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Germinating Seeds (germinating + seed)
Selected AbstractsThe specialist seed predator Bruchidius dorsalis (Coleoptera: Bruchidae) plays a crucial role in the seed germination of its host plant, Gleditsia japonica (Leguminosae)FUNCTIONAL ECOLOGY, Issue 2 2002K. Takakura Summary 1,This paper describes the germination mechanism of hard seeds of a species of honey locust, Gleditsia japonica, which can germinate only when externally damaged, in relation to four germinating factors: feeding damage by two specialist seed predators, a bean weevil (Bruchidius dorsalis) and a cydid bug (Adrisa magna); feeding damage by a generalist seed predator, a wild mouse (Apodemus speciosus); and physical damage. 2,In laboratory experiments, both the bean weevil and physical damage facilitated germination, while damage by the cydid bug and wild mouse did not. 3,In contrast to laboratory findings, field censuses of G. japonica seed survival revealed that more than 99% were damaged either by B. dorsalis or A. magna. Therefore, less than 0·5% of the seeds remained intact, preventing formation of a seed bank. 4,In addition, all germinating seeds found in the field contained B. dorsalis larvae. 5,These results strongly suggest that damage by B. dorsalis is a prerequisite for G. japonica germination, in contrast to the conventional view that physical disturbance, possibly flooding, is the primary germinating factor for hard seeds. [source] Post-dispersal fate of seeds in the Monte desert of Argentina: patterns of germination in successive wet and dry yearsJOURNAL OF ECOLOGY, Issue 6 2000Luis Marone Summary 1,Patterns of seed germination of grass and forb species were studied in open Prosopis woodland of the central Monte desert (Argentina) during several years, to test the hypotheses that (i) seed germination is positively affected by both rainfall and protection afforded by vegetation cover (a facilitative effect), (ii) the number of surviving plants is positively influenced by rainfall but negatively affected by established vegetation (a competitive effect), and (iii) seed loss from soil banks owing to germination is lower than that caused by granivorous animals. 2,Forb species germinated during restricted periods, either in early autumn or in spring. Grasses, however, germinated throughout the growing season, but because seedlings could not be identified to species level, it was impossible to discern whether different species germinated in particular seasons, or if all grasses germinated in all seasons. Grass and forb germination were generally of similar magnitude, but grass germination increased by an order of magnitude during a summer of unusually abundant rainfall related to an El Niņo Southern Oscillation (ENSO) event. 3,Overall, the spatial distribution of neither germinating seeds nor surviving plants could be explained by interactions with established vegetation (facilitation and competition effects, respectively). An alternative explanation may be provided by the distribution of forb and grass seeds in the soil. 4,Seed loss owing to germination was low in both dry and rainy years. For forbs, such loss totalled <,1% of soil-seed reserves, and no forb species suffered losses >,4%. Total grass-seed loss to germination was usually <,0.5%, and the 5% reached in 1997,98 corresponded to an interruption of a prolonged drought by unusually abundant rainfall associated with a reduced seed bank. 5,Grass-seed loss caused by germination was one to two orders of magnitude lower than that reported due to autumn-winter granivory in the central Monte desert. [source] Associations among cytoplasmic molecular markers, gender, and components of fitness in Silene vulgaris, a gynodioecious plantMOLECULAR ECOLOGY, Issue 3 2003D. E. Mccauley Abstract It has been suggested that the dynamics of chloroplast DNA (cpDNA) or mitochondrial DNA (mtDNA) genetic markers used in studies of plant populations could be influenced by natural selection acting elsewhere in the genome. This could be particularly true in gynodioecious plants if cpDNA or mtDNA genetic markers are in gametic disequilibrium with genes responsible for sex expression. In order to investigate this possibility, a natural population of the gynodioecious plant Silene vulgaris was used to study associations among mtDNA haplotype, cpDNA haplotype, sex and some components of fitness through seed. Individuals were sampled for mtDNA and cpDNA haplotype as determined using restriction fragment length polymorphism (RFLP) methods, sex (female or hermaphrodite), fruit number, fruit set, seeds/fruit and seed germination. The sex of surviving germinating seeds was also noted. All individuals in the population fell into one of two cytoplasmic categories, designated haplotypes f and g by a unique electrophoretic signature in both the mtDNA and cpDNA. The subset of the population carrying haplotype g included a significantly higher proportion of females when compared with the sex ratio of the subset carrying the f haplotype. Haplotype g had a significantly higher fitness when measured by fruit number, fruit set and seeds/fruit, whereas haplotype f had significantly higher fitness when measured by seed germination. Offspring of individuals carrying haplotype g included a significantly greater proportion of females when compared with offspring of individuals carrying the f haplotype. Other studies of gynodioecious plants have shown that females generally have higher fitness through seed than hermaphrodites, but in this study not all fitness differences between haplotypes could be predicted from differences in haplotype-specific sex ratio alone. Rather, some differences in haplotype-specific fitness were due to differences in fitness between individuals of the same sex, but carrying different haplotypes. The results are discussed with regard to the potential for hitchhiking selection to influence the dynamics of the noncoding regions used to designate the cpDNA and mtDNA haplotypes. [source] Differential proteomic analysis of the endoplasmic reticulum from developing and germinating seeds of castor (Ricinus communis) identifies seed protein precursors as significant components of the endoplasmic reticulumPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 9 2007Daniel J. Maltman Abstract The endoplasmic reticulum is a major compartment of storage