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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Gas chromatography – selected ion monitoring – mass spectrometry was used to measure the level of indole-3-acetic acid (IAA) in the cambial region at the top and bottom of the branchless portion of the main stem of three large Scots pine trees, at weekly intervals from 28 April to 13 July. During this period, the cambium reactivated from the dormant state and entered its ‘grand’ period of xylem and phloem production, which was monitored by microscopy. The total amount of IAA (ng cm−2) increased steadily from 28 April until late June, and thereafter remained constant. In contrast, the concentration of IAA (ng g−1 fresh weight) was high at the start of cambial reactivation, declined when the number of differentiating tracheids began to increase, and then rose as the number of cells decreased. The timing and magnitude of the changes in xylem and phloem production and in IAA level were similar at the two sampling positions. It is concluded that the seasonal changes in cambial activity in the conifer stem cannot be ascribed simply to a fluctuation in the level of endogenous IAA in the cambial region.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 87 (1993), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Changes in protein synthesis in cambial region cells were monitored in 1-year-old cuttings of Scots pine (Pinus sylvestris L.) collected in November, when the cambium was dormant, and subjected to environmental conditions that promoted or inhibited cambial growth. The proteins were labelled in vivo with L-[35S]-methionine and separated using 2-dimensional polyacrylamide gel electrophoresis. In budded cuttings cultured under environmental conditions favoring cambial reactivation, there was a reproducible quantitative change in 55 proteins (33 induced and 22 repressed), a less certain increase or decrease in 40 proteins, and no apparent change in about 150 proteins. Under the same conditions, 8 proteins were induced and 6 others were repressed in debudded cuttings treated apically with 1 mg indole-3-acetic acid (IAA) in 1 g lanolin, in which cambial reactivation occurred, compared with debudded cuttings treated with plain lanolin in which the cambium did not reactivate. Three of the proteins induced in the IAA-reated cuttings only appeared after cambial cell division and derivative differentiation actually began, and the same proteins were found in budded cuttings after their cambium had become reactivated. In contrast, protein expression in cuttings exposed to environmental conditions that prevented cambial reactivation was similar at the beginning and end of the experimental period. These results indicate that the cambium was in the quiescence stage of dormancy at the start of the experiment, that quiescent cambial region cells can synthesize proteins as soon as exposed to environmental conditions favoring reactivation, and that only 3 of the approximately 250 proteins detected were specifically involved in cambial growth
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gibberellin A4/7 (GA4/7) was applied twice weekly to 2-year-old Pinus sylvestris (L.) seedlings in each of two years, starting close to budbreak and ending after shoot elongation, but before cambial activity ceased. In 1988, the GA4/7 was injected into the 1987 terminal shoot (0, 0.2 or 2 mg seedling−1 application−1), while in 1990 it was applied as a soil drench (0, 10 or 50 mg seedling−1 application−1). In the 1988 experiment, GA4/7 treatment promoted diameter growth, and tended to increase both longitudinal growth and the indole-3-acetic acid (IAA) level in the 1988 terminal. In the 1990 experiment, GA4/7 treatment increased tracheid production, longitudinal growth, and the cambial region IAA concentration in the 1990 terminal, but did not affect its pith diameter, needle number, needle dry weight, or needle IAA level. Tracheid production in the previous-year's terminal was also promoted in both experiments. The 50 mg GA4/7 soil drench markedly elevated the concentrations of GA4, GA7 and GA9 in the needles and cambial region of the 1990 terminal, while the 10 mg treatment raised the GA4 level in the cambial region, providing evidence that GA4 and GA7 applied to the roots reaches the shoot system. The results support the hypothesis that the exogenous GA4/7-induced stimulation of tracheid production in the terminal shoot of intact plants is mediated through an increase in the IAA level in the cambial region. However, per se activity of GA4, GA7 or their metabolites cannot be ruled out.
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 220 (1968), S. 498-499 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] One year old, 20 cm cuttings were taken on March 7 from four species of tree: a diffuse-porous hardwood- red maple (Acer rubrum L.), a ring-porous hardwood- white ash (Fraxinus americana L.), and two softwoods- balsam fir (Abies balsamea L.) and white spruce (Picea glauca (Moench) Voss). The bases ...
