A cultura da batata (Solanum tuberosum L.) é a terceira fonte principal de alimento humano do mundo, posteriormente ao trigo e arroz. No Brasil, é a olerícola com maior área plantada e gera cerca de 160 mil empregos diretos e indiretos. A batateira é afetada por doenças transmitidas por patogénos do solo, ocasionando a migração da cultura para áreas nunca cultivadas ou sem o plantio de Solanaceae de dois a cinco anos consecutivos. A murcha bacteriana, causada pelo complexo de bactérias da Ralstonia spp., é uma das principais doenças que afetam a cultura da batata no mundo. No Brasil, o sistema convencional de produção de batata, adotado em quase totalidade nacional, gera condições ambientais ideias para a proliferação e desenvolvimento do complexo da Ralstonia ssp.. Dessa forma, precisam ser estudados sistemas alternativos de produção que reduzam a incidência de murcha bacteriana e cessem a migração contínua da cultura da batata. O aumento da biodiversidade e abundância dos microrganismos no solo é capaz de suprimir a ação dos patógenos nativos do solo. Para isso, são necessárias práticas de manejo que aumentem ou mantenham a matéria orgânica do solo, como a rotação e sucessão de culturas. O objetivo deste trabalho foi avaliar a capacidade supressiva do solo à murcha bacteriana nos sistemas alternativos de produção de batata, Paces e orgânico, em comparação ao sistema convencional, sistema não-perturbado sob vegetação natural e solo esterilizado. O delineamento experimental foi em blocos ao acaso, com três repetições, em esquema fatorial 4 x 4 + 1; o primeiro fator representou os solos sob diferentes sistemas de produção, enquanto o segundo correspondeu às doses de 0,25, 50 e 75% de solo contaminado com R. solanacearum adicionadas a cada tratamento. O tratamento adicional constituiu-se do solo do sistema convencional com alta incidência de R. solanacearum. Concluiu-se que a dose de 75% foi a que melhor representou a capacidade supressiva do solo à murcha bacteriana para todos os tratamentos. Nessa dose, as maiores incidências de plantas com sintomas de murcha foram para os solos autoclavado e convencional, que não diferiram entre si. O Sistema Paces, dentre todos os estudados, foi o que apresentou maior potencial de supressividade do solo à murcha bacteriana na batateira. / The potato crop (Solanum tuberosum L.) is the third most important source of human food in the world, after wheat and rice. In Brazil, it is the vegetable with largest area of growing and generates about 160 thousand direct and indirect jobs. The potato is affected by diseases transmitted by soil pathogens, causing the migration of the crop to areas never cultivated or without Solanaceaes from two to five consecutive years. The bacterial complex of Ralstonia spp., is one of the major diseases affecting the potato culture in the world. In Brazil, the conventional system of potato production, adopted in almost national conditions, promotes environmental conditions for the proliferation and development of the Ralstonia ssp. complex. In this way, alternative systems of production that reduce the incidence of bacterial wilt and decrease the intensity of the culture should be studied. Increased biodiversity and abundance of microorganisms in the soil is capable of suppressing an action of native soil pathogens. For this, management practices are applied that increase or decrease the production of soil extracts and of expression in bacteria in the alternative systems of production of potatoes, Paces and organic, were compared to conventional, unperturbed system in natural vegetation and sterilized soil. The experimental design was a randomized block design with three replications, in a 4 x 4 + 1 factorial scheme, the first factor represented the soils under different systems of production, while the second corresponded to the doses of 0.25, 50 and 75% of soil contaminated with R. solanacearum added to each action. The additional was conventional soil with high incidence of R. solanacearum. It was concluded that a dose of 75% was the one that best represented a suppressiveness capacity of the soil to bacterial wilt in all the treatments, to the extent that the incidence of plants with wilt were for the treatments of autoclaved and conventional soil, that did not differ each other. The Paces System, was the one that had the greater potential of soil suppressiveness to the bacterial wilt in the potato.

