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  • 1
    Electronic Resource
    Electronic Resource
    A localised decrease of GA1 in shoot tips of Salix pentandra seedings precedes cessation of shoot elongation under short photoperiod (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: By application of a recently developed method allowing analysis of gibberellins (GAs) in mg amounts of tissue, the effect of photoperiod on levels of GAs in shoot tips of individual seedlings of the woody species Salix pentandra was studied. In elongating long day-grown seedlings, maximum levels of GA1 were found 5–20 mm below the apex, approximately twice the levels in other segments. After exposure of plants to 5 or 15 short days, the levels of GA1 were about 50% lower within this specific region of the stem, as compared with seedlings grown under long days. Short day-induced cessation of shoot elongation also correlated with overall declines in the levels of GA53, GA19, GA20 and GA8, Within each photoperiodic treatment the levels of these GAs were generally relatively similar throughout the upper 35 mm of stems. No differences in internode lengths or in lengths of pith or epidermal cells were found in plants grown under long days compared with those exposed to 5 short days. In both cases, cells in mitosis were observed in the subapical stem tissues of shoot tips. After 15 short days, stem elongation was completed, and dividing cells were generally not found in the subapical part of the stem. However, short day exposure did not prevent elongation of internodes and cells differentiated before the treatment was started. Thus, the localised decrease in level of GA1 in shoot tips under short days precedes the morphological and anatomical changes connected with the short day-induced cessation of elongation growth. This supports the hypothesised role for GA1 in photoperiodic control of shoot elongation in S. pentandra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb05532.x
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  • 2
    Electronic Resource
    Electronic Resource
    Growth-promoting activity of gibberellins on shoot elongation in Salix pentandra is reduced by 16,17-dihydro derivatisation (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 99 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The metabolism of GA10 is thought to be under photoperiodic control in the woody plant Salix pentandra. However, in a recent study using 16,17-[3H2]GA19 as a mimic of Ga10, no effect of photoperiod was found on its metabolism to 16,17-dihydro-GA20 and 16,17-dihydro-GA1. To investigate if this was due to differential action of exogenous 16,17-dihydro-GAs and GAs, the effects of the 16,17-dihydro-derivatives of the gibberellins GA19, GA1, and GA1 as compared with their parent GAs, on shoot elongation in seedlings of S. pentandra were studied. 16,17-Dihydro-GA19, and -GA20 were both almost inactive, while 16,17-dihydro-GA1 induced some shoot elongation in seedlings treated with ancymidol as well as under short days. GA19, GA20 and GA1 were all able to counteract the inhibitory effect of ancymidol under continuous light, while inhibition induced by a 12-h photoperiod was antagonised only by GA20 and GA1. Thus, the growth-stimulating activity of the tested GAs is significantly reduced by 16,17-dihydro derivatisation, but the derivatives do not inhibit stem elongation in S, pentandra, as has been found in monocotyledons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb03431.x
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  • 3
    Electronic Resource
    Electronic Resource
    Photoperiodic control of endogenous gibberellins in seedlings of Salix pentandra (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 93 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the temperate-zone woody species Salix pentandra elongation growth is regulated by the photoperiod. Long days sustain active growth, whereas short days induce cessation of apical growth, which is a prerequisite for winter hardening. It is shown that this is correlated to quantitative changes in levels of endogenous GA19 GA20, and GA1. Within two short days the amount of the active GA1 and its immediate precursor GA20, decreased markedly in young leaves us well as in stem tissue. Also, the amount of GA19, declined, but the decrease was delayed relative to that of GA1 and GA20. The ability of S. pentandra seedlings to respond to exogenous GA19, decreased with increasing numbers of short days. Observations that support the hypothesis that the level of GA1 in S. pentandra is regulated by the photoperiod in a quantitative mode with conversion of GA19, to GA20, being one target for control.Different distribution of GAs in various plant parts was observed. The level of GA was higher in young leaves than in other plant parts, and the amount of GA19 was 5–10 times higher in stem tissue than in leaves and roots. The ratios of GA8 to GA1 and GA20, were higher in roots as compared with other parts, as rods contained very low levels of GA1 and GA20, but amounts of GA20 comparable with other parts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb05111.x
