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  • 1
    Keywords: Life sciences ; Biochemistry ; Plant Ecology ; Plant anatomy ; Plant breeding ; Plant physiology ; Life sciences ; Plant Ecology ; Plant physiology ; Plant Genetics & Genomics ; Plant Biochemistry ; Plant Anatomy/Development ; Springer eBooks
    Pages: : digital
    ISBN: 9783642191060
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  • 2
    ISSN: 1617-4623
    Keywords: LMW glutenin ; Seed storage protein ; Molecular evolution ; Tissue-specific expression ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The isolation and characterisation by DNA sequencing of a low molecular weight (LMW) glutenin gene from wheat is described. The deduced protein contains a signal peptide, a central repetitive region rich in proline and glutamine and N and C terminal non-repetitive domains, similar to other prolamins. A detailed comparison of the C terminal domain of 20 prolamin genes enabled us to divide them into 4 families. The LMW glutenin family is distinct from the α, β-and γ-gliadin families of wheat and is closest to the B hordein genes of barley. This and other comparisons were also used to assess the pattern of genetic variation among prolamin sequences and to provide a molecular basis for the interpretation of prolamin size polymorphism. The 5′ flanking fragment of the isolated gene was previously shown to direct endosperm-specific expression of a reporter gene in transgenic tobacco. Evidence is provided that the isolated gene is also active in wheat and its transcription initiation site was determined. Features of the gene which may be relevant to its activity are discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We have used callus tissue of the desiccation-tolerant plant, Craterostigma plantagineum Hochst to probe the stereochemical requirements of ABA in the desiccation tolerance response, using ABA analogs. Callus was treated with (S)-(+)-ABA and (R)-(-)-ABA and two pure isomer derivatives of each, and viability after a drying treatment and the expression of four desiccation-induced late embryogenesis abundant (LEA)-type transcripts and sucrose synthase from Craterostigma were measured. Both stereoisomers alone caused transcript expression and highest viability. The two derivatives of (R)-(-)-ABA gave poor or no transcript expression and no viability, suggesting that alteration of a ring double bond to a single bond in this series of compounds is significant in ABA perception for both responses. One (S)-(+)-ABA derivative was effective in inducing all transcripts and causing callus viability. The other analog derivative induced all protein transcripts without concomitant tissue viability after drying. This suggests that some other ABA-inducible factor(s) are vital for desiccation tolerance of callus.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Proteins inducible by dehydration and abscisic acid (ABA), have been identified in a number of species and have been suggested to play a role in desiccation tolerance. Recently, we identified a novel boiling-stable protein (BspA) which accumulated in shoots of aspen (Populus tremula L.) cultured in vitro, in response to gradual water stress and ABA application (Pelah et al. 1995. Tree Physiol. 15: 673–678.). Accumulation of BspA, and of the water stress-related protein dehydrin dsp- 16 and sucrose synthase from the resurrection plant. Craterostigma plantagineum, was examined in two greenhouse-grown Populus species to investigate the relationship between the presence of the proteins and water stress tolerance. Detached leaves of Populus tomentosa lost more water than Populus popularis, resulting in a significant decrease in leaf water potential. Using electrolyte leakage analysis, it was found that detached leaves of Populus popularis are more tolerant to water stress than those of Populus tomentosa. Using western blots with the corresponding antibodies, we have found in Populus popularis accumulation of BspA and sucrose synthase due to water stress, and the constitutive presence of a dehydrin-like protein. In contrast, a low expression of BspA was found in Populus tomentosa, but not of sucrose synthase and dehydrin-like proteins. Desiccation tolerance in many tissues can be partly attributed to soluble sugars. Analysis of the amount of soluble sugars did not reveal clear-cut differences between the two species, except for significant sucrose accumulation and glucose reduction in water-stressed Populus tomentosa and increase in glucose in water-stressed Populus popularis. The data obtained points to a positive correlation between increased water stress tolerance of one poplar species as compared with another and accumulation of water stress-related proteins and sucrose synthase.
