Carbon flow into developing ovaries has been reported to be important in seed retention and seed size. Invertase, which cleaves sucrose into glucose and fructose has been shown to be important in rapidly expanding tissue, such as early root growth or during tiller expansion. The manipulation of invertase activity with over-the-top applications of agrochemicals may prevent the detrimental effects of abiotic stress by altering the source/sink relationship. These experiments examined economically important tissues in rice production during critical developmental stages under abiotic stress. Field and greenhouse studies were conducted under normal growing conditions using local management practices. Plants were treated with exogenous chemicals that affect the activity of invertase during the early-grain fill stage on field grown plants. Other plants were exposed to elevated nighttime temperature of 30°C for 4 d using a free-air, infrared heating device in the greenhouse. Rice was also treated at mid- to late-grain fill stage of the main crop to identify the impact of the exogenous chemicals on developing ratoon tiller buds. The activity of soluble acid invertase (SAI), concentrations of glucose, fructose, sucrose, and starch were determined in penultimate leaves, panicles, and main-crop stem segments during ratoon tiller bud expansion, using the enzyme-coupled stoichiometric production of NADH measured spectrophotometrically at 340nm. The results suggest SAI, carbohydrates, and agronomic characters are influenced by exogenous chemicals at the applied rates. The thidiazuron treatment caused an unidentified stress event. The stress was confirmed by increased hexose concentration and the proportion of hexose concentration to sucrose concentration. This stress reduced the main-crop grain yield, but not the ratoon yield or total grain yield. An interaction between the ammonium molybdate treatment and high nighttime temperature was seen in the panicle. The ranked difference was reduced by the high nighttime temperature from the ambient nighttime temperature for the SAI activity, TSC content, starch content, and TNC content. The tested chemicals and rates are not appropriate for commercial rice production because the effect of the exogenous chemicals do not appear to consistently aid rice plants to counteract the detrimental effects of abiotic stress.

Carbon flow into developing ovaries has been reported to be important in seed retention and seed size. Invertase, which cleaves sucrose into glucose and fructose has been shown to be important in rapidly expanding tissue, such as early root growth or during tiller expansion. The manipulation of invertase activity with over-the-top applications of agrochemicals may prevent the detrimental effects of abiotic stress by altering the source/sink relationship. These experiments examined economically important tissues in rice production during critical developmental stages under abiotic stress. Field and greenhouse studies were conducted under normal growing conditions using local management practices. Plants were treated with exogenous chemicals that affect the activity of invertase during the early-grain fill stage on field grown plants. Other plants were exposed to elevated nighttime temperature of 30°C for 4 d using a free-air, infrared heating device in the greenhouse. Rice was also treated at mid- to late-grain fill stage of the main crop to identify the impact of the exogenous chemicals on developing ratoon tiller buds. The activity of soluble acid invertase (SAI), concentrations of glucose, fructose, sucrose, and starch were determined in penultimate leaves, panicles, and main-crop stem segments during ratoon tiller bud expansion, using the enzyme-coupled stoichiometric production of NADH measured spectrophotometrically at 340nm. The results suggest SAI, carbohydrates, and agronomic characters are influenced by exogenous chemicals at the applied rates. The thidiazuron treatment caused an unidentified stress event. The stress was confirmed by increased hexose concentration and the proportion of hexose concentration to sucrose concentration. This stress reduced the main-crop grain yield, but not the ratoon yield or total grain yield. An interaction between the ammonium molybdate treatment and high nighttime temperature was seen in the panicle. The ranked difference was reduced by the high nighttime temperature from the ambient nighttime temperature for the SAI activity, TSC content, starch content, and TNC content. The tested chemicals and rates are not appropriate for commercial rice production because the effect of the exogenous chemicals do not appear to consistently aid rice plants to counteract the detrimental effects of abiotic stress.

Made available in DSpace on 2014-06-11T19:28:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-20Bitstream added on 2014-06-13T20:18:17Z : No. of bitstreams: 1 viana_rs_me_jabo.pdf: 161687 bytes, checksum: f5ac1d697b173d61681a955dc7cb0f50 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste experimento foi avaliar as variáveis tecnológicas e o efeito de maturadores químicos na cultura da cana-de-açúcar no final de safra, e a ação na erradicação da soqueira em áreas de reforma do canavial visando a utilização da técnica do plantio direto ou cultivo mínimo, na cultivar RB72454 em cana soca 4o corte. O delineamento experimental utilizado foi em blocos casualizados, em esquema de parcelas subdivididas, sendo os tratamentos principais constituídos pela: testemunha, glifosato aplicado nas dosagens de 0,4, 3,0 e 6,0 L de produto comercial por hectare (p.c.ha-1), e sulfometuron-metil (aplicado na dosagem de 20 g p.c ha-1) e os tratamentos secundários constituíram-se das diferentes épocas de amostragens aos 0, 11, 18, 28, 35, 43 dias após a aplicação (daa) ocorrido em 21/10/05. Foram avaliados em cada amostragem o Brix , Pol, Pureza do caldo, AR (%), Fibra cana (%). Aos 62 dias após a colheita e aos 290 (dac) foram realizadas as contagens do número de perfilhos e a altura de planta. Concluiu-se que a aplicação destes tratamentos como maturadores químicos promoveram aumento significativo sobre as variáveis tecnológicas da planta como: Brix cana(%), Pol cana(%), TPH, e ATR (Kg t-1) ao longo das épocas de amostragens destacando-se o glifosate 0,4 L de p.c ha-1 e sulfometuron-metil 20g ha-1 aos 28 dias após a aplicação, onde houve maior retorno econômico por hectare. Os tratamentos realizados não