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  • 1
    Electronic Resource
    Electronic Resource
    Temperature responses of membrane-associated activities from spring and winter oats (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two-week old, glasshouse-grown seedlings of spring and winter oats (Avena sativa cv. Margam and Pennal respectively) were transferred to growth rooms where the daylength was 8 h and the temperature was either 20° or 5°C. Leaves from the 20°C treatment were harvested 1 week after transfer and those from the 5°C treatment after 3 weeks. Measurements were made, at temperatures in the range 5–20°C, of the rate of senescence of excised leaf sections; the rate of in vivo tetrazolium (TTC) reduction; the NADH-MTT tetrazolium diaphorase (NMD) activity of a membrane preparation isolated by sucrose gradient centri-fugation; and Hill activity of isolated chloroplasts. Data from these experiments, either untransformed or plotted in accordance with the Arrhenius equation, were analysed by the method of maximum likelihood for the occurrence of rate-temperature discontinuities. Distinct breakpoints at 14.2–16.3°C were detected for senescence, TTC reduction and NMD in winter oat leaves from the 20°C treatment, but spring oats grown at the same temperature gave a significant discontinuity only in the rate of senescent yellowing. After the hardening treatment, 3 weeks at 5°C, senescence and TTC reduction in winter oats exhibited breakpoints at 10.1–12.4°C and spring oats gave breaks at 11.8–17.3°C. No breakpoint was observed for Hill activity from either variety under either temperature treatment. The use of this approach in studies of growth at chilling temperatures and its potential as a screening method are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11581828
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  • 2
    Electronic Resource
    Electronic Resource
    Growth, photosynthesis and assimilate partitioning in Lolium temulentum exposed to chilling temperatures (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 59 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Vegetative plants of Lolium temulentum L, grown at 20°C with an 8 h photoperiod were transferred to either 5 or 2°C (8 h photoperiod) at 4th leaf maturity. Measurement of dry weight gain indicated a marked decline in relative growth rate below 5°C, with growth being reduced as much between 5 and 2°C as between 20 and 5°C. This reduction was not associated with increased mortality and was reversible if plants were returned to 20°C. Tissue explants from cold-treated plants retained the ability to extend if returned to 20°C Rates of extension in explants were less temperature sensitive than the relative growth rates observed in intact plants. Measurements of photosynthetic capacity, and of the patterns of accumulation of reserve carbohydrate in plants exposed to different temperatures, suggested that the inhibition of growth caused by chilling is not caused by an inability of the plants to fix sufficient carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb00768.x
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  • 3
    Electronic Resource
    Electronic Resource
    Interaction of [3H]gibberellin A1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls (1980)
    Springer
    Planta 148 (1980), S. 485-490 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin ; Growth temperature ; Lactuca ; Temperature (gibberellin)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between elongation growth and the incorporation of [3H]gibberellin A1 ([3H]GA1) into a 2,000g pelletable (2KP) fraction from lettuce (Lactuca sativa L., cv. Arctic) hypocotyl sections has been examined. Sections were loaded with incremental amounts of GA1 under conditions where growth was arrested (5° C) or permitted (30° C) and, after 16 h, all were transferred to a GA-free medium at 30° C. Growth and 2KP radioactivity were measured at this point and after a further 24 h in the chase medium. Uptake was reduced by 80% at 5° C, as compared to 30° C, but 2KP labelling and protein synthesis were only reduced by half. The growth rate of the 5° C pretreated sections during the chase period was comparable to that observed during the pulse in the 30° C material but the dose/response relationship was flatter. Low temperature sections incorporated a much higher percentage of GA1 uptake into the 2KP fraction (27% at maximum) but the absolute levels of labelling at this temperature were lower than those measured at 30° C. The data are interpreted as showing that 2KP labelling is not a consequence of growth. It must either precede response or be an unconnected concurrent process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395319
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  • 4
    Electronic Resource
    Electronic Resource
    Growth and gibberellin-A1 metabolism in normal and gibberellin-insensitive (Rht3) wheat (Triticum aestivum L.) seedlings (1984)
    Springer
    Planta 161 (1984), S. 432-438 
    Details
    ISSN: 1432-2048
