Eduardo Euclydes de Lima e Borges

Mobilização de reservas durante a germinação das sementes e crescimento das plântulas de Caesalpinia peltophoroides Benth. (Leguminosae-Caesalpinoideae)

Resumo – Este trabalho teve como objetivo estudar a mobilizacao de reservas de sementes de Caesalpinia peltophoroides Benth. durante a germinacao e crescimento inicial das plântulas. As variacoes nas reservas de carbiodratos, lipidios e proteinas foram analisadas desde o periodo pre-germinativo (0 a 5 dias apos a semeadura – DAS) ate a total senescencia e abscisao dos cotiledones, aos 35 DAS, por meio de testes bioquimicos nos cotiledones das sementes. Os resultados indicaram que os lipidios constituem o principal composto de reserva nos cotiledones, contribuindo com cerca de 50% de massa seca. Carboidratos soluveis representaram 32%, as proteinas soluveis 7,7% e o amido 6,8% de massa seca dos cotiledones. Os lipidios sofreram marcante decrescimo entre 5 e 10 dias apos a semeadura, periodo em que se observou elevada taxa de crescimento das plântulas. Carboidratos e proteinas soluveis exibiram tendencia gradativa de queda, enquanto no amido, isso quase nao foi detectado. A reducao do peso de massa seca dos cotiledones foi bem correlacionada com o aumento da biomassa da plântula.

Influência da temperatura de armazenamento na qualidade das sementes de Caesalpinia peltophoroides Benth. (sibipiruna)

Este trabalho teve como objetivo avaliar o efeito da temperatura de armazenamento na porcentagem de germinacao e no vigor das sementes de Caesalpinia peltophoroides Benth. (sibipiruna), por meio de testes fisiologicos. O teor de agua aumentou nas sementes armazenadas a 5 °C e reduziu naquelas a 20 °C. A porcentagem de germinacao das sementes mantidas a 5 e 20 °C apresentou reducao aos 220 e 120 dias, respectivamente. O indice de velocidade de germinacao decresceu de maneira similar. A condutividade eletrica nao foi alterada nas sementes armazenadas a 5 °C e aumentou nas que permaneceram a 20 °C. O envelhecimento acelerado nos periodos de 24, 48 e 72 horas detectou reducao significativa na qualidade das sementes em ambos os ambientes de armazenamento. A reducao da porcentagem de germinacao e do vigor foi maior nas sementes armazenadas a 20 °C.

Characterization and biotechnological application of an acid α-galactosidase from Tachigali multijuga Benth. seeds

Tachigali multijuga Benth. seeds were found to contain protein (364 mg g(-1)dwt), lipids (24 mg g(-1)dwt), ash (35 mg g(-1)dwt), and carbohydrates (577 mg g(-1)dwt). Sucrose, raffinose, and stachyose concentrations were 8.3, 3.0, and 11.6 mg g(-1)dwt, respectively. alpha-Galactosidase activity increased during seed germination and reached a maximum level at 108 h after seed imbibition. The alpha-galactosidase purified from germinating seeds had an M(r) of 38,000 and maximal activity at pH 5.0-5.5 and 50 degrees C. The enzyme was stable at 35 degrees C and 40 degrees C, but lost 79% of its activity after 30 min at 50 degrees C. The activation energy (E(a)) values for p-nitrophenyl-alpha-d-galactopyranoside (pNPGal) and raffinose were 13.86 and 4.75 kcal mol(-1), respectively. The K(m) values for pNPGal, melibiose, raffinose, and stachyose were 0.45, 5.37, 39.62 and 48.80 mM, respectively. The enzyme was sensitive to inhibition by HgCl(2), SDS, AgNO(3), CuSO(4), and melibiose. d-Galactose was a competitive inhibitor (K(i)=2.74 mM). In addition to its ability to hydrolyze raffinose and stachyose, the enzyme also hydrolyzed galactomannan.

Mobilização de reservas em sementes de Apuleia leiocarpa (Vogel) J.F. Macbr. (garapa) durante a embebição

The mobilization of reserves was quantified in the embryonic axis, cotyledons and tegument of seeds of Apuleia leiocarpa (garapa) during imbibition. The results show that there was a significant increase in the contents of starch, estearic acid and protein in the cotyledons during the imbibition process. On the other hand, there was only a significant manose content increase in the embryo while the reserves of fatty acids miristic, palmitic, estearic, oleic and linoleic decreased significantly. Mannose and galactose contents increased significantly in the tegument. Except for the lauric acid, all others were not detected after 48 hours of imbibition.

