Ultrastructural changes in naturally aged Pinus pinea seeds

The decline of germination observed after storage of Pinus pinea L. seeds up to 35 years at room temperature was accompanied by an increase in their ability to leak reducing sugars, probably as a consequence of membrane alterations due to senescence. Results of studies of the cell ultrastructure of viable and non-viable seeds before and after imbibition indicate that such is the case. Noticeable changes occurred in the ultrastructure of endosperm and embryo cells with germinability loss, even in the unimbibed condition. The main alterations were spherosome coalescence, plasmalemma separation from the cell wall and chromatin aggregation.     

Biochemical changes in Pinus pinea seeds during storing

The changes in the germination-rate, the contents in germination-inhibitors and the biochemical differences in soluble proteins and nucleic acids in freshly harvested Pinus pinea seeds stored for various periods of time, up to 24 months, and at two different temperatures (room temperature and 4 degrees C), have been investigated. The present results show that the maturation or after-ripening process of this type of seeds might be induced during the first 6 and 12 months of storage. However, seeds stored for longer periods of time might also be thought to enter into the primary phases of the ageing process where early alterations occur, including the loss of germination-rate and germination-inhibitor contents in the seed coat, together with an incapacity for the seeds to increase their protein and nucleic acid levels during the germination process.     

Modification of the radiosensitivity of barley seed by post-treatment with caffein. IV. Effect of the moisture content of seed and storage temperature after irradiation.

The oxygen-dependent damage which develops in barley seeds with approximately 7-8 per cent moisture content disappears after post-irradiation storage in vacuo for 48 hours at 40 degrees C and for 24 hours at 50 degrees C. When the diration of storage at 40 degrees C is extended to 384 hours, oxygen-independent damage becomes potentiated. There is oxygen-dependent damage in seeds of approximately 13.3 per cent moisture content and after the seeds have been stored in vacuo at 50 degrees C, the oxygen-dependent damage begins to increase by 168 hours, and it is very significantly potentiated by 192 hours. Under these circumstances, caffeine acts as a radioprotector only as long as the precursors of oxic damage are present in the seeds. Once these sites are lost, caffeine acts only as a radiosensitizer. The oxygen-independent damage which increases with storage at high temperature is further potentiated by caffeine.     

Temperature effects on oxidative metabolism of dormant sugar pine seeds

When dormant sugar pine (Pinus lambertiana L.) seeds were imbibed at 5°C, they showed a rapid increase in O₂ uptake, ATP level, and moisture content during the first 4 days. This was followed by a plateau phase until 60 days, after which a second significant increase in all three features occurred as dormancy was broken. During the plateau phase, conventional CN-sensitive respiration accounted for 74 to 79% of the total O₂ uptake. When dormant sugar pine seeds were imbibed at and maintained at 25°C, a different pattern occurred. Water uptake was much more rapid during the first 4 days and no second increase occurred after 60 days because the seeds did not break dormancy. There was an initial burst of O₂ uptake and ATP formation, but these both declined abruptly after 24 to 48 hours. Levels about half those of seeds at 5°C were maintained through the rest of a 90-day period. CN-sensitive respiration declined during imbibition at 25°C, and accounted for only 55 to 61% of the total O₂ uptake. The inability of dormant sugar pine seeds to germinate at temperatures above about 17°C may therefore result from initial temperature effects on membrane properties, leading to reduced O₂ uptake, reduced cytochrome oxidase electron transport activity, and lowered ATP levels.     

Changes in phenolic acids and abscisic acid in sugar pine embryos and megagametophytes during stratification

The phenolic acids and abscisic acid (ABA) of sugar pine ( Pinus lambertiana Dougl.) embryos and megagametophytes, separated by high-pressure liquid chromatography, were analyzed during 90 days stratification of the seeds. The phenolic acids occurred mainly as glycosides. Following hydrolysis, the majority of phenolics present could be identified as common benzoic and ciranamic acid derivatives. Levels of phenolic acids were relatively low in dormant seeds, but increased substantially in the embryos during stratification at 5°C, particularly cinnamic acid, p -coumaric acid, ferulic acid, and one unknown. This active synthesis during stratification did not support an inhibitory function for phenolic acids. During stratification at 5°C, changes in ABA levels in both tissues followed a triphasic pattern, with no loss during the first 30 days, a significant decrease the second 30 days, and a lesser decrease the last 30 days. Loss of ABA from moist seeds at 25°C occurred three times as rapidly, so that by 30 days the ABA level of these seeds was equivalent to that of seeds stratified 90 days at 5°C; however, dormancy was not alleviated at 25°C. Application of exogenous ABA (10⁻⁷ to 10⁻⁴M) to stratified seeds did not significantly reduce germination. Together, the above results did not support a primary role for ABA in the maintenance of dormancy in sugar pines.
A correlated increase in phenylpropanoid metabolism and respiratory capacity with increased germinability during stratification suggests that loss of dormancy may be more closely dependent on increased levels of growth promoters or shifts in metabolic pathways.     

