Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-10T15:46:17Z No. of bitstreams: 1 Frederick Mendes Aguiar.pdf: 412210 bytes, checksum: 4f5f91c02dea9d844bac53a51c2cafa0 (MD5) / Made available in DSpace on 2017-03-10T15:46:17Z (GMT). No. of bitstreams: 1 Frederick Mendes Aguiar.pdf: 412210 bytes, checksum: 4f5f91c02dea9d844bac53a51c2cafa0 (MD5) Previous issue date: 2011-02-24 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Okra is a vegetable crop with high nutritional value, being a rich source of vitamins and mineral salts. Fusarium wilt (caused by Fusarium oxysporum f. sp. vasinfectum – FOV) is one of the major field diseases of okra in tropical areas. In the present work, 53 okra accessions and the commercial cultivar Santa Cruz 47 were evaluated aiming to identify sources of resistance to Brazilian FOV isolates and to study the resistance stability of the selected accessions to different pathogen isolates. An initial screening was carried out with only one FOV isolate (Fus-194). In the second assay, thirty-three accessions identified in the first screening were re-evaluated in two assays (in two different seasons) using two FOV isolates (Fus-194 and Fus-201). The resistance evaluation was carried out with 21 day-old plantlets, using the root-dipping inoculation procedure, utilizing a spore suspension of 1x106 conidia/mL. The evaluation was done using a disease severity grade system with grades ranging from 0 to 4. These grades were used to generate a disease index that was employed for clustering the accessions according to their reaction to FOV. In the evaluation carried out in August (average temperature of 19,8°C) only 12 out the 32 accessions (i.e. 37%) were rated as having high to intermediate resistant response to Fus-194 isolate. Only 28% of the accessions were classified within the high to intermediate resistance cluster when using the Fus-201 isolate. In the assay carried out in October (higher temperatures) 72% of the accessions were classified as resistant and intermediate resistant to Fus-194 isolate, whereas 32% were resistant to isolate Fus-201. Our results indicated that the Fus-201 isolate was more aggressive than Fus-194. Comparative analysis of the assays indicated that the overall aggressiveness of the isolates was higher in August than in October assay. The accessions BR-2399 and BR-1449 as well as the commercial cultivar Santa Cruz 47 were the most promising accessions displaying higher levels of stable resistance against the two Brazilian FOV isolates.Okra is a vegetable crop with high nutritional value, being a rich source of vitamins and mineral salts. Fusarium wilt (caused by Fusarium oxysporum f. sp. vasinfectum – FOV) is one of the major field diseases of okra in tropical areas. In the present work, 53 okra accessions and the commercial cultivar Santa Cruz 47 were evaluated aiming to identify sources of resistance to Brazilian FOV isolates and to study the resistance stability of the selected accessions to different pathogen isolates. An initial screening was carried out with only one FOV isolate (Fus-194). In the second assay, thirty-three accessions identified in the first screening were re-evaluated in two assays (in two different seasons) using two FOV isolates (Fus-194 and Fus-201). The resistance evaluation was carried out with 21 day-old plantlets, using the root-dipping inoculation procedure, utilizing a spore suspension of 1x106 conidia/mL. The evaluation was done using a disease severity grade system with grades ranging from 0 to 4. These grades were used to generate a disease index that was employed for clustering the accessions according to their reaction to FOV. In the evaluation carried out in August (average temperature of 19,8°C) only 12 out the 32 accessions (i.e. 37%) were rated as having high to intermediate resistant response to Fus-194 isolate. Only 28% of the accessions were classified within the high to intermediate resistance cluster when using the Fus-201 isolate. In the assay carried out in October (higher temperatures) 72% of the accessions were classified as resistant and intermediate resistant to Fus-194 isolate, whereas 32% were resistant to isolate Fus-201. Our results indicated that the Fus-201 isolate was more aggressive than Fus-194. Comparative analysis of the assays indicated that the overall aggressiveness of the isolates was higher in August than in October assay. The accessions BR-2399 and BR-1449 as well as the commercial cultivar Santa Cruz 47 were the most promising accessions displaying higher levels of stable resistance against the two Brazilian FOV isolates. / O quiabo é uma hortaliça de alto valor alimentício e uma importante fonte de vitaminas e sais minerais. Dentre os problemas fitossanitários que ocorrem no quiabeiro, a murcha-de-fusário, causada pelo fungo Fusarium oxysporum f. sp. vasinfectum (FOV) é uma das mais importantes por proporcionar grandes perdas na produção. Este trabalho objetivou avaliar, em condições de casa de vegetação, a cultivar comercial Santa Cruz 47 e uma coleção de 53 acessos de quiabeiro, visando identificar fontes de resistência a FOV e analisar a estabilidade da resistência de acessos promissores a diferentes isolados do patógeno. Inicialmente foi conduzida uma triagem utilizando um único isolado de FOV (Fus-194). Em uma segunda etapa, trinta e dois acessos obtidos na primeira etapa, foram reavaliados para resistência ao FOV utilizando dois isolados (Fus-194 e Fus-201), em duas épocas do ano. A inoculação foi realizada em mudas com 21 dias após semeadura, pela imersão das raízes em suspensão de conídios (1x106 conídios/mL) do patógeno. A avaliação da severidade da doença foi realizada usando uma escala de notas, variando de 0 a 4. As notas foram transformadas em índice de doença (ID) e agrupadas em classes de acordo com a reação da doença. Na segunda etapa do trabalho realizado no mês de agosto de 2010 (temperatura média de 19,8°C), dos 32 acessos avaliados, 12 (37%) foram considerados altamente resistentes a medianamente resistentes ao Fus-194. Para o isolado Fus-201 apenas 28% foram classificados dentro dessas duas classes. No ensaio realizado no mês de outubro (temperatura média de 25°C) referente à segunda etapa desse trabalho, 72% dos acessos foram considerados medianamente a altamente resistentes ao Fus-194. Neste ensaio, 32% dos acessos foram resistentes ao isolado Fus-201. Os resultados demonstraram uma maior agressividade do isolado Fus-201 em relação ao isolado Fus-194. Os níveis de agressividade dos isolados testados foram maiores no ensaio realizado no mês de agosto do que em outubro. Os acessos BR-2399, BR-1449 e a cultivar Santa Cruz 47 apresentaram resistência estável aos dois isolados do patógeno tanto na etapa preliminar, quanto nas duas épocas de avaliação da segunda etapa do trabalho.