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  • 1
    Electronic Resource
    Electronic Resource
    Interaction of gibberellins and phytochrome in the control of cowpea epicotyl elongation (1992)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The physiological response of cowpea (Vigna sinensis L.) epicotyl explants to far-red light (FR) and its interaction with gibberellins (GAs) have been investigated. The effect of FR and GA1 varied with the age of the seedlings from which the explants were made: for FR, it decreased progressively with age (though the sensitivity of the epicotyls to FR did not change significantly until at least day 11), whereas it remained essentially constant for applied GA1 between days 5 and 9 after sowing. This indicates that the loss of response to FR may be due to a decrease in endogenous GA levels in the epicotyl. For a range of GA1 and GA20 (0.01–1 µg explant−1), both hormones were more active in FR than in R irradiated epicotyls, suggesting that phytochrome may affect GA sensitivity besides GA metabolism. The location of the epicotyl region most sensitive to FR (between 5 and 20 mm below the apex) was different from that to GAs (the upper 10 mm). Nevertheless, FR extended the region responsive to applied GAs, even in paclobutrazol-treated epicotyls where elongation was due entirely to exogenous GAs. This means that modulation of epicotyl elongation by phytochrome, that occurs in a zone different from though overlapping with the GA-sensitive subapical zone, is also mediated by GAs. Growth in the most FR-sensitive region of the epicotyl stimulated by FR or GA1 was due to cell elongation, and in the most GA-sensitive region to both cell division and elongation. The effect of FR and GA1 was negated by colchicine, indicating that microtubules may be involved in the response to both factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1992.860208.x
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  • 2
    Electronic Resource
    Electronic Resource
    Two dimensional gel electrophoresis patterns of total, in vivo labelled and in vitro translated polypeptides from orange flavedo during maturation and following ethylene treatment (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 85 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Changes in the pattern of silver stained (SS), in vivo [35S]-methionine labelled (IL), and in vitro poly(A+)RNA translated (IT) polypeptides from the flavedo of orange fruits [Citrus sinensis (L). Osbeck cv. Washington Navel] picked at three stages of maturity (mature-green, turning and fully coloured) and treated with different doses of ethylene (0, 1 and 10 μl 1−1) were studied by two dimensional gel electrophoresis (using isoelectric focusing and nonequilibrium pH gradient as a first dimension). More than 500 SS, 300 IL, and 250 IT spots were detected in the gels. During maturation 32 SS, 2 IL and 2 IT spots decreased, whereas 2 SS, 3 IL and 2 IT spots increased. These results indicate that the maturation process is associated with a decrease of many accumulated flavedo proteins and with an increase of a reduced number of specific polypeptides, and that some of them may be regulated at the level of gene expression. All the spots which increased with maturity also increased with ethylene treatment, suggesting a role for this hormone in the maturation process. Ten IT spots which were not affected by maturity increased following ethylene treatment, while only 2 SS and 2 IL spots underwent this pattern of variation. Three spots recognized specifically by tobacco chitinase polyclonal antibodies remained essentially unaltered, whereas one spot whose intensity decreased significantly during maturation and ethylene treatment was identified as the large subunit of ribulose-1,5-bisphosphate carboxylase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb04717.x
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  • 3
    Electronic Resource
    Electronic Resource
    Gene expression during two alternative pathways of ovary development in Pisum sativum: fruit development and ovary senescence (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 85 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pea ovaries are induced to enter a fruit development pathway involving physiological and morphological changes by pollination or application of plant growth regulators. In the absence of these stimuli, overies stop growing and enter an alternative pathway of senesecence that leads to their degeneration. We have used two dimensional polyacrylamide gel electrophoresis in search of molecular changes underlying fruit development and ovary senescence at the level of total accumulated proteins, newly synthesized proteins, and translatable, RNA populations. We have found changes in gene expression during the processes of ovary formation and ovary senescence. Stimuli that induce fruit set do not appreciably alter the overall patterns of synthesized proteins or translatable RNAs, indicating that fruit development is apparently a natural continuation of ovary formation. However, ovary senescence is an alternative pathway that involves the presence of new RNA messengers and proteins as well as the disappearance of others. These changes were detected earlier than any morphological or structural changes could be observed in the ovary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb05265.x
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  • 4
    Electronic Resource
    Electronic Resource