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  • 4
    Electronic Resource
    Electronic Resource
    Lack of effect of photoperiod on metabolism of exogenous GA19 and GA1 in Salix pentandra seedlings (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 effect of photoperiod on metabolism of 16,17-[3H2]GA19, and 1.2-[3H2]GA1 applied to intact seedlings of Salix pentandra, was investigated. No difference was found in conversion of 16,17-[3H2]GA19 to 16,17-[3H2]GA20, and 16,17-[3H2]GA1, or in metabolism of 1,2-[3H2]GA1 to [3H]GA8 between plants grown in continuous light and plants exposed for 14 days to a 12-h photoperiod. Also, leaf discs from plants grown in long or short days, converted 16,17-[3H2]GA19 both in light and darkness. These data on metabolism of 16,17-[3H2]GA19, contrast with previous results, which have indicated a photoperiodic control of the metabolism of GA19 to GA20 in S. pentandra.Presence of these applied labelled GAs and their metabolites in different parts of seedlings was recorded, after application to intact seedlings as well as to isolated plant parts. When 16,17-[3H2]GA19 was applied through the roots of intact plants, the relative amounts of 16,17-[3H2]GA1 present in leaves and shoot apices were higher than in roots and stems. In corresponding experiments with 1,2-[3H2]GA1, relatively higher amounts of [3H2]GA8 were found in roots and stems than in leaves and shoot apices. Twenty-four hours after application of 16,17-[3H2]GA19 to isolated plant parts, 16,17-[3H2]GA20 and 16,17-[3H2]GA1 were found in leaves and roots, but not in internodes. Incubation of isolated plant parts with 1,2-[3H2]GA1 for 24 h resulted in presence of [3H]GA8 in all parts.The results mentioned above were obtained by monitoring metabolites by HPLC with on-line radio counting. The conversions of 17-[2H2]GA19 to 17-[2H2]GA20 and 17-[2H2]GA1 in shoot apices and whole seedlings, and of 17-[2H2]GA8 in whole seedlings, were confirmed by GC-MS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00963.x
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of endogenous gibberellins in roots and shoots of elongating Salix pentandra seedlings (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 90 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gibberellins GA1, GA8. GA19. GA29. GA20 and GA56 (2-epi-GA8). were identified by combined gas chromatography-mass spectrometry in root extracts of elongating Salix pentandra L. seedlings. The presence of GA8 was also demonstrated for the first time in S. pentandra shoots. The levels of GA1, GA8, GA19, GA20 in shoot tissue and in roots were estimated by selected ion monitoring. While the amounts of GA8 and GA19 were similar in both plant parts. the levels of the biologically active GA1 and its immediate precursor GA20. were found to be much lower in roots than in shoots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb00402.x
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  • 6
    Electronic Resource
    Electronic Resource
    The Response to Gibberellin in Pisum sativum Grown under Alternating Day and Night Temperature (1998)
    Springer
    Journal of plant growth regulation 17 (1998), S. 161-167 
    Details
    ISSN: 1435-8107
    Keywords: Key Words. DIF—Gibberellin—Inactivation—Pea—Response—Stem elongation—Temperature—Thermoperiodism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. The application of gibberellins (GA) reduces the difference in stem elongation observed under a low day (DT) and high night temperature (NT) combination (negative DIF) compared with the opposite regime, a high DT/low NT (positive DIF). The aim of this work was to investigate possible thermoperiodic effects on GA metabolism and tissue sensitivity to GA by comparing the response to exogenously applied GA (in particular, GA1 and GA3) in pea plants (Pisum sativum cv. Torsdag) grown under contrasting DIF. Control plants not treated with growth inhibitors or additional GA were 38% shorter under negative (DT/NT 13/21°C) than positive DIF (DT/NT 21/13°C) because of shorter internodes. Additional GA1 or GA3 decreased the difference between positive and negative DIF. In pea plants dwarfed