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-04-27T17:21:31Z No. of bitstreams: 1 texto completo.pdf: 301848 bytes, checksum: 965b4a5e98b835e25f72696745c97da7 (MD5) / Made available in DSpace on 2017-04-27T17:21:31Z (GMT). No. of bitstreams: 1 texto completo.pdf: 301848 bytes, checksum: 965b4a5e98b835e25f72696745c97da7 (MD5) Previous issue date: 2004-04-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho objetivou investigar o potencial de uso do controle biológico no patossistema F. oxysporum f. sp. phaseoli e feijão a partir das seguintes etapas: 1-Selecionar um isolado de F. oxysporum não-patogênico (FO), um isolado de Trichoderma sp. (TR) e outro de Pseudomonas fluorescentes (PF) mais competentes e com alta competitividade rizosférica. 2-Estudar o efeito do tratamento de sementes de feijão com isolados selecionados de Pseudomonas fluorescentes, no desenvolvimento da murcha-vascular. 3-Estudar a relação entre a densidade de inóculo de F. oxysporum f. sp. phaseoli e de F. oxysporum não- patogênicos adicionada no solo para supressão da forma patogênica. 4-Estudar, em solo infestado com F. oxysporum f. sp. phaseoli, o efeito combinado de sementes de feijão tratadas com a bactéria e plantadas em solo infestado com F. oxysporum não-patogênico em casa de vegetação, no desenvolvimento da murcha-vascular. 5-Estudar, em solo infestado com F. oxysporum f. sp. phaseoli, o efeito combinado de sementes de feijão tratadas ou não-tratadas com a bactéria e plantadas em solo infestado com F. oxysporum não-patogênico ou Trichoderma sp. e o efeito de cada potencial antagonista sozinho, no campo, no desenvolvimento da murcha-vascular. Foram testados três isolados de FO, 11 de TR e 150 de PF, obtidos da rizosfera (80), rizoplano (30) e internamente as raízes (40). Nos testes de antibiose “in vitro” foram selecionados 22 isolados de PF e nos testes posteriores de competência e competitividade selecionou-se o isolado PF22 (Pseudomonas putida). Testando-se a competência e competitividade de FO e TR foram selecionados os isolados TR11 de Trichoderma (T harzianum) e FO3 de Fusarium não patogênico. Observou-se que não teve diferença entre as concentrações de FO para um mesmo isolado, no entanto, foi observada diferença entre os isolados e destes com o controle. O isolado FO3 teve uma maior área abaixo da curva de decréscimo da clorofila (AACDCL) para as clorofilas A, B e total (5,38, 1,71 e 7,10, respectivamente), menor severidade da doença (2,37) e maior produção de grãos (6,65g) em relação ao FOPm sozinho, com AACDCL de 2,41, 0,87 e 3,25, respectivamente, severidade 4,25 e produção de grãos de 2,23g. O isolado PF22 sozinho não reduziu a severidade da doença. Quando FO3 e PF22 foram usados em conjunto obteve-se uma maior AACDCL paras as clorofilas A, B e total (4,52, 1,05 e 5,57, respectivamente), maior produção de grãos (12,59g) e redução da severidade da doença (2,50) enquanto que FOPm sozinho teve AACDCL de 0,92, 0,23 e 1,16, respectivamente, severidade de 4,30 e produção de 5,71g de grãos. No campo, os isolados TR11 e FO3 sozinhos ou em conjunto com PF22, não diferiram entre si quanto a AACDCL, mas diferiram do FOPm sozinho. Quanto à produção, observou-se que a associação dos microrganismos FO3 + PF22 e TR11 + PF22 não diferiram entre si, com uma produção de 15 e 14 vagens e 14,7 e 13,1 g de grãos, respectivamente. A produção do tratamento apenas com FOPm foi de 8,3 vagens e 4,5 g de grãos. Esses valores mostram um aumento de aproximadamente 200% na produção de grãos quando utilizados os microrganismos em conjunto no controle da doença no campo. A ação conjunta dos microrganismos usados neste trabalho mostrou-se uma estratégia de controle biológico promissora para a redução no solo da densidade de inóculo de F. oxysporum f. sp. phaseoli e, com isso, propiciar uma redução da ocorrência e dos danos causados por essa doença. / This study aimed to investigate the potential of the biological control upon the pathosystem F. oxysporum f. sp. phaseoli and bean, by the following procedure: 1) Selecting an isolate of non-pathogenic F. oxysporum (FO), an isolate of Trichoderma sp. (TR) and one of fluorescent Pseudomonas (FP), which should be more competent and have a higher degree of rhizosphere competitiveness; 2) Studying the effect of the seed treatment with those selected fluorescent Pseudomonas isolates upon the development of the vascular wilt; 3) Studying the relationship between the inoculum densities of the non-pathogenic F. oxysporum and pathogenic F. oxysporum f. sp. phaseoli added to the soil in order to suppress the pathogenic form. 4) Studying the combined effect of bean seed treatment with F. oxysporum f. sp. phaseoli and sowing in a non-pathogenic F. oxysporum-infested soil upon the development of the vascular wilt, under greenhouse conditions. 5) Comparing the combined effect of bean seed treatment with F. oxysporum f. sp. phaseoli or no treatment followed by sowing in soil infested by either non-pathogenic F. oxysporum or Trichoderma sp., as well as the effect of each antagonistist alone upon the development of the vascular wilt under field conditions. The following isolates were tested: three from FO, 11 from TR and 150 from PF [which were obtained from the rhizosphere (80), rhizoplane (30) and internally from the roots (40)]. In the in vitro antibiosis test, twenty two PF isolates were selected, whereas in the following tests for competence and competitiveness the isolate PF22 (Pseudomonas putida) was selected. When testing FO and TR for competence and competitiveness, the isolates TR11 from Trichodema (T. harzianum) and FO3 from the non-pathogenic Fusarium were selected. No differences were observed among the FO concentrations for the same isolate, but differences between the isolates as well as between these