afetaram os compostos fenólicos, acidez total e acidez volátil. O emprego do glifosato (0,4 L de p.c ha-1), não afetou a brotação da soqueira e o numero de perfilhos por metro; e a altura de plantas quando comparado com a testemunha aos 62 dias após a colheita (dac). Nos tratamentos com glifosato (6,0 e 3,0 L de p.c ha-1) não houve a erradicação da planta embora estas doses tenham afetado negativamente o desenvolvimento inicial da soqueira... / The objective of this work was to evaluate chemical and technological characteristics and study the effect of chemical ripeners in the sugarcane variety RB72454, at the end of the harvest season, and ratoon eradication of the, on a sugarcane reformed area, aiming the use of no-tillage or minimum tillage. The experimental design was arranged in randomized blocks with split split-plots, being the main treatments: Control; Roundup (glyphosate), at a dosage of 0.4 L of commercial product per hectare; Roundup (glyphosate), at a dosage of 3.0 L of commercial product per hectare; Roundup (glyphosate), at a dosage of 6.0 L of commercial product per hectare; Curavial (sulphometuron-methyl) at a dosage of 20 g of commercial product per hectare. The secondary treatments were sampling dates, respectively: 0 days after application (d.a.a.); 11 d.a.a; 18 d.a.a; 28 d.a.a.; 35 d.a.a. and 43 d.a.a. The following variables were measured: number of tillers per linear meter and plant structure at 62 and 290 days after harvest. As result of this study, the application of these treatments as chemical ripeners promoted a significant increase over the technological variables of the plant as: cane Brix (%), cane Pol (%), TPH, cane fiber (%) and ATR along the evaluated sampling seasons, emphasizing glyphosate at a dosage of 0.4 L of commercial product per hectare and sulphometuron-methyl at a dosage of 20 g of commercial product per hectare. Relatively to seasons, the best results were accomplished in the 4th sampling season, 28 days after application, where there was a better economic return per hectare. The use of the chemical ripeners, in the sugarcane crop, did not affect some important technological characteristics, for the industry quality samples, such as: phenolic compounds, total acidity, and volatile acidity. The precipitation that occurred during the sampling period (43 daa) benefited the reestablishment ...(Complete abstract, click electroni access below)

Orientador: Miguel Angelo Mutton / Banca: Marcos Omir Marques / Banca: Carlos Alberto Mathias Azania / Resumo: O objetivo deste experimento foi avaliar as variáveis tecnológicas e o efeito de maturadores químicos na cultura da cana-de-açúcar no final de safra, e a ação na erradicação da soqueira em áreas de reforma do canavial visando a utilização da técnica do plantio direto ou cultivo mínimo, na cultivar RB72454 em cana soca 4o corte. O delineamento experimental utilizado foi em blocos casualizados, em esquema de parcelas subdivididas, sendo os tratamentos principais constituídos pela: testemunha, glifosato aplicado nas dosagens de 0,4, 3,0 e 6,0 L de produto comercial por hectare (p.c.ha-1), e sulfometuron-metil (aplicado na dosagem de 20 g p.c ha-1) e os tratamentos secundários constituíram-se das diferentes épocas de amostragens aos 0, 11, 18, 28, 35, 43 dias após a aplicação (daa) ocorrido em 21/10/05. Foram avaliados em cada amostragem o Brix , Pol, Pureza do caldo, AR (%), Fibra cana (%). Aos 62 dias após a colheita e aos 290 (dac) foram realizadas as contagens do número de perfilhos e a altura de planta. Concluiu-se que a aplicação destes tratamentos como maturadores químicos promoveram aumento significativo sobre as variáveis tecnológicas da planta como: Brix cana(%), Pol cana(%), TPH, e ATR (Kg t-1) ao longo das épocas de amostragens destacando-se o glifosate 0,4 L de p.c ha-1 e sulfometuron-metil 20g ha-1 aos 28 dias após a aplicação, onde houve maior retorno econômico por hectare. Os tratamentos realizados não afetaram os compostos fenólicos, acidez total e acidez volátil. O emprego do glifosato (0,4 L de p.c ha-1), não afetou a brotação da soqueira e o numero de perfilhos por metro; e a altura de plantas quando comparado com a testemunha aos 62 dias após a colheita (dac). Nos tratamentos com glifosato (6,0 e 3,0 L de p.c ha-1) não houve a erradicação da planta embora estas doses tenham afetado negativamente o desenvolvimento inicial da soqueira ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this work was to evaluate chemical and technological characteristics and study the effect of chemical ripeners in the sugarcane variety RB72454, at the end of the harvest season, and ratoon eradication of the, on a sugarcane reformed area, aiming the use of no-tillage or minimum tillage. The experimental design was arranged in randomized blocks with split split-plots, being the main treatments: Control; Roundup (glyphosate), at a dosage of 0.4 L of commercial product per hectare; Roundup (glyphosate), at a dosage of 3.0 L of commercial product per hectare; Roundup (glyphosate), at a dosage of 6.0 L of commercial product per hectare; Curavial (sulphometuron-methyl) at a dosage of 20 g of commercial product per hectare. The secondary treatments were sampling dates, respectively: 0 days after application (d.a.a.); 11 d.a.a; 18 d.a.a; 28 d.a.a.; 35 d.a.a. and 43 d.a.a. The following variables were measured: number of tillers per linear meter and plant structure at 62 and 290 days after harvest. As result of this study, the application of these treatments as chemical ripeners promoted a significant increase over the technological variables of the plant as: cane Brix (%), cane Pol (%), TPH, cane fiber (%) and ATR along the evaluated sampling seasons, emphasizing glyphosate at a dosage of 0.4 L of commercial product per hectare and sulphometuron-methyl at a dosage of 20 g of commercial product per hectare. Relatively to seasons, the best results were accomplished in the 4th sampling season, 28 days after application, where there was a better economic return per hectare. The use of the chemical ripeners, in the sugarcane crop, did not affect some important technological characteristics, for the industry quality samples, such as: phenolic compounds, total acidity, and volatile acidity. The precipitation that occurred during the sampling period (43 daa) benefited the reestablishment ...(Complete abstract, click electroni access below) / Mestre

