GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Effects of mechanical wounding, current application and heat treatment on chlorophyll fluorescence and pigment composition in tomato plants (1999)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 105 (1999), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chlorophyll fluorescence quenching parameters and pigment content of wild-type tomato plants (Lycopersicon esculentum Mill. cv. Moneymaker) were analyzed upon mechanical wounding, current application and heat treatment. Upon all stimuli the non-photochemical quenching increased significantly in local and systemic tissue. Vice versa, the photochemical quenching decreased. Total chlorophyll content remained almost constant, zeaxanthin content increased 5–6-fold, antheraxanthin content rose also, violaxanthin and neoxanthin on the other hand decreased significantly. These data indicate a similarity of processes on the level of photosynthesis and pigment composition that are induced by light-stress and those induced by mechanical wounding, current application and heat treatment, which all lead to an inhibition of photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1999.105126.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Chlorophyll fluorescence quenching and violaxanthin deepoxidation of FBPase antisense plants at low light intensities and low temperatures (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 95 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Genetically modified potato (Solanum tuberosum L. cv. Desiree) and tobacco (Nicotiana tabacum cv. Samsun N.N.) plants were used to analyze the effects exerted by the chloroplastic (cp) fructose- 1,6-bisphosphatase (FBPase) on the regulation of light energy discrimination at the level of photosystem II. The cp-FBPase activity was progressively inhibited by an mRNA antisense to this FBPase. The chlorophyll fluorescence quenching parameters of these transgenic plants were compared to those of wild-type and transgenic plants that were acclimated to low temperatures. In particular various lines of the transgenic potato and tobacco plants were exposed to a temperature treatment of 10 and 20°C for 10 days. Light intensities were kept low to reduce photoinhibition so that we could analyze exclusively the effects of a modification in the carbon fixation cycle on the chlorophyll fluorescence quenching parameters. The photon flux densities (PFDs) employed at the level of the middle leaves of all plants were set to two different values of 10 μmol m−2 s−1 and 50 μmol m−2 s−1. Subsequent to this 10-day acclimation the chlorophyll-fluorescence parameters of all plants were measured. Photoinhibition as expressed by the Fy/Fm ratio was minor in plants subjected to a PFD of 10 μmol m−2 s−1. Higher photon fluence rates of 50 μmol m−2 s−1 at temperatures of 10°C gave rise to a significant reduction in the Fy/Fm ratios obtained from the transgenic plants which were characterized by a restriction in cp-FBPase capacity to 20% of normal activity. Furthermore, a progressive inhibition of the cp-FBPase activity induced an amplified nonphotochemical quenching of chlorophyll fluorescence with in the genetically manipulated species (except at 10°C and 50 μmol m−2 s−1). The increase in nonphotochemical quenching depended upon light and temperature. Photochemical quenching of light quanta within the antisense plants declined relative to that in the wild type. To further characterize the mechanisms producing higher levels of nonphotochemical fluorescence quenching. we analyzed several of the xanthophyll cycle pigments. The deepoxidation state of the xanthophyll cycle pigments in potato plants increased with attenuating FBPase activities under all conditions. For tobacco plants, this elevation of the deepoxidation state was only observed at a PFD of 50 μmol m−2 s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00800.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of fructans in tubers of transgenic starch-deficient potato plants does not result in an increased allocation of carbohydrates (1996)
    Springer
    Planta 199 (1996), S. 528-536 
    Details
    ISSN: 1432-2048
    Keywords: Erwinia ; Fructan ; Levan sucrase ; Transgenic potato ; Sink strength ; Solanum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inhibition of starch biosynthesis in transgenic potato (Solanum tuberosum L. cv. Désirée) plants (by virtue of antisense inhibition of ADP-glucose pyrophosphorylase) has recently been reported to influence tuber formation and drastically reduce dry matter content of tubers, indicating a reduction in sink strength (Müller-Röber et al. 1992, EMBO J 11: 1229–1238). Transgenic tubers produced low levels of starch, but instead accumulated high levels of soluble sugars. We wanted to know whether these changes in tuber development/sink strength could be reversed by the production of a new high-molecular-weight polymer, i.e. fructan, that incorporates