and the control were significant. The FO3 isolate occupied a higher area below the chlorophyll decreasing curve (AACDCL) for A, B and total chlorophylls (5.38, 1.71 and 7.10, respectively), as well as a lower disease severity (2.37) and higher bean yields (6.65g) in relation to FOPm alone, with the respective values of 2.41, 0,87 and 3,25 for AACDCL, 4.25 severity, and 2.23g for bean yield. The isolate PF22 did not reduce by itself the severity of the disease. When using FO3 and PF22 together, a higher AACDCL was obtained for the chlorophylls A, B and total (4.52, 1.05 and 5.57, respectively), as well as higher bean yields (12.59g) and reduced severity of the disease (2.50), whereas FOPm alone showed an AACDCL of 0.92, 0.23 and 1.16, respectively, 4.30 severity, and bean yield of 5.71g. Under field conditions, both the isolates TR11 and FO3 by themselves or combined with PF did not differ from each other for AACDCL, but from the FOPm alone. In relation to the yield, no differences were found for the combination of the microorganisms FO3 + PF22 and TR11 + PF22, since a total of 15 and 14 pods and 14.7 and 13.1 beans were yielded, respectively. In the treatment with FOPm alone, a total of 8.3 pods and 4.5 beans were yielded. These values show an increase of around 200% in bean yield, when the microorganisms were used in combination to control the disease in the field. In this study, the combined action of the microorganisms showed to be a promising biological control strategy for reducing the density of the F. oxysporum f. sp. phaseoli inoculum in the soil providing a reduction in both occurrence and damages caused by this disease. / Tese importada do Alexandria

The diploma thesis concerns observing the health conditions of pea plants. The experiments were established in 2016–2017 in cooperation with AGRITEC, research, breeding and services, s.r.o. company in Šumperk. There were 9 varieties and 3 lines selected for the experimentations. The observation for each experiment was divided into two timing terms. The resistance to pea powdery mildew caused by pathogen Eryshipe pisi, was observed in greenhouse conditions. The highest level of resistance occurred line 1109/13 and variety FRANKLIN. The lowest level of resistance had variety ARVIKA. However this variety also occured to have the highest level of resistance in laboratory tests to resistance to Fusarium solani and Fusarium oxysporum. The pathogens causing the complex of root rot and black stem deseases were observed in conditions of infectious field. Variety ATLAS was infected the least.

Submitted by (ana.araujo@ufrpe.br) on 2017-02-07T16:48:16Z No. of bitstreams: 1 Daniel Oliveira Jordao do Amaral.pdf: 1158857 bytes, checksum: e7a95fb82b8780bf1c190ef328318925 (MD5) / Made available in DSpace on 2017-02-07T16:48:16Z (GMT). No. of bitstreams: 1 Daniel Oliveira Jordao do Amaral.pdf: 1158857 bytes, checksum: e7a95fb82b8780bf1c190ef328318925 (MD5) Previous issue date: 2007-06-14 / To identify tomato plant (Lycopersicon esculentum Mill), cv. BRH, genes which answer to plant pathogen Fusarium oxysporum f. sp. lycopersici and salicylic acid, the carrier molecule for activation of responses of plant defense, it was used the suppression subtractive hybridization (SSH) technique, from leaf cDNAs, 24h after salicylic acid, library denominated AS, and root cDNA, 72h after inoculation with F. oxysporum f. sp. lycopersici, incompatible interaction, library denominated FO. This work represents the first report of global gene expression of tomato plant induced by salicylic acid and F. oxysporum f. sp. lycopersici, using SSH technique; it was identified a total of 307 clones in the two subtractive libraries, being 143 obtained in the AS library and 164 in the FO library. Probable functions for genes were obtained by sequencing of clones and subsequent homology research at datas. These isolated genes are involved in several processes related to resistance against plant pathogen such as: hypersensitive response, programmed cell death, synthesis and transport of antimicrobial metabolites, signal perception and transduction, synthesis of pathogenesis-related proteins, lipid metabolism and selective degradation of proteins. It was identified in FO library a higher number of defense-related genes (26%) than in AS library (24%). In relation to the number of genes encoding antimicrobial proteins, they were only found in FO library (7%). However, genes involved in secondary compound metabolism were higher in AS library (13%) in relation to FO library (4%). These genes related to controlled degradation of proteins were also higher in AS library (3%) than in FO library (1%). The results suggest that the resistance of tomato plant induced by salicylic acid and by plant pathogen occur by distinct mechanisms. / Com o propósito de identificar genes no tomateiro (Lycopersicon esculentum Mill), cv. BRH, que respondem ao fitopatógeno Fusarium oxysporum f. sp. lycopersici e ao ácido salicílico, molécula mensageira na ativação de resposta de defesa em plantas, foi utilizada a técnica de hibridização subtrativa por supressão (HSS), a partir de cDNAs de folhas, 24h após o tratamento com ácido salicílico, biblioteca denominada (AS), e cDNAs de raízes, 72h após a inoculação com Fusarium oxysporum f. sp. lycopersici, interação incompatível, biblioteca denominada (FO). Esse trabalho representa o primeiro relato da expressão gênica global no tomateiro induzido pelo ácido salicílico e pelo F. oxysporum f. sp. lycopersici, utilizando a técnica HSS. Foram identificados um total de 307 clones nas duas bibliotecas subtraídas, sendo 143 clones obtidos na biblioteca (AS) e 164 clones na biblioteca FO. As prováveis funções dos genes foram obtidas pelo sequenciamento dos clones e subseqüente pesquisa de homologia em bancos de dados. Os genes encontrados estão envolvidos em diversos processos relacionados à resistência contra fitopatógenos como: resposta de hipersensibilidade, morte celular programada, síntese e transporte de metabólicos antimicrobianos, percepção e transdução de sinal, síntese de proteínas relacionadas à patogênese, metabolismo de lipídeos e degradação controlada de proteínas. Foram identificados na biblioteca FO um número maior de genes implicados em mecanismos de defesa (26%), do que na biblioteca AS (24%). Em relação ao número de genes codificadores de proteínas antimicrobianas foram encontrados apenas na biblioteca FO (7%). Entretanto, os genes envolvidos no metabolismo de compostos secundários foi maior na biblioteca AS (13%) em relação a biblioteca FO (4%). Os genes relacionados a degradação controlada de proteínas também foi maior na biblioteca AS (3%) do que na biblioteca FO (1%). Os resultados obtidos sugerem que a resistência no tomateiro induzido pelo ácido salicílico e pelo patógeno ocorre por mecanismos distintos.