    Development of fertilized ovules and their role in the growth of the pea pod (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The histological development of fertilized ovules during fruit-set and development in pea (Pisum sativum L. cv. Alaska) has been investigated. Killing the ovules on day 0 (anthesis) or day 1 prevented fruit-set and resulted in ovary degeneration. When the ovules were destroyed at later stages the ovaries developed, though the rate of growth of the pod was reduced significantly. Pollination in pea occurs normally the day before anthesis, and fertilization of the egg cell 32 to 48 h later. The first divisions of the zygote and endosperm nuclei started simultaneously (ca 48 h after pollination) but the endosperm developed more rapidly than the embryo; the embryo sac cavity was lined with free endosperm nuclei at the time of beginning suspensor elongation. Extracts of endosperm and ovule coats from ovules at day 7 after anthesis showed fruit-set activity in pea, the latter material having about 3 times more activity than the former per ovule basis. These results indicate that fertilization of the ovule is necessary for fruit-set in pea, and that compounds which induce fruit-set are probably synthesized in the ovules following fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb00113.x
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  • 5
    Electronic Resource
    Electronic Resource
    The end-of-day far-red irradiation increases gibberellin A1 content in cowpea (Vigna sinensis) epicotyls by reducing its inactivation (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 108 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It has been shown previously that gibberellins (GAs) mediate the phytochrome (Phy) control of cowpea (Vigna sinensis L.) epicotyl elongation induced by end-of-day (EOD)-far-red light (FR). In the present work, the EOD-FR effect on GA metabolism and GA levels in cowpea has been investigated. GA1, GA8, GA19 and GA20 were identified in epicotyls, and GA1, GA19, GA20 and GA29-catabolite in leaves of 6-day-old cowpea seedlings. The content of GA1 in the epicotyl paralleled the decrease of its growth rate, supporting the hypothesis that this is the GA bioactive in controlling cowpea epicotyl elongation. FR enhanced both the amount of [3H]GA1 in the epicotyl produced from applied [3H]GA20, and that of applied [3H]GA1 that remained unmetabolized in epicotyl explants, suggesting that Phy may regulate the inactivation of GA1. In agreement with this effect of light on GA1 metabolism, the contents of GA1 in the epicotyl remained higher in FR-treated than in R-treated explants. Moreover, in intact seedlings EOD-FR treatment increased both epicotyl elongation and GA1 content in the responsive epicotyl, whereas it was not altered in the leaves. These results show, for the first time, that photostable Phys modulate the stem elongation in light-grown plants by locally controlling the GA1 levels through regulation of its inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.t01-1-100413.x
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  • 6
    Electronic Resource
    Electronic Resource
    The ectopic overexpression of a citrus gibberellin 20-oxidase enhances the non-13-hydroxylation pathway of gibberellin biosynthesis and induces an extremely elongated phenotype in tobacco (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Transgenic plants of Nicotiana tabacum overexpressing a gibberellin (GA) 20-oxidase cDNA (CcGA20ox1) from citrus, under the control of the 35S promoter, were taller (up to twice) and had larger inflorescences and longer flower peduncles than those of control plants. Hypocotyls of transgenic seedlings were also longer (up to 4 times), and neither the seedlings nor the growing plants elongated further after application of GA3. Hypocotyl and stem lengths were reduced by application of paclobutrazol, and this inhibition was reversed by exogenous GA3. The ectopic overexpression of CcGA20ox1 enhanced the non-13-hydroxylation pathway of GA biosynthesis leading to GA4, apparently at the expense of the early-13-hydroxylation pathway. The level of GA4 (the active GA from the non-13-hydroxylation pathway) in the shoot of transgenic plants was 3–4 times higher than in control plants, whereas that of GA1, formed via the early-13-hydroxylation pathway (the main GA biosynthesis pathway in tobacco), decreased or was not affected. GA4 applied to the culture medium or to the expanding leaves was found to be at least equally active as GA1 on stimulating hypocotyl and stem elongation of tobacco plants. The results suggest that the tall phenotype of tobacco transgenic plants was due to their higher content of GA4, and that the GA response was saturated by the presence of the transgene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120214.x
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  • 7
    Electronic Resource
    Electronic Resource
    Role of gibberellins in parthenocarpic fruit development induced by the genetic system pat-3/pat-4 in tomato (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 111 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of gibberellins (GAs) in the induction of parthenocarpic fruit-set and growth by the pat-3/pat-4 genetic system in tomato (Lycopersicon esculentum Mill.) was investigated using wild type (WT; Cuarenteno) and a near-isogenic line derived from the German line RP75/59 (the source of pat-3/pat-4 parthenocarpy). Unpollinated WT ovaries degenerated but GA3 application induced parthenocarpic fruit growth. On the contrary, parthenocarpic growth of pat-3/pat-4 fruits, which occurs in the absence of pollination and hormone treatment, was not affected by applied GA3. Unpollinated pat-3/pat-4 fruit growth was negated by paclobutrazol, an inhibitor of ent-kaurene oxidase, and this inhibitory effect was negated by GA3. The quantification of the main GAs of the early 13-hydroxylation pathway (GA1, GA8, GA19, GA20, GA29 and GA44) in unpollinated ovaries at 3 developmental stages (flower bud, FB; pre-anthesis, PR; and anthesis, AN), by gas chromatography-selected ion monitoring, showed that the concentration of most of them was higher in pat-3/pat-4 than in WT ovaries at PR and AN stages. The concentration of GA1, suggested previously to be the active GA in tomate, was 2–4 times higher. Unpollinated pat-3/pat-4 ovaries at FB, PR and AN stages also contained relatively high amounts (5–12 ng g−1) of GA3, a GA found at less than 0.5 ng g−1 in WT ovaries. It is concluded that the mutations pat-3/pat-4 may induce natural facultative parthenocarpy capacity in tomato by increasing the concentration of GA1 and GA3 in the ovaries before pollination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1110416.x
