bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural aspects and trends in the evolution of recalcitrant seeds in dicotyledons
Authors: von Teichman I. , van Wyk A. E. 
Published: September 2008

AbstractThis review focuses on the possible evolutionary status and functional significance of recalcitrance and certain associated ovule/seed characters, within the framework of modern systems of angiosperm classification. The presence of recalcitrant seed viability in 45 dicotyledonous families is significantly associated with bitegmic and crassinucellate ovules and with nuclear endosperm development, all considered ancestral (plesiomorphic) character states of the ovule; as well as with greater seed size, woody habit and tropical habitat, also regarded as ancestral character states in the dicotyledons. In many species with recalcitrant seeds, the predominant storage reserve is carbohydrate. Recalcitrance is significantly associated with the exalbuminous type of reserve storage. It is proposed that in large recalcitrant seeds, the transfer of the main storage function from endosperm to embryo was probably an early development. In many species with recalcitrance, the ovules/seeds are characterized by extensive vascularization of the integument(s)/seed coat or by a pachychalaza. Pachychalazy is proposed to be a significant functional adaptation for a more efficient transfer of nutrients to the embryo/seed. Recalcitrance and some of the other character states proposed to be plesiomorphic in dicotyledons are also present in some gymnosperms, including presumed sister groups of the dicotyledons. In relatively advanced dicotyledonous families, mostly with orthodox seeds, recalcitrance probably persisted only in isolated relict members. Determination of character polarity is particularly problematic at lower taxonomic levels, because there is always the possibility that, in some taxa, a character state such as recalcitrance may have arisen secondarily as a reversal. Available evidence supports our view that seed recalcitrance can be regarded as a relatively ancestral character state in dicotyledons.
Desiccation and the switch from seed development to germination. Alfalfa embryos can synthesize storage proteins after germination if maturation drying is prevented
Authors: Xu N. , Bewley J. D. 
Published: September 2008

AbstractStorage proteins (2S, 7S and 11S) are synthesized at the mid- to late stages of development in alfalfa seeds, mainly within the embryos. Mature dry seeds cannot synthesize these proteins upon subsequent germination and growth. When embryos were isolated from the seed during development (stages VII and VIII) and placed on water or nutrient medium, they germinated. They exhibited a pattern of protein synthesis which was identifiable as germinative/post-germinative, and was identical to the pattern synthesized in embryos of germinated dry seeds, and of embryos from seeds that were subjected to drying prematurely at stages VII and VIII. When, after 48 h from the start of imbibition, abscisic acid or osmoticum was introduced to germinated embryos isolated at stage VII and not desiccated, the synthesis of the 11S storage protein was restored to a rate comparable to that of stage-VII embryos before isolation. This was accompanied by an increase in transcription of the 11S storage protein gene. Transfer of germinated stage-VII embryos, which had first been desiccated, to abscisic acid or osmoticum 48 h after imbibition started did not result in any restoration of storage protein synthesis. Thus, desiccation, prematurely or at maturation, off-regulates storage protein synthesis and within the embryos this process is no longer responsive to abscisic acid or osmoticum.
Desiccation tolerance in two species with recalcitrant seeds: Clausena lansium (Lour.) and Litchi chinensis (Sonn.)
Authors: Fu J. R. , Jin J. P. , Peng Y. F. , Xia Q. H. 
Published: September 2008

AbstractSeeds were collected at weekly intervals from mid-maturation to the fully ripened stage. As seed development progressed, desiccation tolerance increased. Desiccation tolerance of C. lansium seeds was greatest at 67 days after anthesis (DAA), when they tolerated air drying for 9 days; 74 DAA was considered as physiological maturity, and their full viability was only maintained for up to 3 days of drying; overripened seeds (88 DAA) had the lowest desiccation tolerance. In L. chinensis, the desiccation sensitivity of seeds at 98 DAA (fully mature) was higher than that at 84 and 91 DAA (less mature); among the excised embryonic axes at different developmental stages, the less mature ones were less sensitive to desiccation than the fully mature ones; excised embryonic axes of the same stage were more tolerant of desiccation than whole seeds.
α-Amylase isoenzymes and BASI-like proteins in seeds of different grass species
Authors: Cornford C. A. , Hill R. D. 
Published: September 2008