sucrose and thereby should reduce the level of osmotically active compounds. To this end the enzyme levan sucrase from the gram-negative bacterium Erwinia amylovora was expressed in tubers of transgenic potato plants inhibited for starch biosynthesis. Levan sucrase was targeted to different subcellular compartments (apoplasm, vacuole and cytosol). Only in the case of apoplastic and vacuolar targeting was significant accumulation of fructan observed, leading to fructan representing between 12% and 19% of the tuber dry weight. Gel filtration and 13C-nuclear magnetic resonance spectroscopy showed that the molecular weight and structure of the fructan produced in transgenic plants is identical to levan isolated from E. amylovora. Whereas apoplastic expression of levansucrase had deleterious effects on tuber development, tubers containing the levansucrase in the vacuole did not differ in phenotype from tubers of the starch-deficient plants used as starting material for transformation with the levansucrase. When tuber yield was analysed, no increase but rather a further decrease relative to ADP-glucose pyrophosphorylase antisense plants was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195183
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Solute accumulation and decreased photosynthesis in leaves of potato plants expressing yeast-derived invertase either in the apoplast, vacuole or cytosol (1997)
    Springer
    Planta 202 (1997), S. 126-136 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Invertase overexpression ; Photosynthesis ; Solanum (invertase overexpression) ; Transgenic plant (potato) ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Potato (Solanum tuberosum cv. Désirée) plants expressing yeast invertase directed either to the apoplast, vacuole or cytosol were biochemically and physiologically characterised. All lines of transgenic plants showed similarities to plants growing under water stress. Transformants were retarded in growth, and accumulated hexoses and amino acids, especially proline, to levels up to 40-fold higher than those of the wild types. In all transformants rates of CO2 assimilation and leaf conductance were reduced. From the unchanged intercellular partial pressure of CO2 and apoplastic cis-abscisic acid (ABA) content of transformed leaves it was concluded that the reduced rate of CO2 assimilation was not caused by a limitation in the availability of CO2 for␣the ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco). In the transformants the amount of Rubisco protein was not reduced, but both activation state and carboxylation efficiency of photosynthesis were lowered. In vacuolar and cytosolic transformants this inhibition of Rubisco might be caused by a changed ratio of organic bound and inorganic phosphate, as indicated by a doubling of phosphorylated intermediates. But in apoplastic transformants the pattern of phosphorylated intermediates resembled that of leaves of water-stressed potato plants, although the cause of inhibition of photosynthesis was not identical. Whereas in water-stressed plants increased contents of the phytohormone ABA are supposed to mediate the adaptation to water stress, no contribution of ABA to reduction of photosynthesis could be detected in invertase transformants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050111
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Cloning and functional analysis of a cDNA encoding a starch synthase from potato (Solanum tuberosum L.) that is predominantly expressed in leaf tissue (1999)
    Springer
    Planta 208 (1999), S. 503-511 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Antisense potato ; Isoform (starch synthase) ; Solanum (starch synthase) ; Starch structure ; Transgenic potato ; Tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Three isoforms of starch synthase (SS) were shown to be present in soluble potato tuber extracts by activity staining after native gel electrophoresis. A cDNA encoding SSI from rice was used as a probe to clone a corresponding cDNA from potato. The deduced amino acid sequence identified the protein as an SS from potato with an Mr of 70.6 kDa for the immature enzyme including its transit peptide. This novel isoform was designated SSI. An analysis of the expression pattern of the gene indicated that SSI is predominantly expressed in sink and source leaves, and, to a lower extent in tubers. In several independent transgenic potato lines, where the expression of SSI was repressed using the antisense approach, the activity of a specific SS isoform was reduced to non-detectable levels as determined through activity staining after native gel electrophoresis. The reduction in the amount of this isoform of SS did not lead to any detectable changes in starch structure, probably due to the fact that this isoform only represents a minor activity in potato tubers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050587