published_or_final_version / abstract / Biological Sciences / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 110-118).

Ralstonia solanaearum, a soil borne pathogen infects several important crops causing wilting. In 2000-2001, two eucalyptus isolates, BCCF 401 and BCCF 402 were isolated from plantations in Kwa-Zulu Natal and the Democratic Republic of Congo, respectively. Arabidopsis has been recognised as a host for R. solanacearum and as such has been adopted as a model to understand the plant defence response against this pathogen. The aim of this study was to use microarray expression profiling techniques to elucidate the plant defence response and to identify candidate genes possibly contributing towards resistance against the pathogen. As a means to optimise microarray expression profiling, the differential expression in an Arabidopsis mutant, cir1 (constitutively induced resistance 1) and wild-type plants was investigated using a custom 500-probe microarray. Several genes were found to be induced in cir1 at a significance threshold of –log10(p) equal to 3 (p< 0.001) using a mixed model ANOVA approach. The genes AtACP1 (sodium inducible calcium binding protein), AtP2CHA (protein phosphatase 2C), AtGSTF7 (glutathione S transferase), tryptophan synthase betalike and AtPAL1 (phenylalanine ammonia lyase 1), AtEREBP-4 (ethylene response element binding protein 4) and HFR1 (long hypocotyl in far-red 1) were further identified as possible candidate genes which may contribute to disease resistance in cir1 against Pseudomonas syringae pv. tomato. A similar transcript profiling approach, using the optimised protocols, was adopted to investigate the compatible interaction between Arabidopsis ecotype Col-5 and the R. solanacearum isolate BCCF 401. A screen of 5000 Arabidopsis ESTs revealed approximately 120 genes differentially regulated by R. solanacearum infection at a significance threshold of p<0.03 (Bonferroni corrected). Subsequent bioinformatic comparisons revealed that abscisic acid responses appear to be induced in Col-5 in response to the pathogen and that R. solanacearum induces an expression profile consistent with a necrotroph. The basal defence responses in Col-5 against R. solanacearum infection were investigated by comparing the expression data to that during treatment with the pathogen associated molecular patterns (PAMPs) flg22 and lipopolysaccharide, and the Type Three Secretion System deficient Pst hrp- mutant. Expression patterns for a subset of these genes were suggestive of host basal defences manipulated by the pathogen. It is hypothesised that genetic engineering to alter the expression of these “pathogen-manipulated” genes could contribute to resistance against R. solanacearum in the host. Copyright 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Naidoo, S 2008, Microarray expression studies in the model plant Arabidopsis thaliana infected with the bacterial pathogen Ralstonia solanacearum, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11182008-092625 / > D559/gm / Thesis (PhD)--University of Pretoria, 2008. / Plant Science / unrestricted

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Submitted by Inácio de Oliveira Lima Neto (inacio.neto@inpa.gov.br) on 2018-08-23T18:02:17Z No. of bitstreams: 1 Dissertação Final PDF.pdf: 14440240 bytes, checksum: 2af4bf3f84a50787393d47d1dd9daac4 (MD5) / Made available in DSpace on 2018-08-23T18:02:17Z (GMT). No. of bitstreams: 1 Dissertação Final PDF.pdf: 14440240 bytes, checksum: 2af4bf3f84a50787393d47d1dd9daac4 (MD5) Previous issue date: 2018-07-31 / The bacterial wilt, caused by Ralstonia solanacearum, is one of the major diseases that affect Tomato cultivation in tropical climates, limiting production. The present work had as objective to evaluate the potential of solanaceous species as rootstock in commercial tomato, on agronomic characteristics, fruit quality and control of bacterial wilt. The experiment was conducted in a greenhouse, in a randomized complete block design, with four blocks, and six treatments, being the rootstocks: Cubiu (Solanum sessiliflorum); two cultivars of Jiló (Solanum aethiopicum), long pale green and large hill; Jurubebão (Solanum lycocarpum) and Jurubeba Juna (Solanum stramonifolium), grafted with the cultivar Santa Cruz Kada, susceptible to the disease. The glue index, plant height and number of leaves at 15 days after grafting, stem diameter, graft stem diameter and graft point diameter at 30, 60 , 90 and 120 days after transplanting. The fruits were collected regularly for the evaluation of the total number of fruits, number of marketable fruits, number of scrap fruits, average mass