AbstractSeeds from an assortment of 28 grass species (including two cereals), chiefly representing different tribes of the sub-family Pooideae were tested for the presence of BASI-like proteins using Western blotting techniques and antisera raised against the barley amylase/subtilisin inhibitor. A single protein species of the same molecular weight as the BASI protein was detected in each member of the tribes Triticeae and Bromeae tested. Members of the Triticeae and Bromeae were the only species to produce high pi α-amylase isoenzymes following germination of the grain in addition to low pl forms which were present in all species tested. Anti-BASI antibody binding patterns for the other grasses examined were variable with the strongest staining being observed for Lolium species. In these species, either a double or single protein band fractionally larger than the BASI protein was recognized. In most other cases antibody binding was barely or not detectable. Inhibitor preparations from Hordeum vulgare and Lolium perenne were effective at inhibiting wheat α-amylase but neither had any effect against enzyme produced by germinating L. perenne.
Molybdenum deficiency in wheat results in lower dormancy levels via reduced ABA
Authors: Modi A. T. , Cairns A. L. P. 
Published: September 2008

AbstractWheat which was grown in acid-washed sand and irrigated with a molybdenum-free nutrient solution was treated with various concentrations of molybdenum (Mo) as a foliar spray at the flag leaf stage. At maturity, dormancy levels and abscisic acid (ABA) content of the seed were determined. Seed dormancy and ABA content increased with increasing rates of Mo application. In a field experiment, wheat (cv. SST 66) was treated with 100 ppm Mo by foliar application at the flag leaf stage. Embryos were tested for sensitivity to exogenously applied ABA. Embryos from Mo-treated plants showed enhanced sensitivity to ABA-induced inhibition of germination. The Mo application also resulted in significantly higher levels of endogenous ABA and Mo in the seeds. It is postulated that Mo deficiency leads to a lack of dormancy in wheat via reduced synthesis of ABA.
Conifer zygotic embryogenesis, somatic embryogenesis, and seed germination: Biochemical and molecular advances
Authors: Misra Santosh 
Published: September 2008

AbstractThe development of techniques for somatic embryogenesis in conifers has led to rapid advances in the ability to culture conifer tissuein vitro.Somatic embryogenesis now provides a means to clonally propagate commercially valuable conifers of several species and offers anin vitroexperimental system for studying embryogenesis. As a result of these developments, the conifer zygotic and somatic embryo system has recently attracted the attention not only of the cell biologist but also of biochemists and molecular biologists. In this review I have attempted to consolidate the recent information on ultrastructure, biochemical and molecular aspects of conifer zygotic and somatic embryogenesis. In the first section, salient features of zygotic embryogenesis are highlighted followed by biochemical and ultrastructural characterization of development with reference to storage reserve deposition. In the second section, detailed characterization of seed storage proteins, changes in gene expression with emphasis on storage protein genes and Lea genes during zygotic and somatic embryogenesis are described. Effect of culture treatments such as abscisic acid, osmoticum and desiccation on storage protein gene expression in somatic embryos is discussed. Based on these studies, comparisons are presented between angiosperm and gymnosperm embryogeny regarding the unique morphological and developmental patterns of conifer embryogenesis. Finally, a brief discussion of recent progress in biochemical and molecular characterization of conifer seed germination is presented.
The mineral nutrient composition of wheat grains from ears grown to maturity in the field or cultured in media containing different concentrations of P, Mg, K and Ca
Authors: Batten Graeme D. , Ockenden Irene , Lott John N. A. 
Published: September 2008

