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PubMed2006

Computational and experimental analysis identifies Arabidopsis genes specifically expressed during early seed development.

BACKGROUND: Plant seeds are complex organs in which maternal tissues, embryo and endosperm, follow distinct but coordinated developmental programs. Some morphogenetic and metabolic processes are exclusively associated with seed development. The goal of this study was to explore the feasibility of incorporating the available online bioinformatics databases to discover Arabidopsis genes specifically expressed in certain organs, in our case immature seeds. RESULTS: A total of 11,032 EST sequences obtained from isolated immature seeds were used as the initial dataset (178 of them newly described here). A pilot study was performed using EST virtual subtraction followed by microarray data analysis, using the Genevestigator tool. These techniques led to the identification of 49 immature seed-specific genes. The findings were validated by RT-PCR analysis and in situ hybridization. CONCLUSION: We conclude that the combined in silico data analysis is an effective data mining strategy for the identification of tissue-specific gene expression.

Arabidopsis↗
PubMed2006

Epigenetic mechanisms governing seed development in plants.

Seed development in flowering plants is initiated by the fusion of two male gametes with two female gametes--the egg cell and the central cell--which leads to the formation of an embryo and an endosperm, respectively. Fertilization-independent seed formation is actively repressed by the FERTILIZATION-INDEPENDENT SEED (FIS) Polycomb group (PcG) proteins, an evolutionarily conserved class of proteins that ensures the stable transmission of developmental decisions. The FIS proteins act together in a complex and modify their target genes by applying repressive methylation on histone H3 lysine 27. In addition to its function before fertilization, the FIS complex restricts endosperm proliferation. This function is likely to be achieved by imprinting the maternal alleles of FIS target genes. However, imprinting in the endosperm is controlled not only by the FIS complex but also by DNA methylation, and the interconnections between these two processes are now being investigated.

Arabidopsis↗
PubMed1993

Characterization of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Activity during Maize Seed Development, Germination, and Seedling Emergence.

Many isoprenoid compounds are necessary for growth and development of the seed and seedling. The first committed step in the biosynthesis of isoprenoid compounds is the conversion of 3-hydroxy-3-methylglutaryl coenzyme A to mevalonate. This study shows that the specific activity of the rate-limiting enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is developmentally regulated during Zea mays seed development and seedling emergence. The highest activities were observed in seed development during stages of rapid mitotic divisions: 10 to 12 d after pollination in the endosperm (216.1 units) and embryo (140.2 units). During stages of maturation, the endosperm HMGR activity decreases to one-fifth the maximal activity, and the embryo activity remains high at one-half the maximal activity. Both the endosperm and embryo HMGR activities decrease to a basal level (2.0 units) in the desiccated seed. At approximately 48 h after imbibition, the embryo HMGR activity significantly increases to 5.1 units. In seeds germinated under white light, root HMGR activity is 2- to 4-fold higher than shoot activity. In seeds germinated in the dark, both root and shoot HMGR activities are 1- to 5-fold higher relative to activities in light-grown seeds.

Journal Article↗
PubMed2003

Gene expression at early stages of Brassica napus seed development as revealed by transcript profiling of seed-abundant cDNAs.

Approximately 5000 plaques derived from a Brassica napus L. (canola) seed-cDNA library representing 15 days after pollination (DAP) were differentially screened for highly expressed genes at the early stages of seed development. Analysis of 104 differentially expressed sequence tags revealed 54 unique genes, of which 33 had putative homologues described in Arabidopsis thaliana (L.) Heynh. or B. napus. These encoded diverse proteins, ranging from proteins of unknown function to metabolic enzymes and proteins associated with cell structure and development. Twenty-five genes were only expressed in seeds, and 11 of these started to express as early as 5 or 10 DAP. The majority of the seed-specific genes that are expressed at early stages of seed development encoded proteins with high similarity to hypothetical Arabidopsis proteins. Tissue-specificity determined by Northern analysis revealed that four seed-specific genes were expressed only in seed coats and another five in both embryos and seed coats. Analysis of transcript profiles of seed-abundant as well as seed-specific genes, and their expression patterns, implies that the B. napus seed is undergoing an active cell proliferation during 10-20 DAP, while establishing metabolic networks for subsequent seed maturation.

Arabidopsis↗
PubMed1984

Expression of lectin genes during seed development in normal and phytohemagglutinin-deficient cultivars of Phaseolus vulgaris.