protein and lipid biosynthesis. Maximal synthesis of these storage compounds occurs during seed development with breakdown occurring during germination. In this study, we have isolated four independent preparations of ER from both developing and germinating seeds of castor bean (Ricinus communis) and used 2-D DIGE, and a combination of PMF and MS/MS sequencing, to quantify and identify differences in protein complement at both stages. Ninety protein spots in the developing seeds are up-regulated and 19 individual proteins were identified, the majority of these are intermediates of seed storage synthesis and protein folding. The detection of these transitory storage proteins in the ER is discussed in terms of protein trafficking and processing. In germinating seed ER 15 spots are elevated, 5 of which were identified, amongst them was malate synthetase which is a component of the glyoxysome which is believed to originate from the ER. Notably no proteins involved in complex lipid biosynthesis were identified in the urea soluble ER fraction indicating that they are probably all integral membrane proteins. [source] ABA-Hypersensitive Germination1 encodes a protein phosphatase 2C, an essential component of abscisic acid signaling in Arabidopsis seedTHE PLANT JOURNAL, Issue 6 2007Noriyuki Nishimura Summary The phytohormone abscisic acid (ABA) regulates physiologically important stress and developmental responses in plants. To reveal the mechanism of response to ABA, we isolated several novel ABA-hypersensitive Arabidopsis thaliana mutants, named ahg (ABA- hypersensitive germination). ahg1-1 mutants showed hypersensitivity to ABA, NaCl, KCl, mannitol, glucose and sucrose during germination and post-germination growth, but did not display any significant phenotypes in adult plants. ahg1-1 seeds accumulated slightly more ABA before stratification and showed increased seed dormancy. Map-based cloning of AHG1 revealed that ahg1-1 has a nonsense mutation in a gene encoding a novel protein phosphatase 2C (PP2C). We previously showed that the ahg3-1 mutant has a point mutation in the AtPP2CA gene, which encodes another PP2C that has a major role in the ABA response in seeds (Yoshida et al., 2006b). The levels of AHG1 mRNA were higher in dry seeds and increased during late seed maturation , an expression pattern similar to that of ABI5. Transcriptome analysis revealed that, in ABA-treated germinating seeds, many seed-specific genes and ABA-inducible genes were highly expressed in ahg1-1 and ahg3-1 mutants compared with the wild-type. Detailed analysis suggested differences between the functions of AHG1 and AHG3. Dozens of genes were expressed more strongly in the ahg1-1 mutant than in ahg3-1. Promoter,GUS analyses demonstrated both overlapping and distinct expression patterns in seed. In addition, the ahg1-1 ahg3-1 double mutant was more hypersensitive than either monogenic mutant. These results suggest that AHG1 has specific functions in seed development and germination, shared partly with AHG3. [source] Endoreduplication in cucumber (Cucumis sativus) seeds during development, after processing and storage, and during germinationANNALS OF APPLIED BIOLOGY, Issue 3 2009M. Rewers Abstract Flow cytometry was used to study endoreduplication in developing, stored and germinating seeds of cucumber (Cucumis sativus). Fruits growing in a commercial seed production field were collected every 7 days, starting 14 days after pollination (DAP) up to 63 DAP (commercial harvest time). Seeds were isolated and the proportion of nuclei with different DNA contents in the whole seeds and in the embryos was analysed. Germination capacity of fresh and dried seeds at 25°C was established. In addition, the same analyses were performed on the seeds after processing (fermentation, drying and cleaning), following 1 and 2 years of storage, and after imbibition for 3, 6 and 12 h. In the young developing seeds, endoreduplication up to 128C occurred but this decreased to 8C by maturity. The proportion of endosperm nuclei was the highest at 21 DAP (30%) and then decreased to below 14% at harvest and 8% after processing. In the mature processed seeds, the majority of embryo nuclei (about 80%) contained 2C DNA; however, about 2% of endoreduplicated (8C) nuclei were still present. Seeds did not show any germination capacity up to 21 DAP; then it gradually increased to reach 100% as early as 49 DAP, 2 weeks before commercial harvest time. The relationship between seed maturity, germination and cell cycle status is discussed. The mean C-value of the seed cells as well as the (4C + 8C + 16C)/2C ratio are recommended as markers of cucumber seed maturity and the advancement of germination/priming (the stage of germination sensu stricto). [source] Composition, size and dynamics of the seed bank in a mediterranean shrubland of ChileAUSTRAL ECOLOGY, Issue 5 2004Javier A. Figueroa Abstract Analysis was performed of the richness and abundance of woody species, forbs, and annual grasses in the easily germinating soil seed bank (henceforth seed bank) in a mediterranean shrubland of central Chile. The effects of successional development after fire and by microsite type (underneath or outside shrubs) on the density of seeds in the soil, and the relationship of species abundance in the seed bank with its abundance in the above-ground vegetation was examined. A total of 64 plant species were recorded in the seed bank, of which 44 were annual or biannual. Eight species were woody and another eight were perennial herbs. Four could not be identified to species level. The highest richness of established herbaceous species was recorded in late spring, with 31 species. The regeneration of the herbaceous vegetation was driven by the annual production of seeds and by a reserve of short-lived propagules in the soil. Density of all germinating seeds was significantly higher during late spring and late summer. Density of grass seeds was greater during late spring, while that of all other species was greater during late summer. Annual grass seeds accumulated in higher proportion at exposed microsites rather than under woody canopy, and in young (< 5 years old) and intermediate-age patches (10,20 years old) rather than in mature vegetation (30,50 years old). The abundance of established woody and herb species was uncorrelated with that of the seed bank. [source] | |||||||||||||||||||