苦瓜果实发育过程中的主要营养成分变化及种子生活力演进

为明确苦瓜的果实和种子的适宜采收时期,采用"翠中翠"苦瓜为研究对象,对苦瓜果实发育过程中的可溶性蛋白、总可溶性糖、维生素C的含量及种子生活力的变化进行动态监测。结果显示:(1)花后第14天至第26天,随着果实的迅速膨大,可溶性蛋白、总可溶性糖及维生素C含量也迅速增长;(2)种子干物质迅速积累,含水量迅速下降,种子生活力迅速提高,至花后第22天至第26天,种子生活力基本稳定。     

Storage proteins from seeds of Pinus pinea L

The Mediterranean stone pine Pinus pinea L. (gymnosperm, Pinaceae) is much appreciated for its seed production, widely used in food preparation in the Mediterranean Basin. Seeds contain 25% proteins on a dry-weight basis. Pinus pinea accumulate globulins as major storage proteins in seeds (75% of total storage proteins), composed of several subunits of 10 to 150 kDa, revealed by SDS-PAGE. The albumin fraction (15%) represents three subunits of 14, 24 and 46 kDa. Glutelins, the least soluble fraction, represents a small proportion (10%). Their constitutive units have frequent PM of 43 kDa. Prolamins also represent a very small percentage (1 to 2%).     

In vivo effects of octanoate and oleate on glucose-6-phosphate dehydrogenase during germination of Pinus pinea seeds.

During our investigation on the effect of some fatty acids on the germination of Pinus pinea seeds (Vincenzini et al., 1973), we noted a marked decrease of G6PDH activity when octanoate or oleate were added to the culture medium. In an attempt to provide biochemical information on the effect of free fatty acids on G6PDH activity, in vivo, during Pinus pinea seeds germination, we tested different concentrations of octanoate and oleate added to the culture medium. Moreover other enzymes of fundamental metabolic pathways were also considered, particularly 6PGDH, the second enzyme of HMS.     

Fructose 2,6-bisphosphate in germinating oat seeds. A biochemical study of seed dormancy

When dormant oat seeds were imbibed at the non-permissive temperature of 30 degrees C, the concentration of phosphoenolpyruvate and of glycerate 3-phosphate, which are two inhibitors of phosphofructokinase 2, increased almost linearly during 30 h. By contrast, these metabolites increased only after a lag period of about 10 h in non-dormant seeds imbibed at the same temperature. As a consequence of this, the concentration of the C3 derivatives remained always remarkably lower in non-dormant than in dormant seeds. Accordingly, the concentration of fructose 2,6-bisphosphate, which increased similarly in the two types of seeds during the first 8 h after the start of inhibition, then reached a plateau in dormant seeds but continued to increase for another 8 h in non-dormant seeds, reaching a maximal value a few hours before the beginning of radicle protrusion. When the dormant seeds were imbibed at the permissive temperature of 10 degrees C, the evolution of all metabolites was slowed down but behaved like that of non-dormant seeds imbibed at 30 degrees C. Experiments in which the dormant seeds were submitted to a jump from 10 degrees C to 30 degrees C and vice versa, always provoked reverse changes in the concentration of the C3 derivatives and of fructose 2,6-bisphosphate, the latter being increased in all conditions that allowed germination. Dormant seeds were also allowed to germinate at 30 degrees C by imbibition during 24 h in the presence of 3% ethanol. Again, this permissive treatment caused an arrest in the accumulation of C3 derivatives and an increase in fructose 2,6-bisphosphate. Another, apparently unrelated, biochemical difference between dormant and non-dormant oat seeds was their inorganic pyrophosphate content, which was approximately five-fold higher in non-dormant than in dormant seeds. This difference was observed before and persisted during imbibition as long as measurement could be made and was not affected by the temperature jumps or by ethanol. In contrast to the phosphoric esters under investigation, pyrophosphate was not preferentially located in the embryo.     

