Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1977. / Bibliography: leaves 150-154. / Microfiche. / xvi, 154 leaves ill

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 103-108). / 108 leaves, bound col. ill. 29 cm

Resumé<p>La pourriture brune de la cabosse de Theobroma cacao L. induite par Phytophthora palmivora est un maladie qui à l’échelle mondiale, cause de sérieuses pertes dans les plantations de cacao. L'utilisation de fongicides est coûteuse et est nuisible pour l'environnement. L'utilisation de micro-organismes est une alternative écologique<p>attractive pour les producteurs. L’objectif de ce travail est d’isoler et de caractériser des rhizobactéries de T. cacao avec une activité antagoniste contre Phytophthora palmivora, l'agent causal de la pourriture des cabosses. Parmi les 127 rhizobactéries isolés, trois isolats CP07, CP24 et CP30, identifiées comme Pseudomonas chlororaphis, ont montré une activité<p>antagoniste in vitro et in vivo contre P. palmivora. <p>La production d'enzymes lytiques, de sidérophores, de biosurfactants et d’HCN, ainsi que la détection de gènes codant pour des antibiotiques, la formation de biofilm et la mobilité des bactéries ont également été évalués pour les trois souches de rhizobactérie.<p>Le séquençage du génome de CP07 a confirmé la présence de gènes codant pour trois types de sidérophores, d’HCN, de phénazines et de biosurfactants de la famille de la viscosine, notamment. Un mutant de CP07 déficient dans la production viscosine a été généré et les études effectuées sur ce mutant indiquent que ce bio-tensioactif particulier est essentiel à la fois pour la mobilité bactérienne et pour la formation de biofilm, mais pas pour l'antagonisme in vitro contre Phytophthora, bien qu'il puisse contribuer à la bioprotection de T. cacao.<p>Cette étude fournit une base théorique pour l'utilisation potentielle de P. chlororaphis<p>CP07 comme un agent de lutte biologique pour la protection des plantes de cacao contre l'infection par P. palmivora.<p><p><p>Abstract<p>The black pod rot in Theobroma cacao L. is a major problem worldwide and in Cuba, is<p>one of the most important diseases. The use of chemical fungicides is expensive and<p>harmful to the environment. The use of microorganisms is an environmentally<p>attractive alternative for producers. In this work, fluorescent Pseudomonas strains were<p>isolated from cocoa rhizosphère. The in vitro antagonistic activity and bioprotection<p>against Phytophthora palmivora (Butler) was evaluated. Three strains with in vitro<p>antagonistic activity and bioprotection, CP07, CP24 and CP30, belonging to the species Pseudomonas chlororaphis, were obtained. P. chlororaphis CP07 was highlighted for the best behavior in vitro and in vivo. P. chlororaphis CP07 produces siderophores, HCN,<p>biosurfactants, exoproteases, lipases and motility (swarming and twitching). Genome<p>sequencing confirmed the presence of genes encoding three types of siderophores, HCN, phenazines, the biosurfactant viscosin, and exoproteases, among others. A mutant impaired in biosurfactant production was constructed. When the mutant was characterized, it was evident that the biosurfactant was not involved in the antagonistic effect in vitro against P. palmivora Mab1, although it is crucial to the motility and the ability to form biofilms. P. chlororaphis CP07 was selected as a potential biological control agent against Phytophthora. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-17T12:56:22Z No. of bitstreams: 1 Giltemberg Macedo Tavares.pdf: 1201827 bytes, checksum: f3dc6ee4db4cb245f2d3cd6c71898ad7 (MD5) / Made available in DSpace on 2017-03-17T12:56:22Z (GMT). No. of bitstreams: 1 Giltemberg Macedo Tavares.pdf: 1201827 bytes, checksum: f3dc6ee4db4cb245f2d3cd6c71898ad7 (MD5) Previous issue date: 2009-03-10 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Brazil is the main papaya’s producer in the world (Carica papaya L.) and it occupies the first position producing 1,65 million tones, thus, it is an important production with economic and social value, and, in this meaning, Bahia stands out as the largest producing state with a Brazilian production of 724 tons. Many diseases cause damage to the crop by increasing the cost of production, in some cases limiting the exploitation of that production, among those we can highlight diseases like papaya root damage caused by Phytophthora palmivora. This present study aimed: 1) to achieve the level of infestation of P. palmivora in soils of plantations of papaya commercial in the Extreme South of Bahia, to better support the measures of control; 2) ) to evaluate the action of biotic and abiotic inducers in order to increase the root rot in seedlings of papaya inoculated with P. palmivora, in the activity of enzymes of defense, 1,3-glucanase, peroxidase and chitinase, as well as the lignin content of roots; and 3) to analyze the effect of species of Trichoderma spp. on control of P. palmivora etiologic agent of root rot of