In 2007 and 2008 more than 100 million dollars of fresh market tomatoes were grown in Virginia, with the majority of production occurring on the Eastern Shore of Virginia (ESV), according to the National Agricultural Statistics Service. Bacterial wilt of tomato, caused by Ralstonia solanacearum (Smith) and Yabucchi et al., is the most devastating disease of tomato on the ESV. Four 'observational trials' were conducted on the ESV over three growing seasons to determine the temporal and spatial distribution of this disease in commercial tomato fields. Plants were assessed at approximately one-week intervals throughout the growing seasons and the incidence of bacterial wilt for each individual plant was recorded. A steady increase in both disease incidence and clustered distribution of the disease within rows was observed as the growing season progressed. Positive correlations between disease incidence and percentage of rows exhibiting a significant clustered distribution occurred in all trials, which indicated an increase in clustered distribution as disease incidence increased. Research trials were conducted over three years, beginning in the summer of 2007, to investigate the effects of tomato bacterial wilt resistant cultivars on the ESV. In 2008 and 2009, the selective, systemic compound which induces host plant resistance, acibenzolar-S-methyl (ASM) was incorporated into resistant cultivar trials. Results from the 2007 trial revealed significant resistance in some of the breeding lines, CRA 66 and PI 126408. The 2008 and 2009 trials revealed that ASM was not effective at reducing levels of bacterial wilt. Grafted transplants in the spring trials of 2008 and 2009 had varied results in resistance and yield. Results revealed the tomato cultivar BHN 669 was an excellent resistant cultivar with promising yield potential and fruit quality. / Master of Science

Any interaction of plants with phytopathogens involves the generation of various chemical molecules that are critical for activation of their defense machinery. One of the chemicals, salicylic acid (SA)induces systemic acquired resistance (SAR)in plants. The activation of SAR provides a broad-spectrum resistance against a wide range of related or unrelated pathogens. There has been considerable progress in the biochemical and molecular understanding of SAR activation in various plants. In addition, several chemicals including SA and its analogs are known to provide a direct or indirect defense against pathogens when applied to plants. Molecular mechanism of plant defense induced by synthetic chemical inducers is not very well understood. This review highlights the importance of salicylic acid and its most studied analog, Acibenzolar-S-methyl in inducing SAR and it also provides a description of other major chemical elicitors of plant defenses and their possible molecular mechanism.

Active disease resistance in plants is induced during the pathogen infection process that triggers multiple defense-related genes to establish broad-spectrum resistance. Several biotic and abiotic agents can mimic natural induced resistance (IR), categorized as systemic acquired (SAR) or induced systemic resistance (ISR). IR, triggered by acibenzolar-S-methyl (ASM) or plant growth-promoting rhizobacteria (PGPR), was evaluated on two-to-three types of tobacco in greenhouse and field studies. Tobacco mosaic virus (TMV) local lesion assays monitored induction and maintenance of ASM-induced SAR over a 21 day period via proportional reduction in the number of TMV local lesions between an untreated control and ASM-treated plants. Intraspecific variation in SAR was found among tobacco types; burley and flue-cured tobaccos responded by day 3, while oriental tobacco responded between day 3 and 6. The SAR signal was greatest between 6 and 15 days following ASM application, but IR was slightly evident even at 21 days after ASM application in all three tobacco types. Bottom and middle leaves responded similarly on all sample dates, but top leaves showed the weakest SAR response. Tobacco cyst nematode (TCN; Globodera tabacum solanacearum) is one of the most destructive pathogens of tobacco in Virginia. Among four PGPR combinations tested, a mixture of Bacillus amyloliquefaciens IN937a (GB99) and B. subtilis A13 (GB122) most consistently suppressed TCN reproduction in flue-cured and oriental tobacco. Application of ASM similarly reduced final numbers of TCN cysts, but also resulted in chlorosis, stunting, and lower plant fresh weight. GB99+GB122 also suppressed TCN development and reproduction in susceptible and resistant flue-cured cultivars, but reductions by ASM were less consistent. In a split-root trial, soil amendment with GB99+GB122 in one half of an oriental tobacco root system lowered final numbers of TCN more than did ASM. ASM exhibited undesirable effects in phytotoxicity trials in flue-cured and oriental tobacco, but GB99+GB122 was not phytotoxic. When oriental tobacco seedlings were grown in a GB99+GB122-treated soil-less media, a single application of 200 mg ASM/L one week after transplanting significantly suppressed TCN reproduction in the field without phytotoxicity. Further field research is needed to confirm this effect in flue-cured tobacco. / Ph. D.