The ascorbate system in recalcitrant and orthodox seeds

Recalcitrant seeds of Ginkgo biloba L., Quercus cerris L., Aesculus hippocastanum L. and Cycas revoluta Thunb. are shed by the plant at a high moisture content, contain a large amount of ascorbic acid (ASA) and maintain high ascorbate (ASC) peroxidase (EC 1.11.1.11) activity. Three proteins showing ASC peroxidase activity are present in G. biloba seeds. Conversely, dry orthodox seeds ( Vicia faba L., Avena sativa L., Pinus pinea L.) are completely devoid of ASA and ASC peroxidase. Experimentally induced rapid variations of the water level in both recalcitrant and orthodox seeds do not affect the ASC peroxidase; slow dehydration affects the ASC peroxidase activity moderately in recalcitrant seeds, but provokes a complete loss of germinability. Another peculiar difference between orthodox and recalcitrant seeds concerns the ascorbate recycling enzymes, ascorbate free radical (AFR) reductase (EC 1.6.5.4) and dehydroascorbate (DHA) reductase (EC 1.8.5.1). The DHA reduction capability is low in recalcitrant seeds, but is high in the orthodox ones. In contrast, AFR reductase activity is high in recalcitrant seeds and low in the orthodox ones. Data reported here concerning the ASC system appear to contribute to better understanding the recalcitrance. The presence of three different proteins showing ASC peroxidase activity in the archaic seed-bearing plant G. biloba and its involvement in the spermatophyte evolution is discussed.     

Binding, internalization and degradation of colony-stimulating factor by peritoneal exudate macrophages

Iodinated colony-stimulating factor produced by L-cells (125I-CSF-1) binds specifically to murine peritoneal exudate macrophages. At 37 degrees C, the cell-bound 125I-CSF-1 was internalized and degraded very rapidly, with the appearance of radioactive iodotyrosine in the medium. At 0 degree C, the cell-bound 125I-CSF-1 was not internalized and degraded, nor did it dissociate from the membrane. The internalization and degradation at 37 degrees C could be blocked or reduced by the presence of phenylglyoxal, methylamine and NH4Cl. The chemical nature of the CSF-1 binding site is polypeptide as judged by its sensitivity to trypsin treatment. After the binding and degradation of unlabeled CSF-1, the exudate cells were no longer able to rebind freshly added 125I-CSF-1, indicating the removal of CSF-1 binding site. The binding capacity of these cells, however, could be restored by prolonged incubation at 37 degrees C but not at 0 degrees C in culture medium containing fetal calf serum.     

Lipopeptide production in Pseudomonas sp. strain DSS73 is regulated by components of sugar beet seed exudate via the Gac two-component regulatory system

Pseudomonas sp. strain DSS73 isolated from the sugar beet rhizosphere produces the cyclic lipopeptide amphisin, which inhibits the growth of plant-pathogenic fungi. By Tn5::luxAB mutagenesis, we obtained two nonproducing mutant strains, DSS73-15C2 and DSS73-12H8. The gene interrupted by the transposon in strain DSS73-15C2 (amsY) encoded a protein with homology to peptide synthetases that was designated amphisin synthetase. DSS73-12H8 carried the transposon in a regulatory gene encoding a protein with homology to the sensor kinase GacS. Growth of strain DSS73-15C2 (amsY) was impaired during the transition to stationary phase in a minimal medium amended with an exudate of sugar beet seeds. This growth phenotype could be complemented by purified amphisin. Seed exudate further induced expression of bioluminescence from the amsY::luxAB reporter during the transition to stationary phase. This agreed with an increase in amphisin production by the DSS73 wild-type strain during early stationary phase. Amphisin synthesis in DSS73 was strictly dependent on GacS, and even induction by seed exudate depended on a functional gacS locus. Hence, a signal triggering the GacS/GacA two-component system appeared to be present in the seed exudate.     

Fatty acid composition of two Tunisian pine seed oils

Oils were extracted from fully ripen Pinus pinea L. and Pinus halepensis Mill seeds and fatty acid composition has been established by capillary gas chromatography. Seeds are rich in lipids, 34.63-48.12% on a dry weight basis. Qualitatively, fatty acid composition of both species is identical. For P. halepensis linoleic acid is the major fatty acid (56.06% of total fatty acids) followed by oleic (24.03%) and palmitic (5.23%) acids. For P. pinea, the same fatty acids are found with the proportions 47.28%, 36.56%, and 6.67%, respectively. Extracted fatty acids from both species are mainly unsaturated, respectively, 89.87% and 88.01%. Pinus halepensis cis-5 olefinic acids are more abundant (7.84% compared to 2.24%). Results will be important as a good indication of the potential nutraceutical value of Pinus seeds as new sources of fruit oils rich in polyunsaturated fatty acids and cis-5 olefinic acids.     

