bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reserves of aluminium and mineral nutrients in seeds ofEucalyptus calophylla(Myrtaceae) with reference to the globoid inclusions
Authors: Egerton-Warburton Louise M. , Griffin Brendon J. , Kuo John 
Published: September 2008

AbstractAmounts of mineral nutrients and aluminium (Al) were assessed in the globoid inclusions, proteinaceous matrix and druse crystals ofEucalyptus calophyllaseeds collected from trees grown in coal-mine (mean soil pH 4.3, Al 260 μg g−1) and forest soils (pH 5.3, Al 10 μg g−1). Energy-dispersive X-ray microanalysis (EDX) of bulk frozen hydrated samples indicated that significantly higher amounts of Mg, P, S, K and Ca occurred in the globoid inclusions of mine- than forest-site seeds. In both seedstocks, Al was detected in the globoid inclusions but not in the proteinaceous matrix or druse crystals. Significantly higher amounts of Al occurred in mine-site samples of dry and germinating seeds than in forest-site seeds. It was concluded that globoid inclusions may be useful as indicators of the soil conditions in which the parent plant was grown.
A critical update on seed dormancy. I. Primary dormancy
Authors: Hilhorst Henk W. M. 
Published: September 2008

AbstractThe emphasis of modern dormancy research is almost entirely on the form of dormancy that is acquired during seed development, primary dormancy. Abscisic acid (ABA) appears to be intimately involved in its regulation. The action of abscisic acid has also been implied in many other developmental processes. The coincidence of developmental events, such as dehydration and completion of maturation, with the acquisition of primary dormancy suggests that dormancy is influenced by these processes. Germinability, both during development and after maturation, is sometimes directly correlated with ABA content. The lack of such a correlation may be explained by assuming a decisive role for the responsiveness to ABA or other overriding factors. ABA has been detected in all seed components. The different seed tissues may all contribute, to various extents, to the degree of whole seed dormancy. It is concluded that ABA action in dormancy regulation is not restricted to the embryo but is also located in endospermic tissue. In addition, a role of ABA in the morphological development of germination modifying seed tissues is proposed. The mechanism for ABA action appears to be associated with cell wall properties.
Thidiazuron stimulates germination and ethylene production inStriga hermonthica– comparison with the effects of GR-24, ethylene and 1-aminocyclopropane-1-carboxylic acid
Authors: Logan David C. , Stewart George R. 
Published: September 2008

AbstractSeed germination of the hemiparasitic angiospermStriga hermonthicais elicited by compounds present in the root exudates of the host plant. A variety of chemicals can substitute for the host-derived signal although the exact mechanism through which these act is unknown. In the present study, thidiazuron (TDZ), a cytokinin-active urea derivative was found to stimulate germination. This thidiazuron-induced germination was shown to be mediated by endogenous ethylene, by a similar mechanism to germination induced by host-root exudate and the synthetic stimulant GR-24. Comparing the effects of TDZ, host-root exudate, GR-24 and the ethylene precursor 1-aminocyclopropane-1-car-boxylic (ACC) suggests that ethylene production increases as a result of increased ACC synthesis and is consistent with a model forStrigaseed germination in which host-derived signals and other stimulants act by eliciting the synthesis of ethylene via a stimulation of ACC synthase activity. All germination stimulants tested trigger a rapid increase in O2uptake by conditioned seeds. The patterns of O2uptake following TDZ or GR-24 treatments show similarities and three distinct phases of respiration are apparent. In contrast, stimulation of O2uptake by ethylene results in a different pattern, with no distinct phases obvious following the initial burst of activity.
Changes in the composition of globoids in castor bean cotyledons and endosperm during early seedling growth with and without complete mineral nutrients
Authors: Lott John N.A. , West M. Marcia , Clark Ben , Beecroft Penny 
Published: September 2008