A doença crestamento bacteriano comum do feijoeiro, causada pela bactéria Xanthomonas axonopodis pv. phaseoli, ocorre principalmente nas regiões quentes e úmidas do globo. A resistência induzida consiste no aumento da resistência da planta por meio da utilização de agentes externos, sem qualquer alteração em seu genoma. Os objetivos do trabalho foram: (i) verificar a indução de resistência em feijoeiro com o uso do indutor abiótico acibenzolar-S-metil (ASM) contra X. axonopodis pv. phaseoli em casa de vegetação e em campo; (ii) avaliar os parâmetros bioquímicos (carboidratos, proteínas, fenóis, clorofila e atividade da enzima peroxidase) e fisiológico (potencial hídrico) nas interações entre plantas de feijão induzidas com o indutor contra X. axonopodis pv. phaseoli; (iii) avaliar os custos da indução de resistência em função da aplicação do indutor contra X. axonopodis pv. phaseoli em plantas de feijão com base nos parâmetros bioquímicos, fisiológicos e de produção. Para isso, realizaram-se dois experimentos. Os tratamentos foram dispostos da seguinte maneira: Tratamento A Controle água, Tratamento B Controle ASM, Tratamento C Água com inoculação do patógeno ao 7º dias após a emergência das plântulas (dae) (experimento 1) e ao 21º dae (experimento 2), Tratamento D Induzida com ASM e desafiada com o patógeno ao 7º dae (experimento 1) e ao 21º dae (experimento 2). As pulverizações ocorreram, para o experimento 1, aos 0, 7, 14 e 28 dae, a inoculação foi realizada no 7º dae e foram realizadas quatro coletas das amostras aos 0, 7, 21 e 35 dae. Entretanto para o experimento 2, as pulverizações foram feitas aos 0, 7, 14, 28 e 42 dae, a inoculação foi realizada no 21º dae e as cinco coletas foram conduzidas aos 0, 7, 21, 35 e 49 dae. Foram observadas diferenças estatísticas tanto entre tratamentos quanto entre épocas de coleta, bem como na interação dos tratamentos com as diferentes épocas, dependendo do parâmetro observado. De maneira geral, as plantas tratadas com ASM quando comparadas com plantas controle água, bem como as plantas pré-tratadas com ASM e desafiadas com a bactéria quando comparadas com as plantas pulverizadas com água e inoculadas com o patógeno, apresentaram: a) teores de clorofila próximos; b) aumentaram os teores de fenóis, proteínas totais e peroxidase e c) diminuíram os valores de carboidratos totais. As plantas que apresentaram os valores mais negativos de potencial hídrico foram as pulverizadas com água e inoculadas com o patógeno, seguidas das plantas induzidas com ASM e desafiadas com o patógeno. O mesmo padrão ocorreu com relação à produtividade, onde água+patógeno apresentou a maior redução de massa seca, número de vagens/planta e peso de 100 grãos, seguidos de plantas induzidas com ASM e desafiadas com o patógeno, ASM e água, respectivamente. Porém o número de grãos/vagem não sofreu alteração. Houve indução de resistência nas plantas em função da aplicação com ASM, visto que a severidade da doença diminuiu nas mesmas. / The common bacterial blight disease of bean caused by the bacterium Xanthomonnas axonopodis pv. phaseoli, occurs mainly in hot and humid regions of the globe. The induced resistance consists in the increase of the plant resistance by the use of external agents, without any change in its genome. The objectives of this study were: (i) to verify the induction of resistance in bean plants by using the abiotic inducer acibenzolar-S-methyl (ASM) against Xanthomonas axonopodis pv. phaseoli in greenhouse and field conditions, (ii) to evaluate the biochemical parameters (carbohydrates, proteins, phenols, chlorophyll and peroxidase activity) and physiological (water potential) in the interactions between bean plants treated with the inducer against X. axonopodis pv. phaseoli; (iii) to evaluate the costs of the induction of resistance by on the basis of biochemical, physiological and production parameters. Thus, to achieve this purpose, two experiments were carried out. The treatments were arranged as follows: Treatment A - Control water; Treatment B - ASM Control; Treatment C - Water and inoculation 7 days after emergency (dae) of the seedlings (experiment 1) and 21 dae (Experiment 2); Treatment D - Induced with ASM and challenged with the pathogen 7 dae (experiment 1) and 21 dae (experiment 2). The treatments with ASM were made for experiment 1, at 0, 7, 14 and 28 dae, the inoculation was done 7 dae and four samples were collected at 0, 7, 21 and 35 dae. However, for the experiment 2, the treatments with ASM were made at 0, 7, 14, 28 and 42 days after seedling emergence, the inoculation was performed 21 dae and five samples were collected 0, 7, 21, 35 and 49 dae. Statistical differences were observed between treatments, among harvest dates, as well as the interaction of treatments with different harvests, depending on the parameter observed. In general, plants treated with ASM when compared to plants control, as well as plants pretreated with ASM and challenged with the bacteria when compared to plants sprayed with water and inoculated with the pathogen, showed: a) the amount of chlorophyll was close; b) increased levels of phenolics, proteins and peroxidase; c) decreased values of carbohydrate. Plants that showed the more negative water potential were plants sprayed with water and inoculated with the pathogen, followed by plants induced with ASM and challenged with the pathogen. The same pattern occurred with productivity, plants sprayed with water and inoculated with the pathogen exhibited the higgest reduction in dry weight, number of pods per plant and 100 grain weight, followed by plants induced with ASM and challenged with the pathogen, ASM and water, respectively. In all treatments, the number of grains per pods did not change. Finally, there was induction of resistance in plants by ASM application since the disease severity decreased.

