Avaliação da perda da tolerância à dessecação e da quantidade de dna nuclear em sementes de Peltophorum dubium (spreng.) taubert durante e após a germinação
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Data
2011-01-01
Autores
Guimarães, Cristiane Carvalho
Faria, José Marcio Rocha
Oliveira, Julio Maia
Silva, Edvaldo Aparecido Amaral da [UNESP][
Título da Revista
ISSN da Revista
Título de Volume
Editor
Associação Brasileira de Tecnologia de Sementes (ABRATES)
Resumo
O presente trabalho teve por objetivo a avaliação da perda da tolerância à dessecação (TD) em sementes de Peltophorum dubium durante e após a germinação. As sementes foram colocadas para germinar e, ao atingirem 1, 3 e 5 mm de raiz primária (68% de umidade), foram desidratadas em sílica gel, até atingirem o grau de umidade inicial (8%), sendo em seguida reidratadas e avaliadas quanto à sobrevivência (retomada do crescimento e formação de plântulas normais). Procedimento semelhante foi adotado para os ensaios realizados durante a embebição, onde foram amostradas 100 sementes divididas em quatro repetições de 25 para cada um dos seguintes tempos de embebição: 12, 24, 48, 60 e 72 horas. em seguida, foram selecionados diferentes pontos de interesse (12, 48 e 60 horas de embebição e raízes primárias com 1 mm de comprimento) para determinação da quantidade de DNA nuclear, afim de analisar possível correlação entre início do ciclo celular e perda da TD. Com relação ao comportamento de sementes germinadas submetidas à secagem e reidratação, para os três comprimentos de raízes primárias amostradas, não houve sobrevivência. Foi observada queda progressiva na sobrevivência de sementes de Peltophorum dubium relacionada ao tempo de embebição, e posterior secagem e reidratação, sugerindo que a perda da TD desta espécie acontece nos estágios iniciais da germinação, antes da protrusão da radícula. Sementes embebidas por 12 h, 24 h, 48 h, 60 h, 72 h e aquelas germinadas, com 1 mm de comprimento radicular, apresentaram índices iguais a 98%, 93%, 83%, 35%, 17% e 0% de sobrevivência respectivamente. Os estudos relacionados ao conteúdo de DNA nuclear não demonstram correlação entre retomada do ciclo celular e perda da TD.
The objective of this study was to investigate the loss of desiccation tolerance (DT) in seeds of Peltophorum dubium (Sprengel) Taubert, during and after germination. P. dubium seeds were sown, removed after germination when the primary root lengths reached 1, 3 and 5 mm (68% water content), dehydrated in silica gel until they had reached their initial moisture content (8%), rehydrated and evaluated for survival (resumption of growth and development of normal seedlings). This procedure was also followed in the assays during imbibition, where 4 replications of 25 seeds were subjected to 12, 24, 48, 60 and 72 hours of imbibition. Subsequently, different points were selected (12, 48 and 60 hours of imbibition and radicles 1 mm long) to evaluate the nuclear DNA content in order to relate the beginning of the cell cycle with the loss of DT. For the three radicle lengths sampled, there was no survival of seeds which had been dried and rehydrated. There was a progressive decrease in the survival of P.dubium seeds related to the imbibition period and subsequent drying and rehydration, suggesting that the loss of DT occurs early in germination before radicle protrusion. Seeds imbibed for 12, 24, 48, 60, 72 hours and germinated seeds with 1 mm long radicles showed 98%, 93%, 83%, 35%, 17% and 0% survival, respectively. The assays with the nuclear DNA content do not show any relationship between the resumption of the cell cycle and the loss of DT.
The objective of this study was to investigate the loss of desiccation tolerance (DT) in seeds of Peltophorum dubium (Sprengel) Taubert, during and after germination. P. dubium seeds were sown, removed after germination when the primary root lengths reached 1, 3 and 5 mm (68% water content), dehydrated in silica gel until they had reached their initial moisture content (8%), rehydrated and evaluated for survival (resumption of growth and development of normal seedlings). This procedure was also followed in the assays during imbibition, where 4 replications of 25 seeds were subjected to 12, 24, 48, 60 and 72 hours of imbibition. Subsequently, different points were selected (12, 48 and 60 hours of imbibition and radicles 1 mm long) to evaluate the nuclear DNA content in order to relate the beginning of the cell cycle with the loss of DT. For the three radicle lengths sampled, there was no survival of seeds which had been dried and rehydrated. There was a progressive decrease in the survival of P.dubium seeds related to the imbibition period and subsequent drying and rehydration, suggesting that the loss of DT occurs early in germination before radicle protrusion. Seeds imbibed for 12, 24, 48, 60, 72 hours and germinated seeds with 1 mm long radicles showed 98%, 93%, 83%, 35%, 17% and 0% survival, respectively. The assays with the nuclear DNA content do not show any relationship between the resumption of the cell cycle and the loss of DT.
Descrição
Palavras-chave
DNA nuclear, ciclo celular, Peltophorum dubium, Cell cycle, nuclear DNA, Peltophorum dubium
Como citar
Revista Brasileira de Sementes. Associação Brasileira de Tecnologia de Sementes, v. 33, n. 2, p. 207-215, 2011.