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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1974.tde-20240522-110312
Document
Author
Full name
Luiz Carlos Basso
Institute/School/College
Date of Defense
Published
Piracicaba, 1974
Supervisor
Title in Portuguese
Formação de di- e poliaminas em plantas deficientes em potássio e magnésio
Keywords in Portuguese
DEFICIÊNCIAS MINERAIS DE PLANTAS
MAGNÉSIO
NUTRIÇÃO VEGETAL
POLIAMINAS
POTÁSSIO
Abstract in Portuguese
Com o objetivo de melhor compreender o significado e a razão do acúmulo de putrescina em plantas sob condições de deficiências de potássio ou magnésio, realizou-se o presente experimento, em busca de alguma relação com o metabolismo de poliaminas biogênicas de certa atividade fisiológica. Para tal, plantas de cevada (Hordeum vulgare), fava (Vicia faba), espinafre (Spinaceae oleracea) e ervilha (Pisum sativum) foram crescidas em casa de vegetação, com soluções nutritivas completa e deficientes em potássio e/ou magnésio. Em alguns tratamentos foram efetuadas as substituições do potássio pelo sódio e do magnésio pelo cálcio. As folhas dessas plantas foram colhidas em diferentes tempos do seu desenvolvimento, e submetidas às determinações de arginina, agmatina, putrescina, espermina e espermidina. Outros ensaios foram realizados, ministrando-se arginina-U-14C à folhas jovens de cevada, procurando medir alterações na intensidade de degradação de arginina em agmatina e putrescina, devido às deficiências de potássio e de magnésio. No mesmo material vegetal procurou-se aquilatar a intensidade de síntese das poliaminas espermina e espermidina, empregando-se putrescina 1,4-14C como precursor. Os aminoácidos e as aminas foram extraídos das folhas com etanol 80% ou ácido tricloroacético a 5% e fracionados em resina de troca catiônica (DOWEX 50W-X8 e Amberlite IRC-50). Determinações colorimétricas foram empregadas para as dosagens de arginina e agmatina, enquanto que putrescina e as poliaminas espermina e espermidina foram estimadas pela técnica da fluorometria. As radioatividades dos compostos foram dosadas pela cintilação líquida. Os dados demonstraram aumento na intensidade de síntese da amina putrescina nas deficiências de potássio ou magnésio, amina essa que é produzida mais pela degradação de arginina do que mediante a descarboxilação de ornitina. Embora muitos aspectos bioquímicos e fisiológicos de tais aminas ainda não estejam bem compreendidos, algumas considerações são apresentadas, no sentido de se propôr um único mecanismo para o acúmulo de putrescina em plantas deficientes em potássio ou magnésio, fundamentando-se na interação de di- e poliaminas em determinados processos metabólicos, principalmente os relacionados com a síntese de proteínas.
Abstract in English
The present study was carried out to better understand the significance of putrescine accumulation in plants under potassium or magnesium stress. A search was made for some relationship between putrescine accumulation and the metabolism of naturally occurring polyamines of certain physiological activity. With this objective, plants of barley (Hordeum vulgare) broad bean (Vicia faba), spinach (Spinaceae oleracea) and pea (Pisum sativum) were grown in a greenhouse in nutriente solutions either complete or deficient in potassium and/or magnesium. In some experiments potassium was substituted with sodium, and magnesium with calcium. At different times the leaves were harvested and the levels of arginine, agmatine, putrescine, spermine and spermidine determined. Other experiments were set up in which arginine-U-14C was applied to young barley leaves in order to test the effect of potassium and magnesium deficiencies on the rate of degradation of arginine to agmatine and putrescine. With the same experimental material an attempt was made to estimate the rate of spermine and spermidine synthesis using putrescine -1,4-14C as precursor. Amino acids and amines were extracted from the leaves with either 80% ethanol or 5% trichloroacetic acid, and separated on cationic exchange resins (DOWEX, 50W-X8 and Amberlite IRC-50). Arginine and agmatine were determined colorimetrically whereas putrescine, spermine and spermidine were determined fluorimetrically. Radioactivity of the compounds was measured by liquid scintillation counting. The data show that under potassium or magnesium stress there was an increase in putrescine synthesis, and that the formation of this amine was mainly through degradation of arginine rather than decarboxylation of ornithine. Although much of the biochemistry and physiological significance of these amines is not as yet fully understood, some possibilities are discussed and a single mechanism is proposed for the accumulation of putrescine in both potassium and magnesium deficient plants, based on the interaction of di- and polyamines with certain metabolic process, mainly the protein synthesis.
 
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Publishing Date
2024-05-22
 
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