A nutrição mineral representa um dos principais fatores de produção na cultura da cana-de-açúcar, tendo impacto direto na produtividade, na qualidade, e nos custos de produção. A expansão da cultura sobre área de baixa fertilidade natural ou ainda em áreas tradicionais de cultivo com evidente esgotamento dos recursos, reforça a necessidade da aplicação de fertilizantes na recuperação da produtividade, principalmente em áreas de soqueira de cana. O fósforo é um elemento chave nesse processo dada a intensidade das reações de adsorção e fixação, que o tornam pouco disponível para a cultura. Além disso o fato de ser normalmente aplicado na reforma do canavial, não garante o correto fornecimento do mesmo nos ciclos consecutivos de soca. Já os micronutrientes representam um desafio, uma vez que mesmo em áreas deficientes, as resposta não são conclusivas. Neste contexto, o objetivo deste trabalho foi avaliar a eficiência de fertilizantes fosfatos aplicados no solo e micronutrientes aplicados via foliar sobre a produtividade e qualidade tecnológica em soqueira de cana-de-açúcar. Para tanto, foi instalado um experimento no município de Porto Ferreira(SP) na Usina Ferrari S/A, em dezembro de 2010, sob Latossolo Vermelho-Amarelo Distrófico de textura média, com a variedade RB - 85 7515, 3ª soca em área colhida mecanicamente e sem queima. O delineamento experimental utilizado foi de blocos casualizados com parcelas subdivididas. Nas parcelas foram aplicados os tratamentos principais correspondendo às fontes de fósforo: T1 - Controle (sem adubação); T2 - 495 kg ha-1 da formulação 21-00-14 (nitrato de amônio + cloreto de potássio); T3 - 495 kg ha-1 da formulação 21-07-14 (nitrato de amônio +superfosfato triplo + cloreto de potássio); e T4 - 495 kg ha-1 da formulação 21-07-14 (Polifosfatos + ortofosfatos -YaraMila™).Nas subparcelas foram aplicados os tratamentos secundários, compostos pela aplicação ou não de micronutrientes via foliar. As doses e fontes utilizadas formam: Zn= 778g ha-1 (óxidos); B= 150 g ha-1 (Borato de monoetalomina); Cu= 110g ha-1 (óxidos); Mn= 331g ha-1 (Carbonato de Mn); e Mo= 52g ha-1 (Molibdato de sódio). Após a colheita da cana (Agosto de 2011) pode-se constatar que a produtividade média da soqueira de cana-de-açúcar respondeu significativamente a aplicação de N-K, N-P-K e as diferentes fontes de P. A utilização de 104 kg ha-1 de N na forma de nitrato de amônio e 70 kg ha-1 de K2O na forma de cloreto de potássio proporcionam incremento médio de produtividade de 4 t de ha-1 em relação ao controle sem adubação. Em relação ao fósforo, a utilização de 35 kg ha-1 de P2O5 promoveu um ganho médio de produtividade de 12,6 t ha-1 em comparação ao controle sem adubação. Considerando as fontes, o fertilizante 21-07-14 YaraMila contendo polifosfatos em sua formulação proporcionou produtividade média superior em de 4 t ha-1 em relação ao fertilizante 21-07-14 contento como fonte de P o superfosfato triplo. A utilização de micronutrientes nas doses, fontes e forma de aplicação testadas, não proporcionou ganho produtivo significativo em relação a área sem aplicação. Com respeito as variáveis tecnológicas, utilização de fertilizantes contendo N-K e N-P-K e a utilização de micronutrientes aplicados via foliar nas doses e fontes testadas não alterou significativamente os parâmetros, pureza, pol, fibra e ART. / The mineral nutrition is one of the main production factors in the sugar cane culture having a direct impact in productivity, quality, and in production costs. The expansion of culture in low natural fertility area and traditional area with evident source depletion reinforce the necessity of fertilizers application in the productivity recovering, especially in areas of brass knuckles. The phosphorus is a key element in this process due to the intensity of the adsorption and fixation reactions that make it less available for the culture. Besides that, the fact that phosphorus is normally applied in the sugar cane area reform does not guarantee the correct supply of this element in the consecutives cycles of ratoon. On the other hand, the micronutrients present a challenge, knowing that even in deficient areas, the answers are not conclusive. In this context, the main of this work was to evaluate the efficiency of phosphate fertilizers applied in the soil and micronutrients applied via foliar over the productivity and technological quality in ratoon sugar cane. For that purpose, it was installed an experiment in a town called Porto Ferreira (SP), in the Plant Ferrari S/A, in December 2010, under Oxisol Distrophic medium texture with the variety RB - 857515, in the 3ª ratoon sugar cane mechanically harvested and unburned area. The experimental design used was the one with randomized blocks with split plots. In these plots, the main treatments were applied, each one corresponding to the sources of phosphorous: T1- Control (without fertilizer); T2- 495 kg ha-1 from formulation 21-07-14 (ammonium nitrate + triple superphosphate + potassium chloride); and T4- 495 kg ha-1 from formulation 21-07-14 (Polyphosphates + orthophosphates - YaraMila™). In the subplots, the secondary treatments were applied, composed by the application or not of the micronutrients via foliar. The doses and sources used were: Zn= 778g ha-1 (oxides); B= 150 g ha-1 (Borate monoetalomine); Cu= 110g ha-1 (oxides); Mn= 331g ha-1 (Mn Carbonate); and Mo= 52 g ha-1 (Sodium molybdate). After harvesting the sugar cane (August 2011), it could be concluded that the average productivity of the brass knuckles had a significant response to the application of N-K, N-P-K and to the different sources of P. The use of 104 kg ha-1 of N in the form of ammonium nitrate and 70 kg ha-1 of K2O in the form of potassium chloride made possible an average increasing in productivity of 4 t of ha-1 when comparing with the control without fertilizer. Considering the sources, the fertilizer 21-07-14 YaraMila containing polyphosphates in its formulation promoted superior average productivity of 4 t ha-1 when compared to the fertilizer 21-07-14, which contained triple superphosphate as P source. The use of micronutrients in the doses, sources and application forms tested didn\'t promote significant production gain in relation to the area without application. About the technological varieties, the use of fertilizers containing N-K and N-P-K and the use of micronutrients applied via foliar in the tested doses and sources didn\'t change significantly the parameters, purity, pol, fiber and ATR.