    Keywords: Triticum (growth, dwarfism) ; Gibberellin (insensitivity, metabolism)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth parameters were determined for tall (rht3) and dwarf (Rht3) seedlings of wheat (Triticum aestivum L.). Plant statures and leaf length were reduced by 50% in dwarfs but root and shoot dry weights were less affected. Leaves of dwarf seedlings had shorter epidermal cells and the numbers of cells per rank in talls and dwarfs matched the observed relationships in overall length. Talls grew at twice the rate of dwarfs (2.3 compared with 1.2 mm h-1). [3H]Gibberellin A1 ([3H]GA1) was fed to seedlings via the third leaf and metabolism was followed over 12 h. Immature leaves of tall seedlings transferred radioactivity rapidly to compounds co-chromatographing with [3H]gibberellin A8 ([3H]GA8) and a conjugate of [3H]GA8, whereas leaves of dwarf seedlings metabolised [3H]GA1 more slowly. Roots of both genotypes produced [3H]GA8-like material at similar rates. Isotopic dilution studies indicated a reduced 2β-hydroxylation capacity in dwarfs, but parallel estimates of the endogenous GA pool size, obtained by radioimmunoassay, indicated a 12–15 times higher level of GA in the dwarf immature leaves. Dwarfing by the Rht3 gene does not appear to operate through enhanced, or abnormal metabolism of active gibberellins and the act of GA metabolism does not bear an obligate relationship to the growth response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394574
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  • 5
    Electronic Resource
    Electronic Resource
    Gibberellin metabolism in excised lettuce hypocotyls: Response to GA9 and the conversion of [3H]GA9 (1978)
    Springer
    Planta 140 (1978), S. 143-150 
    Details
    ISSN: 1432-2048
    Keywords: Cell elongation ; Gibberellins ; Lactuca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Elongation growth and gibberellin (GA9) metabolism in excised hypocotyls of lettuce (Lactuca sativa L. cv. Arctic) were investigated. Exogenously supplied GA9 stimulates elongation of hypocotyl sections and this response is intermediate between that elicited by GA1 or GA20 and GA4/7 mixture. Although uptake of radioactivity from [3H]GA9 increases with time, this gibberellin does not accumulate in the tissue but is rapidly converted to a compound with HPLC properties resembling those of [3H]GA20. After 2 h incubation in [3H]GA9, the presumptive GA20 represents 90% of the acidic ethyl acetate-soluble radioactivity in the tissue. Radioactivity is also associated with an acidic butanol-soluble fraction containing two components resolvable by HVE. The major component is similar in electrophoretic properties to a GA-glucosyl ether while the other compares to a GA-glucosyl ester. Conversion of [3H]GA9 to its [3H]GA20-like metabolite is reduced by addition of carrier GA9 or GA4/7 at concentrations as low as 1 μM, while GA1, GA3 and L-proline are without effect. Formation of the GA20-like compound can be blocked by the addition of 2,2′-dipyridyl, and this inhibitory effect of dipyridyl can be reversed by addition of Fe2+. At 200 μM dipyridyl, elongation growth as well as [3H]GA9 metabolism are reduced by 80%. The relationship of the metabolism of GA9 to the growth response is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384913
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  • 6
    Electronic Resource
    Electronic Resource
    Gibberellin metabolism in excised lettuce hypocotyls: Evidence for the formation of gibberellin A1 glucosyl conjugates (1977)
    Springer
    Planta 136 (1977), S. 261-269 
    Details
    ISSN: 1432-2048
    Keywords: Conjugates ; Gibberellin ; Lactuca ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The properties of the water-soluble metabolites of [3H]gibberellin A1 ([3H]GA1) from lettuce (Lactuca sativa L.) hypocotyls were compared with those of authentic samples of gibberellin (GA) glucosyl esters and ethers. Partitioning against l-butanol at high and low pH was not an efficient method of differentiating between ester and ether conjugates of GA1 or GA3. Extraction into l-butanol at pH 2.5 was, however, useful as a group purification step. Gel-filtration on acrylamide indicated a mean molecular weight of ca. 600 for the polar material and high-voltage electrophoresis separated two compounds (LH 1 and LH 2) with differing charge properties. Both metabolites incorporated 14C from glucose and 3H from GA1. Subsequent enzymatic hydrolysis of LH 1 released material with identical properties to [14C]glucose together with a second uncharacterised component. Feeding with [3H]GA1 methyl ester greatly reduced the formation of LH 1 but not LH 2. The metabolites were provisionally identified as GA1-glucosyl ester (LH 1) and GA1-glucosyl ether (LH 2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385994
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Interaction of [3H]gibberellin A1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls (1980)
    Springer