A doença crestamento bacteriano comum do feijoeiro, causada pela bactéria Xanthomonas axonopodis pv. phaseoli, ocorre principalmente nas regiões quentes e úmidas do globo. A resistência induzida consiste no aumento da resistência da planta por meio da utilização de agentes externos, sem qualquer alteração em seu genoma. Os objetivos do trabalho foram: (i) verificar a indução de resistência em feijoeiro com o uso do indutor abiótico acibenzolar-S-metil (ASM) contra X. axonopodis pv. phaseoli em casa de vegetação e em campo; (ii) avaliar os parâmetros bioquímicos (carboidratos, proteínas, fenóis, clorofila e atividade da enzima peroxidase) e fisiológico (potencial hídrico) nas interações entre plantas de feijão induzidas com o indutor contra X. axonopodis pv. phaseoli; (iii) avaliar os custos da indução de resistência em função da aplicação do indutor contra X. axonopodis pv. phaseoli em plantas de feijão com base nos parâmetros bioquímicos, fisiológicos e de produção. Para isso, realizaram-se dois experimentos. Os tratamentos foram dispostos da seguinte maneira: Tratamento A Controle água, Tratamento B Controle ASM, Tratamento C Água com inoculação do patógeno ao 7º dias após a emergência das plântulas (dae) (experimento 1) e ao 21º dae (experimento 2), Tratamento D Induzida com ASM e desafiada com o patógeno ao 7º dae (experimento 1) e ao 21º dae (experimento 2). As pulverizações ocorreram, para o experimento 1, aos 0, 7, 14 e 28 dae, a inoculação foi realizada no 7º dae e foram realizadas quatro coletas das amostras aos 0, 7, 21 e 35 dae. Entretanto para o experimento 2, as pulverizações foram feitas aos 0, 7, 14, 28 e 42 dae, a inoculação foi realizada no 21º dae e as cinco coletas foram conduzidas aos 0, 7, 21, 35 e 49 dae. Foram observadas diferenças estatísticas tanto entre tratamentos quanto entre épocas de coleta, bem como na interação dos tratamentos com as diferentes épocas, dependendo do parâmetro observado. De maneira geral, as plantas tratadas com ASM quando comparadas com plantas controle água, bem como as plantas pré-tratadas com ASM e desafiadas com a bactéria quando comparadas com as plantas pulverizadas com água e inoculadas com o patógeno, apresentaram: a) teores de clorofila próximos; b) aumentaram os teores de fenóis, proteínas totais e peroxidase e c) diminuíram os valores de carboidratos totais. As plantas que apresentaram os valores mais negativos de potencial hídrico foram as pulverizadas com água e inoculadas com o patógeno, seguidas das plantas induzidas com ASM e desafiadas com o patógeno. O mesmo padrão ocorreu com relação à produtividade, onde água+patógeno apresentou a maior redução de massa seca, número de vagens/planta e peso de 100 grãos, seguidos de plantas induzidas com ASM e desafiadas com o patógeno, ASM e água, respectivamente. Porém o número de grãos/vagem não sofreu alteração. Houve indução de resistência nas plantas em função da aplicação com ASM, visto que a severidade da doença diminuiu nas mesmas. / The common bacterial blight disease of bean caused by the bacterium Xanthomonnas axonopodis pv. phaseoli, occurs mainly in hot and humid regions of the globe. The induced resistance consists in the increase of the plant resistance by the use of external agents, without any change in its genome. The objectives of this study were: (i) to verify the induction of resistance in bean plants by using the abiotic inducer acibenzolar-S-methyl (ASM) against Xanthomonas axonopodis pv. phaseoli in greenhouse and field conditions, (ii) to evaluate the biochemical parameters (carbohydrates, proteins, phenols, chlorophyll and peroxidase activity) and physiological (water potential) in the interactions between bean plants treated with the inducer against X. axonopodis pv. phaseoli; (iii) to evaluate the costs of the induction of resistance by on the basis of biochemical, physiological and production parameters. Thus, to achieve this purpose, two experiments were carried out. The treatments were arranged as follows: Treatment A - Control water; Treatment B - ASM Control; Treatment C - Water and inoculation 7 days after emergency (dae) of the seedlings (experiment 1) and 21 dae (Experiment 2); Treatment D - Induced with ASM and challenged with the pathogen 7 dae (experiment 1) and 21 dae (experiment 2). The treatments with ASM were made for experiment 1, at 0, 7, 14 and 28 dae, the inoculation was done 7 dae and four samples were collected at 0, 7, 21 and 35 dae. However, for the experiment 2, the treatments with ASM were made at 0, 7, 14, 28 and 42 days after seedling emergence, the inoculation was performed 21 dae and five samples were collected 0, 7, 21, 35 and 49 dae. Statistical differences were observed between treatments, among harvest dates, as well as the interaction of treatments with different harvests, depending on the parameter observed. In general, plants treated with ASM when compared to plants control, as well as plants pretreated with ASM and challenged with the bacteria when compared to plants sprayed with water and inoculated with the pathogen, showed: a) the amount of chlorophyll was close; b) increased levels of phenolics, proteins and peroxidase; c) decreased values of carbohydrate. Plants that showed the more negative water potential were plants sprayed with water and inoculated with the pathogen, followed by plants induced with ASM and challenged with the pathogen. The same pattern occurred with productivity, plants sprayed with water and inoculated with the pathogen exhibited the higgest reduction in dry weight, number of pods per plant and 100 grain weight, followed by plants induced with ASM and challenged with the pathogen, ASM and water, respectively. In all treatments, the number of grains per pods did not change. Finally, there was induction of resistance in plants by ASM application since the disease severity decreased.