Estudos de adubação nitrogenada em cana-de-açúcar normalmente se restringem em avaliar os efeitos no crescimento da parte-aérea. Há evidências de que a fertilização nitrogenada favorece o crescimento de raízes, a absorção de nutrientes e a produtividade da cultura. Objetivou-se com o trabalho avaliar o desenvolvimento de raízes e produtividade da cana-de-açúcar (SP81 3250) nos ciclos de cana-planta e 1ª soca. Foram conduzidos três experimentos, um em LATOSSOLO VERMELHO AMARELO eutrófico (LVAe) e outro em LATOSSOLO VERMELHO distrófico típico (LVd) (ambos de textura média) e um em LATOSSOLO VERMELHO eutrófico (LVe) argiloso. Na cana-planta os tratamentos constaram de doses de nitrogênio (N) de 40, 80 e 120 kg ha-1 e uma testemunha (sem N mineral), em blocos ao acaso, com quatro repetições. Na cana-soca cada parcela da cana-planta foi dividida em quatro subparcelas, às quais foram aplicadas doses de 50, 100 e 150 kg ha-1 N e uma testemunha. No 1º corte o sistema radicular foi avaliado em todos os tratamentos nos três solos. No 2º corte, o sistema radicular foi avaliado somente nas subparcelas dos tratamentos de plantio testemunha e 120 kg ha-1 N, no LVAe e LVd. Para o experimento no solo LVe, somente nas subparcelas testemunha e 150 kg ha-1 N das parcelas principais testemunha e 120 kg ha-1 N foi avaliado o sistema radicular da cana soca. A amostragem de raízes com sonda resultou em massa de raízes que não diferiu da avaliação em monólito, indicando que esse método pode ser usado para avaliações de raízes de cana-de-açúcar. A fertilização nitrogenada de plantio promoveu maior concentração de raízes até 0,2 m no LVd. No ciclo da cana-planta, no LVAe e no LVd houve crescimento pronunciado de raízes de outubro de 2005 a fevereiro de 2006, com redução da massa de fevereiro até a colheita, porém sem afetar o desenvolvimento da parte aérea. Em fevereiro, 20% do N acumulado na planta toda foi encontrado nas raízes, diminuindo para 5% na colheita como decorrência da redução da massa de raízes. As doses de N no plantio favoreceram o crescimento de raízes e a produtividade de colmos no LVAe e no LVe, e o acúmulo de sacarose no LVd. As doses de N na soqueira favoreceram a produtividade de colmos e açúcar nos três solos. No 1º corte, foi obtida maior produtividade de colmos (152 t ha-1) e menor massa de raízes (1,35 t ha-1) no LVe em relação ao LVAe e LVd (139 e 145 t ha-1 de colmos e 2,5 e 2,4 t ha-1 de raízes, respectivamente). Em relação ao 1º corte, a produtividade do 2º corte se manteve estável no LVd (120 t ha-1) e diminuiu drasticamente no LVe (80 t ha-1). Esse fato foi devido à pequena massa de raízes no LVe no 1º corte, tendo em vista que nas duas áreas ocorreu acentuado déficit hídrico em alguns meses antes e após o 1º corte. A adubação nitrogenada de soqueira favoreceu o crescimento de raízes somente no LVe, porém a massa de raízes diminuiu do 1º para o 2º corte, enquanto que no LVAe e no LVd a massa permaneceu constante. / Studies of nitrogen fertilization in sugarcane are usually restricted to evaluations of the effects on growth and productivity of the shoots. There are evidences that nitrogen fertilization favors the growth of roots, the absorption of nutrients and sugarcane productivity. This work was designed to evaluate root development and sugarcane productivity (SP81 3250) in the crop cycles of the cane-plant and of the first ratoon. Three experiments were conducted in a randomized blocks design, with four replications, in three different soils, a Typic Eutrustox (TE) and an Arenic Kandiustults (AK) (both of medium texture), and a clayey Rhodic Eutrustox (RE). Treatments for the cane-plant were nitrogen (N) rates of 0, 40, 80 and 120 kg ha-1 N. In the first ratoon crop each plot of cane-plant was split in four subplots to which rates of 0, 50, 100 and 150 kg ha-1 of N was applied. In the first harvest, the root system was evaluated in all of the treatments applied on the three soils (TE, AK and RE), whereas in the second harvest the root system was evaluated only for the subplots of the planting treatments control and 120 kg ha-1 N in TE and AK. For the experiment in the RE soil, only control and 150 kg ha-1 N subplots of the control and 120 kg ha-1 N main plots had the ratoon root system evaluated. The sampling of roots with probe resulted in a mass of roots that did not differ from the monolith evaluation, indicating that this method can be used for the evaluation of sugarcane roots. Nitrogen fertilization at planting resulted in a higher concentration of roots in the top 0.2 m in AK. There was a pronounced growth of roots in TE and in AK from October, 2005 to February, 2006, and a reduction of the mass from February until harvest; however development of the above ground part of the plant was not affected. Until February, about 20% of accumulated N in the whole plant was found in the roots, decreasing to 5% at harvest, as a consequence of root mass reduction. The N rates applied to the cane-plant favored the roots growth and crop productivity in TE and RE, and the sucrose accumulation in AK. The rates of fertilizer-N in the ratoon favored the productivity of stalks and sugar yield in the three soils. In the first harvest, it was obtained a larger productivity of stalks (152 t ha-1) and a smaller mass of roots (1.35 t ha-1) in RE in relation to TE and AK (139 and 145 t ha-1 of stalks and 2.5 and 2.4 t ha-1 of roots, respectively). The productivity of the second harvest was similar to that of the first harvest in AK (120 t ha-1), but it decreased drastically in RE (80 t ha-1), as a consequence of the small mass of roots in RE in the first harvest, attributed to a high water deficit in the months prior to and after harvest. Nitrogen fertilization applied after the first harvest influenced root growth only in the RE soil; however the mass of roots decreased from the first to the second harvest while in the TE and AK soils the root mass remained constant.

