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Made available in DSpace on 2015-03-26T13:36:46Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3423486 bytes, checksum: 6f5dcf6dbf9fc0e69461e7967c2babfd (MD5) Previous issue date: 2013-07-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study was carried out to analyze the physiological, metabolic and anatomic impacts promoted by both the endogenous and/or artificial variation of gibberellins (GAs) on tomato plants (Solanum lycopersicum L.). To this end, different experiments were performed using wild-type (WT) and mutant plants in the biosynthesis of gibberellins (gib3, moderately deficient; gib2, mildly deficient and gib1, extremely deficient). In the first experiment I used WT and the mutant plants gib3, gib2 and gib1 and evaluated the effects of endogenous reduction of GA levels. It was observed that the reduced levels of GAs negatively affected the growth and that this slower growth is not associated with lower photosynthetic rates. The higher net photosynthesis (A N ) found in the mutants were associated with both increased stomatal density and higher stomatal (g s ) and mesophyll (g m ) conductances. One clear imbalance between carbon metabolism and growth seems to occur in plants with reduced GAs levels, given that reductions in the levels of the majority of the metabolites occurred concomitantly to higher A N . Moreover, higher A N was accompanied by elevated respiratory rate and increments in protein concentration, suggesting a shift of energy in the form of ATPs to other routes, since more energy production was not associated with higher biomass accumulation. In the second experiment I used plants WT and gib3, the genotype most similar to WT in the first experiment, and subjected those plants to artificial variations in the content of GAs by applying GAs and/or paclobutrazol (PBZ), a GA biosynthesis inhibitor. The results obtained allowed the identification of both metabolic and physiological changes associated with both endogenous GAs variation, as well as the artificial variation caused by varying the GAs regime. In both genotypes growth was strongly reduced in presence of PBZ whereas it was incremented when applying GAs. Lower growth rates were accompanied by higher dark respiration (R d ) and higher A N , the former being influenced by larger stomatal density and stomatal opening, leaf thickness, as well as g s and absorptance. The levels of the majority of metabolites evaluated were positively associated with GAs content. Little or no variation in chlorophyll fluorescence a and antioxidative system parameters indicated no apparent stress. Taken as a whole, the information obtained within this study provide a better understanding of the physiological, molecular and metabolic disorders associated with GA deficiency in plants; however, future metabolic and molecular studies are still required to allow us a better understanding of the effects of reduced GA levels on the metabolism of these plants. / O presente trabalho foi conduzido com intuito de analisar os impactos causados pela variação endógena e/ou artificial (aplicação de GAs e paclobutrazol-PBZ) dos níveis de giberelinas sobre a fisiologia, metabolismo e anatomia de plantas de tomate (Solanum lycopersicum L.). Para tal, diferentes experimentos foram realizados utilizando-se plantas tipo selvagem (WT) e mutantes na biossíntese de giberelinas (gib3: moderadamente deficiente, gib2: medianamente deficiente e gib1: extremamente deficiente). No primeiro experimento foram utilizadas plantas WT e os mutantes gib3, gib2 e gib1 avaliando-se os efeitos da redução endógena dos níveis de GAs. Os resultados mostraram que a redução dos níveis de GAs afetou negativamente o crescimento dessas plantas e que este menor crescimento não estaria associado a menores taxas fotossintéticas. A elevada fotossíntese (A N ) nos mutantes apresentou-se associada com uma maior densidade e abertura estomática, assim como maiores condutâncias estomática (g s ) e mesofílica (g m ). Um desbalanço entre o metabolismo do carbono e crescimento parece ocorrer plantas com redução na concentração de GAs, visto que reduções nos teores da maioria dos metabólitos ocorreram concomitantemente com elevada A N . Ademais, maior A N foi acompanhada de uma elevada taxa respiratória e incrementos na concentração de proteínas, sugerindo um desvio de energia em forma de ATPs para outras rotas, já que uma maior produção de energia não se traduziu em acúmulo de biomassa. No segundo experimento foram utilizadas plantas WT e gib3, genótipo mais semelhante ao WT no primeiro experimento, submetidas à variações artificiais no conteúdo