AbstractA study was conducted to assess the effect of the supply of phosphorus and the major cations on the mineral nutrient composition of whole mature wheat grains and the electron-dense globoid crystals found in the aleurone cells. Ears of wheat plants, growing in the field, were detached after anthesis. The ears were cultured to maturity in a sterile control solution which contained all essential elements. Other ears were cultured in solutions which contained no phoshorus, no calcium, no magnesium, combinations of these (−P, −Ca; −P, −Mg) or a solution which contained additional potassium but no phosphorus, calcium or magnesium. Ears cultured in the control solution produced grains with higher concentrations of P, Mg, K and Ca than grains from ears which matured on plants in the field. All the −P treatments produced grains with lower concentrations of P and higher concentrations of Mg, K and Ca than the plants grown in the field. The appearance and elemental composition of the globoid crystals in the aleurone cells support the hypotheses that the size of globoid crystals is regulated, in part, by the amount of phosphorus deposited in the grain and also by the relative proportions of K, Mg and Ca in the tissue. The culture of individual ears of cereal plants is a useful technique by which to study the transfer to and deposition of mineral nutrients in cereal grains.
Seed stability during storage: Raffinose content and seed glassy state
Authors: Bernal-Lugo I. , Leopold A. C. 
Published: September 2008

AbstractIt has been proposed that sucrose and raffinose play a role in the storability of maize seeds. The levels of these sugars in the embryos and the glassy state were compared in maize seeds of contrasting storage stability to determine the relationship between sugar composition, glassy state and the storability of the seed. Sucrose was the predominant sugar but its content was not correlated with good storage. The content of raffinose as a mass fraction of total sugars and the magnitude of the glassy state showed positive correlations with storage stability. It is suggested that in maize seeds dry storage stability is a reflection not of the total soluble sugars, but of the mixture of sucrose with raffinose. Apparently raffinose amplifies the magnitude of the glass signal and this in turn is associated with enhanced storability.
A comparison of the synthesis of DNA, RNA and proteins in the embryos of after-ripened and thermo- or FR-dormantAgrostemma githagoL. seeds
Authors: Gerth U. , Bernhardt D. 
Published: September 2008

AbstractImbibed embryos of after-ripened and secondarily thermo- and FR-dormantAgrostemma githagoseeds were investigated as to their ability to synthesize DNA, RNA and proteins with the aim of finding characteristic differences connected with the induction and maintenance of developmental arrest. A gradual decrease in DNA synthesis was observed during the induction of thermodormancy. However, DNA synthesis was stimulated up to that of embryos of 30–h-imbibed after-ripened seeds within 24 h approximately after transferring the thermodormant seeds into temperatures which normally allow germination. DNA synthesis of embryos of FR-dormant seeds remained constant at a relatively low level during 7 d FR and another 7 d dark incubation. RNA synthesis decreased to different extents during induction of thermo- and FR-dormancy when it was arrested at a relatively low level in seeds transferred to temperatures which normally allow germination. Processes leading to an increase in RNA synthesis such as in embryos of after-ripened seeds appeared to be quantitatively and/or qualitatively repressed. Interestingly, protein synthesis was extremely depressed during induction of thermodormancy whereas it was slightly stimulated during induction of FR-dormancy. Nevertheless two-dimensional protein PAGE revealed several polypeptides which were new, increased, decreased or not synthesized predominantly in axes of thermo- and FR-dormant seeds in comparison to germinating after-ripened seeds. It is suggested that a connection exists between these polypeptides and the repression of germination. After transferring seconarily dormant seeds to temperatures which normally allow germination, a temporary stimulation of protein synthesis could be observed in both cases.
Development of the strophiole in seeds of white clover (Trifolium repens L.)
Authors: Martens Helle , Jakobsen Henrik B. , Lyshede Ole B. 
Published: September 2008

AbstractThe seed coat of Trifolium repens L. was studied with special emphasis on the development of the strophiole, which is the site for water entry during imbibition in leguminous seeds. The epidermal cells of the strophiole are longer than the cells in the remainder of the seed epidermis in the mature ovule. During seed development the median cells of the strophiolar epidermis divide periclinally into an outer layer of palisade cells and an inner layer of isodiametric cells. Prior to maturity a fissure is formed between some of the palisade cells in the centre of the strophiole. It is suggested that tension develops between the palisade cells and the iso-diametrical cells during later maturation stages causing the formation of the fissure which it is believed functions in water uptake. It is indicated that the ‘light line’ is caused by alteration of cellulose microfibrillar orientation in palisade cell walls. It is confirmed that removal of the epicuticular wax from hard seeds by rinsing in absolute alcohol or hexane does not induce water imbibition. Only when seed coats are mechanically abraded do hard seeds germinate.
A comparison of desiccation-related proteins (dehydrin and QP47) in peas (Pisum sativum)
Authors: Baker Ellen H. , Bradford Kent J. , Bryant John A. , Rost Thomas L. 
Published: September 2008