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-16T12:53:24Z No. of bitstreams: 1 Eddy Enrique Barraza Andrion (1).pdf: 947495 bytes, checksum: aa5e0f6002d19bd71d54a71eae9dc237 (MD5) / Made available in DSpace on 2017-03-16T12:53:24Z (GMT). No. of bitstreams: 1 Eddy Enrique Barraza Andrion (1).pdf: 947495 bytes, checksum: aa5e0f6002d19bd71d54a71eae9dc237 (MD5) Previous issue date: 2009-07-31 / The cowpea (Vigna unguiculata L.) is one of the main crops in the Northeast of Brazil especially for the small farmers. The Fusarium wilt and Rhizoctonia canker caused by Fusarium oxysporum f.sp. tracheiphilum and Rhizoctonia solani, respectively are the cowpea diseases showing more frequency and intensity in the Northeast of Brazil. This work aimed to evaluate the natural suppressiveness of 66 soils of this region to the Fusarium wilt and Rhizoctonia canker, and to analyze the physical, chemical and biological characteristics of this soils associated with disease suppressiveness or conducivity. The evaluated soils were grouped from highly suppressive to highly conducive in relation to Fusarium wilt and Rhizoctonia canker severities. The main variables involved in Fusarium wilt suppressiveness were high levels of phosphorus and potassium, basal respiration (CO2 evolution) and indexes of microbial diversity and equitability. For Rhizoctonia canker important correlations were determined with levels of phosphorus, potassium and sodium, basal respiration and enzymatic activity of fluorescein diacetate. There was no correlation between physical factors and suppressiveness to Fusarium wilt, but it was possible to correlate the levels of sand, clay and silt with suppressiveness and/or conducivity of Rhizoctonia canker. Three soils previously classified as highly supressive to Rhizoctonia canker were evaluated in relation to eight strains and three inoculum densities of R. solani. There was significant difference among soils and strains in relation to levels of disease severity. In the three soils the severity levels induced by the strain CMM-1053 were similar to those observed in former studies. Most of the strains showed different behavior in relation to soils, except for CMM-1064 and CMM-1066. There was significant difference among disease severity levels and different inoculum densities. The three soils presented good stability in relation to the different R. solani strains, but the inoculum density may be a limiting factor in the implementation of the natural soil suppressiveness or the supressivity induction in conducive soils. / O caupi (Vigna unguiculata L.) é uma das culturas mais importantes da região Nordeste do Brasil, principalmente na economia de pequenos produtores rurais. A murcha-de-fusário e a rizoctoniose, causadas pelos fungos Fusarium oxysporum f.sp. tracheiphilum e Rhizoctonia solani, respectivamente, são as doenças mais freqüentes e de maior intensidade em caupi no Nordeste brasileiro. Esta tese teve como objetivos avaliar a supressividade natural de 66 solos do Nordeste brasileiro à murcha-de-fusário e rizotoniose do caupi, analisar as características físicas, químicas e biológicas dos solos associadas com a supressividade ou conducividade às doenças, bem como avaliar a estabilidade da supressividade de três solos à rizoctonose do caupi, considerando diferentes isolados e densidades de inóculo de R. solani. Em relação à severidade da murcha-de-fusário e da rizoctoniose do caupi, os solos avaliados foram agrupados desde fortemente supressivos a altamente conducivos. As principais variáveis envolvidas na supressividade da murcha-de-fusário foram elevados teores de fósforo e potássio, respiração basal (CO2 evoluído) e os índices de diversidade e eqüitabilidade microbiana. Para a rizoctoniose, foram determinadas correlações importantes com os níveis de fósforo, potássio e sódio, respiração basal e atividade enzimática de diacetato de fluoresceína. Não foram correlacionados fatores físicos com a supressividade à murcha-de-fusário, porém foi possível correlacionar os teores de areia, argila e silte com asupressividade e/ou conducividade da rizoctoniose. Três solos classificados como fortemente supressivos à rizoctoniose foram avaliados em relação a oito isolados e três densidades de inoculo de R. solani. Houve diferença significativa entre os solos e os isolados quanto aos níveis de severidade da doença. Nos três solos os níveis de severidade induzidos pelo isolado CMM-1053 foram similares aos verificados nos estudos prévios. A maioria dos isolados apresentou comportamentos diferente em função dos solos, com exceção dos isolados CMM-1064 e CMM-1066. Foi verificada diferença significativa entre os níveis de severidade da doença e as diferentes densidades de inoculo. Os três solos evidenciaram estabilidade em relação aos diferentes isolados de R. solani, porém a densidade de inóculo pode ser um fator limitante na implementação da supressividade natural dos solos ou da indução da supressividade em solos conducivos.