of marketable fruits and scrap, vertical diameter and horizontal diameter, yield of marketable fruits, . Fruit quality was measured by the analysis of total soluble solids, pulp pH, titratable acidity and soluble solids ratio and titratable acidity. The incidence of the disease was evaluated weekly after the first wilting plant was investigated. Morphological and histological observations of the healing callus of the evaluated treatments were performed. All evaluated rootstocks presented glue index ≥ 93.33%, indicating that there was no initial incompatibility between the combinations evaluated. The number of commercial fruits differed significantly in the rootstocks, which were long, light green and covered, being the treatment with lower total number of fruits and number of commercial fruits among the evaluated treatments. Cubiu presented the lowest values of commercial fruit production and productivity in relation to treatments, except for the jurubeba juna in which it did not differ. There was no incidence of bacterial wilt in the long-green jiló and jurubeba juna rootstocks, which conferred disease resistance on the grafted plants. The histological sections showed incompatibility characteristics of the tomato evaluated with the cubiu, jurubebão and jurubeba juna rootstocks. The rootstocks, long jiló light green and jurubeba juna presented high index of adhesion, resistance to bacterial wilt, and productivity statistically equal to the control in the conditions of the present work, so that they have great potential for use as rootstocks in the crop of the tomato. Key-words: Solanaceae, Ralstonia solanacearum, Solanum lycopersicum, Resistance. / A murcha-bacteriana, causada por Ralstonia solanacearum, é uma das principais doenças que acometem o cultivo do Tomateiro em climas tropicais, limitando a produção. O presente trabalho teve como objetivo avaliar a potencialidade de espécies de solanáceas como porta-enxerto em tomate comercial, sobre características agronômicas, qualidade dos frutos e no controle da murcha bacteriana. O experimento foi conduzido em casa de vegetação, em delineamento experimental em blocos ao acaso, com quatro blocos, e seis tratamentos sendo eles os porta-enxertos: Cubiu (Solanum sessiliflorum); duas cultivares de Jiló (Solanum aethiopicum), a comprido verde claro e a morro grande; Jurubebão (Solanum lycocarpum) e Jurubeba Juna (Solanum stramonifolium), enxertados com o tomateiro cultivar Santa Cruz Kada, susceptível à doença. Foram avaliados o índice de pegamento, a altura da planta e o número de folhas aos 15 dias após a enxertia, e o diâmetro do caule do porta-enxerto, o diâmetro do caule do enxerto e o diâmetro do ponto de enxertia aos 30, 60, 90 e 120 dias após o transplantio. Os frutos foram colhidos regularmente para a avaliação do número total de frutos, número de frutos comerciáveis, número de frutos refugo, massa média dos frutos comerciáveis e refugo, diâmetro vertical e diâmetro horizontal, produção de frutos comerciáveis, produção de frutos refugo, e produtividade. A qualidade dos frutos foi mensurada pela análise de sólidos solúveis totais, pH da polpa, acidez titulável e relação entre sólidos solúveis e acidez titulável. A incidência da doença foi avaliada semanalmente após a averiguação da primeira planta murcha. Observações morfológicas e histológicas do calo cicatricial dos tratamentos avaliados foram realizadas. Todos os porta-enxertos avaliados apresentaram índice de pegamento ≥ 93,33%, indicando não haver incompatibilidade inicial entre as combinações avaliadas. O número de frutos comerciais diferiu significativamente nos porta-enxertos jiló comprido verde claro e cubiu, sendo este o tratamento com menor número total de frutos e número de frutos comerciais dentre os tratamentos avaliados. O cubiu apresentou os menores valores de produção de frutos comerciais e produtividade em relação aos tratamentos, com exceção da jurubeba juna em que não diferiu. Não houve incidência da murcha-bacteriana nos porta-enxertos jiló comprido verde claro e jurubeba juna, que conferiram resistência a doença nas plantas neles enxertadas. Os cortes histológicos evidenciaram características de incompatibilidade do tomateiro avaliado com os portaenxertos cubiu, jurubebão e jurubeba juna. Os porta-enxertos jiló comprido verde claro e jurubeba juna apresentaram alto índice de pegamento, resistência à murcha-bacteriana, e produtividade estatisticamente igual à testemunha nas condições do presente trabalho, de forma que possuem grande potencial para o uso como porta-enxertos na cultura do tomate. Palavras-chave: Solanaceae, Ralstonia solanacearum, Solanum lycopersicum, Resistência.