with paclobutrazol, which inhibits GA biosynthesis at an early step, the response to GA1 was reduced more strongly by negative compared with positive DIF than the response to GA3. The induced stem elongation by GA19 and GA20 did not deviate significantly from the response to GA1. Plants treated with prohexadione-calcium, an inhibitor of both the production and the inactivation of GA1, grew equally tall under the two temperature regimes in response to both GA1 and GA3. We hypothesize that the reduced response to GA1 compared with GA3 in paclobutrazol-treated plants grown under negative DIF is caused by a higher rate of 2β-hydroxylation of GA1 into GA8 under negative than positive DIF. This contributes to lower levels of GA1 and consequently shorter stems and internodes in pea plants grown under negative than positive DIF. Differences in tissue sensitivity to GA alone cannot account for this specific thermoperiodic effect on stem elongation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007030
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  • 7
    Electronic Resource
    Electronic Resource
    Gibberellins and Subapical Cell Divisions in Relation to Bud Set and Bud Break in Salix pentandra (1999)
    Springer
    Journal of plant growth regulation 18 (1999), S. 167-170 
    Details
    ISSN: 1435-8107
    Keywords: Key Words. Bud set—Bud break—Gibberellin—Growth cessation—Photoperiod—Salix pentandra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. In young plants of Salix pentandra, a temperate zone deciduous woody species, elongation growth ceases and a terminal bud is formed at day lengths shorter than a critical length. This is the first step in dormancy development, making survival under harsh winter conditions possible. Early studies strongly indicate that gibberellin is involved in the photoperiodic control of bud set and bud break. GA1 action was studied by application under short days to plants where cessation of shoot elongation had occurred, followed by subsequent anatomic investigations of shoot tips. Under short days the frequency of cell division decreased rapidly along with the earlier observed decrease in GA1 levels. Application of GA1 to short-day–induced terminal buds rapidly stimulated cell division in apices several days before visible shoot elongation in response to this treatment was observed. One day after GA1 application a fourfold increase in cell division frequency in apices was observed, increasing to a maximum of sevenfold 2 days after application. Long-day treatment leading to induction of bud break after about 4–6 days was followed by slowly increasing frequency of cell divisions. In earlier studies of this species, short days and gibberellins had no effect on cell elongation. These data show that increased GA1 content, by application or long-day treatment, results in increased frequency of mitosis. This strongly indicates that GA1 affects stem elongation in connection with bud set and bud break primarily by affecting cell divisions in subapical tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007065
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of the female flowering environment on autumn frost-hardiness of Picea abies progenies (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 797-802 
    Details
    ISSN: 1432-2242
    Keywords: Pre-conditioning ; After-effects ; Microsporogenesis ; Pollen selection ; Embryogenesis ; Imprinting ; Gene regulation ; Provenance variation ; Photoperiod ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two experiments were designed to test possible effects of photoperiod and temperature during microsporogensis to anthesis on early autumn frost-hardiness of Picea abies progenies. Pollen lots were produced in phytotron rooms and used in crosses in a seed orchard. No biologically important differences in progeny performance were evident either between high and low temperature or between long and short-day treatments, and no significant interaction between photoperiod and temperature was found. In a third experiment, however, an effect of the environment during female flowering was obtained. Crosses performed in early spring (March) inside a heated greenhouse (short day, high temperature) produced progenies which were less hardy than their full-sibs reproduced from crosses indoors (long day, high temperature) and outdoors (long day, low temperature) in May. The most hardy siblings originated from the late-spring outdoor crosses. These results indicate that some stages in reproduction during female flowering, such as female meiosis, pollen tube growth, syngamy, early embryogenesis and embryo competition, may be sensitive to temperature and/or photoperiodic signals which can be transmitted to the progeny. We suspect that the altered performance of the progenies could be due to an activation of a regulatory mechanism affecting the expression of genes controlling adaptive traits. Both the present and earlier results have implications for the genetic interpretation of provenance differences in Norway spruce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221890