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Mitochondrial citrate synthase from potato: predominant expression in mature leaves and young flower buds (1995)
    Springer
    Planta 196 (1995), S. 756-764 
    Details
    ISSN: 1432-2048
    Keywords: Citrate synthase (cDNA cloning, expression analysis) ; Gene expression (flower enhanced) ; Solanum ; Tricarboxylic acid cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone encoding mitochondrial citrate synthase (EC 4.1.3.7), the first enzyme of the tricarboxylic-acid cycle, was isolated from potato (Solanum tuberosum L.) and expression of the enzyme analyzed. The deduced amino-acid sequence of the potato mitochondrial citrate synthase showed high similarity to known citrate synthases from fungi, mammals and Arabidopsis thaliana. The expression pattern of this clone was determined by Northern blot analysis. Expression was detected in all tissues analyzed. The highest level of expression was found in green flower buds. In photosynthetic tissues, stronger mRNA expression was detected in mature than in immature leaves. This rise in expression with leaf age was accompanied by an increase in citrate-synthase activity. Within flowers, expression was severalfold stronger in anthers than in ovaries, indicating a role of mitochondrial citrate synthase during anther or pollen development. A comparatively low level of transcript was detected in underground heterotrophic tissues, such as stolons, tubers and roots. When tubers were stored at low temperature (4°C), mitochondrial citrate-synthase gene expression increased slightly. From the data obtained, we conclude that expression of the mitochondrial citrate-synthase gene is regulated by developmental and environmental factors. The relatively high expression in leaves is in line with the assumption that mitochondria play an important role in photosynthetically active tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197342
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Analysis of phloem protein patterns from different organs of Cucurbita maxima Duch. by matrix-assisted laser desorption/ionization time of flight mass spectroscopy combined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1999)
    Springer
    Planta 207 (1999), S. 612-619 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Cucurbita (phloem proteins) ; Phloem protein ; Protein modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Sieve tubes mediate the long-distance transport of nutrients and signals between source and sink organs of plants. To detect mobile phloem proteins that are differentially distributed in source and sink organs of Cucurbita maxima, we used both one-dimensional gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Both techniques revealed that phloem protein patterns depend on the sampling site: whilst several proteins were consistently observed in all phloem samples studied others appeared to occur in a organ-specific manner. For a characterization and identification of distinct phloem polypeptides, two approaches were chosen. First, protein bands resolved by SDS-PAGE were eluted from the polyacrylamide gel and the masses of the proteins were then determined by MALDI-TOF MS. Second, proteins resolved by SDS-PAGE were subjected to proteolytic degradation and the resulting peptides were analyzed by MALDI-TOF MS; the masses of the proteolytic peptides were used for a database search. By the latter approach, three mobile phloem compounds were identified as the phloem-specific protein PP2 (D.E. Bostwick et al., 1992, The Plant Cell 4, 1539–1548) a chymotrypsin and an aspartic proteinase inhibitor. None of the other polypeptides studied corresponded to any of the protein sequences present in the database. Furthermore, MALDI-TOF MS analyses indicated that some of the mobile phloem proteins occur in a covalently modified form and that the extent of the modification depends upon the plant organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050525
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Remote stimulation by heat induces characteristic membrane-potential responses in the veins of wild-type and abscisic acid-deficient tomato plants (1998)
    Springer
    Planta 206 (1998), S. 146-153 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Electrical signal pathway ; Heat application ; Lycopersicon (mutant ; signal transduction) ; Membrane potential ; Mutant (tomato) ; Signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The systemic induction of proteinase inhibitor genes in tomato plants is either mediated by fast electrical signals or alternatively by chemical messengers. In the present study we analyzed the pathway of the electrical signal. The question of which cell types are involved in this pathway of long-distance signaling within plants is still controversial. To identify these we inserted microelectrodes into the veins of tomato leaves (Lycopersicon esculentum Mill. cv. Moneymaker). A newly developed computer program and microcomputer interface