Vigor de sementes de soja: estudos fisiológicos e moleculares relacionados ao déficit hídrico
Carregando...
Data
2018-12-07
Autores
Ducatti, Karina Renostro
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O vigor de sementes está associado a vários aspectos do desempenho de sementes, como velocidade e uniformidade de germinação e tolerância a condições adversas. Os eventos metabólicos ativados nas primeiras horas da embebição podem fornecer informações importantes para explicar as variações de comportamento entre sementes de diferentes níveis de vigor. O objetivo geral foi estudar o vigor de sementes de soja utilizando diferentes abordagens. As sementes de soja das cultivares BRS 133 e MG/BR 46 Conquista foram produzidas sob condições ideais e déficit hídrico (a partir de R5.5). No capítulo 1, as sementes foram submetidas a avaliação da qualidade fisiológica, análises bioquímicas, atividade biospeckle ao longo da embebição e estudos de expressão de genes relacionados ao vigor avaliados no eixo embrionário em 0, 6 e 10 horas de embebição. O capítulo 2 teve como objetivo estudar dois protocolos de hidrocondicionamento (imersão direta e entre papel) e avaliar os efeitos no desempenho fisiológico e na expressão gênica de sementes das sementes de soja produzidas no capítulo 1. No capítulo 1, o déficit hídrico durante a fase final de desenvolvimento e maturação de sementes não apenas reduz o vigor das sementes de soja produzidas, como também altera os níveis de atividade enzimática, de atividade biospeckle e de expressão gênica ao longo da embebição. Durante as primeiras horas de embebição, notam-se alterações significativas na expressão de genes relacionados a diversos processos, como no reparo ao DNA, combate ao estresse oxidativo, atividades respiratórias e alongamento celular. No capítulo 2, o hidrocondicionamento entre papel proporcionou maior porcentagem e velocidade de germinação, e início mais rápido da protrusão, especialmente em temperaturas subótimas. A análise de expressão de genes demonstrou que as sementes condicionadas, de ambas as cultivares e condições de produção, apresentaram maior expressão de transcritos envolvidos na respiração celular e mobilização de reservas, no alongamento e no remodelamento, modificação e síntese de parede celular, refletindo o efeito benéfico do hidrocondicionamento sobre o desempenho fisiológico das sementes.
Seed vigor is a multiple and complex trait associated with various aspects of seed performance, such as rate and uniformity of germination and tolerance to adverse conditions. The metabolic events activated in early imbibition may provide important information to explain behavior variations in seeds with different vigor levels. The objective was to study soybean seed vigor using different approaches. For this experiment, soybean seeds of cultivars BRS 133 and MG/BR 46 (Conquista) were produced under ideal conditions and under drought stress (from R5.5). In chapter 1, the seeds were submitted to physiological quality tests, biochemical analyzes, biospeckle activity during imbibition and expression of genes related to vigor evaluated in the embryonic axis at 0, 6 and 10 hours after imbibition. In chapter 2, the objective was to study two hydropriming protocols (soaking in water and between paper) and to evaluate the effects on the physiological performance and gene expression of soybean seeds produced in chapter 1. In chapter 1, the results indicated that the drought stress during seed development and maturation not only reduces the vigor of the soybean seeds produced, but also changes the levels of enzymatic activity, biospeckle activity and gene expression during imbibition. During early imbibition, there are significant changes in the gene expression of genes related to several processes, such as DNA repair, oxidative stress, respiratory activities, cell elongation and cell wall modification. In chapter 2, the hydropriming between paper provided higher percentage and speed of germination, and faster onset of the protrusion, especially in suboptimal temperatures. Gene expression analysis demonstrated that the primed seeds of both cultivars and production conditions showed higher expression of transcripts involved in cellular respiration and reserve mobilization, cell elongation, cell wall loosening and biosynthesis of cell wall, which may indicate the beneficial effects of priming on physiological performance in primed seeds during germination.
Seed vigor is a multiple and complex trait associated with various aspects of seed performance, such as rate and uniformity of germination and tolerance to adverse conditions. The metabolic events activated in early imbibition may provide important information to explain behavior variations in seeds with different vigor levels. The objective was to study soybean seed vigor using different approaches. For this experiment, soybean seeds of cultivars BRS 133 and MG/BR 46 (Conquista) were produced under ideal conditions and under drought stress (from R5.5). In chapter 1, the seeds were submitted to physiological quality tests, biochemical analyzes, biospeckle activity during imbibition and expression of genes related to vigor evaluated in the embryonic axis at 0, 6 and 10 hours after imbibition. In chapter 2, the objective was to study two hydropriming protocols (soaking in water and between paper) and to evaluate the effects on the physiological performance and gene expression of soybean seeds produced in chapter 1. In chapter 1, the results indicated that the drought stress during seed development and maturation not only reduces the vigor of the soybean seeds produced, but also changes the levels of enzymatic activity, biospeckle activity and gene expression during imbibition. During early imbibition, there are significant changes in the gene expression of genes related to several processes, such as DNA repair, oxidative stress, respiratory activities, cell elongation and cell wall modification. In chapter 2, the hydropriming between paper provided higher percentage and speed of germination, and faster onset of the protrusion, especially in suboptimal temperatures. Gene expression analysis demonstrated that the primed seeds of both cultivars and production conditions showed higher expression of transcripts involved in cellular respiration and reserve mobilization, cell elongation, cell wall loosening and biosynthesis of cell wall, which may indicate the beneficial effects of priming on physiological performance in primed seeds during germination.
Descrição
Palavras-chave
Glycine max, Qualidade fisiológica, Atividade enzimática, Condicionamento fisiológico, Priming, Physiological quality, Enzymatic activity