AbstractThe endosperm and cotyledon tissues of Ricinus communis seeds and young seedlings were examined for changes in the mineral nutrient composition of globoids during early seedling growth. The effect on globoid composition of providing mineral nutrients to the developing seedling was also investigated. Globoids in endosperm and cotyledon tissues of castor bean seeds contained P, Mg and K, as well as trace amounts of Ca, Fe and Zn. Irrespective of the addition of mineral nutrients, K content in globoids of endosperm and cotyledon tissues declined significantly during initial seedling growth. During early seedling growth, amounts of Fe, Zn and Ca increased in cotyledon globoids. Ca contents of globoids of endosperm tissues also increased. The changes in Fe, Zn and Ca globoid contents were not influenced by providing mineral nutrients to growing castor bean seedlings.
The high reducing sugar content during germination contributes to desiccation damage in lettuce (Lactuca sativa L.) radicles
Authors: van der Toorn P. , McKersie B. D. 
Published: September 2008

AbstractAt the time of protrusion, radicles of lettuce seeds became susceptible to desiccation damage. Concomitant with radicle elongation, both the reducing sugar content and the amount of lipid-aldehydes increased. The role of the hydroxy- and lipid-aldehydes in browning reactions that occurred during desiccation and re-imbibition was analysed. It was concluded that both types of aldehydes reacted with amino-groups during desiccation and that the increase in lipid-aldehydes during germination could be due to the augmented reducing sugar content. Therefore, the high reducing sugar content in radicles of germinated lettuce seeds may be the primary source of hydroxyl radicals, and thereby, a principal cause of desiccation damage.
Does benzyladenine stimulate DNA metabolism by modifying gene expression during maize germination?
Authors: Zúñiga-Aguilar José Juan , López Imelda , Gómez Alberto , Vázquez-Ramos Jorge M. 
Published: September 2008

AbstractBenzyladenine, a synthetic cytokinin, stimulates DNA metabolism during maize germination; apparently such stimulation occurs in two phases, and during the first phase stimulations of DNA synthesis, of protein kinase activity (both α-amanitin repressible), of DNA polymerase and poly ADP-ribosyl polymerase activities are observed. Since the evidence suggested that the effects produced by BA were due, at least partially, to transcriptional activation, attempts were made to discover genes, by subtractive hybridization of a cDNA library or by differential display, whose expression depended on the presence of BA; however these were unsuccessful. BA modulated the expression of a limited number of genes only. The possible mechanism by which BA could be promoting DNA metabolism during maize germination is discussed.
Maize DNA polymerase 2 (an α-type enzyme) suffers major damage after seed deterioration
Authors: Coello Patricia , Vázquez-Ramos Jorge M. 
Published: September 2008

AbstractDNA polymerase 2 holoenzyme is an α-type polymerase present as a major activity in 24-h germinated maize embryo axes. At this time, several of the polypeptides that compose this multisubunit enzyme are phosphorylated. During the germination of artificially deteriorated maize embryo axes, total DNA polymerase activity decreases by around 50% when compared with activity in non-deteriorated axes. DNA polymerase 2 appears to be damaged by the deterioration treatment, greatly reducing its activity. This decrease in activity is related to protein degradation during germination since the amount of both the holoenzyme and the different polymerase 2 subunits is reduced as imbibition progresses. The decrease in amount is more dramatic for some of the subunits than for others, i.e., the amount of the 90-kDa catalytic subunit is reduced by about half, whereas all other subunits totally disappear at different times during germination. The phosphorylation state of the different polypeptides is also greatly affected.
Factors affecting endo-β-mannanase activity in the endosperms of fenugreek and carob seeds
Authors: Kontos Fanouris , Spyropoulos Caroline G. , Griffen Alison , Bewley J. Derek 
Published: September 2008