Phytohemagglutinin (PHA), the major lectin of the common bean Phaseolus vulgaris, is synthesized during the development of the seeds. In most cultivars PHA makes up 5-10% of the total seed protein, but certain cultivars do not contain PHA. In vivo labeling of a normal cultivar (Greensleeves) and a PHA-minus cultivar (Pinto 111) showed that PHA was not synthesized in the PHA-minus cultivar. To find out whether the lack of synthesis was due to the absence of mRNA for PHA, recombinant cDNA clones for PHA were obtained. Total poly(A)+ RNA was isolated from cotyledons of developing seeds of Greensleeves and used to direct cDNA synthesis. The double stranded cDNA was cloned in pUC8 and transformants of Escherichia coli screened with pPVL134, a recombinant plasmid which contains the complete coding sequence for a PHA-like protein. Two weakly hybridizing clones (pSC1 and pSC2) were selected. Hybrid selection experiments showed that these two clones selected mRNAs which could be translated into polypeptides identical in size to PHA and recognized by antibodies to PHA. The recombinant pPVL134 selected mRNA which translated into polypeptides which were slightly smaller than those of PHA, and poorly recognized by antibodies to PHA. The recombinant clones were used to demonstrate that the genes for PHA and for the PHA-like protein are under temporal control during seed development. The cultivar Pinto 111, which has no detectable PHA, also has greatly reduced levels of mRNA for PHA. However, the gene for the PHA-like protein encoded by pPVL134 is expressed to the same degree in the cultivars Greensleeves and Pinto 111.

Fabaceae↗
PubMed2001

Maternal control of seed development.

Maternal control of higher plant seed development is likely to involve female sporophytic as well as female gametophytic genes. While numerous female sporophytic mutants control the production of the ovule and the embryo sac true maternal effect mutations affecting embryo and endosperm development are rare in plants. A new class of female gametophytic mutants has been isolated that controls autonomous development of endosperm. Molecular analyses of these genes, known as FIS class genes, suggest that they repress downstream seed development genes by chromatin remodelling. Expression of the FIS genes in turn is modulated by parent specific expression or genomic imprinting which in turn is controlled by DNA methylation. Thus maternal control of seed development is a complex developmental event influenced by both genetic and epigenetic processes.

Arabidopsis Proteins↗
PubMed1997

Downregulation of ovule-specific MADS box genes from petunia results in maternally controlled defects in seed development.

A maternally determined seed defect has been obtained by downregulation of the petunia MADS box genes Floral Binding Protein 7 (FBP7) and FBP11. These genes have been previously shown to play central roles in the determination of ovule identity. Aberrant development of the seed coat and consequent degeneration of the endosperm have been observed in transgenic plants in which these two genes are downregulated by cosuppression. Analysis of the expression pattern of FBP7 and FBP11 and genetic analysis confirmed the maternal inheritance of the phenotype. The FBP7 promoter was cloned and fused to reporter genes. One of these reporter genes was the BARNASE gene for targeted cell ablation. Our results indicate that FBP7 promoter activity is restricted to the seed coat of developing seeds and that it is completely silent in the gametophytically derived tissues. The mutants used in this study provided a unique opportunity to investigate one of the poorly understood aspects of seed development: the interaction of embryo, endosperm, and maternal tissues.

Bacterial Proteins↗
PubMed1999

Rice calcium-dependent protein kinase isoforms OsCDPK2 and OsCDPK11 show different responses to light and different expression patterns during seed development.

We investigated the spatial and temporal expression patterns of two rice calcium-dependent protein kinases (CDPKs), OsCDPK2 and OSCDPK11, using isoform-specific antisera. Bands of the expected molecular sizes for OsCDPK2 (59 kDa) and OsCDPK11 (61 kDa) were detected on western blots. OsCDPK2 and OsCDPK11 mRNA and protein levels increased in unison during flower development. However, at the onset of seed development, the protein expression profiles diverged significantly. OsCDPK2 protein was expressed at low levels during early seed development, but increased to high levels that were maintained in later stages (20 days after fertilisation, DAF). Conversely, OsCDPK11 protein levels were high at the beginning of seed development, but fell rapidly from 10 DAF onwards. This decrease in the level of OsCDPK11 protein was associated with the abundant synthesis of a truncated mRNA species. OsCDPK2 expression was also closely associated with light perception. OsCDPK2 protein was barely detectable in green leaves exposed to light, but levels increased sharply when plants were shifted to darkness. Initially, this increase reflected a rapid elevation in the levels of OsCDPK2 mRNA, which was normally located in the mesophyll. Conversely, OsCDPK11 mRNA and protein levels were unaffected by light. These data strongly indicate that two rice CDPK isoforms have different functions in seed development and in response to light in leaves.

