[Effect of gibberellins on the sprouting of seeds and development of juvenile ginseng plants].
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Gibberellins↗
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Globulins of developing maize seeds: preliminary characterization.
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Albumins↗
Seed-specific immunomodulation of abscisic acid activity induces a developmental switch.
A single-chain Fv antibody (scFv) gene, which has previously been used to immunomodulate abscisic acid (ABA) activity in transgenic tobacco to create a 'wilty' phenotype, was put under control of the seed-specific USP promoter from Vicia faba and used to transform tobacco. Transformants were phenotypically similar to wild-type plants apart from their seeds. Anti-ABA scFv embryo development differed markedly from wild-type embryo development. Seeds which accumulated similar levels of a scFv that binds to oxazolone, a hapten absent from plants, developed like wild-type embryos. Anti-ABA scFv embryos developed green cotyledons containing chloroplasts and accumulated photosynthetic pigments but produced less seed storage protein and oil bodies. Anti-ABA scFv seeds germinated precociously if removed from seed capsules during development but were incapable of germination after drying. Total ABA levels were higher than in wild-type seeds but calculated free ABA levels were near-zero until 21 days after pollination. We show for the first time seed-specific immunomodulation and the resulting switch from the seed maturation programme to a germination programme. We conclude that the immunomodulation of hormones can alter the development programme of target organs, allowing the study of the directly blocked endogenous molecules and manipulation of the system concerned.
Abscisic Acid↗
Seeding of human endothelial cells on valve containing aortic mini-roots: development of a seeding device and procedure.
PURPOSE: Complete covering of an artificial valvular scaffold with endothelial cells may prevent thromboembolic complications and lead to an excellent biocompatibility. For this purpose, we developed a seeding device for reproducible cell seeding on valve containing aortic roots. DESCRIPTION: Human endothelial cells and fibroblasts were obtained from saphenous vein pieces. Cryopreserved aortic roots (n = 25) were put into an especially developed tube, set on a rotator, and incubated with the cell suspension. The device rotated in two axes (sagittal and axial), ensuring slight movements of the leaflets. The rotation alternated with resting periods, allowing cell attachment to the surface. Different resting periods were tested (groups 1, 2, and 3 were 30, 45, and 60 min, respectively; n = 5 each). Total incubation time was 24 hours followed by further culturing for 6 days. In two further groups (groups 4 and 5; n = 5 each), a modified inlay was used to allow the cell suspension to flow around the entire graft. In group 4 the grafts were again incubated with human endothelial cells; however, in group 5 pre-seeding with autologous fibroblasts was done in addition. Immunohistochemical staining with antibodies against factor VIII, CD31, laminin, collagen IV, and CD90 were done, and scanning electron microscopy was done after initial seeding and after 6 days in culture. EVALUATION: Seeding resulted in homogenous cell layers on the luminal surface of the free walls in all groups. With resting periods of 45 minutes, these results were also obtained on the leaflets, whereas the other resting times resulted in defects of the endothelial cell layer on the cusps. After 6 days under culture conditions, the endothelial cell layers were confluent and viable, with the exception of the leaflets in group 1. With the modified inlay (groups 4 and 5), confluent cell layers were also achieved on the outer surface. In group 5 pre-seeding with autologous fibroblasts resulted in enhanced synthesis of extracellular matrix proteins, as was demonstrated with immunohistochemical staining for collagen IV and laminin. CONCLUSIONS: With this newly developed seeding device, confluent cell layers on valve containing aortic roots were reproducibly achieved. The technique enables further experimental research and even clinical application.
Aortic Valve↗
Molecular characterization of a cDNA encoding putative calcium binding protein, HvCaBP1, induced during kernel development in barley (Hordeum vulgare L.).