Tobacco SABP2, a 29. kDa protein catalyzes the conversion of methyl salicylic acid (MeSA) into salicylic acid (SA) to induce SAR. Pretreatment of plants with acibenzolar-. S-methyl (ASM), a functional analog of salicylic acid induces systemic acquired resistance (SAR). Data presented in this paper suggest that SABP2 catalyzes the conversion of ASM into acibenzolar to induce SAR. Transgenic SABP2-silenced tobacco plants when treated with ASM, fail to express PR-1 proteins and do not induce robust SAR expression. When treated with acibenzolar, full SAR is induced in SABP2-silenced plants. These results show that functional SABP2 is required for ASM-mediated induction of resistance.

Espécies de Phytophthora tem se destacado ao longo da história devido ao seu potencial destrutivo, se iniciando com a devastadora P. infestans na Irlanda e se estende até os dias de hoje com P. nicotianae em citros e P. plurivora em faia. Uma característica importante deste grupo de patógenos é que as medidas de controle da doença se baseiam na prevenção da entrada do patógeno na área visto que, uma vez instalado, o produtor precisa conviver com o mesmo, pois não se dispõem de métodos efetivos de controle. Neste sentido, a busca por métodos de controle torna-se primordial. O endofítico radicular Piriformospora indica, tem-se destacado em vários patossistemas devido a sua habilidade de induzir resistência contra patógenos, aumentar a tolerância à estresses abióticos e promover o crescimento de plantas. Taxtomina A, produzida por Streptomyces scabies, é capaz de ativar mecanismos de defesa de plantas, os quais são efetivos contra agentes patogênicos. Objetivou-se com este trabalho avaliar o efeito de P. indica e da taxtomina A sobre P. nicotianae em citros e P. plurivora em faia. Ambos foram avaliados quanto ao seu efeito direto sobre os patógenos em questão. O indutor de defesa vegetal Bion® foi utilizado em alguns ensaios para fins de comparação. Plântulas de citros e faia foram tratadas com concentrações crescentes de taxtomina e parâmetros fisiológicos, bioquímicos e de controle da doença foram avaliados. Taxtomina A não apresenta efeito direto sobre os patógenos avaliados. Os dados de incidência da doença em plântulas de faia tratadas com taxtomina A nas concentrações de 10, 25, 50 e 100 μg se mostraram consistentes com a quantidade de DNA do patógeno no sistema radicular, demonstrando que, aparentemente, a toxina induziu suscetibilidade nas plântulas de faia. Em citros, para os parâmetros fisiológicos e bioquímicos avaliados, em linhas gerais, a taxtomina A nas concentrações de 50 e 100 μg demonstrou potencial de aplicação no patossistema citros - P. nicotianae. Quando avaliada a mortalidade de plantas inoculadas com o patógeno e tratadas com taxtomina, bem como, quando quantificado o DNA do oomiceto no sistema radicular, as referidas concentrações também apresentaram os melhores desempenhos. Plântulas das mesmas espécies foram submetidas a inoculação com P. indica, sendo avaliados os efeitos na promoção de crescimento, na atividade de enzimas e de genes relacionados ao processo de defesa, bem como, no controle da doença. Não foi observado efeito direto do endofítico radicular sobre os patógenos avaliados. Quando plântulas de citros foram inoculadas com P. indica e depois com P. nicotianae, não foi observada promoção de crescimento e controle da doença. As análises histológicas e moleculares demonstraram a presença do endofítico no sistema radicular de plântulas de citros e faia. Análises bioquímicas revelaram apenas aumentos pontuais no teor de proteínas e na atividade da β-1,3-glucanase e da peroxidase no tratamento com P. indica + P. nicotianae. Os genes PR-1.4, PR-1.8, PR-β-glucosidase e Hsp70 foram induzidos em plântulas