Aline da Consolação Sampaio Clemente

Physiological and biochemical alterations during germination of sucupira-preta (Bowdichia virgilioides Kunth.) seeds

This research aimed to evaluate the alterations in black sucupira seeds during imbebetion and the modifications in some enzymes and proteins during this process. The seeds were imbibed in wet paper roll at 30°C and weighted for 6 hours until the root protrusion of 50% of the seeds, then the seeds were submitted to the protein analysis by electrophoresis technique. The imbebition curve of the black sucupira has a triphasic model. The evaluation of enzymatic systems shoed the same pattern for the enzymes superoxide dismutase and malate dehidrogenase. For the enzymes alcohol dehidrogenase, catalase and α-amylase, the band intensity varied according to the seed lot used. For the protein resistant to heat, the presence of bands was observed throughout the germination, with alterations in intensity during the process.

Métodos para a superação da dormência em sementes de sucupira-preta (Bowdichia virgilioides Kunth.)

Neste estudo foram avaliados diferentes metodos para a superacao da dormencia em sementes de sucupira-preta. O experimento foi realizado inteiramente ao acaso em esquema fatorial 3 x 7, correspondendo a tres lotes de sementes e sete tratamentos, com 4 repeticoes de 25 sementes. Foram utilizados acido sulfurico por 4, 8 e 12 minutos, agua a 80°C por 5 e 10 minutos, escarificacao mecânica, mantendo-se uma testemunha. Foi observado que a especie possui dormencia tegumentar e que todos os tratamentos utilizados permitiram a entrada de agua nas sementes. Contudo, alguns metodos estudados, como a agua a 80°C por 10 minutos, resultou em um elevado numero de sementes mortas. O metodo mais eficiente para a superacao da dormencia de sementes de sucupira-preta e a imersao em acido sulfurico, por 4, 8 ou 12 minutos, beneficiando a porcentagem e a velocidade de germinacao.

Marcador isoenzimático de dormência em sementes de arroz

Aiming to evaluate the alterations that occur during the dormancy period of irrigated rice seeds, three experiments were carried out at different storage conditions. Seeds from Rio Grande cultivar, highly post-harvest dormant seeds, after preparation, were placed in multilayered paper bags and stored for 12 months, in a cold and dry (10oC and 50% of relative humidity) and in three conventional storage. Every three months, water content, germination, alterations in the electrophoretical profile of the isoenzymes Polyphenoloxidase (PPO), Peroxidase (PO), Alpha-amylase (a-AM), Beta-amylase (b-amylase) in polyacrilamide gel and reducing groups by spectrophotometer were evaluated. Storage conditions and duration have influenced the dormancy breakage, and, in the conventional storage environment, rice seeds have broken dormancy faster than the ones stored in cold and dry chamber. Changes in a-AM and PPO activities are related to alterations in the germination percentage, that is, while the a-AM activity increases, PPO activity decreases as dormancy is broken, suggesting these enzymes activities as a promising indicator of dormancy intensity. However, PO and b-AM activities are not related to dormancy in rice seeds.

Preparo das sementes de café para avaliação da viabilidade pelo teste de tetrazólio

The tetrazolium test (TZ) is a rapid alternative for evaluating seed viability and has been adopted for the commercialization of coffee seeds. One of the barriers to using this test is the difficulty of extracting the parchment, which requires time and specialized labor. The use of sodium hypochlorite has been recommended for parchment extraction in coffee seeds but this method has not been tested for the TZ. Coffee seeds of four lots of two varieties were submitted to four methods in the test: manual extraction or use of sodium hypochlorite (200 mL 5% NaClO) to remove the parchment and various periods for soaking seeds in water (36 to 48 hours), to remove the embryos. The results of the viability from the TZ were compared with those from the germination of seeds with different moisture contents. The use of 5% NaClO with 6 hours of soaking is not effective in removing the parchment and adversely affects the results of the TZ in coffee seeds with a moisture content below 25%. The imbibition period of coffee seeds in water for 48 hours in the preparation phase for the TZ, facilitates embryo extraction without affecting the test results.