AbstractEndosperms of fenugreek and carob which have been leached following their isolation exhibit increased activity of endo-β-mannanase, part of which is released into the surrounding incubation medium. This activity was suppressed by the addition to the endosperms of abscisic acid or endosperm/seed coat leachate. The leachate from carob inhibited the increase of endo-β-mannanase activity in fenugreek and that from fenugreek inhibited enzyme activity in carob but more weakly; neither of these leachates inhibited the production of α-amylase in wheat endosperm. Polyethylene glycol-induced stress on non-leached endosperms inhibited endo-β-mannanase production, but not when the stress was applied following endosperm leaching. However, the stress did reduce the amount of enzyme released into the surrounding incubation medium. Several isoenzymes of mannanase could be detected on isoelectric focusing activity gels in the endosperms of both fenugreek and carob, but their pis differed between the two species. When activity was suppressed by ABA or leachate, all pl forms declined equally.
Effects of pre-storage hydration treatments on germination performance, moisture content, DNA synthesis and controlled deterioration tolerance of tomato (Lycopersicon esculentum Mill.) seeds
Authors: van Pijlen Jaap G. , Groot Steven P. C. , Kraak H. Lieke , Bergervoet Jan H. W. , Bino Raoul J. 
Published: September 2008

AbstractStorage of tomato seeds under deteriorating conditions reduced the rate of germination, the uniformity of germination, total germination and the proportion of normal seedlings. Pre-storage humidification and hydropriming of seeds resulted in a significant increase in resistance to deterioration. In contrast, osmoprimed seeds were more deterioration sensitive. Humidification or hydropriming for one day did not allow nuclei to enter the S phase of the cell cycle. Osmopriming strongly increased the percentage of nuclei with replicated DNA in the embryonic root tip, indicating initiation of the cell cycle and progression towards the G2 phase. The interaction between the prestorage treatments, cell cycle progression and deterioration resistance, is discussed. Based on the changes in moisture content equilibrium and cell cycle activity it is hypothesized that the beneficial effects of pre-storage humidification and hydropriming were related to metabolic activities induced by the partial hydration and that the adverse effects of osmopriming were caused by a decrease in DNA repair activity due to progression in the cell cycle.
A hydrothermal time model of seed after-ripening in Bromus tectorum L.
Authors: Christensen Maren , Meyer Susan E. , Allen Phil S. 
Published: September 2008

AbstractBromus tectorum L. is an invasive winter annual grass with seeds that lose dormancy through the process of dry after-ripening. This paper proposes a model for after-ripening of B. tectorum seeds based on the concept of hydrothermal time. Seed germination time course curves are modelled using five parameters: a hydrothermal time constant, the fraction of viable seeds in the population, base temperature, mean base water potential and the standard deviation of base water potentials in the population. It is considered that only mean base water potential varies as a function of storage duration and incubation temperature following after-ripening. All other parameters are held constant throughout after-ripening and at all incubation temperatures. Data for model development are from seed germination studies carried out at four water potentials (0, −0.5, −1.0 and −1.5 MPa) at each of two constant incubation temperatures (15 and 25°C) following different storage intervals including recently harvested, partially after-ripened (stored for 4, 9 or 16 weeks at 20°C) and fully after-ripened (stored for 14 weeks at 40°C). The model was fitted using a repeated probit regression method, and for the two seed populations studied gave R2 values of 0.898 and 0.829. Germination time course curves predicted by the model generally had a good fit when compared with observed curves at the incubation temperature/water potential treatment combinations for different after-ripening intervals. Changes in germination time course curves during after-ripening of B. tectorum can largely be explained by decreases in the mean base water potential. The simplicity and good fit of the model give it considerable potential for extension to simulation of after-ripening under field conditions.
Respiratory enzyme activities during germination inBrassicaseed lots of differing vigour
Authors: Bettey Mary , Finch-Savage W.E. 
Published: September 2008

AbstractThe rate of oxygen consumption by cabbage seeds increased on imbibition and there was a further sharp increase on germination. This was delayed in artificially aged seeds of low vigour. The increases in oxygen consumption reflect the increased oxidation of carbohydrates via respiratory pathways. The activities of key regulatory enzymes of glycolysis and the oxidative pentose phosphate pathway were measured in aged and unaged seed lots of cabbage. Differences in the activities of glucose 6-phosphate dehydrogenase and pyrophosphate:fructose 6-phosphate 1-phosphotransferase were correlated with the rate of germination (T50) in seed lots with large differences in seed vigour induced experimentally by artificial aging. However, the activities of these enzymes could not be used to distinguish between untreated seed lots which had smaller vigour differences apparent only under stress. The enzymes are presumably not controlling and determining seed vigour, but merely reflecting actual seed performance under the current conditions.
A comparative study of the seed germination biology of a narrow endemic and two geographically-widespread species ofSolidago(Asteraceae). 1. Germination phenology and effect of cold stratification on germination
Authors: Walck Jeffrey L. , Baskin Jerry M. , Baskin Carol C. 
Published: September 2008