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of the female flowering environment on autumn frost-hardiness of Picea abies progenies (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 797-802 
    Details
    ISSN: 1432-2242
    Keywords: Key words  Pre-conditioning ; After-effects ; Microsporogenesis ; Pollen selection ; Embryogenesis ; Imprinting ; Gene regulation ; Provenance variation ; Photoperiod ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Two experiments were designed to test possible effects of photoperiod and temperature during microsporogensis to anthesis on early autumn frost-hardiness of Picea abies progenies. Pollen lots were produced in phytotron rooms and used in crosses in a seed orchard. No biologically important differences in progeny performance were evident either between high and low temperature or between long- and short-day treatments, and no significant interaction between photoperiod and temperature was found. In a third experiment, however, an effect of the environment during female flowering was obtained. Crosses performed in early spring (March) inside a heated greenhouse (short day, high temperature) produced progenies which were less hardy than their full-sibs reproduced from crosses indoors (long day, high temperature) and outdoors (long day, low temperature) in May. The most hardy siblings originated from the late-spring outdoor crosses. These results indicate that some stages in reproduction during female flowering, such as female meiosis, pollen tube growth, syngamy, early embryogenesis and embryo competition, may be sensitive to temperature and/or photoperiodic signals which can be transmitted to the progeny. We suspect that the altered performance of the progenies could be due to an activation of a regulatory mechanism affecting the expression of genes controlling adaptive traits. Both the present and earlier results have implications for the genetic interpretation of provenance differences in Norway spruce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050195
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  • 10
    Electronic Resource
    Electronic Resource
    Temperature alternations and the influence of gibberellins and indoleacetic acid on elongation growth and flowering of Begonia x hiemalis Fotsch (1997)
    Springer
    Plant growth regulation 21 (1997), S. 135-144 
    Details
    ISSN: 1573-5087
    Keywords: BX-112 ; endogenous ; GAs ; growth retardant ; thermoperiodism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of this study was to investigate the role of plant hormones, particularly the gibberellins (GAs), in the thermoperiodic regulation of stem elongation in the short day plant (SDP) Begonia x hiemalis. Effects of GAs and some GA precursors were tested on plants grown under alternating day/night temperatures (DT/NT; 12/12 h), and the effects of these temperature regimes on endogenous plant hormones were analyzed using combined gas chromatography and mass spectrometry (GC-MS). Compared with constant temperatures (19/19 °C; 21/21 °C), stem elongation was significantly inhibited by low DT/high NT (14/24 °C; 18/24 °C) and enhanced by the opposite treatments (24/14 °C; 26/17 °C). GA1 stimulated elongation of internodes and petioles while ent-kaurene, kaurenoic acid, GA12, GA19, GA20 had no significant effect. The effect of GA1 was enhanced by a simultaneous application of calcium 3,5-dioxo-4-propionylcyclohexanecarboxylate (BX-112). BX-112 inhibited internode elongation at high DT/low NT (24/14 °C) but not at the reverse temperature regime. Gibberellins A53, A19, A20, A1, A4, A9, and indoleacetic acid (IAA), were identified by GC-MS from both leaves, including the petioles, and stems of B. x hiemalis. There were no apparent relationships between elongation of internodes and petioles and endogenous contents of gibberellins A53, A19, A20, and A1. Recoveries of deuterated GA4 and GA9 were generally too low for estimation of endogenous levels of these GAs. Constant temperature resulted in more open flowers and flower buds compared to alternating DT and NT. BX-112 decreased the time to anthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005708422020
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