Seed development is known to involve complex physiological and molecular events. In order to gain information on the molecular events that occur in the grains of barley during kernel development, we conducted suppression subtractive hybridization (SSH) using grains of barley cv. Karl at 14 days after fertilization (DAF) as the tester and grains at 5 DAF as the driver. We isolated an SSH clone that showed homology with a specific calcium binding protein in rice called EFA27. Screening the cDNA library, we identified two clones as a calcium binding protein. These clones, each carrying one calcium-binding EF-hand motif, were designated HvCaBP1 (Hordeum vulgare Calcium Binding Protein 1). HvCaBP1 possesses an N-terminal region with a conserved single Ca(2+)-binding EF-hand motif and one transmembrane helix. Northern hybridization showed that the highest expression occurred in grains and that expression increased in kernels at 8 DAF. As shown in situ hybridization, the HvCaBP1 gene was highly expressed in the embryo and tissues of the endosperm near the embryo and was detected in the vascular tissues of the glume in the kernel at 8 DAF. Accumulation of HvCaBP1 mRNAs subsequently increased in vegetative tissues for up to 48 h after abscisic acid (ABA) treatment. Transcripts of HvCaBP1 mRNAs may be regulated by endogenous ABA in the grains during kernel development.
Amino Acid Sequence↗
Arabidopsis mutants with a reduced seed dormancy.
The development of seed dormancy is an aspect of seed maturation, the last stage of seed development. To isolate mutants of Arabidopsis thaliana that are affected in this process, we selected directly for the absence of dormancy among freshly harvested M2 seeds. The screen yielded two mutants exhibiting a reduced dormancy, rdo1 and rdo2, that are specifically affected in dormancy determined by the embryo. The rdo1 and rdo2 mutants show normal levels of abscisic acid and the same sensitivity to abscisic acid, ethylene, auxin, and cytokinin as the wild type. The rdo2 mutant but not the rdo1 mutant has a reduced sensitivity to the gibberellin biosynthesis inhibitor tetcyclacis. Double-mutant analysis suggested that the RDO1 and RDO2 genes are involved in separate pathways leading to the development of dormancy. We assume that the RDO2 gene controls a step in the induction of dormancy that is most likely induced by abscisic acid and is expressed as an increase of the gibberellin requirement for germination.
Arabidopsis↗
Endosperm: an integrator of seed growth and development.
Plant reproduction relies on interactions between parental and zygotic components. Elaborate reciprocal signaling pathways enable coordination of the genetic programs between these components. A first and important step in this communication is the tight control of cell cycle events in the gametes prior to fertilization. This prepares for coordinated fertilization and the initiation of seed development. The dialog between the various actors of reproduction extends after fertilization, with the endosperm taking a central role. Importantly, the endosperm mediates a maternal input that is based on memory of the transcriptional states of imprinted genes, which is crucial for harmonious seed growth. Our current knowledge suggests that the endosperm is an integrator of the different components and genetic programs that are involved in seed development.
Plants↗
Aspects of the barley seed proteome during development and germination.
Analysis of the water-soluble barley seed proteome has led to the identification of proteins by MS in the major spots on two-dimensional gels covering the pI ranges 4-7 and 6-11. This provides the basis for in-depth studies of proteome changes during seed development and germination, tissue-specific proteomes, cultivar differences related to quality parameters, analysis of the genetic basis for spot variations and targeted investigations of specific proteins.
Electrophoresis, Gel, Two-Dimensional↗
A soybean cell wall protein is affected by seed color genotype.
The dominant I gene inhibits accumulation of anthocyanin pigments in epidermal cells of the soybean seed coat. We compared saline-soluble proteins extracted from developing seed coats and identified a 35-kilodalton protein that was abundant in Richland (genotype I/I, yellow) and much reduced in an isogenic mutant line T157 (genotype i/i, imperfect black seed coats). We purified the 35-kilodalton protein by a novel procedure using chromatography on insoluble polyvinylpolypyrrolidone. The 35-kilodalton protein was composed primarily of proline, hydroxyproline, valine, tyrosine, and lysine. Three criteria (N-terminal amino acid sequence, amino acid composition, and sequence of a cDNA) proved that the seed coat 35-kilodalton protein was PRP1, a member of a proline-rich gene family expressed in hypocotyls and other soybean tissues. The levels of soluble PRP1 polypeptides and PRP1 mRNA were reduced in young seed coats with the recessive i/i genotype. These data demonstrated an unexpected and novel correlation between an anthocyanin gene and the quantitative levels of a specific, developmentally regulated cell wall protein. In contrast, PRP2, a closely related cell wall protein, was synthesized later in seed coat development and was not affected by the genotype of the I locus.