Ratoon stunting disease (RSD) is a serious disease that affects all sugarcane producing countries. The major symptom of RSD is plant growth reduction, which is only seen in ratoon plants, causing up to 80% biomass reduction depending on environmental conditions. The disease is due to Leifsonia xyli subsp. xyli (Lxx), a gram-positive and nutritionally fastidious bacterium that so far has been found to specifically colonize the xylem vessels of sugarcane. However, the successful early detection of this pathogen is currently the main challenge for RSD prevention. Breeding for resistance to RSD, although not in practice, is a viable control measure. Since sugarcane varieties differ in relation to their degree of colonization by Lxx and losses are directly related to population densities of the pathogen in the plant, a promising breeding strategy would be to select for genotypes that are resistant to bacterial multiplication. Thus, knowledge on the responses of sugarcane to RSD at the \"omics\" level is an essential starting step to identify key metabolic targets for breeding resistant varieties. The overall goal of this study is to determine the metabolic profiles of a susceptible (CB49-260) and resistant (SP80-3280) variety inoculated or not with Lxx and to compare the results with existing proteomic and transcriptomic data to define a core of targets (proteins, genes, and metabolites) that can be tested as markers of resistance in a collection of sugarcane varieties. Bacterial titers were quantified by Real-Time PCR (qPCR). The metabolites were profiled from the leaves and from the xylem saps collected at 30 and 120 days after inoculation (DAI). Untargeted analysis were performed with Gas Chromatography - Mass Spectrometry (GC-MS) and were carried out on leaves and sap from 120 DAI. Targeted analysis was executed with Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS) on both tissues at both timepoints. To validate metabolomics results, a set of metabolites was chosen to be tested in vitro, in order to detect growth alterations caused to Lxx. qPCR confirmed the susceptibility of CB49-260 as it had higher titers than SP80-3280. Global analysis revealed that both varieties and tissues have different metabolic profiles but that those differences are more quantitative than qualitative. The targeted approach identified more amino acids, sugars, organic acids and phosphorylated compounds in the non-inoculated susceptible genotype, while the resistant one had higher abundance of phenolics. It was also shown that inoculation with Lxx results in more relative abundance of amino acids, organic acids, phosphorylated compounds and phenolics. Furthermore, a key amino acid for Lxx survival was related to inoculation on both varieties, as well as a known phenolic compound related to plant defense. Distinguished phenolics resulting from the targeted analysis were selected to evaluate their effect on Lxx growth in vitro. Although some compounds caused inhibition, further optimization of the methodology is needed to confirm these results. / O Raquitismo-da-soqueira (RSD) é uma grave doença que afeta todos os paises produtores de cana-de-açúcar. O principal sintoma do RSD é tamanho reduzido das plantas, observado apenas nas plantas-soca, o que pode resultar em perdas de biomassa em até 80%, dependendo das condições climáticas. A doença é causada por Leifsonia xyli subsp. xyli (Lxx), uma bactéria gram-positiva e fastidiosa, descrita até o presente momento como hospedeira natural apenas da cana-de-açúcar, colonizando principalmente os vasos do xilema. Todavia, a detecção precoce deste patógeno é o principal desafio para prevenção do RSD. O melhoramento genético para resistência ao RSD, apesar de viável, não é uma medida de controle adotada na prática. Como existe diferenças entre as variedades de cana em relação ao grau de colonização por Lxx e as perdas estão diretamente relacionadas ao título bacteriano, uma estratégia de melhoramento promissora é a seleção de genótipos que apresentam resistência à multiplicação bacteriana. Portanto, o conhecimento das respostas da cana-de-açúcar ao RSD em termos \"ômicos\" é um passo inicial primordial para a identificação de alvos-chave para melhorar variedades resistentes. O objetivo geral deste estudo foi determinar os perfis metabólicos de duas variedade, uma suscetível (CB49-260) e uma resistente (SP80-3280) inoculada ou não com Lxx e comparar os resultados com dados já existentes de proteômica e transcriptômica para definir um núcleo de alvos (proteínas, genes e metabólitos) que possam ser testados como marcadores de resistência em uma coleção de cana-de-açúcar. Os títulos bacterianos foram quantificados por PCR em tempo real (qPCR). Os perfis metabólicos foram elaborados a partir de folhas e fluído xilemático coletados aos 30 e 120 dias após inoculação (DAI). A análise não-direcionada foi realizada por cromatografia gasosa acoplada à espectrometria de massas (GC-MS), usando folhas e extratos coletados aos 120 DAI. Já a análise direcionada foi efetivada via cromatografia líquida acoplada à espectrometria de massas em tandem (LC-MS/MS), em ambos tecidos e tempos de coleta. Para validar os resultados de metabolômica, um grupo de metabólitos destacado nas análises de metabolômica foi escolhido para testes in vitro e por fim detectar alterações no crescimento de Lxx. O resultado do qPCR confirmou a suscetibilidade da CB49-260, pois esta continha títulos superiores à SP80-3280. A análise global revelou que ambos variedades e tecidos possuem perfis metabólicos distintos, porém essas diferenças foram mais quantitativas que qualitativas. A análise direcionada identificou mais aminoácidos, açúcares, ácidos organicos e compostos fosforilados no genótipo suscetível não-inoculado, enquanto que o resistente apresentou maior abundância de compostos fenólicos. Também foi demonstrado que a inoculação com Lxx resultou em maior quantidade de aminoácidos, ácidos orgânicos, compostos fosforilados e fenólicos. Ademais, um aminoácido essencial à sobrevivência de Lxx foi relacionado à inoculação de ambas variedades, assim como um composto fenólico relacionado a defesa de plantas. O teste in vitro mostrou que, apesar de alguns compostos causarem inibição, é necessário aprimorar a metodologia utilizada para confirmar os resultados obtidos.