AbstractSolidago shortiiis endemic to a small area in northcentral Kentucky (USA), whereas two of its sympatric congeners,S. altissimaandS. nemoralis, are geographically widespread. Seeds (achenes) ofS. shortii(0.370 mg) are significantly larger (PLSD,P=0.05) than those ofS. altissima(0.070 mg) andS. nemoralis(0.068 mg). Germination percentages of freshly-matured seeds of the threeSolidagospecies collected in November 1991, 1992 and 1994 were 0–2% in light at 15/6°C, 1–37% at 20/10°C, 9–56% at 25/15°C and 10–85% at 30/15 and 35/20°C. Stratification increased the percentage and rate of germination and decreased the time to the onset of germination (measured by Timson's index only at 20/10°C in light) in the three species. Following 12 weeks of cold stratification in light, seeds of the three species germinated to 72–100% in the light and to 22–100% in darkness over the range of thermoperiods; those cold-stratified in darkness germinated to 39–100% in light. Freshly-matured seeds ofS. altissimaand ofS. nemoralisgerminated to 0–4% in darkness, whereas those cold-stratified for 12 weeks in darkness germinated to 0–28% in darkness. On the other hand, freshly-matured and cold-stratified (in darkness) seeds ofS. shortiigerminated to 0–13 and 13–73%, respectively, in darkness. Under near-natural temperatures in a glasshouse without temperature control, germination of the three species peaked in March. Thus, the primary difference in dormancy-breaking and germination requirements of the three species is that the endemic germinates to a much higher percentage in darkness than its two congeners. Seeds ofS. shortiido not have any special dormancy-breaking or germination requirements that could not be fulfilled outside its present-day geographic range.
2nd International Workshop on Desiccation-Tolerance and -Sensitivity of Seeds and Vegetative Plant Tissues
Authors: Berjak Patricia , Osborne Daphne , Pammenter Norman 
Published: September 2008

AbstractHow some plant cells can survive a period of desiccation to live again when other cells will die, was the theme of the recent Workshop in the mountain retreat of Franschhoek, near Cape Town, South Africa. Sixty-two biochemists and cell physiologists from around the world assembled to discuss these problems for the second time in three years.
Approaches to elucidate the basis of desiccation-tolerance in seeds
Authors: Kermode Allison R. 
Published: September 2008

AbstractPlants undergo a series of physiological, biochemical and molecular changes in response to adverse environmental conditions or stresses such as drought, low temperature or high salt. Several genes and their corresponding proteins have been described that may play a role in withstanding water-deficit-related stresses or full desiccation. In particular, sugars and late-embryogenesis-abundant (LEA) proteins have received the most attention. Plant responses to water-deficit and desiccation have been well-characterized at the molecular level; however, pinpointing the precise roles of the gene products in protecting cells under conditions of water deficit remains a challenging task. While few plants are capable of withstanding full desiccation, most seeds undergo this event as a pre-programmed and final stage in their development. These are the so-called ‘orthodox’ seeds. In contrast to seeds of orthodox species, those of recalcitrant species do not acquire desiccation tolerance during their development and are shed from the parent plant at relatively high water contents. The essential components of desiccation tolerance of seeds are likely to involve the ability to effect repair upon subsequent rehydration as well as the ability to accumulate protective substances that limit the amount of damage which otherwise would be caused by water loss. Studies have begun to examine whether the desiccation sensitivity of recalcitrant seeds is at least partially the result of an insufficient accumulation of LEA-type proteins, or whether other factors (including a lack of protective sugars) are more important. This review assesses some of these studies as well as recent research to understand gene and protein function using transgenic host plant systems.
The most prevalent protein in a heat-treated extract of pea (Pisum sativum) embryos is an LEA group I protein; its conformation is not affected by exposure to high temperature
Authors: Russouw Pauline S. , Farrant Jill , Brandt Wolf , Lindsey George G. 
Published: September 2008