    Planta 148 (1980), S. 485-490 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin ; Growth temperature ; Lactuca ; Temperature (gibberellin)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between elongation growth and the incorporation of [3H]gibberellin A1 ([3H]GA1) into a 2,000g pelletable (2KP) fraction from lettuce (Lactuca sativa L., cv. Arctic) hypocotyl sections has been examined. Sections were loaded with incremental amounts of GA1 under conditions where growth was arrested (5° C) or permitted (30° C) and, after 16 h, all were transferred to a GA-free medium at 30° C. Growth and 2KP radioactivity were measured at this point and after a further 24 h in the chase medium. Uptake was reduced by 80% at 5° C, as compared to 30° C, but 2KP labelling and protein synthesis were only reduced by half. The growth rate of the 5° C pretreated sections during the chase period was comparable to that observed during the pulse in the 30° C material but the dose/response relationship was flatter. Low temperature sections incorporated a much higher percentage of GA1 uptake into the 2KP fraction (27% at maximum) but the absolute levels of labelling at this temperature were lower than those measured at 30° C. The data are interpreted as showing that 2KP labelling is not a consequence of growth. It must either precede response or be an unconnected concurrent process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552664
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  • 8
    Electronic Resource
    Electronic Resource
    Interaction of [3H]gibberellin A1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls (1979)
    Springer
    Planta 146 (1979), S. 353-361 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin ; Lactuca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of [3H]gibberellin A1 ([3H]GA1) amongst sub-cellular fractions from lettuce (Lactuca sativa L.) hypocotyl sections was examined by differential centrifugation. Material pelleting at 2000 g (2KP) accounted for 2–5% of the total tissue radioactivity and no other significant interactions were detected. After rigorous washing procedures, the 2KP fraction was found to consist mainly of cell wall material and the radioactivity remained associated during sucrose density-gradient centrifugation. 2KP-labelling increased linearly with time and was only partially removed by chasing for up to 40 h in the presence of unlabelled GA1. A linear plot was obtained for the relationship between external concentration and the log of 2KP GA1 content with a maximum percentage incorporation at 10-5 mol 1-1. Incorporation of radioactivity was reduced by chasing with unlabelled GA1 or GA9, but not by GA8. Labelling of the 2KP fraction increased uniformly with temperature between 15°C and 30°C but showed little change below 15°C. Growth rate and 2KP labelling were highly correlated (r=0.989). The possible significance of these findings is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387808
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  • 9
    Electronic Resource
    Electronic Resource
    Interaction of [3H] gibberellin A1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls (1979)
    Springer
    Planta 146 (1979), S. 363-368 
    Details
    ISSN: 1432-2048
    Keywords: Cell walls ; Gibberellin ; Growth ; Lactuca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radioactive 2,000 g pellets (2KP) derived from lettuce (Lactuca sativa) hypocotyl sections incubated with [3H]gibberellin A1 ([3H]GA1) were subjected to a range of treatments to test the stability of labelling. The labelled association was stable in 0.1 M buffer at pH 3 and pH 9 and also in 1 M salt, organic solvents, protease or cellulase. Both 1 M potassium hydroxide (KOH) and a quaternary ammonium hydroxide tissue solubiliser effected an 80% release of incorporated [3H]. No radioactivity was released during polyacrylamide gel electrophoresis. Gel chromatography of KOH digests indicated the presence of labelled compounds with a higher molecular weight than GA1. This material remained near to the origin during high-voltage paper electrophoresis. Calculations based upon KOH extraction of 2KP material suggested that 5 to 20% of the total uptake of [3H]GA1 could be recovered from this fraction. The implications of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387809
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of [3H]gibberellin A1 with a sub-cellular fraction from lettuce (Lactuca sativa L.) hypocotyls (1979)
    Springer
    Planta 147 (1979), S. 264-268 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin ; Growth ; Lactuca ; Protein-synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between protein synthesis and the incorporation of [3H]gibberellin A1 ([3H]GA1) into a 2,000xg pelletable (2KP) fraction from lettuce (Lactuca sativa L.) hypocotyl sections has been investigated. Concentrations of D-2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide (MDMP) between 10-7 M and 10-4 M caused increasing inhibition of growth, 2KP labelling and incorporation of [14C]leucine into soluble protein. Growth and 2KP radioactivity were highly correlated (r=0.996). Transfer to MDMP early or late in the course of GA response caused reductions in both growth and incorporation into the 2KP fraction. Exposure to the inhibitor had more effect at 4 h than at 20 h. The proportions of alkali-soluble and insoluble radioactivity in the 2KP fraction were also altered by this treatment. The implications of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388749
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