enabled us to position these microelectrodes inside the vein with an accuracy of 1 μm. Due to this precision in positioning we were able to demonstrate that the pathway of the electrical signal is not restricted to a specific tissue type, e.g. the phloem. In particular, the entire vein contributes to the propagation of the electrical wave along the plant. Therefore, an apoplastic contribution to the long-distance signal transduction mechanism appears most likely. To furthermore investigate the involvement of cis-abscisic acid (ABA) in this long-distance signal transduction pathway, ABA-deficient tomato mutants (Lycopersicon esculentum cv. Sitiens) were used in comparison to the wild type. Significant differences between the membrane-potential relaxation kinetics of the wild type and the mutants could be detected. Wild-type tomato plants exhibited six characteristic classes of membrane-potential relaxation kinetics following heat treatment. In contrast, the ABA-deficient mutants were more restricted in terms of their relaxation upon heat stimulation. The responses in the membrane potential of all cells within a vein consisted of only three categories. In conclusion, ABA did not affect all cells within the vein in a similar manner. Single cells exhibited different response patterns to systemic heat application in the presence of ABA. Moreover, ABA had a pronounced effect on the resting potentials of individual cells within the veins of tomato.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050385
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The influence of alterations in ADP-glucose pyrophosphorylase activities on starch structure and composition in potato tubers (1999)
    Springer
    Planta 209 (1999), S. 230-238 
    Details
    ISSN: 1432-2048
    Keywords: Key words: ADP-glucose pyrophosphorylase ; Amylopectin structure ; Amylose ; Solanum (starch ; tuber) ; Starch granule size ; Starch phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. In order to examine whether alterations in the supply of precursor molecules into the starch biosynthetic pathway affected various characteristics of the starch, starch was isolated from potato (Solanum tuberosum L.) tubers containing reduced amounts of the enzyme ADP-glucose pyrophosphorylase (AGPase). It was found that although the type of crystalline polymorph in the starch was not altered, the amylose content was severely reduced. In addition, amylopectin from the transgenic plants accumulated more relatively short chains than that from control plants and the sizes of starch granules were reduced. The starch granules from the transgenic plants contained a greater amount of granule-bound starch synthase enzyme, which led to an increase in the maximum activity of the enzyme per unit starch tested. The K m for ADP-glucose was, at most, only slightly altered in the transgenic lines. Potato plants containing reduced AGPase activity were also transformed with a bacterial gene coding for AGPase to test whether this enzyme can incorporate phosphate monoesters into amylopectin. A slight increase in phosphate contents in the starch in comparison with the untransformed control was found, but not in comparison with starch from the line with reduced AGPase activity into which the bacterial gene was transformed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050627
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The contribution of adenosine 5′-diphosphoglucose pyrophosphorylase to the control of starch synthesis in potato tubers (1999)
    Springer
    Planta 209 (1999), S. 330-337 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Adenosine 5′-diphosphoglucose pyrophos-phorylase ; Metabolic control analysis ; Solanum (starch synthesis) ; Starch synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The aim of this work was to investigate the extent to which starch synthesis in potato (Solanum tuberosum L.) tubers is controlled by the activity of ADPglucose pyrophosphorylase (EC 2.7.7.27; AGPase). In order to do this, fluxes of carbohydrate metabolism were measured in tubers that had reduced AGPase activity as a result of the expression of a cDNA encoding the B subunit in the antisense orientation. Reduction in AGPase activity led to a reduction in starch accumulation, and an increase in sucrose accumulation. The control coefficient of AGPase on starch accumulation in intact plants was estimated to be around 0.3. The fluxes of carbohydrate metabolism were measured in tuber discs from wild-type and transgenic plants by investigating the metabolism of [U-14C]glucose. In tuber discs, the control coefficient of AGPase over starch synthesis was estimated as 0.55, while the control coefficient of the enzyme over sucrose synthesis was −0.47. The values obtained suggest that AGPase activity exerts appreciable control over tuber metabolism in potato.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050640
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...