AbstractThe LEA-like protein previously isolated from a homogenate of pea (Pisum sativumL.) embryonic axes heated at 80°C for 10 min (Russouwet al., 1995) was purified without exposure to heat. Peptides produced by trypsin digestion were separated by HPLC and sequenced. The protein was identified as a member of the LEA group I family. The conformation of the protein was compared before and after heat treatment by antibody affinity, circular dichroism spectroscopy, fluorescence spectroscopy and 8-anilino-1-naphthalenesulfonic acid binding. No differences could be detected, demonstrating that the protein was not irreversibly denatured by exposure to high temperature.
Subcellular organization and metabolic activity during the development of seeds that attain different levels of desiccation tolerance
Authors: Farrant Jill M. , Pammenter N. W. , Berjak Patricia , Walters Christina 
Published: September 2008

AbstractWater contents, desiccation tolerance, respiratory rates and subcellular characteristics of three contrasting seed types were studied during development.Avicennia marina(a tropical wetland species) andAesculus hippocastanum(a temperate species) produce recalcitrant seeds andPhaseolus vulgarisproduces orthodox seeds. During development,A. hippocastanumandP. vulgarisseeds showed a decline in water content and respiration rate with a concomitant increase in desiccation tolerance. These parameters did not change during the development ofA. marinaseeds once they had become germinable. There was a decrease in the degree of vacuolation and an increase in the deposition of insoluble reserves inA. hippocastanumandP. vulgarisseeds, whileA. marinaseeds remained highly vacuolated and did not accumulate insoluble reserves. Mitochondria and endomembranes degenerated during the development ofA. hippocastanumandP. vulgarisseeds, but remained unchanged inA. marinaseeds. The data are consistent with the hypothesis that extensive vacuolation and high metabolic rates contribute to desiccation sensitivity. However, the development of recalcitrantA. hippocastanumseeds is similar to that of orthodoxP. vulgarisseeds. These data are in accord with the concept of seed recalcitrance being a consequence of truncated development. The results suggest that there may be three categories of seeds: orthodox seeds which develop desiccation tolerance, seeds which show similar development to orthodox seeds, but are shed before desiccation tolerance is well developed, and seeds which show no developmental trends giving rise to increased tolerance.
Removal of the testa during germination or establishment increases germinant mortality, decay and water loss
Authors: Lamont B. B. , Milberg P. 
Published: September 2008

AbstractBy means of direct manipulation, this study showed that the testa protects the germinating seed and germinant from decay (an advantage in moist soils) and desiccation (an advantage in periodically dry soils) in four species, all of which retain their testas until the cotyledons are lifted above the soil. Furthermore, the testa prevents early spreading of the cotyledons (an advantage when elongating through soil and litter). Almost all germinants ofBanksia hookerianaandLeucadendron eucalyptifolium, with their testas removed, died and rotted away after being sown on the soil surface or at a range of depths.Hakea cyclocarpaandH. strumosashowed only minor losses compared with the intact germinants. All naked germinants were smaller than the controls at any depth, except amongH. cyclocarpa. Absence of the testa did not differentially affect the length of the hypocotyl in the dark or light, but lateral spread of the cotyledons was accelerated, especially in the dark. Removal of a small fraction of the testa was sufficient to cause general mortality ofB. hookerianagerminants but not ofH. cyclocarpaorH. strumosa. After imbibition, water content of the naked embryos ofB. hookerianareverted to the air-dry state within 24 h of sowing in air-dry sand, while intact seeds were still moist even after 7 days of drying. Compared with intact seeds, drying periods of 3–7 days decreased the amount of germination and root growth of naked embryos after rewetting, and increased microbial infection of the survivors. Removal of the testa from germinants was sufficient to cause general mortality after only 6 h in air-dry sand. In contrast, most intact germinants with short radicles recovered after drying for 2 days.