Amino Acid Sequence↗
A serine carboxypeptidase gene (PsCP), expressed in early steps of reproductive and vegetative development in Pisum sativum, is induced by gibberellins.
A cDNA clone encoding a serine carboxypeptidase (PsCP), isolated from young fruits of Pisum sativum L., was used to study the temporal and spatial expression and hormonal regulation of serine carboxypeptidase during reproductive and vegetative development. In unpollinated pea ovaries PsCP transcript levels decreased during senescence. However, during early fruit development, PsCP transcript were accumulated in both pericarp and seeds, preferentially in the nucellus, with a polar distribution at the chalazal region of the embryo sac, suggesting a role in seed development. PsCP transcript levels increased also when fruit set was induced in unpollinated ovaries by gibberellins, although the distribution was uniform. PsCP expression was also induced by auxins but not cytokinins, indicating a selective hormonal regulation of PsCP transcription. Localization of PsCP transcript after pollination parallel reported changes in gibberellin distribution, suggesting that PsCP transcription in developing fruits and seeds is induced by gibberellins. PsCP is also expressed in developing seedlings but not in cotyledons, suggesting that it is not involved in the mobilization of storage materials. PsCP transcripts were suppressed by treatment of seedlings with paclobutrazol and restored by gibberellic acid (GA3) treatment. In addition, PsCP transcript levels decreased in etiolated pea seedlings when they were exposed to continuous light but not when exposed to light in the presence of GA3. These results indicate that PsCP transcript accumulation is induced by gibberellins in developing seedlings. This is the first report of a serine carboxypeptidase-like gene induced by gibberellins in reproductive and vegetative developing tissues in dicotyledoneous plants.
Blotting, Northern↗
fusca3: A Heterochronic Mutation Affecting Late Embryo Development in Arabidopsis.
Molecular studies of late embryogenesis and seed development have emphasized differential gene expression as a means of identifying discrete stages of embryogenesis. Little has been done to identify factors that regulate the length of a given developmental stage or the degree of overlap between adjacent developmental programs. We designed a genetic screen to identify mutations that disrupt late embryo development in Arabidopsis without loss of hormonal responses. One such mutation, fusca3 (fus3), alters late embryo functions, such as the establishment of dormancy and desiccation tolerance, and reduces storage protein levels. fus3 cotyledons bear trichomes, and their ultrastructure is similar to that of leaf primordia. Immature fus3 embryos enter germinative development, and the shoot apical meristems develop leaf primordia before seed desiccation begins. The cotyledons resemble leaf primordia, yet retain some cotyledon characteristics; thus, cotyledon- and leaf-specific functions are expressed simultaneously. Together, these observations are consistent with a heterochronic interpretation of the fus3 mutation.
Journal Article↗
First flight of the ASTROCULTURE (TM) experiment as a part of the U.S. Shuttle/MIR program.
A number of space-based experiments have been conducted to assess the impact of microgravity on plant growth and development. In general, these experiments did not identify any profound impact of microgravity on plant growth and development, though investigations to study seed development have indicated difficulty in plants completing their reproductive cycle. However, it was not clear whether the lack of seed production was due to gravity effects or some other environmental condition prevailing in the unit used for conducting the experiment. The ASTROCULTURE (TM) flight unit contains a totally enclosed plant chamber in which all the critically important environmental conditions are controlled. Normal wheat (Triticum aestivum L.) growth and development in the ASTROCULTURE (TM) flight unit was observed during a ground experiment conducted prior to the space experiment. Subsequent to the ground experiment, the flight unit was transported to MIR by STS-89, as part of the U.S. Shuttle/MIR program, in an attempt to determine if super dwarf wheat plants that were germinated in microgravity would grow normally and produce seeds. The experiment was initiated on-orbit after the flight unit was transferred from the Space Shuttle to MIR. The ASTROCULTURE (TM) flight unit performed nominally for the first 24 hours after the flight unit was activated, and then the unit stopped functioning abruptly. Since it was not possible to return the unit to nominal operation it was decided to terminate the experiment. On return of the flight unit, it was confirmed that the control computer of the ASTROCULTURE (TM) flight unit sustained a radiation hit that affected the control software embedded in the computer. This experience points out that at high orbital inclinations, such as that of MIR and that projected for the International Space Station, the danger of encountering harmful radiation effects are likely unless the electronic components of the flight hardware are resistant to such impacts.