inoculadas com P. indica e com o patógeno, bem como no tratamento com Bion® e patógeno, porém em menor magnitude. O endofítico P. indica ativa o sistema de defesa de plântulas de citros, no entanto, os mecanismos ativados não são efetivos para o controle da doença na interação citros - P. nicotianae. / Phytophthora species has been important throughout history because of its destructive potential, starting with the devastating P. infestans in potatos in Ireland and extending to the present day with Phytophthora nicotianae on citrus and Phytophthora plurivora on beech. An important feature of this group of pathogens is that the disease control measures are based upon prevention of pathogen entry into the area since, once installed, producers have to live with it, because they do not have effective methods of control. Accordingly, the search for control methods becomes essential. The root endophytic fungus Piriformospora indica has been shown to induce resistance against pathogens, increase tolerance to abiotic stresses and promote the growth of plants. On the other hand, the phytotoxin thaxtomin A, produced by Streptomyces scabies, is able to activate plant defense mechanisms, which are effective against pathogens. Thus, the objective of this study was to evaluate the effect of P. indica and thaxtomin A on the control of P. nicotianae on citrus and P. plurivora on beech. Both were assessed for their direct effect on these pathogens. The plant defense inducer Bion® was used in some tests for comparison. Besides that, seedlings of citrus or beech were treated with P. indica or increasing concentrations of thaxtomin and physiological / biochemical parameters as well as those related to induction of resistance and disease control were evaluated. The results showed that thaxtomin A did no exhibit any direct effect on the pathogens. The incidence of disease on beech seedlings treated with thaxtomin A, in concentrations of 10, 25, 50 and 100 ug, were consistent with the amount of DNA of the pathogen in the root tissue, demonstrating that, apparently, the toxin induced susceptibility in the seedlings. In citrus, for the physiological and biochemical parameters evaluated, in general, the thaxtomin in the concentrations of 50 and 100 ug showed potential for application in the citrus pathosystem - P. nicotianae. When the mortality of the seedlings treated with thaxtomin and inoculated with the pathogen as well as the oomycete DNA amount in the root system were evaluated these concentrations also had the best performances. As mentioned above, seedlings of beech or citrus were also inoculated with the endophyte and its effect on growth promotion, enzyme activities, the expression of genes related to defense process and on disease control was measured. There was no direct effect of the root endophyte on the pathogens. When citrus seedlings were inoculated with P. indica and then with P. nicotianae, there was no growth promotion or disease control. Histological and molecular analysis showed the presence of the endophytic fungus inside the root system of citrus and beech seedlings. Biochemical analyzes revealed only occasional increases in protein content and the activities of β-1,3-glucanase and peroxidase in the treatment with P. indica + P. nicotianae in citrus seedlings. The genes PR-1.4, PR- 1.8, PR-β-glucosidase and Hsp70 were induced in seedlings inoculated with P. indica and challenged with the pathogen as well as in the treatment with the resistance inducer Bion® plus pathogen, but to a lesser magnitude. Finally, the endophytic P. indica is able to active defense system in citrus, however, the activated mechanisms seems not to be effective in controlling the disease in the interaction citrus - P. nicotianae.

