV). Pelo fato da resistência ser quantitativa, torna-se difícil a avaliação e seleção fenotípica de genótipos superiores, feita apenas no campo ou em associação com marcadores moleculares genéticos tipo QTL. Neste contexto, a metodologia da análise proteômica torna-se uma alternativa viável, pois pode fornecer importantes informações e ferramentas para maior entendimento das rotas metabólicas da interação planta-patógeno e assim auxiliar no desenvolvimento de futuras estratégias para o desenvolvimento de cultivares de tomateiro resistentes. Com o auxílio de ferramentas proteômica, os objetivos deste estudo foram: analisar possíveis diferenças entre os proteomas constitutivos de genótipos de tomateiro contrastantes quanto a resistência à requeima; e identificar proteínas frente a infecção do patógeno que possam explicar possíveis mecanismos moleculares de resistência do tomateiro a esta doença. Foram avaliados o acesso BGH-2127 e o cultivar Santa Clara, resistente e suscetível à requeima, respectivamente. Para avaliação do proteoma constitutivo, as proteínas foram extraídas de amostras das folhas dos genótipos sem que tivesse ocorrido a inoculação, apenas comparando a constituição proteica do BGH-2127 e do Santa Clara. Na avaliação à resposta ao patógeno, as plantas foram inoculadas com uma mistura de esporângios de P. infestans, na concentração de 1x10 3 esporângios mL -1 , coletados em regiões da Zona da Mata Mineira, e as proteínas foram extraídas de folhas de cada genótipo inoculado e não inoculado (controle) coletadas nos tempos 0, 2 e 48 horas. Na análise proteômica foi utilizada a técnica da eletroforese bidimensional (2-DE), com a primeira dimensão (focalização isoelétrica) realizada em tiras IPG de 24 cm, pH 3-10, e a segunda dimensão em SDS-PAGE, em gel 12,5%T. Foram obtidos três géis por tratamento, correspondendo a três repetições biológicas. Em seguida, os géis foram revelados por coloração com azul de coomassie coloidal. Posteriormente as imagens dos géis foram digitalizadas usando o equipamento Image Scanner III e analisadas no software ImageMaster 2D Platinum 7.5. Spots com variação de sobreposição acima de 1,5 e ANOVA p<0,05 foram considerados diferencialmente abundantes. Os spots das proteínas diferencialmente abundantes foram identificados em espectrômetro de massas do tipo MALDI-TOF/TOF Ultraflex III. As listas de massas obtidas foram confrontadas contra os bancos de dados de proteínas obtidos do UNIPROT, com auxílio do software MASCOT e os resultados obtidos, validados pelo aplicativo SCAFFOLD com pelo menos 90% de probabilidade. As proteínas identificadas foram categorizadas funcionalmente usando o software Mapman. Uma vez listadas as proteínas diferencialmente abundantes para os genótipos BGH-2127 e Santa Clara foi realizada a construção de uma rede de interação proteína-proteína utilizando o software STRING. Ensaios de PCR em Tempo Real (RT-PCR) foram realizados para confirmar os níveis de abundância de algumas proteínas identificadas. O RNA total foi extraído de amostras de folhas e o cDNA obtido foi quantificado pelo equipamento SpectraMax M5 microplate/cuvette reader. A amplificação dos fragmentos alvo foi realizada utilizando o equipamento StepOneTM Real-Time PCR System e para a quantificação da expressão gênica foi utilizado o software REST. Na avaliação do proteoma constitutivo, 19 proteínas foram identificadas, e estão relacionadas com metabolismo e energia, fotossíntese, estresse e defesa e à transcrição. Aproximadamente 90% destas proteínas foram mais abundantes no cultivar Santa Clara. As proteínas endoquitinase ácida de 26 kDa e ribonuclease T2 foram mais abundantes no BGH-2127. Atividade enzimática confirmou maior abundância de quitinase no acesso BGH-2127 em relação à Santa Clara. Os padrões de expressão avaliados por PCR em tempo real diferiram dos resultados da análise proteômica. Na avaliação da resposta ao patógeno, 56 proteínas diferencialmente abundantes foram identificadas, sendo 39 referentes ao genótipo resistente e 17 ao suscetível. Estas proteínas foram categorizadas em grupos de funções biológicas de energia e metabolismo, fotossíntese, estresse e defesa, transcrição, outras proteínas e não caracterizadas. Para o acesso BGH-2127, proteínas do estresse oxidativo (2-cis peroxirredoxina BAS1 e 2-cis peroxirredoxina) e relacionadas à patogênese da família PR-5 (taumatina) tiveram os níveis de abundancia relativa aumentados nos tempos 0 e 48 horas após a inoculação, respectivamente, e foram consideradas importantes para o mecanismo de defesa deste genótipo. Os padrões de expressão avaliados por PCR em tempo real diferiram dos resultados da análise proteômica. Redes de interações proteína-proteína forneceram importantes informações sobre atividades celulares envolvidas na resistência do BGH-2127 à requeima. Diferenças na abundância das proteínas endoquitinase