Agriculture↗
Redundant proteolytic mechanisms process seed storage proteins in the absence of seed-type members of the vacuolar processing enzyme family of cysteine proteases.
Seed-type vacuolar processing enzyme (VPE) activity is predicted to be essential for post-translational proteolysis of seed storage proteins in the protein storage vacuole of developing seeds. To test this hypothesis, we examined the protein profiles of developing and germinating seeds from Arabidopsis plants containing transposon-insertional knockout mutations in the genes that encode the two seed-type VPEs in Arabidopsis, betaVPE, which was identified previously, and deltaVPE, which is described here. The effects of these mutations were studied individually in single mutants and together in a double mutant. Surprisingly, we found that most of the seed protein still was processed proteolytically in seed-type VPE mutants. The minor differences observed in polypeptide accumulation between wild-type and betaVPE mutant seeds were characterized using a two-dimensional gel/mass spectrometric analysis approach. The results showed increased amounts of propolypeptide forms of legumin-type globulins accumulating in mutant seeds. However, the majority of protein (>80%) still was processed to mature alpha- and beta-chains, as observed in wild-type seeds. Furthermore, we identified several legumin-type globulin polypeptides, not corresponding to pro or mature forms, that increased in accumulation in betaVPE mutant seeds compared with wild-type seeds. Together, these results indicate the existence of both redundant and alternative processing activities in seeds. The latter was substantiated by N-terminal sequencing of a napin-type albumin protein, indicating cleavage consistent with previous in vitro studies using purified aspartic protease. Analysis of genome-wide transcript profiling data sets identified six protease genes (including an aspartic protease gene and betaVPE) that shared spatial and temporal expression patterns with seed storage proteins. From these results, we conclude that seed-type VPEs constitute merely one pathway for processing seed storage protein and that other proteolytic enzymes also can process storage proteins into chains capable of stable accumulation in mature seeds.
Amino Acid Sequence↗
Expression of DC8 is associated with, but not dependent on embryogenesis.
DC8 is a late embryogenesis-abundant (LEA) protein gene isolated from carrot (Daucus carota). Deletion analysis of the DC8 promoter was performed to determine the sequences required for ABA and seed-specific regulation of DC8 transcription. To investigate the mechanism of DC8 expression during seed development, chimeric gene constructs containing DC8 promoter fragments fused to a promoterless beta-glucuronidase gene (DC8:GUS) were introduced into carrot, tobacco (Nicotiana tobacum) and Arabidopsis thaliana plants. Seed-specific DC8 expression patterns was conserved among the three plant species. However, differences among the species in the patterns of DC8 expression in the embryo and endosperm that correlated with differences in the rates of embryo and endosperm growth were found. Lack of correspondence between DC8 activation and embryo development among the seeds of the three species suggests that DC8 expression, which is associated with seed maturation, is not coupled to the embryo development program. The presence of DC8 activity in carrot callus and endosperm is consistent with the notion that DC8 expression is independent of embryo morphogenesis. A similar DC8 activity time-course during callus induction and seed development suggests that explantation and 2,4-D treatment initiates a course of events similar to that in the carrot ovule. After fertilization, two pathways one leading to embryo development and another to seed maturation are initiated, but they are not closely linked. As a result we find DC8, part of the maturation program, being activated at different embryonic stages in different plant species.
Arabidopsis↗
Developmental genetic analysis of seed size in soybean (Glycine max).