de GAs mediante a aplicação de GAs e/ou PBZ. Os resultados obtidos permitiram a identificação de mudanças metabólicas e fisiológicas associadas tanto à variação endógena de GAs, assim como as ocasionadas pela variação artificial de GAs. Para ambos os genótipos, o crescimento foi bastante reduzido em presença de PBZ e apresentou incrementos quando da aplicação de GAs. Menores taxas de crescimento foram acompanhadas de maiores respiração no escuro (R d ) e A N , a última influenciada por maiores densidade e abertura estomática, espessura foliar, assim como g s e absortância. A maioria dos metabólitos foi positivamente correlacionada com o conteúdo de GAs. Pouca ou nenhuma variação em parâmetros da fluorescência da clorofila a e sistema antioxidativo indicam ausência de estresses aparentes. Consideradas em conjunto, as informações obtidas com o presente estudo oferecem uma melhor compreensão dos mecanismos fisiológicos, moleculares e metabólicos associados à deficiência de GAs em plantas; contudo, estudos metabólicos e moleculares mais detalhados ainda serão necessários para uma melhor compreensão dos efeitos da redução dos níveis de GAs sobre o metabolismo dessas plantas.

Due to the recent changes in the economy of Kentucky tobacco production, some producers are seeking an alternative crop that will provide similar economic gains to tobacco without needing more acreage. Tomatoes are an existing crop in Kentucky that have been declining in acreage over the last five years. There is evidence to suggest that, through niche and local marketing, tomatoes may be able to fill the void left by tobacco. However, there is concern among producers that they will lose yield and/or quality if they switch to one of these niche production systems or cultivars. A two year study at Western Kentucky University compared the yield and quality of three tomato cultivars, two heirlooms and one hybrid, under organic and conventional management techniques to see if producers concerns are valid. The heirloom cultivars used were 'Cherokee Purple' (CP) and 'Mr. Stripey', (MS) the hybrid cultivar was 'Crista' (CR). The study was a split block design, with four randomized replications within each block. Plants were grown under black plastic mulch, with drip irrigation under the mulch. Plants were harvested weekly throughout the season and data were collected on individual fruit weight, size, grade and the number of fruit produced per plant. Production and quality were compared between management techniques for each cultivar, and the cultivars were compared to each other under individual management techniques. When comparing organic and conventional management practices, CP produced significantly (p<.05) larger, heavier, and higher quality fruit under organic practices and showed no significant differences in fruit number in 2008. MS and CR showed no significant differences between production systems for fruit weight or size, CR produced significantly higher quality fruit under conventional treatment and MS produced significantly more fruit per plant in 2008. In 2009, CP did not produce enough fruit under organic management to allow statistical comparison between management systems. MS however did not show any significant differences between management systems for any of the traits studied. CR produced significantly larger fruit under organic management, but no other differences were observed. When comparing cultivars in 2008, CP and CR produced fruit of similar weight but significantly heavier than MS under both production systems. CP produced the largest fruit under organic management, with CR following and MS producing the smallest fruit. Under conventional management, CP and CR produced fruit of similar size and both were larger than MS. MS produced the highest quality fruit under organic management, and CR produced the nicest grade under conventional management. No differences were seen for number of fruit per plant between cultivars under organic management, while MS produced the most fruit per plant under conventional management. In 2009 CP did not produce enough fruit to be statistically compared to the other cultivars under organic management. MS and CR produced fruit of similar weight under both organic and conventional management, while CP produced the greatest weight under conventional management. CR produced larger fruit than MS under organic management, while under conventional management CP and CR were of similar size as were CR and MS, but CP was significantly larger than MS. No significant differences were found between cultivars for fruit grade or number of fruit per plant under either management system in 2009.