Physiological and biochemical characterization of the assai palm (Euterpe oleracea Mart.) during seed germination and seedling growth under aerobic and anaerobic conditions

Physiological and biochemical aspects of assai palm during seed germination and early seedling growth were investigated. Seeds collected from plants growing in flooded and upland forests were used to determine the influence of normoxic (aerobic) and anoxic (anaerobic) conditions in germination and the initial and average time of development in the roots and shoots. After 75 days, seedlings germinated under normoxia were transferred to trays and submitted to flooding. Seed reserves (lipids, proteins, soluble sugars and starch) were monitored for quiescent and germinated seeds maintained under normoxic and anoxic conditions, as well as after 5, 10 and 20 days of seedling growth. Alcohol dehydrogenase (ADH) activity was quantified in roots and leaves of seedlings without or with flooding (partial and total). Seeds were not able to germinate under anoxia. Different strategies of storage mobilization of lipids, proteins, soluble sugars and starch were observed in seeds of each environment. ADH activity was induced by anoxia, with the highest level observed in the leaves. This study showed that, under normoxic conditions, the best developmental performance of assai palm seeds, from flooded or upland forest areas, during germination was associated with primary metabolites mobilization and seedling flooding tolerance with increased ADH activity. We conclude that the assai palm is well adapted to the anoxic conditions provoked by flooding.

Alterações fisiológicas em sementes de tachigalia multijuga (benth.) (mamoneira) relacionadas aos métodos para a superação da dormência

This work aimed to study the effects of methods to overcome the dormancy of Tachigalia multijuga (Benth) seeds. It was compared the effects of the sulfuric acid, of the boiling water and of the it blunts in the imbibition percentage, in the percentage and speed of germination, in the activity of alpha galactosidase and beta mananase, in the protein synthesis and in the alteration in the membrane that recovers the embryo. There was no germination in seeds treated with hot water. All the treatments resulted in germination percentage superior (P<0.05) to the control, except for the seeds of Cachoeira, where the treatment with sulfuric acid for 10 minutes was the same. On the other hand, the speed of germination of the control was only different (P<0.05) from all the treatments in seeds of Araponga 2. The water percentage of the seeds treated with hot water by 60 seconds went the same to those of the control and different (P<0.05) from the treated with hot water by 30 minutes and by acid for 20 minutes. The activities of the enzymes and proteins content during the germination were different (P<0.05) among the treatments with water and acid. It is discussed the alterations of the membrane sugars content that recovers the embryo seeds. Key word: Dormancy, Tachigalia multijuga, seed, carbohydrate.

Alterations in seed reserves of Dalbergia nigra ((Vell.) Fr All. ex Benth.) during hydration

Seed imbibitions is the first stage of the germination process and is characterized by the hydration of tissues and cells and the activation and/or induction of the enzymes responsible for mobilizing reserves for respiration and the construction of new cell structures. The objective of this study was to investigate the alterations in reserve substances during slow hydration of Bahia Rosewood (Dalbergia nigra) seeds in water. Seeds from two different lots (Lot I and II) were placed in saturated desiccators (95-99% RH) to hydrate at 15 and 25 °C until water contents of 10, 15, 20 and 25% were reached. At each level of hydration, changes in lipid reserves, soluble carbohydrates, starch and soluble proteins were evaluated. The mobilization of reserves was similarly assessed in both lots, with no differences being observed between the two hydration temperatures. Lipid contents showed little variation during hydration, while the contents of soluble carbohydrates and starch decreased after the 15% water content level. Soluble proteins showed a gradual tendency to decrease between the control (dry seeds) up to 25% water content.