Bacterial degradation is an important way to detoxify environmental pollutants haloacids, and the key enzyme involved is dehalogenase. In contrast to the well characterized dehalogenases, haloacids transporters that mediate uptake of haloacids are poorly understood. The deh4p gene in a haloacids-degrading bacterium Burkholderia species MBA4 is the first reported haloacids transporter gene. It is located downstream of the dehalogenase gene deh4a and the two forms a haloacids operon. The role of Deh4p as a haloacids transporter was confirmed by heterologous expression. It was later found that a mutant of MBA4 without functional Deh4p was still able to grow in monochloroacetic acid (MCA), and Deh4p seems to be not the only haloacids transporter in MBA4. This study aimed at gaining a deeper understanding of the haloacids transport process in MBA4, and establishing the role of a newly identified gene dehp2 as a conserved haloacids transporter gene in the Burkholderia genus. Disruption of deh4p in MBA4 caused a 32% decrease in MCA uptake rate, confirming the role of Deh4p as a haloacids transporter, but not the only one. A gene showing homology to deh4p in MBA4 was identified and named dehp2. The role of Dehp2 as a second haloacids transporter in MBA4 was confirmed by both gene disruption and heterologous expression. Like deh4p, the expression of dehp2 is also MCA-inducible. A double mutant with both deh4p and dehp2 disrupted only retained 36% MCA uptake rate, further confirming the roles of Deh4p and Dehp2 as haloacids transporters. Dehp2 and Deh4p were also shown to be the two major haloacids transporters. Both Dehp2 and Deh4p are specific toward acetate and its halogenated derivatives, but Dehp2 has a broader spectrum of substrates than Deh4p. Deh4p was found to be a better MCA transporter than Dehp2, and also has a higher affinity for MCA. The effects of protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) and pH on MCA uptake supported the symport of proton(s) and the inclusion of both Dehp2 and Deh4p in the metabolites:H+ symporter family. Orthologs of dehp2 are widely found in the Burkholderia genus, and phylogenetic analysis showed that they were conserved in the genus. The roles of dehp2 orthologs in haloacids transport in three non-pathogenic Burkholderia species were studied. The three species were engineered to gain the ability to utilize MCA as the sole carbon source, and were shown to have MCA-inducible MCA uptake activities. Expressions of the dehp2 orthologs in them are MCA-inducible, strongly suggesting their relationship with MCA uptake. Fusion analysis with lacZ as a reporter gene confirmed the presence of MCA-inducible promoter activity in the upstream non-coding region of dehp2, and the results of electrophoretic mobility shift assay (EMSA) suggested a positive regulation of dehp2. This study established Dehp2 as a second haloacids transporter in MBA4, and also confirmed dehp2 as a conserved haloacids transporter gene in the Burkholderia genus. The presence of at least two haloacids transporters in MBA4 demonstrated the complexity of this process, and future work should figure out the transport mechanisms. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy