Dubium Seeds Research Articles

Imbibition curve in forest tree seeds and the triphasic pattern: theory versus practice

Although providing the basis for seed germination studies, there is little information available on seed imbibition curves for Brazilian forest species. Among the few studied species, the theoretical triphasic pattern may not apply, hampering the conduction of subsequent studies that require a clear definition of imbibition phases. In this paper, we characterize the seed imbibition curves of 25 Brazilian forest species and compare them with those from other studies and with the classic triphasic pattern. We collected seeds of the chosen species in the region of Lavras, MG, Brazil, and measured their fresh weight before and during the entire germination process. Seed weight data were used to calculate the weight gain percentage of each species. We defined the imbibition curves of Peltophorum dubium seeds using seed fresh weight and seed weight gain percentage of both single and multiple samples, as well as using water content (on fresh and dry bases) to compare potential changes in imbibition patterns caused by differences in data. When only weight gain was considered, we observed the triphasic pattern in 11 species; however, only in four of them, the germination coincided with the third phase of imbibition. The triphasic pattern did not emerge for the remaining 14 species. Considering seed water content instead of weight resulted in some changes in the pattern of the imbibition curve, influencing the accuracy of the results.

Isolation, Purification and Partial Characterization of a Serine-Like Protease from Solanum dubium Seeds

The aim of this study was to extract, purify and characterize an enzyme from Solanum dubium (S. dubium) seeds and to investigate the seed extractability in milk clotting activity. The extracted were using different buffers of sodium phosphate (pH 7.1), Tris HCl (pH 8.5), Sodium Acetate (pH 5.2) in addition to a distilled water treatment. The results shows that buffer extraction (sodium phosphate pH 7.1) and presoaking produced more extractable protein with better clotting ability. The extracted enzymes were filtered and fractionated on Sephadex G-75, anion exchange, and gel filtration chromatography columns. The purified enzyme is characterized by being thermostable (up to 70oC) with a pH range of 6-7 (for 1% casein substrate). The enzyme is inhibited by serine protease inhibitors. It is, therefore, concluded that the enzyme is of the chymotrypsinlike serine protease class. Gel filtration and SDS-PAGE methods showed that the purified enzyme consists of three bands with molecular masses of 11KD, 35KD, and 40KD. The enzyme has a Km value of 0.6 mM and a Vm value of 66.7unit/min. mg. Crude extracts obtained from S. dubium seeds were shown to exhibit milk clotting activity.

Seeds of Peltophorum dubium submitted to osmotic conditioning increases germination and vigor

Peltophorum dubium (Spreng.) Taub. é uma espécie florestal nativa do Brasil utilizada em programas de restauração ambiental, paisagismo e construção civil. Sua propagação ocorre de forma seminal, porém, problemas na qualidade fisiológica das sementes aliados a ação de fatores bióticos e abióticos podem reduzir os percentuais de germinação e emergência. Neste contexto, técnicas que permitam a expressão do potencial fisiológico das sementes podem melhorar a germinação e o vigor em menor espaço de tempo. Uma destas técnicas é o condicionamento osmótico das sementes, o qual visa proporcionar a germinação mais rápida e uniforme, especialmente sob condições de estresse. O objetivo deste trabalho foi estudar se o condicionamento osmótico aumenta a germinação e o vigor de sementes de P. dubium. O estudo constituiu-se de três etapas: I – seleção do potencial osmótico ideal para a embebição; II - vigor e germinação de sementes osmocondicionadas e com diferentes teores de água; III - osmocondicionamento de quatro lotes de sementes com diferenças no vigor. A solução de PEG 6000 com -0,6 MPa é recomendada para o condicionamento osmótico de sementes de P. dubium com o objetivo de melhorar a germinação e o vigor. Sementes com teor de água próximo a 10% para o condicionamento osmótico influenciam positivamente o vigor. O condicionamento osmótico pode melhorar os aspectos fisiológicos de sementes de P. dubium com boa qualidade fisiológica, podendo reduzir o tempo de germinação e emergência e favorecendo os talhões com maior uniformidade e menor probabilidade de influência dos fatores bióticos e abióticos.

ULTRASTRUCTURAL CHANGES AND INTEGRITY OF GENOMIC DNA IN GERMINATED SEEDS OF Peltophorum dubium (Spreng.) TAUBERT SUBJECTED TO DRYING1

ABSTRACT The aim of this study was to evaluate DNA integrity and to identify ultrastructural changes in the primary root of Peltophorum dubium seeds subjected to drying, since these changes may reflect the germination capacity. Seeds were germinated and were dehydrated when reached 1 mm in length of the primary root, until reaching different moisture contents, being then rehydrated and evaluated in relation to survival. After this procedure, different points of interest (control, 20% and 10% moisture content) were selected to evaluate DNA and cell ultrastructure integrity in order to detect possible cellular changes in primary roots after dehydration. When dried down to 32% moisture, there was no influence on the growth resumption of the germinated seeds, but when they were dehydrated to 20% moisture, the survival was reduced to 67%, reaching nullity in the survival with drying to 8% moisture. By the evaluation of ultrastructural changes in root cells, it was observed that drying to approximately 20% moisture content marked the onset of damages by desiccation, both physiologically and ultrastructurally. Drying to levels close to 10% moisture content was not only responsible for total disorganization and rupture of membranes, but also promoted intracellular collapse. Loss of genomic DNA integrity was observed during drying.

Seed structures in water uptake, dormancy release, and germination of two tropical forest Fabaceae species with physically dormant seeds

The morphoanatomy and germination of dormant seeds of Peltophorum dubium (Spreng.) Taub. and Mimosa bimucronata (DC) O. Kuntze, Atlantic forest Fabaceae species, were examined. Temperature treatments for breaking physical dormancy were applied, and the effects of three forest environment on seed germination were examined. The location of water inlet was carried out soaking in water nondormant seeds with parts of the integument waterproofed with glue. Scanning electron microscopy and optical microscopy were employed to observe the morphoanatomy of seed coat’s surface. Wet shocks of 40 and 50 °C were effective in breaking the physical dormancy of seeds. Higher temperatures in forest clearing had greater effect on germination and emergence of seedlings. Both species presented external and internal seed morphology similar to that of most Fabaceae species. In P. dubium seeds, the water inlet appears to occur not only by the lens, but also by the micropyle and hilum. In M. bimucronata, the sites of water intake were the micropyle and lens.

Does thermal time for germination vary among populations of a tree legume (Peltophorum dubium)?

Few works report the use of degree-days (DD) - used in crops to predict events and schedule management activities - to describe the germination of tropical trees. The cardinal temperatures (base, optimum and ceiling temperature) for germination of the species may vary depending on the seed provenance. Peltophorum dubium (Spreng.) Taub. is an early successional leguminous tree widely distributed in South America, often occurring as cultivated or naturalized trees, thus considered to be a good example for testing DD model in tree species. The main objective of this study was to describe the seed germination response of different populations of P. dubium as function of DD accumulation during germination assays in semi-controlled (fluctuating temperatures) conditions. Germination assays with manually scarified seeds sown in aluminum sheet trays filled with a composed substrate were performed under greenhouse conditions at different times. Three methods were employed in order to describe the accumulation of thermal time throughout the assays and, considering the seed lot and sowing time, a trapezoid area method was relatively more effective in describing the germination. The germination curves of P. dubium seeds from different populations, expressed in degree-days estimated directly from temperature records schedules, tend to be more clustered suggesting little variation among thermal time requirements in different seed provenances. Otherwise, the thermal time requirement can vary depending on the time of sowing, and any increase in DD requirement when the assays were performed under higher mean temperatures can be related to a thermal effect on the germination of scarified seeds.

Changes in gene expression and soluble carbohydrate contents during the imbibition and re-induction of desiccation tolerance in Peltophorum dubium seeds

Desiccation tolerance (DT) is the capacity of organisms to tolerate drying and rehydration without losing viability. DT is induced during orthodox seed development and usually lost during germination. Here we show that Peltophorum dubium seeds lose DT at the end of germination when its radicle protrudes and that DT can be re-induced in this species by the application of the plant hormone abscisic acid under a low temperature regime. The re-induction of DT in P. dubium seeds coincides with the accumulation of transcripts of a putative superoxide dismutase and a heat shock protein indicating that protection against reactive oxygen species and coordinated protein folding might be key features in the maintenance of DT. Furthermore, we explored the soluble sugar content of dry, germinating and DT-re-induced seeds. Dry seeds had high sugar content, which reduced during germination indicating a relationship between sugar content and the loss of DT. However, DT-reinduced seeds did not accumulate soluble sugars indicating either that those sugars are not required in the re-induction of DT in P. dubium seeds or that the low contents reached during germination are still sufficient to guarantee the protection during and after drying and an increase in their contents was not needed.

Effect of temperature and substrate on germination of Peltophorum dubium (Sprengel) Taubert seeds

Peltophorum dubium (Spreng.) Taub. is a species belonging to the family Fabaceae, and is known popularly as golden shower tree. Its wood has multiple uses in reforestation programs and as an ornamental tree, and is also considered an endangered species, requiring studies that assist in its preservation. The present work was conducted with the objective of determine the ideal substrate type and temperature to perform germination and vigor tests with P. dubium seeds. The experiment was carried out at the Seed Analysis Laboratory (Centro de Ciencias Agrarias, Universidade Federal Paraiba, Areia, Paraiba, Brazil), in a completely randomized design. The treatments were distributed in a 4 x 6 factorial scheme; temperatures (constant temperatures of 25, 30 and 35°C; and alternate temperatures of 20- 30°C) and substrate (paper towel, over blotting paper, in sand, in vermiculite, Bioplant ® and Plantmax ® ) on four replications of 25 seeds. The following parameters were analyzed: germination percentage, germination speed index, first germination count, length and dry mass of seedlings. The constant temperature of 30°C and 20-30°C alternate, and the substrates into sand and paper towel can be recommended for germination and vigor tests of P. dubium seeds. The temperature of 25°C should not be used in germination and vigor tests of P. dubium seeds in any of the tested substrates.

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

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.

Use of Jiben Seeds Extract to Manufacture Soft White Cheese

Rennet substitute was applied for preparation of white cheese with Jiben (Solanum dubium seeds extract). Time effect 0, 15, 30, 45, 60, 75, 90, 120 and 150 days was studied at 30°C on the prepared cheese, kept at room temperature as well as in the refrigerator at 5±1°C. Cheese analysis includes pH and the percentage content of moisture, salt, fat and protein. Use of Rennet to manufacture white cheese was served as a control. Results and statistical analysis indicated that, cheese prepared using Jiben Extract has high quality with a very small variations as well as it has a long storage time. Thus, Solanum dubium is a suitable extract for preparation of white cheeses with a long storage time in the refrigerator 5°C as well as at room temperature 30°C.

Efeitos do extracto aquoso de Nerium Oleander L. na germinação e na sanidade de sementes de Peltophorum dubium (Sprengel) Taubert

The use of plant extracts in the fungi control can be an alternative to the use of chemicals. This work has the purpose to test the efficiency of the aqueous extract obtained from leaves of Nerium oleander (espirradeira) on seed germination of Peltophorum dubium (canafistula), as well on seedling vigour and seed sanity. Nine treatments were tested, with three concentrations of extract: 0, 50 and 100%, and three assay times: 15, 30 and 45 minutes. It was found that the aqueous extract of N. oleander was not effective for controlling the pathogens associated with P. dubium seeds, and there is an increase of fungi incidence. However, the aqueous extract of N. oleander helped seed germination and vigour of the resulting seedlings and the most infected seeds were the ones showing better germination and development.

Peltophorum dubium and soybean Kunitz-type trypsin inhibitors induce human Jurkat cell apoptosis

Plants constitute an important source of compounds which can induce apoptosis in a variety of cells. Previously, we reported the isolation of a trypsin inhibitor from Peltophorum dubium seeds (PDTI). This inhibitor, as well as soybean trypsin inhibitor (SBTI), both belonging to the Kunitz family, have lectin-like properties and trigger rat lymphoma cell apoptosis. In the present study, we demonstrate for the first time that PDTI and SBTI induce human leukemia Jurkat cell death. Induction of apoptosis was confirmed by flow cytometry after propidium iodide labeling of apoptotic nuclei, showing a considerable increase of the sub G 0/ G 1 fraction, with no cell cycle arrest. With the purpose of gaining insight into the signaling pathways involved, we investigated the activation of caspases and the effect of caspase inhibitors, and showed caspases-3 and -8-like activation by PDTI or SBTI-treatment. Consistent with these results, pan caspase inhibitor and caspase-8 inhibitor protected Jurkat cells from apoptosis. However, there was no caspase-9 activation, confirmed by the failure of caspase-9 inhibitor to prevent cell death. No significant release of cytochrome c from mitochondria was detected suggesting that the intrinsic mitochondrial pathway is not predominant in the apoptotic process. On the other hand, recruitment of Fas-associated death domain (FADD) to the cell membrane indicates the involvement of this adaptor protein in PDTI- and SBTI-induced apoptosis in Jurkat cells. Furthermore, human peripheral lymphocytes, either stimulated with phytohemagglutinin or not, are also susceptible to viability decrease induced by these inhibitors.

Imbibitions, energy test and accelerated ageing in primed and non-primed seeds ofPeltophorum dubium

Peltophorum dubium seeds were set to imbibe with four treatments, soaked with solution Captan 0.2% under 10 and 27°C, PEG 6000-1.0 MPa under 10 and 27°C. For each treatment there were four replicates with 40 seeds incubated in 9-cm Petri dishes with double filter paper moistened with testing solution. The imbibition curves showed that the final weight increase were from 70% to 150% in the treatments when inbibition entered a lag phase. Seeds were tested for effects on germination of five treatments: control group (nonprimed), primed with PEG6000-1.0 MPa at 10 and 27°C, primed with Captan 0.2% at 10 and 27°C. For each treatment, there were three sub-treatments: seeds were soaked in distilled water for 12,24 and 36h before the energy test. Germination percentages of nonprimed seeds and primed in PEG 27°C soaked in distilled water during 12 h were the highest, reaching 100%. The lowest germination percentage occurred primed seeds with PEG6000 27°C and soaked in distilled water during 36 h, which was only 52%. Germination mean time of primed seeds in PEG at 10°C, soaked 24 h was 1.08 days, mean time of primed seeds in PEG at 27°C soaked 12 h was 2.42 days. Accelerated ageing results showed low or no germination after ageing 72 h. Control group had a higher germination percentage and seeds were more resistant to deterioration than those in primed groups, both in Petri dish (27°C) and vermiculate (room temperature).