Caracterização de alfagalactosidase e sua relação com a germinação das sementes de Caesalpinia peltophoroides (Leguminosae Caesalpinioideae)

Sementes de Caesalpinia peltophoroides (Leguminosae Caesalpinioideae) - sibipiruna - foram colocadas para embebicao por 144 h, sendo retiradas amostras para analise de proteina, quantificacoes da atividade de alfagalactosidase e de acucares presentes na micropila. A germinacao iniciou-se com 96 h de embebicao, sem que fossem detectadas modificacoes na parede celular da micropila. Nesta, observou-se maior proporcao de arabinose, que mostrou tendencia de aumento com o decorrer da embebicao. A atividade especifica da alfagalactosidase foi detectada em sementes secas, tanto no eixo embrionario quanto nos cotiledones, aumentando no primeiro a partir de 24 h de embebicao. O aumento da atividade nos cotiledones foi mais lento, sendo mais acentuado a partir de 120 h de embebicao. O teor de proteina decresceu continuamente no eixo embrionario a partir de 24 horas de embebicao, enquanto se manteve estavel nos cotiledones. A atividade da alfagalactosidase foi maxima nas temperaturas de 55 e 50 oC para o eixo embrionario e para os cotiledones, respectivamente. O pH que mais estimulou a atividade da enzima foi na faixa de 5,5 a 6,0 para o eixo embrionario e na de 4,5 a 5,0 para os cotiledones. As alfagalactosidase do eixo embrionario e dos cotiledones foram inibidas por SDS, CuSO4, galactose e melibiose. Nao houve efeito estimulante sobre a atividade da alfagalactosidase do eixo embrionario por nenhum dos efetores, enquanto o mercaptoetanol estimulou a atividade da enzima dos cotiledones. Os KM para o substrato r-NPGal para a alfagalactosidase do eixo embrionario e dos cotiledones foram de 1,74 e 2,64 mM, respectivamente.

Histochemical aspects of reserves mobilization of Caesalpinia peltophoroides (Leguminosae) seeds during germination and seedlings early growth

The objective of this study was to investigate reserve mobilization in Caesalpinia peltophoroides seeds during germination and initial seedling growth. The variation in these compounds was analyzed from the pre-germination period (0 to 5 days after sowing - DAS) to the total cotyledon senescence and abscission at 35 DAS. For this histochemical tests were made on cotyledons fixed in FAA50 or included in glycol-metacrylate. To follow the mobilization of the main reserve compounds, sudan III was used to detect total lipids, xylidine Ponceau to detect total proteins, lugol to detect starch and polarized light to visualize the crystals. The lipids, present in a great quantity in the cotyledon, gradually decreased in the period studied. A greater quantity of starch was observed on the 10th DAS than in the previous periods and it was totally consumed by 30 DAS. The distribution pattern and the morphology of the protein material were very modified by 10 DAS, a period during which it was intensely consumed, remaining only parietally fragments distributed, that practically disappeared at 25 DAS. The calcium oxalate druses were not consumed during the period studied, there was only crystal agglutination.

Purificação e caracterização de alfa-galactosidases de sementes de Platymiscium pubescens Micheli

The objective of this work was to determine seed biochemical composition of forest species and to characterize a-galactosidase enzyme of germinated seeds of Platymiscium pubescens. The highest lipid levels were found in seeds of Chorisia speciosa, Caesalpinia peltophoroides, Tabebuia serratifolia and Tabebuia velanedae, whereas seeds of Enterolobium contortisiliquum, Schizolobium parahyba and Cassia grandis showed the highest protein levels. a-galactosidase catalyzes the hydrolyzis of raffinose oligossacarides in legume seeds during germination. The highest activity of a-galactosidase was found in seeds of Platymiscium pubescens after 72 h of soaking in the water. Two forms of a-galactosidases, C1 and C2, were purified from germinated seeds of P. pubescens, using partition with ammonium sulfate, and gel filtration and affinity chromatographies. These enzymes presented maximum activity at pH 5.5, 50-55oC. Km ap values in the C1 and C2 forms forr-nitrophenyl-a-D-galactopyranoside substrate were 0.54 mM and 0.78 mM, and 4.64 mM and 5.09 mM for raffinose, respectively. These enzymes showed moderate thermal stability, maintaining 70% of the original activity after 3 h incubation at 45oC. The C1 and C2 enzymatic activity was totally lost in the presence of CuSO4 and sodium dodecyl sulfate (SDS). These enzymes also hydrolyzed melibiose, raffinose and stachyose, indicating a potential for biotechnological applications.