Seed size is one of the important factors of soybean [Glycine max (L.) Merrill] yield. There have been lots of reports about genetic effects and physiology--ecological researches on seed size, but the genetic behaviors of genes during seeds development were rarely discussed. Analysis of main genetic effects for fresh seed size (FSS) and dry seed size (DSS) of soybean was conducted with diallel cross data by using a seed genetic model. Analyses of unconditional and conditional variances and correlations were used to evaluate the developmental behavior of soybean. The phenotypic means of FSS and DSS in soybean at eight stages among three generations reached the highest value at 9/6 and 9/13, respectively. The means of FSS decreased dramatically after 9/6, but the means of DSS maintained relatively stable tendency at corresponding periods. The unconditional variance analysis showed that FSS and DSS were controlled by embryo, cytoplasmic and maternal effects in the whole growth period. Genetic effects due to cytoplasmic and maternal effects were relatively important for FSS and DSS at most of the growth periods. Conditional variance analysis showed that genes from different genetic system expressed discontinuously in the whole growth period. The net genetic effects due to cytoplasmic and maternal plant on FSS and DSS were larger than those of embryo effects at most of the growth periods. Different genetic system can affect the relationship of various stages to mature solely or simultaneously. Embryo additive effects at 8/16, embryo dominance effects at 8/9 and 8/16, maternal plant dominance effects at 8/2 and 8/16 could ultimately affect the performance of FSS at maturing stage. Embryo additive effects at 8/2 and 9/13, cytoplasm effects at 8/9, maternal plant dominance effects at 8/2 could ultimately affect the performance of DSS.
Analysis of Variance↗
GLUCOSE TRANSFER FROM ADENOSINE DIPHOSPHATE-GLUCOSE TO STARCH IN PREPARATIONS OF WAXY SEEDS.
Preparation of starch granules from the developing seeds of 17 different waxy mutants of maize all transfer glucose from adenosine diphosphate-glucose to starch at about one-tenth of the rate of similar preparations from seeds of non-waxy maize. The source of most, if not all, of the activity in preparations from waxy mutants is a limited number of enzymatically active starch granules from the embryo and maternal tissue of the seed. All starch granules in these tissues appear to be enzymatically active. The endosperm which is the site of most starch synthesis and storage is apparently devoid of transferase activity.
Adenine Nucleotides↗
Major isoforms of starch branching enzymes in premature seeds of kidney bean (Phaseolus vulgaris L.).
Developing seeds of the kidney bean (Phaseolus vulgaris L.) contain several isoforms of starch branching enzymes. Two of them, KBE1 and KBE2, which are the major forms in the premature seeds, were purified as a single band of protein on SDS-PAGE and native PAGE by chromatographies on DEAE-Sepharose, Bio-Gel P-200, and amylose-binding Sepharose 6B. The enzymes had similar pH optimum (7.0), pH stability (7.0-9.5), temperature optimum (25-30 degrees C), and temperature stability (up to 40 degrees C). Additionally, both were inhibited by various divalent metal ions and activated by citrate. Finally, though their N-terminal amino acid sequences were identical, their molecular masses and affinities for amylose differed; 80 kDa and 1.27 mM for KBE1 and 77 kDa and 0.74 mM for KBE2.
1,4-alpha-Glucan Branching Enzyme↗
Characterization of a cDNA clone encoding a Brassica napus 12 S protein (cruciferin) subunit. Relationship between precursors and mature chains.
Cruciferin (12 S globulin) is a large, neutral, oligometric protein synthesized in rapeseed (Brassica napus) during seed development. It is the major seed protein and is composed of six subunit pairs. Each of these pairs is synthesized as a precursor containing one heavy alpha-chain and one light beta-chain. Electrophoretic analysis of cruciferin showed that four different alpha- and four different beta-chains exist. A cruciferin clone was selected from an embryo cDNA library. This clone, pCRU1, contains a 1518-base pair open reading frame corresponding to a truncated NH2-terminal signal sequence followed by an alpha-chain of 296 and a beta-chain of 190 amino acid residues. Individual cruciferin chains as well as peptides thereof were subjected to NH2-terminal amino acid sequence analysis. The sequences obtained from a specific alpha- and beta-chain pair (alpha 1 and beta 1) showed total identity with the deduced amino acid sequence from pCRU1. Further comparisons revealed that a previously characterized cruciferin cDNA clone encodes one of the precursors for the closely related alpha 2/ alpha 3-beta 2/beta 3 subunits. The deduced amino acid sequences of the two cDNA clones display 64% similarity.
Allergens↗