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  • 5
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hydrophilins are a wide group of proteins whose defining characteristics are high hydrophilicity index (〉 1.0) and high glycine content (〉 6%). The transcripts of most hydrophilins accumulate in response to water deficit in organisms such as plants, fungi and bacteria. In plants, most of the known Late Embryogenesis Abundant (LEA) proteins belong to this group (Garay-Arroyo et al., Journal of Biological Chemistry 275, 5668–5674, 2000). To gain insight into the function of hydrophilins, an in vitro assay was developed in which the enzymes malate dehydrogenase (MDH) or lactate dehydrogenase (LDH) are subjected to controlled partial water removal. Subtle changes in conformation during partial water removal were detected using 1-anilinonaphtalene-8-sulphonate (ANS), a fluorescent probe, whose emission at 460 nm increases when bound to hydrophobic groups. The results show that water limitation conditions imposed in this in vitro assay induce changes in MDH or LDH protein structures, which correlate with enzyme inactivation. It is also shown that plant, fungal and bacterial hydrophilins are able to protect enzymatic activities from water-loss effects in this in vitro system, in a wide range of water potentials. In addition, the data in this work indicate that the presence of hydrophilins also avoids the MDH and LDH conformational modifications caused during the assay. These results show that hydrophilins are able to protect enzymatic activities from inactivation due to in vitro partial water limitation and thus suggest a function for these proteins in vivo.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To understand mechanisms of osmoprotection, the composition of sugars and related compounds were analyzed in extracts of fully hydrated and desiccated leaves of the desiccation-tolerant resurrection plant Myrothamnus flabellifolia. During the dehydration process the concentrations of fructose and glucose decrease, whereas sucrose, arbutin and glucopyranosyl-β-glycerol increase. The substances were identified by GC-MS and NMR-analyses. This is the first report of large amounts of glucopyranosyl-β-glycerol in higher plants which may act as an osmoprotectant. Significant levels of the nonreducing sugar trehalose were present in all samples tested.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2048
    Keywords: Key words: Abscisic acid ; Craterostigma ; Desiccation tolerance ; Gene expression ; Promoter analysis ; Resurrection plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. In order to understand the molecular mechanisms which are responsible for desiccation tolerance in the resurrection plant Craterostigma plantagineum Hochst. a thorough analysis of the CDeT11-24 gene family was performed. CDeT11-24 comprises a small gene family whose genes are expressed in response to dehydration, salt stress and abscisic acid (ABA) treatment in leaves. The gene products are constitutively expressed in roots and disappear only when the plants are transferred to water. It is therefore suggested that the proteins are involved in sensing water status. The predicted proteins are very hydrophilic; they share some features with late-embryogenesis-abundant proteins, and sequence similarities were found with two ABA- and drought-regulated Arabidopsis genes. The analysis of β-glucuronidase reporter genes driven by the CDeT11-24 promoter showed high activity in mature seeds in both transgenic Arabidopsis and tobacco. In vegetative tissues the promoter activity in response to ABA was restricted to young Arabidosis seedlings. The responsiveness to ABA during later developmental stages was regained in the presence of the Arabidopsis gene product ABI3. Dehydration-induced promoter activity was only observed in Arabidopsis leaves at a particular developmental stage. This analysis indicates that some components in the signal transduction pathway of the resurrection plant are not active in tobacco or Arabidopsis.
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  • 8
    ISSN: 1432-2048
    Keywords: Key words:Craterostigma ; Dehydration stress ; Gene isolation ; Promoter analysis ; Resurrection plant ; Sucrose synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The enzyme sucrose synthase (UDP-glucose: D-fructose 2α-glucosyltransferase, EC 2.4.1.13) is a key enzyme in carbohydrate metabolism, catalyzing the reversible conversion of sucrose uridine-diphosphate into fructose and UDP-glucose. We report the molecular characterization of two classes of cDNA and genomic clones encoding sucrose synthase from Craterostigma plantagineum Hochst., a resurrection plant in which the turnover of sucrose is considered to have an important role in the unique phenomenon of surviving desiccation. Sucrose-synthase transcript and protein levels are modulated by dehydration and rehydration. In-situ hybridization revealed that transcripts preferentially accumulate in phloem tissues. Promoter analysis underlined a role for class-I sucrose-synthase genes in dehydration stress and in response to cis-abscisic acid. A DNA sequence motif common to class-I sucrose-synthase and sucrose-phosphate-synthase genes was discovered.
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  • 9
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An efficient procedure for Agrobacterium tumefaciens- mediated transformation of the desiccation-tolerant plant Craterostigma plantagineum has been developed. Leaf explants were inoculated with A. tumefaciens strain GV3101 carrying the gene for kanamycin- or hygromycin-resistance and the ßglucuronidase reporter gene. Parameters which affected the transformation efficiency were the age of the explant, the degree of wounding and the presence of an antioxidant in the medium. Under optimal conditions, calli originated in more than 80% of leaf explants. Transformed plants were obtained from more than 50% of the cultured calli during regeneration in the presence of a suitable antibiotic. The stable integration of T-DNA was confirmed by Southern blot analysis and its expression by assays for ß-glucuronidase activity.
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  • 10
    ISSN: 1432-2048
    Keywords: Abscisic acid (desiccation tolerance) ; Callus (desiccation tolerance) ; Craterostigma ; Desiccation tolerance (protein, RNA induction) ; Resurrection plant RNA induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaves of the resurrection plant Craterostigma plantagineum Hochst, can be desiccated up to 1% relative water content and are still viable after rehydration. To clone genes related to this extreme desiccation tolerance, an in-vitro system was first developed which allows the induction of the same resurrection response in callus tissue upon treatment with abscisic acid (ABA). Several proteins and in-vitro-synthesized polypeptides were then identified which can be induced both in desiccation-tolerant, naturally dried leaves and in ABA-treated calli surviving after rehydration. Complementary-DNA clones corresponding to mRNAs expressed only in desiccation-tolerant tissues were obtained and classified into several gene families. In hybrid-selected translation experiments, representative cDNA clones were associated with water stress and ABA-inducible polypeptides abundantly expressed in dried leaves and ABA-treated calli. The expression pattern of several of these abundant transcripts was analyzed in RNA-hybridization experiments. Upon stress or ABA treatment the transcription levels increased rapidly, but they declined after relief from the stress state. This, together with data on genomic copy numbers indicated that a set of abundantly expressed genes are involved in the desiccation process of resurrection plants. Data on endogenous ABA contents before and after stress applications and on the physiological effects of exogenous ABA treatments indicate that in Craterostigma plantagineum the induction of an extreme desiccation tolerance is mediated by this plant hormone.
    Type of Medium: Electronic Resource
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