O presente trabalho teve por objetivo estudar a influência de um ativador de plantas e de dois fungicidas sobre o comportamento de plantas de tomate (Lycopersicon esculentum Mill.), cultivadas em vasos no interior de casa-de-vegetação, no município de Piedade, SP, e submetidas a diferentes condições de fornecimento de água. Os produtos químicos aplicados de forma isolada foram respectivamente dois fungicidas, a piraclostrobina (PRT) e a azoxistrobina (AZT); um ativador de plantas, o acibenzolar-s-metil (ASM). Foi incluída uma testemunha, sem aplicações de produtos. Todos os tratamentos mantiveram-se sob quatro níveis de água (90%, 72 %, 54% e 36% da capacidade de recipiente do substrato). Foram realizadas quatro aplicações dos produtos, sendo a primeira um dia antes do plantio definitivo das mudas, a segunda aos 10 dias após o plantio (DAP), seguindo-se mais duas aplicações com intervalo de 10 dias entre as mesmas. As avaliações foram efetuadas medindo os seguintes parâmetros: a) peso da massa seca da raiz, da parte aérea e total de cada planta aos 30 e 50 DAP; b) determinação do teor de clorofila das plantas aos 35 DAP, tomando-se como padrão o segundo folíolo da primeira folha abaixo do primeiro cacho floral; c) altura das plantas aos 29 e 49 DAP; d) número de folhas abaixo do primeiro cacho floral, aos 29 DAP; e) número total de folhas por planta aos 29 DAP; f) porcentagem de plantas com o primeiro cacho floral totalmente aberto aos 28 DAP; g) sintomas de deficiência hídrica aos 7 dias após a terceira e quarta aplicação dos produtos. Os resultados indicaram que as aplicações do acibenzolar-s-metil (ASM), piraclostrobina (PRT) e azoxistrobina (AZT) evitaram sintomas visíveis de murcha ocasionada pelo estresse hídrico, enquanto que em situações com maiores níveis de fornecimento de água, ocorreu maior acúmulo de matéria seca nas raízes e na parte aérea do tomateiro. / The aim of this study was to evaluate the influence of a systemic acquired resistance activator and two fungicides on tomato (Lycopersicon esculentum Mill.) plants, cultivated in pots in a greenhouse, which was exposed to different conditions of water supply. The products which were sprayed without tank mixtures (applied in their isolated form), were respectively two fungicides: piraclostrobina (PRT) and azoxistrobina (AZT); and one systemic acquired resistance activator, the acibenzolar-s-methyl (ASM), and one without products. All treatments were rent on four water levels (90%, 72%, 54% and 36% of container capacity). Four sprays of these produtcs were done: the first was done one day before planting, and the second 10 days after planting. Two more spray was done with 10 days interval between them. The following parameters were taken into measured to do the evaluations: a) dry weights of the root mass, the leaf area, and the entirely plant at 30 and 50 days after the planting (DAP); b) determination of the chlorophyll contents of the plants at 35 DAP, taking as the standard the second leaflet of the first leaf, immediately bellow the first inflorescence; c) plant height at 29 and 49 DAP; d) number of leaves below the first inflorescence at 29 DAP; e) total number of leaves for each plant at 29 DAP; f) percentage of plants with the first inflorescence totally opened at 28 DAP; g) water stress symptoms evaluation at the 7th day after the third and the fourth product sprays. The results indicated that the sprays of acibenzolar-s-methyl (ASM), piraclostrobina (PRT) and azoxistrobina (AZT) avoided the visible wilt symptoms due to the hydric stress, while in situations with higher water supply levels, the accumulation of dry material in the roots and in the leaf area of tomato plants increased.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-17T13:39:56Z No. of bitstreams: 1 Camila Cristina Lage de Andrade.pdf: 845467 bytes, checksum: ef8d7e269cd9b79e14fc8dbcd17e8edd (MD5) / Made available in DSpace on 2017-02-17T13:39:56Z (GMT). No. of bitstreams: 1 Camila Cristina Lage de Andrade.pdf: 845467 bytes, checksum: ef8d7e269cd9b79e14fc8dbcd17e8edd (MD5) Previous issue date: 2012-02-16 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The bacterial speck caused by Pseudomonas syringae pv. tomato (Pst) (Okabe) Young, Dye & Wilkie has economic relevance to the tomato for industry in Brazil. The use of products that potentiate and/or induce plant defenses is an alternative that meets the requirements of integrated disease management. This study aimed to evaluate the effect of silicon (Si) and chemical inducers in some components of tomato resistance to bacterial speck and activity of enzymes involved in plant defense. In the first study, tomato plants were grown in: soil without calcium silicate (control) (T1), soil without calcium silicate and plants sprayed with Supa Silica® (SS) (2 mL/L SS) (T2) and soil with calcium silicate (0.38 g) (T3), being inoculated by spraying with a suspension of the pathogen. Our research evaluated the incubation period (IP), number of lesions (NL) per plant, severity estimated by the software QUANT 1.0 (SEQ) and leaf concentration of Si, as well as the activity of enzymes peroxidases (POX), polyphenoloxidases (PPO) β-1,3-glucanases (GLU), phenylalanine ammonia lyases (PAL), lipoxygenases (LOX) and concentration of malondialdehyde (MDA). It was assessed the effect of SS in the Pst growth in vitro. There was no significant difference between treatments for the IP and the foliar concentration of Si. No significant differences were found for the NL per plant and SEQ between T3 and control. T2 significantly reduced NL in 46.8 and 45.1% and SEQ in 61.5 and 56.2% when compared with control and T3, respectively. There was negative linear response of SS doses on the Pst growth in vitro. The activity of POX, PPO and GLU was significantly higher in T2 and T3. The activity of FAL and LOX was significantly higher in T3. The MDA concentration was significantly higher in T2 compared to control, in non-inoculated plants and at 7 days after inoculation (d.a.i.), being significantly lower at 10 d.a.i. In the second study, three experiments were conducted to evaluate the effect of jasmonic acid (JA; 0.1 mM), ethephon (ET, 0.5 mM) and acibenzolar-S-methyl (Bion®, ASM; 300 mg/L) sprayed 48 h before inoculation with Pst, evaluating the IP and NL per plant, and the activity of enzymes POX, PPO, GLU and LOX. It was also assessed the effect of JA and ET in the growth of Pst in vitro. Only in experiment 3 incubation period increased significantly by one day in the plants sprayed with ASM compared with control. In all experiments, NL per plant was significantly reduced by JA, ET e ASM in relation to the control reaching values of 38.9, 45.3 and 68.1%, respectively, in experiment 2. The growth of Pst in vitro was not significantly influenced. In some evaluation times JA has significantly raised the activity of POX, PPO and GLU; ASM has elevated the activity of PPO, GLU and LOX, while ET only significantly raised the activity of GLU and LOX compared to the control. The results of these studies suggest that spraying tomato plants with SS and the inducers JA, ET and ASM affected some components of tomato resistance to bacterial speck, and activated the enzymes POX, PPO, GLU, PAL and LOX, involved in defense responses of tomato plants to Pst. / A pinta bacteriana causada por Pseudomonas syringae pv. tomato (Pst) (Okabe) Young, Dye & Wilkie tem importância econômica para a cultura do tomateiro industrial no Brasil. O uso de agentes potencializadores e/ou indutores das defesas das plantas é uma alternativa que atende aos requisitos do manejo integrado de doenças. Este estudo avaliou o efeito do silício (Si) e de indutores químicos em alguns componentes de resistência do tomateiro à pinta bacteriana e na atividade de enzimas envolvidas na defesa das plantas. No primeiro estudo plantas de tomateiro foram cultivadas em: solo sem silicato de cálcio (controle) (T1), solo sem silicato de cálcio e plantas pulverizadas com Supa Sílica® (SS) (2 mL/L de SS) (T2) e solo com silicato de cálcio (0,38 g) (T3), sendo inoculadas por pulverização com suspensão do patógeno. Foram avaliados o período de incubação (PI), número de lesões (NL) por planta, severidade estimada pelo software QUANT 1.0 (SEQ) e concentração foliar de Si, bem como a atividade das enzimas peroxidases (POX), polifenoloxidases (PFO), β-1,3-glucanases (GLU), fenilalanina amônia-liases (FAL), lipoxigenases (LOX) e concentração de aldeído malônico (MDA). Também foi avaliado o efeito do SS no crescimento de Pst in vitro. Não houve diferença significativa entre os tratamentos para o PI e para a concentração foliar de Si. Não houve diferença significativa para o NL por planta e a SEQ entre o tratamento T3 e o controle. O tratamento T2 reduziu significativamente o NL 46,8 e 45,1% e a SEQ 61,5 e 56,2%, em relação ao controle e ao tratamento T3, respectivamente. Houve resposta linear negativa das doses de SS no crescimento da Pst in vitro. A atividade das POX, PFO e GLU foi significativamente maior nos tratamentos T2 e T3. A atividade das FAL e das LOX foi significativamente maior no T3. A concentração de MDA foi significativamente maior no tratamento T2 em relação ao controle, nas plantas não inoculadas com Pst e aos 7 dias após inoculação (d.a.i.); sendo significativamente menor aos 10 d.a.i. No segundo estudo, três experimentos foram realizados para avaliar o efeito dos indutores ácido jasmônico (AJ; 0,1 mM), ethephon (ET; 0,5 mM) e acibenzolar-S-metil (Bion®, ASM; 300 mg/L) pulverizados 48 h antes da inoculação da Pst, avaliando-se o PI e o NL por planta, além da atividade das enzimas POX, PFO, GLU e LOX. Também foi avaliado o efeito do AJ e do ET no crescimento da Pst in vitro. Apenas no experimento 3 o PI aumentou significativamente em 1 dia nas plantas pulverizadas com ASM em relação ao controle. O NL por planta foi significativamente reduzido pelos tratamentos AJ, ET e ASM em relação ao controle para todos os experimentos, atingindo valores de 38,9, 45,3 e 68,1%, respectivamente, no experimento 2. O crescimento da Pst in vitro não foi influenciado significativamente pelo AJ ou ET. Em determinadas épocas de avaliação, o AJ elevou significativamente a atividade das POX, PFO e GLU; ASM elevou a atividade das PFO, GLU e LOX e o ET elevou a atividade das GLU e LOX em relação ao controle. Os resultados desses estudos evidenciam que a pulverização com SS e com indutores AJ, ET e ASM afetaram alguns dos componentes de resistência do tomateiro à pinta bacteriana, além de potencializar as enzimas POX, PFO, GLU, FAL e LOX, relacionadas com a defesa das plantas em resposta à Pst.