Atualmente, o Brasil é o maior produtor de cana-de-açúcar (Saccharum ssp.), no qual o estado de São Paulo é responsável por mais de 50% da produção. Esta cultura é hospedeira de diversos patógenos que podem limitar sua produção, dentre os quais se destaca a bactéria Leifsonia xyli subsp. xyli (Lxx), agente causal do raquitismo da soqueira (ratoon stunting disease - RSD). Pouco se sabe sobre a fisiologia deste organismo e quais as estratégias utilizadas por este para colonizar seu hospedeiro. No entanto, sabemos que para infectar e colonizar seus hospedeiros, é necessário que bactérias parasíticas superem estresses de diversas naturezas impostas durante estes processos, como os estresses oxidativo e o osmótico. Neste contexto, os objetivos deste trabalho foram identificar in silico e analisar a expressão in vitro, por qPCR, de genes relacionados a estes dois estresses. Uma análise da sequência do genoma de Lxx identificou 35 genes, sendo 8 relacionados ao estresse oxidativo, 9 relacionados ao estresse osmótico e 11 relacionados a estresse gerais, incluindo um cluster de 6 genes envolvidos na síntese de carotenoides. A expressão destes foi avaliada 60 minutos após exposição a 30mM de H2O2 ou 7% (p/v) de polietilenoglicol 6000 (PEG 6000). Sete genes foram avaliados como normalizadores das reações de qPCR. A quantificação do grau de peroxidação lipídica indicou que ambos os tratamentos resultaram em sensível peroxidação, muito embora o efeito do tratamento com PEG 6000 tenha sido maior do que o tratamento com H2O2. A exposição ao H2O2 aumentou a expressão dos genes katA (catalase), sodA (superóxido dismutase), msrA (Sulfóxido de metionina redutase) e msrB (Sulfóxido de metionina redutase) bem como de todos os genes responsáveis pela síntese de carotenoides. Por outro lado, todos os genes relacionados ao estresse osmótico foram menos expressos na presença deste composto. Já quando a bactéria foi exposta a PEG 6000, o oposto ocorreu, ou seja, os genes relacionados ao estresse osmótico, que são otsA (Trealose-6-fosfato sintase), otsB (Trealose fosfatase), treY (Malto-oligosil trealose sintase), treZ (Malto-oligosil trealose trealoidrolase), treS (Trealose sintase), proX (Proteína de ligamento em substrato, tipo ABC glicina betaína transportadora), proW (Proteína permease, tipo ABC glicina betaína transportadora), proZ (Proteína permease, tipo ABC glicina betaína transportadora) e Naggn (Amidotransferase), além dos genes do cluster carotenoide, foram mais expressos, ao passo que alguns dos genes ligados à resposta ao estresse oxidativo foram menos expressos. Verificou-se também, através de PCR convencional utilizando primers para amplificar as regiões entre os genes carotenoides, que estes são expressos como um RNA policistrônico, constituindo assim um operon. Estes resultados validam predições anteriores baseadas na análise in silico da sequência do genoma de Lxx, confirmando que Lxx possui mecanismos responsivos aos estresses osmótico e oxidativo aos quais é submetida durante o processo de infecção de seu hospedeiro. / Currently, Brazil is the largest producer of sugarcane (Saccharum spp.) and the state of São Paulo accounts for over 50% of the national production. This crop is host to many pathogens that may limit its production, among which the bacterium Leifsonia xyli subsp. xyli (Lxx), causal agent of ratoon stunting disease (RSD), is one of the most important. Little is known about the physiology of this organism and the strategies it uses to colonize its host. However, it is known that to infect and colonize their hosts, parasitic bacteria have to overcome stresses of various natures imposed during these processes, such as oxidative and osmotic stresses. In such context, the objectives of this study were to identify in silico and to analyze in vitro, by qPCR, the expression of Lxx genes related to these two stresses. The analysis of the genome sequence of Lxx identified 35 genes, of which 8 were related to oxidative stress, 9 to osmotic stress and 11 to general stress, including a cluster of 6 genes involved in the synthesis of carotenoids. The expression of these genes was assessed 60 minutes after exposure to either 30 mM of hydrogen peroxide (H2O2) or 7% (w/v) of polyethylene glycol 6000 (PEG6000). Seven genes were tested as normalizers of the qPCR reactions. The quantification of the level of lipid peroxidation in cells of Lxx indicated that both treatments induced substantial peroxidation, even though the effect of PEG6000 was greater than that of H2O2. The exposure to H2O2 resulted in higher expression of the genes katA (catalase), sodA (superoxide dismutase), msrA (sulfoxide methionine reductase) and msrB (sulfoxide methionine reductase), as well as all genes involved in the synthesis of carotenoids. On the other hand, the expression of all genes related to osmotic stress was reduced in the presence of this compound. When Lxx was