AbstractDehydrin and QP47, proteins present in mature pea seeds (Pisum sativum), have been proposed to play protective roles during desiccation. To identify possible relationships between these proteins and desiccation tolerance, their tissue locations and patterns of synthesis and degradation have been examined during germination. Tissue locations were determined by immunocytochemistry using polyclonal antibodies raised against a conserved dehydrin amino acid sequence and against purified QP47. In embryonic axis and cotyledon cells, QP47 and dehydrin were distributed uniformly with no apparent nuclear or organellar specificity. Both proteins were present in 24 h-imbibed axes that had not initiated radicle growth but were completely absent from 24 h-imbibed axes that had begun to grow. The amounts of QP47 and dehydrin in embryonic axes decreased with time after the start of imbibition and were undetectable by 48 h. When germination was prevented by polyethylene glycol (PEG) or abscisic acid (ABA), both proteins remained at their original amounts. Thus, both QP47 and dehydrin disappeared coincidently with the beginning of growth and not simply as a function of the time after imbibition. QP47 persisted in cotyledons until at least 31 days into seedling growth, whereas dehydrin was not detectable in cotyledons after 7 days. Dehydrin, but not QP47, could be re-induced in pea shoots and cotyledons by dehydration. The timing of degradation of both proteins was correlated with the loss of desiccation tolerance during germination of pea axes.
Germination of 110-year-old cereal and weed seeds, the Vienna Sample of 1877. Verification of effective ultra-dry storage at ambient temperature
Authors: Steiner A.M. , Ruckenbauer P. 
Published: September 2008

AbstractAfter 110 years of hermetic sealed storage at temperatures between 10 and 15°C and at a moisture content of 3.12%, Hordeum vulgare showed 90% germination and Avena sativa 81%. In addition, some seeds of Agrostemma githago, Lolium temulentum, Sinapis alba, Sinapis arvensis, and Vaccaria hispanica were still capable of germinating. This demonstrates that ultra-dry, long-term seed storage under ambient temperature conditions can successfully be achieved with the intention of cutting down risks and costs in germplasm conservation.
Characterization of carboxypeptidase I of mung bean seeds
Authors: Wilson Karl A. , Russell Mary , Quackenbush John F. , Tan-Wilson Anna L. 
Published: September 2008

AbstractThere is a carboxypeptidase in mung bean seeds that is localized in the protein bodies, the same vacuoles in which seed storage proteins are sequestered. This carboxypeptidase, called carboxypeptidase I (or Cpase I) has been purified by a series of ion-exchange and gel filtration columns. The pure enzyme consists of a single polypeptide chain with a MW of 41700 by SDS-PAGE or 42000 by size-exclusion HPLC. It has a pl of 4.36 and is a serine carboxypeptidase as shown by its inactivation by phenylmethylsulfonyl fluoride, and its resistance to other proteolytic inhibitory reagents. A survey of its activity with Cbz-dipeptides shows preference for C-terminal amino acids that are large, hydrophobic residues, and a small aliphatic amino acid such as alanine, but not glycine, at the penultimate amino acid residue. Cpase I can convert a trypsin inhibitor of the mung bean to its proteolytic intermediate lacking four amino acid residues at its C-terminus. This proteolytic intermediate is detected in the mung bean cotyledons during early growth. Levels of both the activity and immunological cross-reacting forms of this enzyme start high and decrease during early growth.
Seed production environment and storage longevity of japonica rices (Oryza sativa L.)
Authors: Kameswara Rao N. , Jackson M.T. 
Published: September 2008