Blotting, Western↗
PubMed1989

Coated Vesicles Are Involved in the Transport of Storage Proteins during Seed Development in Pisum sativum L.

During seed development, various storage proteins and hydrolases accumulate in specialized storage vacuoles, the protein bodies, via an elaborate intracellular transport system involving the rough endoplasmic reticulum, the Golgi apparatus, and transit vesicles. Clathrin-coated vesicles, similar to those which transport lysosomal proteins to lysosomes, an organelle analogous to the vacuole, in animal cells, could be involved in this intracellular transport mechanism. Clathrin-coated vesicles have been isolated from cotyledons of developing pea (Pisum sativum L.) seeds at the time of rapid protein accumulation and analyzed for the presence of protein body constitutents. A 23,000 M(r) polypeptide, corresponding to pea lectin precursor, was found associated with the vesicles, as determined by immunoblotting. The lectin precursor was apparently sequestered within the vesicles, as the polypeptide was only susceptible to proteolysis if detergents were included in the digestion buffer. A number of glycosidase activities, including alpha-mannosidase, alpha-galactosidase, and beta-N-acetylhexosaminidase, were also associated with the vesicles. Thus, it appears that clathrin-coated vesicles are involved in the intracellular transport of storage proteins during seed development.

Journal Article↗
PubMedDate not supplied

Sugars as signal molecules in plant seed development.

Higher plants as sessile organisms react very flexible to environmental changes and stresses and use metabolites like glucose, sucrose and nitrate not only as nutrients but also as signals as part of their life strategies. The role of metabolites as signal molecules has attracted considerable interest during recent years. Data reviewed here for developing plant seeds suggest a trigger function of especially sugars also in development in that metabolic regulatory control can override developmental regulation, i.e., the developmental programme only continues normally if a certain metabolic state is sensed at a given time point in a given cell or tissue. Several experimental strategies have provided mainly correlative evidence that certain sugar levels and/or the resulting changes in osmotic values are necessary within defined tissues or cells to maintain a distinct stage of differentiation or to proceed with the developmental programme. In young legume seeds, but certainly also in other tissues, a high hexose (probably mainly glucose) level seems to maintain the capacity of cells to divide whereas - later in seed development - a certain sucrose level is necessary to induce storage-associated cell differentiation. A major determinant of embryo hexose levels in young legume seeds is an apoplastic invertase preferentially expressed in the inner cell layers of the seed coat. The enzyme cleaves the incoming photoassimilate sucrose into glucose and fructose. During development the tissue harbouring the invertase is degraded in a very specific spatial and temporal pattern as part of the developmental programme and is thus creating steep glucose gradients within the cotyledons. These gradients can be measured at nearly cellular resolution and were found to be correlated positively with cell division rate and negatively with cell differentiation and storage activities. A hexose and a sucrose transporter accumulating only in the epidermal cell layer of the cotyledons seem to be essential in creating and maintaining these gradients. To gain further insights into the role of metabolites, especially sugars, as triggers of developmental processes we foremost have to identify receptor molecules already characterised in yeast, and to describe and understand the signal transduction networks involved.

Glucose↗
PubMed1994

The rice bZIP transcriptional activator RITA-1 is highly expressed during seed development.

Systematic protein-DNA binding studies have shown that plant basic leucine zipper (bZIP) proteins exhibit a differential binding specificity for ACGT motifs. Here, we show that the rice transcription activator-1 (RITA-1) displays a broad binding specificity for palindromic ACGT elements, being able to bind A-, C-, and G-box but not T-box elements. By using gel mobility shift assays with probes differing in sequences flanking the hexameric core, we identified high-affinity A-, C-, and G-box binding sites. Quantitative and competition DNA binding studies confirmed RITA-1 specificity for these sites. Using rice protoplasts as a transient expression system, we demonstrated that RITA-1 can transactivate reporter genes possessing high-affinity but not low-affinity RITA-1 binding sites. Our results established a direct relationship between in vivo transactivation and in vitro binding activity. Transient expression assays that demonstrated the ability of RITA-1 to transactivate a construct containing rita-1 5' flanking sequences suggest that the factor may be autoregulated. Histochemical analysis of transgenic rice plants showed that a rita-1-beta-glucuronidase transgene is expressed in aleurone and endosperm cells of developing rice seeds. We propose that RITA-1 plays a role in the regulation of rice genes expressed in developing rice seeds.