exposed to PEG6000, the opposite was detected: the expression of the genes related to osmotic stress, otsA (Trehalose-6- phosphate synthase), otsB (trehalose phosphatase), treY (Malto-oligosil trehalose synthase) treZ (Malto-oligosil trehalose trehaloidrolase), treS (trehalose synthase), proX (ligament protein substrate, type ABC glycine betaine carrier), proW (permease protein, ABC type glycine betaine carrier), proZ (protein permease, type ABC glycine betaine carrier) and naggn (amidotransferase), along with the carotenoid genes was increased, while some of the genes linked to oxidative stress response were less expressed. It was also concluded through conventional PCR that the genes of the carotenoid cluster are expressed as a polycistronic RNA and, therefore, this arrangement constitutes an operon. These results validate previous in silico predictions that Lxx has mechanisms responsive to osmotic and oxidative stresses to which it is subjected during the process of infection of its host.

Estudos de adubação nitrogenada em cana-de-açúcar normalmente se restringem em avaliar os efeitos no crescimento da parte-aérea. Há evidências de que a fertilização nitrogenada favorece o crescimento de raízes, a absorção de nutrientes e a produtividade da cultura. Objetivou-se com o trabalho avaliar o desenvolvimento de raízes e produtividade da cana-de-açúcar (SP81 3250) nos ciclos de cana-planta e 1ª soca. Foram conduzidos três experimentos, um em LATOSSOLO VERMELHO AMARELO eutrófico (LVAe) e outro em LATOSSOLO VERMELHO distrófico típico (LVd) (ambos de textura média) e um em LATOSSOLO VERMELHO eutrófico (LVe) argiloso. Na cana-planta os tratamentos constaram de doses de nitrogênio (N) de 40, 80 e 120 kg ha-1 e uma testemunha (sem N mineral), em blocos ao acaso, com quatro repetições. Na cana-soca cada parcela da cana-planta foi dividida em quatro subparcelas, às quais foram aplicadas doses de 50, 100 e 150 kg ha-1 N e uma testemunha. No 1º corte o sistema radicular foi avaliado em todos os tratamentos nos três solos. No 2º corte, o sistema radicular foi avaliado somente nas subparcelas dos tratamentos de plantio testemunha e 120 kg ha-1 N, no LVAe e LVd. Para o experimento no solo LVe, somente nas subparcelas testemunha e 150 kg ha-1 N das parcelas principais testemunha e 120 kg ha-1 N foi avaliado o sistema radicular da cana soca. A amostragem de raízes com sonda resultou em massa de raízes que não diferiu da avaliação em monólito, indicando que esse método pode ser usado para avaliações de raízes de cana-de-açúcar. A fertilização nitrogenada de plantio promoveu maior concentração de raízes até 0,2 m no LVd. No ciclo da cana-planta, no LVAe e no LVd houve crescimento pronunciado de raízes de outubro de 2005 a fevereiro de 2006, com redução da massa de fevereiro até a colheita, porém sem afetar o desenvolvimento da parte aérea. Em fevereiro, 20% do N acumulado na planta toda foi encontrado nas raízes, diminuindo para 5% na colheita como decorrência da redução da massa de raízes. As doses de N no plantio favoreceram o crescimento de raízes e a produtividade de colmos no LVAe e no LVe, e o acúmulo de sacarose no LVd. As doses de N na soqueira favoreceram a produtividade de colmos e açúcar nos três solos. No 1º corte, foi obtida maior produtividade de colmos (152 t ha-1) e menor massa de raízes (1,35 t ha-1) no LVe em relação ao LVAe e LVd (139 e 145 t ha-1 de colmos e 2,5 e 2,4 t ha-1 de raízes, respectivamente). Em relação ao 1º corte, a produtividade do 2º corte se manteve estável no LVd (120 t ha-1) e diminuiu drasticamente no LVe (80 t ha-1). Esse fato foi devido à pequena massa de raízes no LVe no 1º corte, tendo em vista que nas duas áreas ocorreu acentuado déficit hídrico em alguns meses antes e após o 1º corte. A adubação nitrogenada de soqueira favoreceu o crescimento de raízes somente no LVe, porém a massa de raízes diminuiu do 1º para o 2º corte, enquanto que no LVAe e no LVd a massa permaneceu constante. / Studies of nitrogen fertilization in sugarcane are usually restricted to evaluations of the effects on growth and productivity of the shoots. There are evidences that nitrogen fertilization favors the growth of roots, the absorption of nutrients and sugarcane productivity. This work was designed to evaluate root development and sugarcane productivity (SP81 3250) in the crop cycles of the cane-plant and of the first ratoon. Three experiments were conducted in a randomized blocks design, with four replications, in three different soils, a Typic Eutrustox (TE) and an Arenic Kandiustults (AK) (both of medium texture), and a clayey Rhodic Eutrustox (RE). Treatments for the cane-plant were nitrogen (N) rates of 0, 40, 80 and 120 kg ha-1 N. In the first ratoon crop each plot of cane-plant was split in four subplots to which rates of 0, 50, 100 and 150 kg ha-1 of N was applied. In the first harvest, the root system was evaluated in all of the treatments applied on the three soils (TE, AK and RE), whereas in the second harvest the root system was evaluated only for the subplots of the planting treatments control and 120 kg ha-1 N in TE and AK. For the experiment in the RE soil, only control and 150 kg ha-1 N subplots of the control and 120 kg ha-1 N main plots had the ratoon root system evaluated. The sampling of roots with probe resulted in a mass of roots that did not differ from the monolith evaluation, indicating that this method can be used for the evaluation of sugarcane roots. Nitrogen fertilization at planting resulted in a higher concentration of roots in the top 0.2 m in AK. There was a pronounced growth of roots in TE and in AK from