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-05-26T20:53:49Z No. of bitstreams: 1 2010 - Joice de Jesus Lemos.pdf: 529861 bytes, checksum: 869aef193d0f1b7b1b385f7ee3a2de73 (MD5) / Made available in DSpace on 2017-05-26T20:53:49Z (GMT). No. of bitstreams: 1 2010 - Joice de Jesus Lemos.pdf: 529861 bytes, checksum: 869aef193d0f1b7b1b385f7ee3a2de73 (MD5) Previous issue date: 2010-08-31 / CAPES / With the aims to study the efflux of H+ or OH- due nitrogen sources on the process of infection of Fusarium oxysporum f. sp. phaseoli in the rhizosphere of two beans cultivars Diamante Negro (susceptible) and Ouro Negro (more resistant), a series of experiments were done in greenhouse and growth chamber. Were applied to three different sources of nitrogen (N-N2 N-NO3- and N-NH4+) in three nitrogen concentrations (0, 30 and 120 kg ha-1), in plants grown in clay and sand soil. In addition, an experiment was conducted with different concentrations of inoculum of Fusarium (0, 10 ? and 106 conidia mL-1) in greenhouse in order to know the concentration that would affect the infection and when applied the fungi. Overall, the results suggested that nitrate decreased the infection process of Fusarium and ammonium increase. The association between nitrate with the cultivar more tolerant Ouro Negro, decreased the perceptual infection of fungi. The source of nitrogen influence of pH of rhizosphere occurred interaction with the type of soil. In all the experiments, found lower numbers of nodules. The concentration of inoculum or the times of inoculation not produce effect in the perceptual of infection. / Foram realizados estudos com duas cultivares de feijoeiro comum (Phaseolus vulgaris L.), a Diamante Negro, considerada suscet?vel ao Fusarium oxysporum f. sp. phaseoli e a Ouro Negro, mais resistente a esse fungo causador da murcha-de-fus?rio. Os experimentos foram instalados em c?mara crescimento ou em casa de vegeta??o. O objetivo deste trabalho foi o de analisar a influ?ncia da libera??o OH- ou H+ devido ao uso de fontes nitrogenadas na infec??o do fungo. Foram utilizadas tr?s fontes de nitrog?nio (N-N2, N-NO3 ? e N-NH4+) e diferentes doses de nitrog?nio (0, 30 e 120 kg ha-1) com plantas inoculadas com o referido fungo, crescidas no substrato areia ou em solos com diferentes teores de argila. Tamb?m foi realizado um experimento utilizando diferentes concentra??es de in?culo do Fusarium (0, 10? e 106 con?dios mL-1) com o objetivo de analisar qual concentra??o afetaria mais a infec??o na presen?a de fontes nitrogenadas. Foram analisados, o percentual de infec??o do Fusarium, o pH da rizosfera e n?o rizosf?rico, massas da parte a?rea e ra?zes secas, e o n?mero de n?dulos em diferentes ?pocas de amostragem. De modo geral foi observado que a fonte nitrato diminuiu o processo de infec??o do Fusarium e a fonte am?nio aumentou. Foi confirmado que a cultivar Ouro Negro ? mais tolerante ao fungo e que quando associada ? fonte de nitrog?nio nitrato aumentou ainda mais a resist?ncia. O pH da rizosfera e n?o rizosf?rico foram influenciados pela fonte de nitrog?nio: nitrato aumenta, e am?nio diminui. Os dados do trabalho sugeriram haver intera??o entre a fonte de nitrog?nio x dose x cultivar x solo. O n?mero de n?dulos encontrado nas condi??es experimentais foi baixo, especialmente nas amostragens na fase inicial do ciclo.

Banana is the most important fruit crop in the world but ironically one of the crops least studied. This fruit constitutes a major staple food for millions of people in developing countries and also it is considered the highest selling fruit in the world market making this crop a very important export commodity for the producing countries. At the present time, one of the most significant constraints of banana production that causes significant economical losses are fungal diseases. Among these, Panama disease, also known as Fusarium wilt has been the most catastrophic. Panama disease is caused by the soil-borne fungus Fusarium oxysporum formae specialis (f.sp) cubense (FOC), which infects susceptible bananas through the roots causing a lethal vascular wilt. To date, the race 4 of this pathogen represents the most serious threat to banana production worldwide since most of the commercial cultivars are highly susceptible to this pathogen. Introduction of FOC resistance into commercial cultivars by conventional breeding has been difficult because edible bananas are sterile polyploids without seeds. Genetic transformation of banana, which has already been established in various laboratories around the world has the potential to solve this problem by transferring a FOC race 4 resistance gene into susceptible banana cultivars (eg. Cavendish cultivars). However, a FOC resistant (R) gene has not been isolated. Genes that confer resistance to Fusarium oxysporum have been isolated from tomato and melon using a map-based positional cloning approach. The tomato I2 and melon Fom-2 genes belong to the non-Toll/interleukin like receptors (TIR) subclass of nucleotide-binding site and leucine-rich repeat (NBS-LRR) R genes. These genes confer resistance only to certain races of F. oxysporum in their corresponding plant families limiting their use in other plant families. The fact that these two Fusarium resistance genes share the same basic non-TIR-NBS-LRR structure suggests a similar Fusarium resistance mechanism is shared between the families Solanaceae and Cucurbitaceae. This observation opens the possibility to find similar Fusarium resistance genes in other plant families including the Musaceae. A remarkable discovery of a population of the wild banana Musa acuminata subspecies (ssp.) malaccensis segregating for FOC race 4 resistance was made by Dr. Ivan Buddenhagen (University of California, Davis) in Southeast Asia. Research carried out at Queensland Department of Primary Industries (Australia) using this plant material has demonstrated that a single dominant gene is involved in FOC race 4 resistance (Dr. Mike Smith, unpublished results). Tissue-culture plantlets of this FOC race 4 segregating population were kindly provided to the Plant Biotechnology Program (Queensland University of Technology) by Dr. Mike Smith to be used in our research. This population holds the potential to assist in the isolation of a FOC race 4 resistance gene and other potential Fusarium resistance genes. The overall aims of this research were to isolate and characterise resistance gene candidates of the NBS-type from M. acuminata ssp. malaccensis and to identify and characterise potential Fusarium resistance genes using a combination of bioinformatics and gene expression analysis. Chapter 4 describes the isolation by degenerate PCR of five different classes of NBS sequences from banana (Musa acuminata ssp malaccensis) designated as resistance gene candidates (RGCs). Deduced amino acid sequences of the RGCs revealed the typical motifs present in the majority of known plant NBS-LRR resistance genes. Structural and phylogenetic analyses showed that the banana RGCs are related to non-TIR subclass of NBS sequences. The copy number