Alterações fisiológicas e bioquímicas em sementes de café secas em sílica gel e soluções salinas saturadas

O objetivo deste trabalho foi avaliar alteracoes fisiologicas e bioquimicas em sementes de cafe submetidas a secagem rapida, em silica gel, e a secagem lenta, em solucoes salinas saturadas. As sementes foram secas ate que atingissem os seguintes teores de agua: 40, 30, 20, 15, 10 e 5% (base umida). Apos a secagem, uma parte das sementes foi imediatamente avaliada quanto ao desempenho fisiologico e ao perfil de enzimas do processo oxidativo, e outra parte foi avaliada apos armazenagem em condicao hermetica, em câmara fria e seca, por quatro meses. A velocidade de secagem e o teor final de agua tiveram efeito significativo sobre a qualidade fisiologica das sementes. Apos a secagem rapida em silica gel, as sementes toleraram teores finais de agua mais baixos. No entanto, apos a secagem lenta, as sementes com teores finais de agua mais elevados apresentaram maior qualidade. O periodo de armazenamento nao afetou a germinacao, mas prejudicou o vigor das sementes. A secagem rapida apresenta maior potencial de dano ao endosperma do que aos embrioes. O perfil enzimatico das sementes de cafe e afetado pelo teor final de agua e pela velocidade de secagem.

SUITABILITY OF THE TETRAZOLIUM TEST METHODOLOGY FOR RECENTLY HARVESTED AND STORED COFFEE SEEDS

Germination of coffee seeds occurs in a slow and non-uniform manner and the tetrazolium test (TZ) may be a quick alternative for assessment of viability, as long as the preparation and imbibition of the seeds is established. This study was performed in two stages: in the first, recently harvested seeds from three coffee cultivars were submitted to four methodologies for removal of the parchment: manual extraction or use of sodium hypochlorite (NaClO at 5%) and two periods of imbibition of the seeds in water (36 and 48 hours) for removal of the embryos. In the second phase, manual removal and the use of NaClO were compared for elimination of the parchment of stored seeds for monthly performance of the tetrazolium test for six months. Sodium hypochlorite is not efficient in total extraction of the parchment and has a negative effect on the results of the TZ test on low moisture coffee seeds. An imbibition time of 48 hours facilitates extraction of embryos and does not affect test results. The tetrazolium test on coffee seeds with different moisture and deterioration levels must be undertaken with manual removal of the parchments.

Determinação do ponto de colheita na produção de sementes de pimenta malagueta e alterações bioquímicas durante o armazenamento e a germinação

The harvest point interferes with the quality of the seeds, and in species with fleshy fruits and irregular maturation, there is difficulty in defining it. This study aimed to assess the dormancy of chili in three maturity stages during storage, in order to determine the best point of reaping and sowing and also enzymatic changes during the process of seed germination processed in different stages of maturation during storage. The seeds were manually extracted from fruits at three developmental stages: E1 (fruits with first signs of yellowing), E2 (ripe fruit) and E3 (mature and subjected to seven days of rest Fruits). After drying the seeds with 8% water content were stored in cold storage for 0, 4 and 8 months. After these periods seed quality was evaluated by means of the germination, vigor and enzyme activity tests. For the evaluation of the enzymes during the germination of seeds from each treatment, the seeds of each treatment were sampled for periods of 0, 48, 96 and 144 hours after sowing. We used a randomized block design, factorial trial 3 harvest times x 3 storage periods with Cientifica, Jaboticabal, v.42, n.2, p.187-197, 2014 ISSN: 1984-5529 188 four replications. There dormancy in seeds of chillies especially when newly stored and is surmounted by four months of storage. Chili seeds should be harvested when the E3 stage are sold after processing and at E2 or E3 when stored for periods up to four months. Enzyme changes are evident in the germination process and the different stages of maturation during storage. Additional keywords: Capsicum frutescens; seed maturation; seed quality.