Amino Acid Sequence↗
PubMed2001

Genomic imprinting and seed development: endosperm formation with and without sex.

During seed development, coordinated developmental programs lead to the formation of the embryo, endosperm and seed coat. The maternal effects of the genes affected in the fertilisation-independent seed class of mutants play an important role in seed development. The plant Polycomb proteins MEDEA and FERTILIZATION-INDEPENDENT ENDOSPERM physically interact and form a complex, in a manner similar to that of their counterparts in animals. Maternal-effect phenotypes can result from regulation by genomic imprinting, a phenomenon of critical importance for both sexual and apomictic seed development.

Fertilization↗
PubMed1978

Carbon Dioxide Fixation in the Carbon Economy of Developing Seeds of Lupinus albus (L.).

The effects of CO(2) concentration and illumination on net gas exchange and the pathway of (14)CO(2) fixation in detached seeds from developing fruits of Lupinus albus (L.) have been studied.Increasing the CO(2) concentration in the surrounding atmosphere (from 0.03 to 3.0% [v/v] in air) decreased CO(2) efflux by detached seeds either exposed to the light flux equivalent to that transmitted by the pod wall (500 to 600 micro-Einsteins per square meter per second) in full sunlight or held in darkness. Above 1% CO(2) detached seeds made a net gain of CO(2) in the light (up to 0.4 milligrams of CO(2) fixed per gram fresh weight per hour) but (14)CO(2) injected into the gas space of intact fruits (containing around 1.5% CO(2) naturally) was fixed mainly by the pod and little by the seeds.Throughout development seeds contained ribulose-1,5-bisphosphate carboxylase activity (EC 4.1.1.39), especially in the embryo (up to 99 micromoles of CO(2) fixed per gram fresh weight per hour) and phosphoenolpyruvate carboxylase (EC 4.1.1.31) in both testa (up to 280 micromoles of CO(2) fixed per gram fresh weight per hour) and embryo (up to 355 micromoles of CO(2) fixed per gram fresh weight per hour).In kinetic experiments the most significant early formed product of (14)CO(2) fixation in both light and dark was malate but in the light phosphoglyceric acid and sugar phosphates were also rapidly labeled. (14)CO(2) fixation in the light was linked to the synthesis of sugars and amino acids but in the dark labeled sugars were not formed.

Journal Article↗
PubMed2006

Accumulation of tocopherols and tocotrienols during seed development of grape (Vitis vinifera L. cv. Albert Lavallée).

Tocopherols and tocotrienols are present in mature seeds. Yet, little is known about the physiological role and the metabolism of these compounds during seed development. Here we present data on tocopherol and tocotrienol accumulation during seed development in Vitis vinifera L. cv. Albert Lavallée (Royal). This species was chosen for its ability to synthesize both tocopherols and tocotrienols. It is shown here for the first time that during seed development there are significant differences in localization and accumulation kinetics of tocopherols and tocotrienols. Tocopherols are found homogeneously dispersed throughout all tissues of the seed, in concentrations ranging from 20 to 100 microg tocopherol per g dry weight. Tocopherol levels decrease gradually during seed development. In contrast, tocotrienols are only found in the endosperm of the seeds, accumulating in a sigmoid fashion during the maturation period of seed development. Tocotrienol levels were found to be (54+/-7.4) microg/g dry seed in 90-day-old seeds of V. vinifera L. Furthermore, tocotrienol biosynthesis is demonstrated in these seeds during tocotrienol accumulation and in an endosperm fraction isolated at 75 days after flowering.

Seeds↗
PubMed2005

[Genomic imprinting and seed development].

The endosperm, a seed tissue that mediates the transfer of nutrients from the maternal parent to the embryo, is an important site of imprinting in flowering plants. In Arabidopsis thaliana, three genes were identified that prevent fertilization-independent seed development: FIS1/MEDEA, FIS2 and FIS3/FIE. MEDEA (MEA), a master regulator of endosperm development, is known to be imprinted in the endosperm. FWA is also imprinted in the endosperm of the model plant Arabidopsis. The following aspects were included in the present review: the imprinting mechanism in angiosperms, the latest progress in the control of MEA and FWA imprinting, the parental conflict theory to explain imprinting, the imprinting methods and other imprinted genes found in plants.