of each class was estimated by Southern hybridisation and each RGC was found to be in low copy number. The expression of the RGCs was assessed by RT-PCR in leaf and root tissues of plants resistant or susceptible to Fusarium oxysporum f. sp. cubense (FOC) race 4. Four classes showed a constitutive expression profile whereas no expression was detected for one class in either tissue. Interestingly, a transcriptional polymorphism was found for RGC2 whose expression correlated with resistance to FOC race 4 suggesting a possible role of this gene in resistance to this devastating FOC race. Moreover, RGC2 along with RGC5 showed significant sequence similarity to the Fusarium resistance gene I2 from tomato and were chosen for further characterisation. The NBS sequences isolated in this study represent a valuable source of information that could be used to assist the cloning of functional R genes in banana. Chapter 5 describes the isolation and characterisation of the full open reading frame (ORF) of RGC2 and RGC5 cDNAs. The ORFs of these two banana RGCs were predicted to encode proteins that showed the typical structure of non-TIR-NBS-LRR resistance proteins. Homology searches using the entire ORF of RGC2 and RGC5 revealed significant sequence similarity to the Fusarium resistance gene I2 from tomato. Interestingly, the phylogenetic analysis showed that RGC2 and RGC5 were grouped within the same phylogenetic clade, along with the Fusarium resistance genes l2 and Fom-2. These findings suggest that the banana RGC2 and RGC5 are potential resistance gene candidates that could be associated with Fusarium resistance. The case of RGC2 is more remarkable because its expression was correlated to FOC race 4 resistance (Chapter 4). As a first step to test whether RGC2 has a role in FOC race 4 resistance, different expression constructs were made with the ORF of this sequence. One of the constructs contains a RGC2 putative promoter region that was successfully cloned in this work. These constructs will be used to transform susceptible banana plants that can then be challenged with FOC race 4 to assess whether resistance has been acquired by genetic complementation. The results of this thesis provide interesting insights about the structure, expression and phylogeny of two potential Fusarium resistance genes in banana, and provide a rational starting point for their functional characterisation. The information generated in this thesis may lead to the identification of a Fusarium resistance gene in banana in further studies and may also assist the cloning of Fusarium resistance genes in other plant species.

In previous studies silicon has been associated with reduced disease severity and incidence, the enhanced accumulation of phenolic compounds and lignin, and with changes in the defence-related enzyme activity and transcript abundance of defence and stress related genes. All of these aspects of plant defence were considered in this study on cotton infected with Fusarium oxysporum f. sp. vasinfectum (Fov), and the results obtained have greatly enhanced our understanding of the effects of silicon on this interaction. In all experiments conducted, defence responses were only significantly enhanced by silicon treatment following inoculation with Fov, strongly suggesting that silicon can prime defence responses in cotton infected with Fov. Sicot F-1 was the cultivar most resistant to Fov infection at the commencement of this research, whilst Sicot 189 was considered to have moderate resistance to the pathogen. Vascular discolouration was significantly reduced in the more resistant cultivar, Sicot F-1 following treatment with potassium silicate, compared to mock inoculated plants and inoculated plants treated with potassium sulphate or calcium sulphate. No significant differences between treatments were observed in the moderately resistant cultivar, Sicot 189, though further trials may need to be conducted to confirm this result. In both cultivars, silicon content was significantly greater in plants which had been treated regularly with liquid potassium silicate, rather than with calcium silicate powder. Histological investigation of cotton infected with Fov, with and without silicon treatment, was conducted to ascertain the effects of this element on the accumulation of fungitoxic phenolic compounds, cell ultrastructural changes and fungal infection structures. Fov proliferated through the cortex and stele of plants from both the resistant (Sicot F-1), and moderately resistant (Sicot 189) cultivars, regardless of silicon treatment. However, defences were more rapidly and intensely induced in endodermal and vascular regions of inoculated, potassium silicate treated Sicot F-1 plants. Significantly more phenolic compounds were present at seven days post infection (dpi) in root extracts of inoculated, potassium silicate treated Sicot F-1 plants. Phenolic compounds were not significantly increased in inoculated, potassium silicate treated root extracts of Sicot 189 plants at three or seven dpi. Lignin assays demonstrated that the dry weight percentage of lignin in root material from inoculated, potassium silicate treated Sicot F-1 plants was significantly higher than that of extracts from inoculated plants not receiving silicon treatment at three dpi. This trend was also observed at seven dpi; however lignin content was not significantly different in this case. Percentage lignin content in the roots of Sicot 189 plants was not significantly different between inoculated potassium silicate treated plants and those not treated with silicon. Histological alterations were not observed in mock inoculated water or potassium silicate treated plants, nor were any significant increases in phenolic compounds or lignin accumulation detected in control treatments not inoculated with the pathogen. The expression of several defence related genes was assessed with quantitative reverse transcriptase real-time polymerase chain reaction. The results obtained verify that potassium silicate can enhance defence responses in Sicot 189 and Sicot F-1 plants inoculated with Fov, with silicon having a more pronounced effect on the more resistant cultivar, Sicot F-1. Genes upregulated at three and four dpi in potassium silicate treated, Fov inoculated Sicot F-1 plants