Loblolly pine seed dormancy. I. The relationship between protein synthesis and the loss of dormancy

Embryos from the mature unstratified loblolly pine ( Pinus taeda L.) seeds used in this study were nondormant: however, they failed to germinate in situ because of constraints imposed by the surrounding tissues. During a stratification period of 35 days of moist chilling at 2°C, seed germinability increased from 19 to 76%. The total lipid content of the megagametophyte did not change during stratification, whereas the total protein content of both megagametophyte and embryo was more variable. The rate of synthesis of buffer soluble proteins in these two tissues increased and electrophoretic analysis showed that while similar proteins were synthesized during the stratification period, changes in the patterns of synthesis of some proteins did occur. In both the embryo and megagametophyte the synthesis of a set of proteins with molecular masses below 46 kDa decreased markedly after 14 days of chilling (DOC). In the megagametophyte, the synthesis of a more diverse set of proteins with molecular masses ranging from 16 to 78 kDa increased after 14 DOC. It is noteworthy that these changes in the patterns of protein synthesis coincided with the greatest relative increase in seed germinability of 35%.     

Isocitrate lyase: artifacts and multiple enzyme forms

Multiple enzyme forms of isocitrate lyase from various sources have been frequently reported. Protease action after cell rupture was sporadically claimed to explain the observed multiple enzyme forms. In this communication studies which are consistent with a protease action in vitro on isocitrate lyase of Pinus pinea germinating seeds are reported. Moreover, changes in DEAE-Sephacel patterns, mainly related to the age of germination, were observed. Differences regarding the heat stability of the detected enzyme forms were also found. The results indicate that isocitrate lyase from P. pinea may be detected in at least three different forms, one of which is heat stable and may be obtained only at the early stages of germination.     

Aging in Pinus sylvestris L. seeds: changes in viability and lipids

Aging of Scots pine seeds (Pinus sylvestris L.) leads to changes in seed quality, such as loss of germinability, delayed growth and abnormality in developing seedlings. The knowledge of biochemical changes responsible for these aging processes is plentiful in some seeds, which are of world-wide interest, but for pine seeds these studies are rare. The aim of the present study, was to analyse pine seeds of varying ages in order to identify biochemical changes occurring in aged pine seeds, and to see if a correlation existed between these results and traditionally used seed-quality parameters, such as germinability and electrolyte leakage.     

Occurrence of cyclic AMP and related enzymes during germination of Pinus pinea seeds

The occurrence of cAMP, adenylate cyclase and cAMP phosphodiesterase has been tested in Pinus pinea seed during germination. The study has been carried out on dormant and imbibed seeds, seedlings, endospermic residues, roots and cotyledons. cAMP has been detected by the protein binding method and its occurrence has been verified by HPLC detections. cAMP phosphodiesterase shows a very high activity at acidic pH, while being completely inactive at pH 7.4. At this pH value, well detectable levels of adenylate cyclase have been observed. Therefore, the classical pathway of synthesis and breakdown of cAMP, already accepted for animal and bacterial cells, seems to be operating in Pinus pinea plant too.     

California pignolia: Seeds of pinus sabiniana

The pignolia nut or seed of the Italian stone pine (Pinus pinea) is. well-known as a food item, especially in Mediterranean cuisine. By contrast, the seed of Pinus sabiniana, a species of pine found only in California and once much utilized by the aboriginal population, is little-known commercially. When examined in terms of nutritional value, shell-to-kernel ratio, and kernel weight, the seeds of these 2 species appear to be similar. It would seem that the difference between them for commercial purposes is the 2000-yr cultivation of P. pinea in Europe as opposed to the general neglect of the California species, at least since the Euro-american domination of the area.     

Changes in the albumin and globulin fractions in seeds of Pinus pinea during artificial aging

The alterations on the electrophoretic patterns of albumin and globulin fractions in both embryo and endosperms of Pinus pinea seeds during artificial ageing have been investigated. The results show that the electrophoretic patterns of aged seeds are drastically different from those of seeds with high germination capacity. These alterations were observed even when the quantitative analysis did not show any significant changes.     

Germination and Food Reserves in Bambarra Groundnut Seeds (Voandzeia subterranea Thouars) after Different Periods of Storage

Studies were made on bambarranut seeds (Voandzeia subterraneaThouars) after 0, 6, 12, 18 and 24 months of storage in gunnybags under laboratory conditions (25–35 °C). Seeddeterioration during storage was indicated by delayed germination,reduced germinability, reduced growth of seedlings and increasednumber of stunted seedlings culminating in a total failure ofgermination after two years. Slight depletion of food reserves occurred during seed storage.The loss in fat was higher than starch or protein. Total solublesugars decreased while the content of total fatty acids andamino acids and soluble protein increased. Total nitrogen (N)remained unaffected while soluble-N and amino-N increased. Allthese components showed a rapid change (increase or decrease)from 12 months to 18 months of storage which was associatedwith commencement of rapid decline in germinability of the seedsand growth of the seedlings. Initial rapid imbibition of water was observed in viable aswell as non-viable seeds, though at a higher rate in the latterand followed by a lag period in both. At the end of 24 h ofimbibition, water content in non-viable seeds was less thanthat in viable ones. Key words: Voandzeia subterranea, Seed germination, Seed storage