papaya. In evaluating of the results of infestation of the soil of papaya orchards, it was showed that in those 33 areas assessed, only two of them, the presence of P. palmivora was not found. There was also no significant differences (p <0.05) for incidence of that pathogen, as those varieties of papaya grown in samples soil evaluated. In all eight municipalities that had sampled orchards the presence of the pathogen was detected, and it showed its wide distribution in the Extreme South of Bahia. To evaluate the control of foot rot in papaya seedlings, it was noted that the treatments using ASM, except the dosage 0.15 g / L 6 days before inoculation, showed levels of larger control to the other inductors. Plants sprayed with ASM showed increased activity of peroxidase and -1,3-glucanase and a highest concentration of lignin in relation to the witness. However,these treatments have no effect on the activity of chitinase. The ASM is a potential inducer of resistance to P. palmivora for using it in the management of root rot of papaya. As the assessment of agents of biocontrol happened it was noted that as using 33 isolated of Trichoderma only 2 isolated (T70 - T. harzianum, T68 - T. virens) did not differ statistically from that treatment with the standard fungicide and showed the percentage of survival of 58.3 and 52.4 respectively. The effect of these two isolated of Trichoderma on increase of dry mass and fresh in seedlings of papaya was also evaluated and it was noted that those two isolates showed higher increases in these parameters when compared with witness. The isolated T70 and T68 showed an increase of fresh and dry mass total of 110, 73% and 59; 59% respectively, compared with those witnesses only planted in the soil. The isolates of T. harzianum and T. virens presented potential with biocontrol agent of P. palmivora for being used in the management of root rot of papaya. / O Brasil é o principal produtor de mamão (Carica papaya L.) do mundo ocupando a primeira posição com uma produção de 1,65 milhão de toneladas, sendo assim, uma importante cultura tanto de valor econômico como social, e a Bahia se destaca como o maior Estado produtor brasileiro com uma produção de 724 mil toneladas. Várias doenças causam danos à cultura aumentando o custo de produção, sendo em alguns casos limitantes a exploração da cultura, dentre essas doenças podemos destacar a podridão do pé do mamoeiro causada por Phytophthora palmivora. Os objetivos do presente estudo foram: 1) realizar o nível de infestação de P. palmivora em solos de plantações de mamoeiros comerciais na região Extremo Sul da Bahia, para melhor subsidiar as medidas de controle; 2) avaliar a ação de indutores biótico e abióticos na redução da podridão de raízes em mudas de mamoeiro inoculadas com P. palmivora, na atividade das enzimas de defesa, 1,3-glucanase, peroxidase e quitinase, assim como no teor de lignina dasraízes; e 3) avaliar o efeito de espécies de Trichoderma spp. sobre controle de P. palmivora agente etiológico da podridão radicular do mamoeiro. Para a avaliaçãos dos resultados de infestação do solo de pamares de mamoeiro observou-se que das 33 áreas avaliadas apenas em duas não se constatou a presença de P. palmivora. Também não houve diferenças significativas (p<0,05) para incidência do patógeno, quanto às variedades de mamoeiro plantadas nas amostras de solos avaliados. Em todos os oito municípios que tiveram pomares amostrados foi detectada a presença do patógeno, atestando sua ampla distribuição no Extremo Sul da Bahia. Para avaliação do controle da podridão do pé em mudas de mamoeiro constou-se que os tratamentos com ASM, com exceção da dosagem 0,15 g/L 6 dias antes da inoculação, apresentaram níveis de controle supeiores aos demais indutores. Plantas pulverizadas com ASM apresentaram aumento deatividade da peroxidase e 1,3-glucanase e maior concentração de lignina em relação à testemunha. No entanto, estes tratamentos não tiverem efeito sobre a atividade da quitinase. O ASM é um potencial indutor de resistência a P. palmivora para ser usado no manejo da podridão de raízes do mamoeiro. Quanto a avaliação dos agentes de biocontrole observdos ou-se que 33 isolados de Trichoderma utilizados apenas 2 isolados (T70 - T. Harzianum, T68 - T. virens) não diferiram estatisticamente do tratamento com o fungicida padrão, apresentaram o percentual de sobrevivência de 58,3 e 52,4 respectivamente. Foi avaliado também o efeito destes dois isolados de Trichoderma sobre incremento de massa seca e fresco em mudas de mamoeiro e contatou-se que dois isolados apresentaram maiores aumentos nestes dois parâmetros quando comparados com testemunha. O isolado T70 e T68 de apresentaram um incremento de massa fresca e seca total de 110; 73% e 59; 59% respectivamente, comparados com a testemunha apenas plantadas no solo. Os isolados de T. harzianum e T. virens apresentaram potencial com agente biocontroladorde P. palmivora para ser usado no manejo da podridão de raízes do mamoeiro.