included peroxidase, cadinene synthase and polygalacturonase inhibiting protein (PGIP), with peroxidase associated with phenol oxidation and lignification and cadinene synthase with phytoalexin biosynthesis. Osmotin-like protein and chitinase class I were consistently upregulated in potassium silicate treated, inoculated Sicot 189 plants; both genes coding for pathogenesis related (PR) proteins, with chitinase also classified as an antifungal protein. In both cultivars, silicon treatment without Fov inoculation did not result in the significant up-regulation of any of the defence genes assessed, providing further evidence for the role of silicon in priming in this interaction. The activities of three defence related enzymes, peroxidase, chitinase and β-1, 3- glucanase was assessed in root and shoot material by colourimetric assays. Regular application of potassium silicate significantly increased the activity of peroxidase in root extracts from the highly resistant cultivar Sicot F-1, at three, four and seven dpi with Fov, and in root extracts from the moderately resistant Sicot 189 at three and four dpi. Significant increases in chitinase activity in inoculated, silicon treated Sicot 189 plants were observed in root extracts at three dpi, and in shoot extracts at four dpi. Soluble potassium silicate treatment resulted in significant increases in β-1, 3- glucanase activity in Sicot 189 root extracts at four dpi. Few significant differences between treatments in terms of chitinase and β-1, 3- glucanase activity were detected in Sicot F-1 plants, though higher levels of each of these enzymes were present in root and shoot extracts from this cultivar. In this study the effects of acibenzolar-S-methyl, applied in the form of Bion®, on defence gene expression and enzyme activity in cotton infected with Fov were more pronounced in plants cultivated from treated seed, rather than in plants treated via foliar spray; a finding which is particularly relevant to the industry presently. Significant up-regulation of chitinase class I, peroxidase, and β-1, 3-glucanase transcripts and enzyme activities occurred in the Bion® seed soak treatment with Fov inoculation compared to all other treatments. It was possible to compare the actions of silicon with those of Bion® in this study. Bion® primed defence responses in cotton infected with Fov, in a manner similar to that observed in silicon treated cotton. The use of silicon and Bion® treatments, both alone and in combination as part of integrated disease management programmes, may potentially contribute to increased protection against this pathogen in Australian cotton fields in the future.

The cowpea is very important for the poor populations of the North and Northeast of the Brazil. Several factors corroborate to production low of the culture, among them we can quote the disease, focusing on cowpea Fusarium wilt , caused by the fungus Fusarium oxysporum f.sp. tracheiphilum. This study aimed to evaluate the influence of incorporation of crop succession on the severity of cowpea Fusarium wilt. In all experiments we used soil without previous history of cultivation with this culture. There were no observed F. oxysporum populations indigenous in the soil. The experiments were conducted in microplots of concrete pipes containing soil artificially infested with the pathogen structures, the density of 5x103 cfu g-1 of soil. The experiment consisted of three cultivation cycles being: (i) cowpea, (ii) succession cultural and (iii) cowpea. The culture succession were: corn - MI, sorghum - SO, cotton - AL, castor - MN and sunflower - GI; legumes: Crotalaria juncea - CJ, Crotalaria spectabilis - CS, bean-pig - FP, pigeon pea Dwarf - GA, lab-lab - LA and black velvet - velvet MP and dwarf - MA. There were still some treatments: plots with cowpea without inoculum of F. o. f. sp. tracheiphilum - TEST, plots of cowpea inoculated with F. o. f. sp. tracheiphilum (cowpea) - CA, and plots infested with the pathogen in fallow system - PO. The incorporation of succession before of the cowpea planting provided a range in the disease severity of 56.67% to 26.33%. Among the legumes studied the FP and MP were the most suitable for reducing the severity of the disease and offer better grain yield. For succession crops to the OS and GI showed a greater reduction in severity of Fusarium wilt of cowpea. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O feijão-caupi é muito importante para as populações carentes do Norte e Nordestes brasileiro. Diversos fatores corroboram para as baixas produções da cultura, dentre eles podemos destacar as doenças, com foco à murcha-de-fusário do feijão-caupi, causada pelo fungo Fusarium oxysporum f.sp. tracheiphilum. O presente trabalho teve como objetivo avaliar a influência da incorporação de sucessões de cultivo na severidade da murcha-de-fusário do feijão-caupi. Em todos os experimentos utilizouse solo sem histórico anterior de cultivo com a cultura. Não foram detectadas populações autóctones de F. oxysporum no solo. Os experimentos foram conduzidos em microparcelas constituídas de manilhas de concreto contendo solo infestado artificialmente com estruturas do patógeno, na densidade de 5x103 ufc g-1 de solo. O experimento foi constituído de três ciclos de cultivos: (i) feijão-caupi, (ii) sucessões culturais e (iii) feijão-caupi. As sucessões culturais foram compostas por cultivos agrícolas: milho - MI, sorgo - SO, algodão - AL, mamona - MN e girassol - GI; leguminosas: crotalária juncea - CJ, crotalária spectabilis - CS, feijão-de-porco - FP, guandu anão - GA, lab-lab - LA e mucuna-preta - MP e mucuna-anã - MA. Constaram ainda como tratamentos: parcelas com feijão-caupi sem inóculo de F. o. f. sp. tracheiphilum - TEST, parcelas de feijão-caupi inoculadas com F. o. f. sp. tracheiphilum (caupi) CA, e parcelas Infestadas com o fitopatógeno em sistema de pousio - PO. A incorporação das sucessões antecedendo o plantio do feijão-caupi proporcionou uma amplitude na severidade da doença de 56,67% a 26,33%. Dentre as leguminosas estudadas o FP e a MP foram os mais indicados, por reduzirem a severidade da doença e apresentarem melhor produção de grãos. Para os cultivos agrícolas as sucessões com o SO e GI, apresentaram a maior redução da severidade da murcha- de-fusário do caupi.

