Metabolismo de plantas de cana-de-açúcar cultivadas in vitro sob diferentes concentrações de nitrogênio

Abstract

Resumo -Variedades de cana-de-açúcar (RB 732577, RB 83102, RB 75126, CB 45-3, Caiana e Co 997) foram cultivadas in vitro em meio nutritivo básico MS com diferentes concentrações de N (9,83 mM, 7,37 mM, 4,92 mM, 2,46 mM, 0,49 mM e 0,0 mM), com o objetivo de avaliar a eficiência no processo de assimilação desse elemento. Após 45 dias de cultivo, foram determinados os ganhos de biomassa e os teores de amônio, aminoácidos e açúcares solúveis. A variedade Co 997 apresentou maior ganho de biomassa e maior quantidade de N incorporado em aminoácidos livres em relação às demais variedades, sugerindo maior eficiência no processo de assimilação. Os teores mais elevados de amônio foram observados nas variedades RB 83102 e RB 75126, quando cultivadas em meio desprovido de N, mostrandose menos eficientes no processo de assimilação uma vez que apresentaram os menores valores de aminoácidos livres nas mesmas condições de cultivo.Termos para indexação: Saccharum, biomassa, aminoácido, fixação do nitrogênio. Metabolism of sugar cane plant cultivated in vitro at different nitrogen levelsAbstract -Sugar cane varieties (RB 732577, RB 83102, RB 75126, CB 45-3, Caiana and Co 997) were cultivated in vitro at basic MS nutritive media with different N levels (9.83 mM, 7.37 mM, 4.92 mM, 2.46 mM, 0.49 mM and 0.0 mM), in order to evaluate the efficiency in the assimilation process of this element. After 45 days of cultivation, the biomass and the ammonium, amino acid and soluble sugars contents were determined. Co 997 variety presented higher biomass gain and higher N quantity incorporated to free amino acid, showing higher efficiency in the assimilation process. Higher proportions of ammonium were observed on RB 83102 and RB 75126 varieties when cultivated at media without N, suggesting lower efficiency on the assimilation process due to the presence of lower values of free amino acids.

Effects of cytokinins on in vitro mineral accumulation and bud development in Annona glabra L.

“…Statistical analyses were performed using the SISVAR 4.3 software program (Ferreira, 1999). Averages were compared by using the Scott-Knott test at a 5% probability level.…”

“…Carvalho & Biasi (2004) demonstrated that the amount of zeatin (ZEA) and indoleacetic acid (AIA) used to induce budding in explants of "caqui" (Diospyros kaki) can be reduced to 1µM and 0.01µM, respectively, when these explants are cultivated in MS medium (Murashige & Skoog, 1962) containing only half the normal concentration of NO 3 . It has also been suggested that the use of growth regulators (especially cytokinins) affects the rates of absorption and translocation of essential minerals in plants under in vitro conditions as they directly influence the formation and differentiation of the vascular system and the regulation of enzymes involved in the assimilatory metabolism of minerals, principally nitrogen (Aloni, 2001;Donato et al, 2003).…”

Comparative Study Between the Growth Regulators Benzyl Adenine (BAP) and Thydizoronate (TDZ) and Nano Iron in the Growth and Multiplication of Citrumelo Shoots in Vitro

“…As for the reason for the increase in the content of the shoots of the elements Table 2, 3, 4 that the cytokines act as a sink for nutrients, which leads to an increase in the percentage of elements within the explant and an increase in the percentage of sugars in the nutritional medium that is important in the construction processes in the tissues, which works on the accumulation of sugars in it, reflected in an increase vegetative growth table 2.Thus, increasing the accumulation of mineral elements in addition to their vital role, increases the opening of the stomata, which may reach the width of the stomata opening by 50%.Which leads to an increase in transpiration and thus an increase in the process of absorption of elements from the medium [25]. The use of cytokinins also affects the rate of absorption of basic elements in plants under laboratory conditions, where it directly affects the formation and differentiation of vessels and the regulation of enzymes involved in vital processes, especially nitrogen [26,27]. The positive effect of cytokinin BAP may be due to its being a source of the reduced form of nitrogen, which stimulates the biosynthesis of natural cytokinins.…”

Macronutrientes, aspectos nutricionais e bioquímicos no crescimento de brotações de Eucalyptus grandis in vitro

“…Aos 45 dias de cultivo, a variedade Co 997 apresentou maior ganho de massa seca e maior quantidade de nitrogênio incorporado em aminoácidos livres em relação às demais variedades, sugerindo maior eficiência no processo de assimilação. Nas variedades RB 83102 e RB 75126 foram obtidos os maiores teores de amônio quando cultivadas em meio de cultura sem a presença de nitrogênio, sendo estas menos eficientes no processo de assimilação uma vez que apresentaram os menores teores de aminoácidos livres (DONATO et al, 2003).…”