Effect of priming on the germination ofPeltophorum dubium seeds under water stress

Peltophorum dubium seeds provided by Anhembi, SP were scarified in 98% H2SO4 for 15 min to overcome mechanical dormancy. Seeds were primed in solutions of 0.2% Captan at 10 °C and 27°C, PEG 6000 −1.0 MPa at 10°C and 27°C, 0.5 mol KNO3, 0.75 Mol KNO3, 1.0 Mol KNO3. Eight treatments including the primed seeds and nonprimed seeds, five replicates with 100 seeds for each treatment, were set to 15-cm-Petri dish with double filter paper moistened with testing solution PEG in refrigerator at 27°C. For the experiments of all the groups, osmotic potential were 0.0, −0.2, −0.4, −0.6, −0.8, −1.0, −1.2, and −1.4 MPa.P. dubium seeds were also set to water stress experiment in rolled paper with PEG solutions from 0.0 to −1.0 M Pa. Germination percentage decreased with the increase of PEG concentration. Control group had a better germination percentage than other groups. Germination hardly occurred in PEG −1.4 MPa.

A trypsin inhibitor from Peltophorum dubium seeds active against pest proteases and its effect on the survival of Anagasta kuehniella (Lepidoptera: Pyralidae)

A novel trypsin inhibitor was purified from the seeds of Peltophorum dubium (Spreng.). SDS-PAGE under reducing conditions showed that the inhibitor consisted of a single polypeptide chain (ca. 20 kDa). The dissociation constants of 4×10 −10 and 1.6×10 −10 M were obtained with bovine and porcine trypsin, respectively. This constant was lower (2.6×10 −7 M) for chymotrypsin. The inhibitory activity was stable over a wide range of temperature and pH and in the presence of DTT. The N-terminal sequence of the P. dubium inhibitor showed a high degree of homology with other Kunitz-type inhibitors. When fed to the insect Anagasta kuehniella, in an artificial diet (inhibitor concentration 1.6%), the inhibitor produced ∼56% and delayed the development of this lepidopteran. The concentration of inhibitor in the diet necessary to cause a 50% reduction in the weight (ED50) of fourth instar larvae was ∼1%. The action of the P. dubium trypsin inhibitor (PDTI) on A. kuehniella may involve inhibition of the trypsin-like activity present in the larval midgut, resistance of the inhibitor to digestion by midgut enzymes and bovine trypsin, and association of the inhibitor with a chitin column and chitinous structures in the peritrophic membrane and/or midgut of the insect.

A novel trypsin inhibitor from Peltophorum dubium seeds, with lectin-like properties, triggers rat lymphoma cell apoptosis

A trypsin inhibitor (PDTI) was isolated from Peltophorum dubium seeds by affinity chromatography on a thyroglobulin–agarose or a trypsin–agarose column. In both cases, SDS–PAGE showed two bands of M r 20,000 and 22,000, which could not be resolved. Their amino-terminal sequences were identical and similar to that of Kunitz-type soybean trypsin inhibitor (SBTI). Mass spectrometry analysis of tryptic digests of both bands showed 16 coincident peaks, suggesting that they are closely related proteins. The K is for trypsin and chymotrypsin inhibitory activity of PDTI were 1.6×10 −7 and 1.3×10 −5 M, respectively. Lectin-like activity of PDTI and SBTI, detected by hemagglutination of rabbit erythrocytes, was inhibited by sialic acid-containing compounds. PDTI and SBTI caused apoptosis of Nb2 rat lymphoma cells, demonstrated by decrease of viability, DNA hypodiploidy, DNA fragmentation, and caspase-3-like activity. They had no effect on normal mouse splenocytes or lymphocytes, whereas they caused apoptosis of concanavalin A-stimulated mouse lymphocytes.

SPECIES DIFFERENTIATION IN PAPAVER DUBIUM

Summary Papaver dubium seeds were obtained from several European countries. Two different chromosome numbers were found: 2n= 42 and 2n= 28. The forty‐two chromosome races are most widespread. Four races with 2n= 28 chromosomes can be distinguished.From results of cytological investigation especially of chromosome pairing behaviour during meiosis, it is suggested that the two 2n= 28 chromosome races, Alb and Upps II, may be considered as subspecies whereas the other two (Cors II and Ca Sw) are best regarded as chromosome races of P. dubium L.