ácida de 26 kDa e ribonuclease T2 entre os proteomas constitutivos dos genótipos avaliados podem contribuir para o mecanismo de resistência do BGH-2127 à requeima. Proteínas relacionadas ao estresse oxidativo (PR-9) e família taumatina (PR-5) possuem papel importante no mecanismo de defesa do acesso BGH- 2127 resistente a requeima do tomateiro. / Growing tomatoes has significant economic and social importance in brazilian agriculture. Nevertheless, the tomato production is considered an activity of high economic risk and major agronomic complexity. Among the main problems with regard to pests and diseases, there is the late blight, caused by the oomycete Phytophthora infestans (Mont.) de Bary. Disease control is highly dependent on the use of pesticides and there is no resistant cultivars. The main strategy to reverse that one situation is the introgression of resistance genes present in tomato accessions stored in germplasm banks. So, after eight years of research, BGH-2127 access (Solanum lycopersicum) was selected as a source of resistance to late blight, among the 870 tomato accessions of Vegetable Germplasm Bank of the Federal University of Viçosa (BGH-UFV). Due to the resistance to be quantitative it becomes difficult to practice selection of superior genotypes, made only in the field or associated with genetic molecular markers. In this context, the methodology of proteomics becomes viable alternative to provide valuable information and tools to better understanding the different ways of plant-pathogen relationship, thus this methodology can help future proposals genetic strategies to develop resistance cultivars of tomatoes. With the help of proteomic tools, the objectives of this study were: to analyze differences between the constitutive proteomes of tomato genotypes contrasting in resistance to late blight; and identify proteins against infection of the pathogen that may explain possible molecular mechanisms of resistance of tomato to this disease. The BGH-2127 and Santa Clara cultivar, resistant and susceptible to late blight respectively, were evaluated. For the evaluation of the constitutive proteome, proteins were extracted from leaf samples of the genotypes without inoculation, only comparing the protein constitution of BGH-2127 and Santa Clara. In evaluating the response to the pathogen, the plants were inoculated with a mixture of sporangia of P. infestans sporangia at a concentration of 1 x 10 3 sporangia mL −1 from different regions of Zona da Mata. Proteins were extracted from leaves of each genotype inoculated and non-inoculated (control) collected at time 0, 2 and 48 hours. In the proteomic analysis, the two-dimensional electrophoresis technique (2-DE) was used, with the first dimension (isoelectric focusing) performed using a 24-cm strip containing an immobilized pH gradient (IPG) ranging from 3 to 10 and the second dimension was performed on SDS-PAGE 12.5%T. Three gels were obtained by treatment, corresponding to three biological replicates. Then the gels were stained with colloidal coomassie blue. Posteriorly the gels were scanned with the aid of Image Scanner III and analyzed using ImageMaster 2D Platinum 7.0 software. The expression values were considered significant according to the analysis of variance (ANOVA) at p<0.05. Proteins in which the abundance ranged at least 1.5 times were considered to be differentially abundant. Protein identification was performed using the MALDI- TOF/TOF Ultraflex III type mass spectrometer. The standard list of proteins was obtained UNIPROT, through the use of the MASCOT application. The result obtained by MASCOT was validated by the SCAFFOLD application, with a minimum of 90% probability. Identified proteins were functionally categorized using Mapman program. Once the differentially abundant proteins for BGH-2127 and Santa Clara genotypes were listed, the construction of a protein-protein interaction network was carried out using the STRING software. Real-time PCR assays (RT-PCR) were performed to confirm the levels of abundance of some identified proteins. Total RNA was extracted from leaf samples and the cDNA obtained was quantified by the SpectraMax M5 microplate/cuvette reader. The PCR reaction was performed using StepOneTM Real- Time PCR System. Quantification of gene expression was performed using REST software. In evaluation of the constitutive proteome, nineteen proteins were identified, which were then related to metabolism and energy, photosynthesis, transcription, stress and defenses. Approximately 90% of these proteins were more abundant in Santa Clara, a susceptible cultivar. Acidic 26 kDa endochitinase and ribonuclease T2 proteins were more abundant in BGH-2127 access. The enzymatic activity confirmed a greater abundance of chitinase in the BGH-2127 access as compared to the cultivar Santa Clara. Gene expression analyses by