October, 2005 to February, 2006, and a reduction of the mass from February until harvest; however development of the above ground part of the plant was not affected. Until February, about 20% of accumulated N in the whole plant was found in the roots, decreasing to 5% at harvest, as a consequence of root mass reduction. The N rates applied to the cane-plant favored the roots growth and crop productivity in TE and RE, and the sucrose accumulation in AK. The rates of fertilizer-N in the ratoon favored the productivity of stalks and sugar yield in the three soils. In the first harvest, it was obtained a larger productivity of stalks (152 t ha-1) and a smaller mass of roots (1.35 t ha-1) in RE in relation to TE and AK (139 and 145 t ha-1 of stalks and 2.5 and 2.4 t ha-1 of roots, respectively). The productivity of the second harvest was similar to that of the first harvest in AK (120 t ha-1), but it decreased drastically in RE (80 t ha-1), as a consequence of the small mass of roots in RE in the first harvest, attributed to a high water deficit in the months prior to and after harvest. Nitrogen fertilization applied after the first harvest influenced root growth only in the RE soil; however the mass of roots decreased from the first to the second harvest while in the TE and AK soils the root mass remained constant.

Ratoon stunting disease (RSD), caused by the bacterium Leifsonia xyli subsp xyli, is well established in most sugarcane growing regions of the world and is considered to cause more yield losses worldwide than any other sugarcane disease (Hughes, 1974). In South Africa, field trials have demonstrated that yield reductions under rainfed conditions can exceed 40% in highly susceptible varieties (Bailey and Bechet, 1986). When cane is grown under irrigation, yield losses are less noticeable but still significant in many varieties (Bailey and Bechet, 1995). It is estimated that RSD currently results in a one percent reduction in industrial production in South Africa and between 10 and 20% in other African countries where South African varieties are grown (Bailey and McFarlane, 1999; Rutherford et al., 2003). For many years, the reaction of different sugarcane varieties to RSD has been based on large, replicated yield loss trials grown over a number of years under rainfed and irrigated conditions. Although these trials provide valuable information, they are time-consuming and require large areas of uniform land. They are therefore not suitable for incorporation into a routine disease screening programme in which large numbers of genotypes are assessed for their reactions to the important diseases occurring in the industry. As a result, the susceptibility of new commercial varieties to RSD is only known several years after release to the growers. The main objective of this study was to establish a suitable method to reliably evaluate sugarcane genotypes for RSD resistance as part of the plant breeding and selection programme. Emphasis was placed on the use of the tissue blot immunoassay (TBlA) developed by Harrison and Davis (1988) and modified by Davis et al (1994), in relation to the more traditional methods of variety assessment, such as the rate of spread of RSD in the field at harvest and yield loss trials. Although the immunoassay protocol was not altered, slight modifications to the blotting procedure resulted in clearer blots that were easier to interpret. Internode position and the age of the cane were shown to have a marked effect on the extent of colonisation and ultimately the RSD resistance rating. A trial investigating the effect of the extent of colonisation on the rate of spread of RSD at harvest was conducted and showed that the relationship between spread and colonisation was highly significant. This indicated that RSD spread more rapidly through varieties such as N14 and N22 that supported high populations of L. xyli subsp xyli. The control plots in the same trial provided useful information on the extent of colonisation in the twelve varieties planted. In another trial, the effect of RSD on the yield components of six commercially grown varieties was investigated and TBIA was also conducted to compare the two methods of variety assessment. The relationship between yield loss and the extent of colonisation was significant in both the plant and first ratoon crops. TBIA produced consistent results and the ranking of the six varieties was virtually identical, despite the different growing conditions during the two crop cycles. In an attempt to screen large numbers of genotypes under controlled glasshouse conditions, .TBIA was also tested on RSD-infected sugarcane transplants (seedlings). The results of this trial were variable and could not be reliably used as a screening tool. Based on the findings of this study, TBIA has now been adopted as a quicker and cheaper alternative to immunofluorescence microscopy for diagnosing RSD in sugarcane transplants. More importantly, TBIA has been accepted as a method of screening genotypes routinely for resistance to RSD and the first screening trial was planted in November 2002. It will now be possible to inform sugarcane growers of the RSD status of the new varieties as they are released, enabling them to make more informed decisions on how to manage each variety. This information will also be valuable when selecting parents in the crossing programme, with a long term view of improving the general resistance of commercially grown varieties to RSD. This should ultimately result in a substantial reduction in RSD levels in the industry. / Thesis (M.Sc.)-University of Natal, Durban, 2003.