Alterações nas reservas de sementes de Melanoxylon brauna Schott. (Fabaceae Caesalpinoideae) durante a germinação em diferentes temperaturas

Abstract

RESUMODurante a germinação, as sementes utilizam os compostos de reserva para fornecerem os nutrientes necessários até que as plântulas se tornem autotróficas. Neste trabalho objetivou-se investigar as alterações nas reservas de carboidratos, amido, lipídios e proteínas em sementes de Melanoxylon brauna durante o período germinativo em diferentes temperaturas. Para tanto, sementes da espécie foram colocadas para germinar sob temperaturas de 10, 25, 30 e 40 °C, sendo retiradas amostras de sementes a cada 24 horas durante o período de 96 horas. Uma pequena redução nos teores de lipídios foi observada durante a germinação nas temperaturas analisadas, enquanto os teores de açúcares solúveis decresceram a partir de 48 horas de embebição, sendo prontamente utilizados, especialmente nas temperaturas de 25 e 30 °C. Para as proteínas solúveis, verificou-se declínio desde o início do período germinativo às temperaturas de 25 e 30 °C, sendo este mais intenso no período pós-germinativo à temperatura de 30 °C. Conclui-se que as reservas de carboidratos solúveis, lipídios e proteínas decresceram durante o período germinativo de sementes de Melanoxylon brauna, variando esses decréscimos de acordo com a temperatura. Palavras-chave: amido; carboidratos; lipídios; proteínas Changes in seed reserves of Melanoxylon brauna Schott. (Fabaceae Caesalpinoideae) during germination at different temperatures ABSTRACTDuring germination, seeds use the reserve compounds to provide the nutrients until the seedlings become autotrophic. The aim of this study was to investigate the changes in carbohydrates, starch, lipids and proteins reserves during germination of Melanoxylon brauna seeds at different temperatures. For both, the seeds were germinated at temperatures of 10, 25, 30 and 40 °C, and samples were collected every 24 hours during 96 hours. Was observed small reduction of lipid levels during germination in temperatures analyzed, while the levels of soluble sugars decreased from 48 hours of soaking, being readily used, especially at temperatures of 25 and 30 °C. For soluble proteins, there was a decrease from the beginning of the germination period at temperatures of 25 to 30 °C, this being more intense in the post-germination at 30 °C period. It is concluded that soluble carbohydrate, lipid and protein reserves decreased during the germination period of Melanoxylon brauna seeds, varying these decreases according to temperature.

Molecular aspects during seed germination of Erythrina velutina Willd. under different temperatures (Part 1): reserve mobilization

“…Seed germination occurs only within a minimum and maximum temperature limits, with the ideal value being that at which the maximum germination is obtained the fastest (Bewley et al, 2013;Marcos-Filho, 2015;Correa et al, 2020). Ambient conditions between 20 and 30 °C are indicated for seed germination of several tropical and subtropical forest species (Silva et al, 2016;Ataíde et al, 2017;Benedito et al, 2019). In those circumstances, deterioration reactions due to high temperatures (45 °C) do not take place during germination, thus preventing metabolism changes, cell damages (membrane degradation), and alterations in essential biomolecules, remarkably nucleic acids (DNA deterioration), lipids (lipid peroxidation), and proteins (protein denaturation and enzyme inactivation) (Bewley et al, 2013;Önder et al, 2020).…”

“…M. brauna seeds also showed a significant depletion of carbohydrates and proteins in the cotyledons during germination at 25 and 30 °C (Ataíde et al, 2017), while higher temperatures triggered thermal stress and metabolic alterations (Santos et al, 2020). In the process, amylases and other enzymes break the starch within the granules in the cell plastids into smaller units, producing glucose and fructose.…”

“…This kind of investigation is particularly important in a scenario of global warming, which might lead to plant extinction due to metabolic changes (Santos et al, 2020). In order to better understand the propagation strategies and mechanisms of these species, research on the physiology and biochemistry of seeds is paramount to elucidate which the main reserve compounds are, and how they are mobilized during the processes of germination and establishment of the seedlings (Ataíde et al, 2017).…”

Germination on the nutritional properties of seeds of four melon varieties

“…Germination involves the mechanisms of hormone regulation and protein hydration, besides the transportation of reserves, synthesis of macromolecules, heightened respiration and cell elongation (RAJJOU et al, 2012;BEWLEY et al, 2013). During the germination process, the reserve materials namely, carbohydrates, lipids and proteins require conversion into soluble compounds, which must later be transported to the growth regions to make the necessary nutrients available until the seedlings acquire autotrophic capacity (ATAÍDE et al, 2017). Germination involves wide-ranging phytochemical changes which result from the dynamic and complex flow of nutrients, in which remobilization, degradation and accumulation (NELSON et al, 2013) take place.…”

Ação do mercúrio na germinação de sementes de Melanoxylon brauna Schott. (Fabaceae-Caesalpinoidae)

“…Usualmente, a propagação de braúna é feita por meio de sementes (BORGES et al, 2015), e sua germinação já é bastante estudada (FLORES et al, 2013;FLORES et al, 2014;LIMA E BORGES et al, 2015; LIMA E BORGES; ATAÍDE; MATOS, 2015; ATAÍDE; LIMA E BORGES; LEITE FILHO, 2016;ATAÍDE et al, 2017;SANTOS et al, 2017). Entretanto, há poucas informações na literatura relacionadas a sua germinação em condições de estresse, como por contaminação por elementos traço.…”