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  • 8
    Electronic Resource
    Electronic Resource
    Light regulation of gibberellin A1 content and expression of genes coding for GA 20-oxidase and GA 3β-hydroxylase in etiolated pea seedlings (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 108 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: White light (WL) inhibited the stem elongation of etiolated pea (Pisum sativum L.) seedlings and the inhibition was partially reversed by the application of gibberellin A1 (GA1), the active GA in shoot growth. The amount of GA1 in the apical shoot was reduced to about 25% after 2 h of WL, and to a trace level after 4 h. The effect of light on GA1 content was reversed when the plants were transferred again to the dark after 6 h of WL. The effect of light on the expression of GA 20-oxidase and GA 3β-hydroxylase genes, coding for the last steps of GA1 biosynthesis, was also investigated. Contrary to expectations, the amounts of GA 20-oxidase and GA 3β-hydroxylase transcripts increased in the entire apical shoot of WL-irradiated seedlings, and this increase was negated in seedlings treated with GA1 before WL irradiation, probably as a result of negative feed-back regulation. The effect of WL on GA 20-oxidase transcripts was mainly localized in the apex (hook) whereas the effect on GA 3β-hydroxylase transcripts was mainly localized in the subapical tissues. Red and far-red light also enhanced the GA 20-oxidase transcript level, but not that of GA 3β-hydroxylase, suggesting that different photoreceptors are involved in the regulation of these genes by WL. The results presented indicate that the inhibition of stem elongation by light is due, at least partially, to a decrease of GA1 content by a still unknown mechanism. The increase of GA8 upon WL irradiation raises the possibility that an inactivation activity may be involved in the control of the content of GA1 by light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.100216.x
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  • 9
    Electronic Resource
    Electronic Resource
    An acylcyclohexadione retardant inhibits gibberellin A1 metabolism, thereby nullifying phytochrome-modulation of cowpea epicotyl explants (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 94 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The regulation by phytochrome of stem elongation in light-grown plants depends on gibberellins (GAs). To investigate whether this is mediated by a change in GA metabolism, the effect of the GA biosynthesis inhibitor LAB 198 999 (an acylcyclohexadione derivative) on the end-of-day far-red (FR) response in cowpea (Vigna sinensis L.) epicotyl explants has been investigated. Growth of epicotyl explants of light-grown seedlings was enhanced when treated with far-red light before incubation in the dark (end-of-day FR effect). Low doses of LAB 198 999 (0.05 and 0.5 μg explant−1) reduced the effect of FR, whereas 5 to 50 μg explant−1 stimulated elongation of both red light (R)- and FR-treated epicotyl explants while nullifying the differences between R and FR treatments. In paclobutrazol-treated epicotyl explants, FR enhanced the response to applied GA1 and GA20, whereas LAB 198 999 increased the activity of GA1 and decreased that of GA20, [3H]Gibberellin A1, injected into the basal part of the epicotyl, was transported and metabolized mainly to [3H]GA8 in the apical 20 mm of the epicotyl. The conversion of [3H]GA1 to [3H]GA8 was dramatically reduced by both end-of-day FR treatments and LAB 198 999 applications. In addition, both treatments enhanced epicotyl elongation. It is proposed that the regulation of cowpea epicotyl growth by phytocrome is mediated, at least partially, by modifying GA1 degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00988.x
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  • 10
    Electronic Resource
    Electronic Resource
    Proteolysis of ribulose-1,5-bisphosphate carboxylase/oxygenase in Citrus leaf extracts (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 66 (1986), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBP carboxylase, EC 4.1.1.39) has been purified from orange [Citrus sinensis (L.) Osbeck cv. Washington Navel] leaves using sucrose gradient centrifugation in a fixed angle rotor. Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two major bands corresponding to the two subunits of RuBP carboxylase were found. The large subunit coincided with the polypeptide band that has been previously reported to be preferentially mobilized during the spring and summer flush periods.The degradation of RuBP carboxylase during autodigestion of Citrus leaf extracts, investigated by SDS-PAGE, occurred mainly at acidic (2.5-5.5) pH. The two subunits showed differences in the rate of degradation, the smaller being more rapidly hydrolyzed than the larger. At least four proteolytic activities were identified by means of inhibitor experiments: 1) a pepstatin A-sensitive activity that acts on both RuBP carboxylase subunits, 2) a mercurial (p-hydroxymercuribenzoate and p-chloromercuriphenylsulfonate)-sensitive activity that degrades only the small subunit, 3) an EDTA-sensitive activity that hydrolyzes both the large and small subunits, and 4) a mercurial-stimulated activity that acts only on the large subunit. It is suggested that the last two proteases may be responsible for the degradation of RuBP carboxylase observed in vivo during the periods of mobilization of leaf protein in Citrus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1986.tb05938.x
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