real time PCR demonstrated that the mRNA levels were not correlated with the respective protein levels. Abundance of the acidic 26 kDa endochitinase and ribonuclease T2 proteins in the constitutive proteomes of BGH-2127 may be associated with the answer to the resistance of this access. In evaluating the response to the pathogen, fifty-six differentially abundant proteins were identified, with thirty-nine referring to the resistant genotype and seventeen to the susceptible genotype. These proteins were categorized into functional groups of energy and metabolism, photosynthesis, stress and defense, transcription, other proteins and not characterized. For access BGH-2127, oxidative stress proteins (2-cis peroxiedoxin BAS1 and 2-cis peroxiredoxin) and thaumatin-like protein had levels of relative abundance increased at times 0 and 48 hours after respectively, and were considered important for the defense mechanism of this genotype. The expression standards evaluated by RT-PCR differed from the results of the proteomic analysis. Protein-protein interaction networks provided important information on cellular activities involved in the resistance of BGH-2127 late blight. Abundance of the acidic 26 kDa endochitinase and ribonuclease T2 proteins in the constitutive proteomes of BGH-2127 may be associated with the answer to the resistance of this access. Proteins related to oxidative stress (PR-9) and thaumatin-like family (PR-5) play an important role in the BGH-2127 access defense mechanism resistant to tomato late blight.

No description available.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

The bacterial mechanosensitive channels MscS and MscL have been shown to protect cells from hypo-osmotic shock-induced lysis. Bacterial strains deficient for MscS and MscL are severely compromised and fail to survive a hypo-osmotic shock. Both channels exhibit redundant function such that re-introduction of either of these proteins is sufficient to restore cell survival. Several proteins paralogous to MscS have been identified in E. coli, but their function remains unknown. Mechanosensitive channel homologues are also being discovered in a variety of organisms including Archaea, plants and fungi and their function is starting to emerge.

Potato is one of the most important crops grown in Canada and all over the world. Late blight caused by P. infestans is one of the major diseases of potato and is mainly managed by fungicides application. The extensive use of fungicides not only causes adverse effects on the environment but also accelerates the development of resistance in this pathogen. Horizontal resistance is considered as the best choice to control P. infestans as it is durable over years. Breeding for durable resistance requires evaluation of hundreds of breeding lines in greenhouses and in the field. This is usually done by testing several epidemiological parameters such as infection efficiency, lesion size, latent period, and area under disease progress curve (AUDPC). These methods are time-consuming and expensive. The present study reports standardization of metabolic profiling protocols and exploration of metabolic profiling based on GC/MS as an additional tool to discriminate resistance in potato against late blight. Potato cultivars varying in horizontal resistance against late blight have been inoculated with water or the pathogen and more than 100 metabolites have been tentatively identified by GC/MS. Univariate analysis has been used to identify several pathogenesis related (PR) and defense related (DR) metabolites that have potential for application as resistance biomarker metabolites. Multivariate analysis of the abundances of metabolites (the mass spectral (MS) ion trap detector outputs were obtained using Saturn Lab Software Version 5.52 and these abundances are positively proportional to the concentration of mass ions of metabolites) in cultivars were mainly used to identify pathogenesis and resistance functions. Following pathogen inoculation, several metabolites such as amino acids, organic acids, fatty acids and sugars, were significantly increased in abundances, especially in the resistant cultivar. Other metabolites such as phenylalanine, tyrosine, shikimic acid and malonic acid detected here are well known for their direct participation in the shikimic acid, the phenylpropanoid, and the malonic acid metabolic pathways. These pathways lead to the production of several defense metabolites including antimicrobial compounds including phenolics, flavonoids and phytoalexins. The metabolic profiling technology developed here has the potential application for screening of potato breeding lines for horizontal resistance against late blight.

Thesis (Ph. D.)--Ohio State University, 2005. / Document formatted into pages; contains 215 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 March 3.