AbstractChanges in seed dry weight, moisture content and germinability of three japonica cultivars of rice during development and maturation in the dry season (November–May) field multiplication at Los Baños, Philippines were compared with those in a cooler controlled environment (24°/18°C). Under field conditions, maximum dry weight accumulation, which indicates mass maturity, was attained 18–21 days after flowering in all cultivars. In the cooler environment however, mass maturity was achieved 21 days after flowering in Fujisaka 5 and Minehikare, and 28 days in Shuang cheng nuo. The moisture content of the seeds at mass maturity varied between 28 and 35% among cultivars in the two environments. Although the ability of seeds to germinate differed in early harvests (7 and 14 days) among cultivars and across two environments, germination of the mature seeds was similar in all. There were no significant differences in potential longevity of the seeds harvested at 28, 35 and 42 days after flowering within each cultivar, which was determined by the germination of seeds that had been hermetically stored with 15% moisture content at 35°C. Differences among cultivars within each seed production environment were also not significant. However, potential longevity of the seeds harvested from the cooler environment was higher than those from the field (P<0.05), which confirmed that japonica cultivars which evolved under temperate regions are sensitive to warmer seed production environments. However, the magnitude of differences in potential seed longevity between the two environments was not high. This indicates that the seed production environment during the dry season at Los Baños is not harsh for japonica cultivars.
Operational and philosophical decisions in seed dormancy research
Authors: Cohn Marc Alan 
Published: September 2008

AbstractMany research questions focused upon seed dormancy and germination remain unanswered due to problems created by inappropriate assumptions concerning the design and implementation of experiments. Lack of attention to the genetic background and growing conditions required for seed production and subsequent storage may compromise an investigator's ability to pool data or assimilate data trends due to variability in seed performance from year to year. Seed aging events during the afterripening process can be mistaken for those involved in the transition from the dormant to nondormant state. After imbibition, inaccurate criteria for and scoring of the germination event may lead to confusion of seed vs. seedling physiology and biochemistry. In addition, a sufficient number and proper spacing of data points during timecourse experiments are required to properly stage a sequence of events. Studies comparing dormant vs. nondormant seeds must be supplemented with kinetic experiments examining the effect of a dormancy-breaking treatment upon the transition between the dormant and nondormant states. In comparisons of the relative efficacy of various dormancy-breaking chemical treatments, the physical properties of substances under evaluation (e.g. lipophilicity) should be considered. In addition, since many dormancy-breaking chemicals are toxic to vegetative growth, there is a danger of introducing pharmacological artifacts that confuse interpretation of the results obtained. These toxic properties also necessitate the use of viability tests during construction of dose-response curves to avoid confusing seed death with dormancy. Seed scientists must also avail themselves of the extensive literature on developmental arrest in other organisms, which may generate fresh ideas for experimentation.
Species differences in seed water status during seed maturation and germination
Authors: Egli D.B. , TeKrony D.M. 
Published: September 2008

AbstractMaize (Zea maysL., cv. B73 × Mo17), wheat (Triticum aestivumL., cv. Clark), and soybean (Glycine maxL. Merrill, cv. Elgin 87) were grown in the field and seed samples were collected at frequent intervals for the determination of seed fresh and dry weight and water potential of excised embryos (maize and wheat) and axes (soybean). Seed water concentration declined during seed development and the concentration at physiological maturity (PM, maximum seed dry weight) was highest in soybean (550–590 g kg−1FW), lowest in maize (326–377 g kg−1) and intermediate in wheat (437 g kg−1). The embryo/axis water potential was relatively constant during much of seed filling before decreasing rapidly as the seeds approached PM and there was little variation among species (soybean −1.52 to −1.63 MPa, maize −1.61 to −1.99 MPa and wheat −1.66 MPa). Seed water concentration when 10% of the seeds germinated (radicle ≥3 mm) was highest in soybean (514 g kg−1), lowest in maize (332 g kg−1) and intermediate in wheat (345 g kg−1) while the water potential of the embryo/axis varied from −2.07 to −2.20 MPa across the three species. There was little variation in the water potential of the embryo/axis among species at the end of seed growth (PM) or at the beginning of germination. This similarity is consistent with the suggestion that the water status of critical seed structures may play a regulatory role in seed growth and germination.