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O melÃo tem grande importÃncia para a economia brasileira, sendo sua produÃÃo exportada principalmente para os paÃses da UniÃo EuropÃia. Assim, à fundamental o controle de doenÃas pÃs-colheita deste fruto. O Fusarium pallidoroseum à um importante fitopatÃgeno que provoca podridÃes no melÃo. Esta doenÃa representa um obstÃculo sÃrio em sua comercializaÃÃo. Este trabalho avaliou os efeitos do BTH, um anÃlogo estrutural e funcional do Ãcido salicÃlico, nas respostas bioquÃmicas da defesa do melÃo desafiado com o F. pallidoroseum e do meloeiro nÃo desafiado. Doze horas depois de colhidos, os melÃes foram mergulhados em soluÃÃes de BTH (concentraÃÃes de 0,5, 1,0, e 2,0 mM de ingrediente ativo) e, depois 60 horas, foram inoculados com o fungo. Amostras dos frutos (2 cm diÃmetro x 1 cm de profundidade), prÃximos ao local de infecÃÃo, foram retiradas em 3, 7 e 10 dias apÃs inoculaÃÃo, pesadas e armazenadas à -84 ÂC atà serem utilizadas. Plantas do melÃo de 8 dias foram borrifadas com 300 ÂL de BTH nas concentraÃÃes de 0,3, 0,5, e 1,0 mM. As folhas secundÃrias foram colhidas em 2, 4, 6, 8, 10, 12, e 14 dias apÃs tratamento. AlÃm da avaliaÃÃo do sintoma nos frutos, extratos totais do fruto e das folhas secundÃrias foram preparados com tampÃo acetato 50 mM, pH 5.2, contendo 150 mM de NaCl, e os Ãndices de proteÃna e as atividades enzimÃticas da peroxidase (POX), da fenilalanina amÃnia liase (PAL), da β-1,3-glucanase (GLU), da peroxidase do ascorbato (APX) e da superoxide dismutase (SOD) foram medidos. Observou-se que BTH nÃo reduziu significativamente a incidÃncia e a severidade da podridÃo causada pelo patÃgeno. Nem 2 mM de BTH modificou significativamente as atividades de enzimas relacionadas a defesa do fruto. Ao contrÃrio, nas plantas do melÃo, BTH aumentou as atividades da POX, GLU e da SOD, mas nÃo modificou a PAL e APX foi inibida. Estes resultados sugerem que BTH nÃo trabalhou como um indutor de defesas bioquÃmicas no melÃo, mas induziu respostas de defesa nas plantas. ConseqÃentemente, sugere-se que BTH poderia ser usado como uma estratÃgia tecnolÃgica para a proteÃÃo de frutas do melÃo contra a podridÃo causada pelo F. pallidoroseum atravÃs da induÃÃo das respostas bioquÃmicas de defesa da prÃpria planta, que, provavelmente, estarà transferindo estas caracterÃsticas aos frutos. Entretanto, esta hipÃtese que està sendo proposta necessita ser avaliada. / Melon fruit constitutes one of the main segments of the Brazilian economy. Its production is exported particularly to countries in the European Union. Thus it is fundamental the control of postharvest diseases of melon. Fusarium pallidoroseum is an important phytopathogen which provokes rot in melon fruits. This disease represents a serious obstacle in its commercialization as a foreign commodity. In this present work the effects of BTH, a structural and functional analogue of salicylic acid, on the biochemical defense responses of melon fruits challenged with F. pallidoroseum and of unchallenged melon plants were assessed. Twelve hours after harvesting melon fruits were immersed in BTH (0.5, 1.0, and 2.0 mM concentrations of active ingredient) and 60 hours later inoculated with the fungus. Fruit cuts (2 cm diameter x 1 cm deep), close to the inoculation sites, were excised at 3, 7, and 10 days after fungal inoculation, weighed and kept at -84 ○C until used. Eight day-old melon plants were sprayed with 300 ÂL BTH at 0.3, 0.5, and 1.0 mM concentrations. Secondary leaves were harvested at 2, 4, 6, 8, 10, 12, and 14 hours after sprayings. Besides to symptom evaluation in melon fruits, crude extracts from the fruit cuts and leaves were prepared with 50 mM acetate buffer, pH 5.2, containing 150 mM NaCl, and the protein contents and enzymatic activities of peroxidase (POX), phenylalanine ammonia lyase (PAL), β-1,3-glucanase (GLU), ascorbate peroxidase (APX), and superoxide dismutase (SOD) were measured. It was observed that BTH did not reduce significantly the incidence and severity of the rot caused by the pathogen. Neither 2 mM BTH significantly modify the activities of defense-related enzymes in melon fruits. Contrary, in the melon plants, BTH increased the activities of POX, GLU, and SOD, but did not modify PAL and further inhibited APX. These results suggest that BTH did not work as an inductor of biochemical defenses in melon fruits, but it induced defense responses in the melon plants. Therefore it is suggested that BTH could be used as a technological strategy for protection of melon fruits from the rot caused by F. pallidoroseum by means of induction of biochemical defense responses of the melon plant itself which will likely be transferring these traits to its fruits. However, this hypothesis that is being proposed needs to be assessed.