Expression of genes associated with the biosynthetic pathways of abscisic acid, gibberellin, and ethylene during the germination of lettuce seeds

Seed germination and dormancy are complex phenomena that are controlled by many genes and environmental factors. Such genes are indicated by phytohormones that interact with each other, and may cause dormancy or promote seed germination. The objective of this study was to investigate gene expression associated with the biosynthetic pathways of abscisic acid (ABA), gibberellic acid (GA), and ethylene (ET) in dormant and germinated lettuce seeds. The expressions of LsNCED, LsGA3ox1, and ACO-B were evaluated in germinating and dormant seeds from the cultivars Everglades, Babá de Verão, Verônica, Salinas, Colorado, and Regina 71. The expressions of LsNCED, LsGA3ox1, and ACO-B were related to the biosynthesis of ABA, GA, and ET, respectively; therefore, the presence of these substances depends on genotype. LsNCED expression only occurred in dormant seeds, and was connected to dormancy. LsGA3ox1expression only occurred in germinated seeds, and was connected to germination. The ACO-B gene was involved in ET biosynthesis, and was expressed differently in germinated and dormant seeds, depending on the genotype, indicating different functions for different characteristics. Furthermore, sensitivity to phytohormones appeared to be more important than the expression levels of LsNCED, LsGA3ox1, or ACO-B.

Tolerance of Coffea arabica L. seeds to sub zero temperatures

A preservacao da qualidade de sementes de cafe e dificultada pelo comportamento intermediario no armazenamento. Porem, a conservacao a longo prazo em temperaturas subzero pode ser conseguido com o ajuste do teor de agua das sementes. Objetivou-se neste trabalho avaliar a tolerância de sementes de cafe ao congelamento, com relacao as modificacoes fisiologicas e enzimaticas. As sementes foram submetidas a dois tipos de secagem, rapida e lenta, ate os teores de agua de interesse, de 0,67, 0,43, 0,25, 0,18, 0,11, 0,05 g H2O g-¹ dw (base seca). Apos secagem, as sementes foram armazenadas em temperatura de -20 e de -86 oC, por 24 horas e por 12 meses, sendo comparadas as sementes armazenadas em câmara fria a 10 oC. As sementes foram avaliadas pela porcentagem de plântulas normais, plântulas com folhas cotiledonares expandidas, materia seca de raizes e de hipocotilos e viabilidade dos embrioes no teste de tetrazolio. A expressao das enzimas superoxido dismutase, catalase e peroxidase foi avaliada por meio de analise eletroforetica. Apenas as sementes secadas lentamente ate 0,18 g H2O g-¹ dw apresentam relativa tolerância ao armazenamento a -20 °C por 12 meses. Sementes de cafe nao toleram o armazenamento a temperatura de -86 oC por 12 meses. Umidades abaixo de 0,11g H2O g-¹ dw e acima de 0,43 g H2O g-¹ dw sao prejudiciais a qualidade fisiologica das sementes de cafe, independentemente do tipo de secagem, temperatura e periodo de armazenamento. Embrioes de sementes de cafe sao mais tolerantes a dessecacao e ao congelamento quando comparado as sementes inteiras, principalmente quando as sementes sao secadas ate 0,05 g H2O g-¹ dw. A enzima catalase pode ser usada como um marcador bioquimico para estudar a tolerância de sementes de cafe ao congelamento.

Endo-β-mannanase and β-tubulin gene expression during the final phases of coffee seed maturation

Coffee seeds begin to develop shortly after fertilization and can take 6 to 8 months to complete their formation, a period during which all the characteristics of the mature seed are determined, directly influencing physiological quality. However, little is known about the molecular mechanisms that act during coffee seed maturation. The objective of the current study was to analyze expression of the β-tubulin (TUB) and endo-β-mannanase (MAN) genes during different phases at the end of development and in different tissues of Coffea arabica seeds. The transcription levels of the TUB and MAN genes were quantified in a relative manner using qRT-PCR in whole seeds, and dissected into embryos and endosperms at different developmental stages. Greater expression of MAN was observed in whole seeds and in endosperms during the green stage, and in the embryo during the over-ripe stage. High TUB gene expression was observed in whole seeds during the green stage and, in the embryos, there were peaks in expression during the over-ripe stage. In endosperms, the peak of expression occurred in both the green stage and in the cherry stage. These results suggest participation of endo-β-mannanase during the initial seed developmental stages, and in the stages of physiological maturity in the embryo tissues. TUB gene expression varied depending on the developmental stage and section of seed analyzed, indicating the participation of β-tubulin during organogenesis and coffee seed maturation.