Alleles↗
PubMed1997

Correlation of ATP/citrate lyase activity with lipid accumulation in developing seeds of Brassica napus L.

The temporal distribution of ATP/citrate lyase (ACL) activity in developing seeds of Brassica napus L. closely paralleled both that of acetyl-CoA carboxylase and the overall rate of lipid biosynthesis. Maximum ACL activities (250 nmol acetyl-CoA formed min-1.g fresh seed) were recorded between 35 to 42 d after pollination and, if the in vitro data could be extrapolated to the situation in vivo, could account for half of the acetyl-CoA required for the measured rate of fatty acid biosynthesis during seed development. The enzyme appeared to be localized in a subcellular compartment, which was clearly separated from mitochondria on a sucrose gradient and by differential centrifugation, and which corresponded to the chloroplast organelle.

ATP Citrate (pro-S)-Lyase↗
PubMed2026

Natural variation in Miniature5 determines mitochondrial nad1 splicing and seed development in maize.

Seed size is a key determinant of cereal grain yield, but natural variations in defective-kernel genes have rarely been applied in maize breeding. Here, we report the positional cloning of maize Miniature5 (Mn5), which encodes a mitochondrial-targeted P-class pentatricopeptide repeat (PPR) protein. Further analysis shows that a missense mutation of Mn5, Mn5Val109, presents in maize populations and correlates with reduced seed size. The Mn5Val109 variant exhibits compromised function in the miniature5 (mn5-ref) mutant, failing to trans-splice mitochondrial nad1 intron1, drastically reducing the abundance and activity of respiratory complex I, accompanied by disorganized mitochondrial cristae. Mn5 directly binds to domain IV of the pre-nad1.1 transcript. Notably, this binding site is located downstream of the previously presumed 3'-terminus bound by MITOCHONDRIA STABILITY/PROCESSING PPR FACTOR1 (MSP1), thus redefining the 3'-end of the nad1.1 pre-RNA. Furthermore, Mn5 physically interacts with the maturases ZmnMAT1 and ZmnMAT3, as well as the PPR proteins PPR-SMR1 and SPR2, which are broadly involved in organellar group II intron splicing. Together, our results suggest that Mn5 recruits maturases and PPR proteins to form spliceosomal complexes responsible for the trans-splicing of nad1 intron1. Importantly, natural variations in Mn5 confer differences in seed size control, offering potential for breeding high-yield maize varieties.

Zea mays↗
PubMed2000

Changes in N-linked oligosaccharides during seed development of Ginkgo biloba.

Structural changes in N-linked oligosaccharides of glycoproteins during seed development of Ginkgo biloba have been explored to discover possible endogenous substrate(s) for the Ginko endo-beta-N-acetylglucosaminidase (endo-GB; Kimura, Y., et al. (1998) Biosci. Biotechnol. Biochem., 62, 253-261), which should be involved in the production of high-mannose type free N-glycans. The structural analysis of the pyridylaminated oligosaccharides with a 2D sugar chain map, by ESI-MS/MS spectroscopy, showed that all N-glycans expressed on glycoproteins through the developmental stage of the Ginkgo seeds have the xylose-containing type (GlcNAc2 approximately 0Man3Xyl1Fuc1 approximately 0GlcNAc2) but no high-mannose type structure. Man3Xyl1Fuc1GlcNAc2, a typical plant complex type structure especially found in vacuolar glycoproteins, was a dominant structure through the seed development, while the amount of expression of GlcNAc2Man3Xyl1Fuc1GlcNAc2 and GlcNAc1Man3Xyl1Fuc1GlcNAc2 decreased as the seeds developed. The dominantly occurrence of xylose-containing type structures and the absence of the high-mannose type structures on Ginkgo glycoproteins were also shown by lectin-blotting and immunoblotting of SDS-soluble glycoproteins extracted from the developing seeds at various developmental stages. Concerning the endogenous substrates for plant endo-beta-N-acetylglucosaminidase, these results suggested that the endogenous substrates might be the dolicol-oligosaccharide intermediates or some glycopeptides with the high-mannose type N-glycan(s) derived from misfolded glycoproteins in the quality control system for newly synthesized glycoproteins.

Carbohydrate Sequence↗