La fusariose vasculaire du cyclamen est une maladie causée par le champignon tellurique Fusarium oxysporum f. sp. cyclaminis. Elle est considérée comme l’une des maladies les plus graves du cyclamen et se traduit par des pertes atteignant jusqu’à 50 % de la production. Actuellement, les moyens de lutte ne permettent pas de contrôler la maladie. Dans ce contexte, une collaboration s’est engagée entre l’institut technique de l’horticulture, Astredhor, représentant les producteurs, l’INRA de Dijon pour son expertise sur F. oxysporum et la société Agrene pour son expertise en lutte biologique. Les objectifs de cette collaboration étaient doubles : i) identifier un marqueur spécifique de la forme spéciale cyclaminis et développer un outil de détection de l’agent pathogène permettant de mettre en place des méthodes de lutte appropriées ; ii) identifier un agent de lutte biologique efficace contre le pathogène. Le travail s’est donc structuré autour de ces deux objectifs.Une collection de souches représentatives de la diversité des populations de F. oxysporum f. sp. cyclaminis a été constituée. Elle regroupe des souches provenant de collections internationales et des isolats obtenus de cyclamens symptomatiques ou non. L’analyse moléculaire de cette collection a permis de caractériser son importante diversité génétique et a mis en exergue la difficulté d’identifier un marqueur moléculaire spécifique. Néanmoins, un fragment d’ADN spécifique de l’agent pathogène a pu être mis en évidence par amplification aléatoire d’ADN polymorphe. A partir de ce fragment, un couple d’amorces spécifiques a été dessiné et un outil moléculaire a été développé. Ce dernier permet une détection du champignon in planta en PCR conventionnelle et en PCR en temps réel.Parallèlement, une étude bibliographique approfondie relative aux méthodes de lutte biologique contre les fusarioses induites par F. oxysporum sur les plantes ornementales a été effectuée. Cette revue a souligné la possibilité d’utiliser des ressources d’origine microbienne et d’origine végétale pour contrôler F. oxysporum, mais cette stratégie impliquant une étape de sélection nous est apparue lourde et laborieuse. Nous avons opté pour une autre démarche visant à identifier, parmi des produits déjà sur le marché, ceux susceptibles de réduire significativement la gravité de la maladie. Des bioessais ont été conduits en serre, dans des conditions proches de celles de la production pour tester sept produits reposant sur la formulation de bactéries, de champignons ou de combinaisons de ces microorganismes. Les produits les moins performants ont été éliminés à l’issue d’un premier essai. Des bioessais ont été conduits à nouveau avec trois produits. Un seul de ces produits donne satisfaction mais son efficacité devra être validée en conditions de production réelles.En conclusion, l’outil de détection spécifique permettra aux producteurs de s’assurer de la qualité sanitaire de la culture et des supports de culture. L’agent de lutte biologique retenu à l’issue de nos essais permettra dans un premier temps aux producteurs de prévenir le risque d’activité infectieuse de F. oxysporum f. sp. cyclaminis. Cependant, un travail de recherche d’un agent de lutte plus performant s’avère nécessaire. Des pistes sont proposées. / Fusarium wilt of cyclamen is one of the most damaging diseases of cyclamen. The causal agent, Fusarium oxysporum f. sp. cyclaminis, is a soil-borne fungus. Losses can reach more than 50 % of the production. Several methods of control are available, but none of them offer an efficient and environmentally friendly solution. In this context, a project was developed in collaboration with the French institute of horticulture, Astredhor, which represents the producers, the INRA of Dijon, for its expertise on F. oxysporum and the company Agrene for its expertise in biological control. The project has two goals: i) design a molecular marker specific of Fusarium oxysporum f. sp. cyclaminis allowing a better management of the disease, ii) identify one or several efficient biological control agents.A collection of strains representative of the diversity of F. oxysporum f. sp. cyclaminis populations was made up with strains from international collections and isolates collected from symptomatic and asymptomatic cyclamens. A molecular study of the collection demonstrated the high genetic diversity of the forma specialis, which makes the identification of a specific molecular marker more complicated. However, a specific DNA fragment was identified by random amplified polymorphic DNA. A primer pairs was designed and a specific tool of detection was developed. Thanks to this tool, it is now possible to detect the fungus in planta by conventional and real-time PCR.Simultaneously, a broad literature analysis on the biocontrol of ornamental plant diseases caused by F. oxysporum was performed. The review emphasized that biocontrol of F. oxysporum encompassed both microbial biocontrol agents and botanicals. To avoid the laborious and time-consuming screening step, we decided to assess the antagonistic activity of seven commercial products containing bacteria, fungi or a combination of both microorganisms. Greenhouse trials were performed under conditions similar to those of the production. First trial led to the exclusion of the less efficient products. Other trials were conducted with the three remaining products. Disease reduction was obtained with one of these products although it must be validated in production.Finally, the molecular tool of detection will allow producers to insure the health status of the culture. In addition, the efficient biocontrol agent identified will prevent the disease progress for a while but more investigations are needed to obtain reliable, efficient and sustainable biocontrol agents. Proposals to improve Fusarium wilt control are discussed.