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  • 5
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The nuclear DNA content in ray cells from the 1-year-old vascular cambium of white ash (Fraxinus americana L.) trees was determined at intervals during the annual cycle of cambial activity and dormancy by using Feulgen microspectrophotometry. By 10 September, these cells had entered dormancy in G1 with a normal DNA distribution and a minimal average DNA content of 2.65 pg. The average amount of DNA increased to 3.51 pg by 30 November, remained at this elevated value until at least 30 March, when the cambium was still dormant, then declined to the minimum level on 1 May and 10 June, when the cells were mitotically active. The springtime decline appeared to occur both before and during cell division. Between 1 May and 10 June, the prophase (4C) and telophase (2C) DNA contents decreased significantly. The amount of nuclear DNA measured by microspectrophotometry was verified by using flow cytometry and image analysis. The results support the view that there is an annual oscillation in the nuclear genome size of shoot meristematic cells in tree species native to the northern temperate zone.
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  • 6
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The relationship between from hardiness and growth potential, and their dependence on temperature and photoperiod, was investigated in the one-year-old cambium of balsam fir [Abies balsamea (L.) Mill.]. Six-year-old trees were exposed for 9 weeks to either the natural environment or one of 4 controlled environments in the fall (18 September-18 November), spring (12 April–14 June) and summer (19 July – 19 September). The 4 controlled environments were (1) WS, warm temperature (24/20°C in day/night) + short day (8 h). (2) WL. warm temperature (24/20°C) + long day (8 h + 1 h night break), (3) CS. cold temperature (9/5°C) + short day (8 h) and (4) CL, cold temperature (9/5°C) + long day (8 h + 1 h night break). At the beginning and end of each exposure, cambial activity was measured by recording the number of xylem, cambium and phloem cells, frost hardiness was estimated from the cambium's ability to survive freezing to –40°C, and cambial growth potential was deduced from the duration of the cell cycle and the production of xylem, cambium and phloem cells in cuttings cultured for 4 weeks with exogenous indole-3-acetic acid (IAA) under environmental conditions favourable for cambial activity. In the natural environment, frost hardening began in September and was completed in November, while dehardening occurred when the cambium reactivated. CL, CS, and to a lesser extent WS, promoted hardening in the summer and fall, but did not prevent dehardening in the spring. The cambial growth potential in the natural environment declined from a maximum in April to a low level in June, reached a minimum in September, then increased to a high level in November. This potential was promoted by CL and CS on all dates by WL in the summer and fall. The ratio of xylem to phloem induced by IAA treatment was greatest in June and least in September in cuttings from trees exposed to the natural environment, and was increased by CL and CS in the fall. The cambium in intact branches of trees protected from chilling during the fall and winter resumed cell cycling after less than 9 weeks of dormancy, but produced mostly or only phloem in the subsequent growing period. It is concluded that the frost hardiness of the cambium, the IAA-induced cycling of cambial cells, and IAA-induced xylem to phloem ratio vary independently with season, temperature and photoperiod, and that the periodicity of these processes is regulated endogenously.
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  • 7
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previously, we showed that the size of the nuclear genome, measured cytophotometrically in Feulgen-stained fusiform cambial cells of Abies balsamea (L.) Mill., oscillates annually between a maximum in spring and a minimum in late summer, the labile, extra DNA being synthesized during the fall. To determine it the oscillation is induced by the concomitant seasonal changes in temperature and photoperiod, genome size was measured in cambial cells obtained from one-year-old branches of 6-year-old potted trees at the beginning and end of 9 weeks of exposure during the fall, spring and summer to either the natural environment or one of 4 controlled environments, viz. (1) WS, warm temperature (24/20°C in day/night) and short photoperiod (8 h). (2) WL, warm temperature (24/20°C) and long photoperiod (8 h + 1 h night break), (3) CS, cold temperature (9/5°C) and short photoperiod (8 h). and (4) CL, cold temperature (9/5°C) and long photoperiod (8 h + 1 h night break). Overall, genome size (2C) varied between 20 and 34 pg. In the fall, when the cambium was initially dormant, the genome size increased in the natural environment, did not change under short days (WS and CS), and decreased under long days (WL and CL). The cambium reactivated in both WS and WL conditions. In the spring, while the cambium reactivated, the size of the genome decreased in the natural, WS and WL conditions, but not in the CS environment. In the CL conditions, the genome size started to decrease at the end of the 9-week exposure period. The decrease apparently occurred between prophase and telophase, which suggests that the extra DNA is extrachromosomal. In the summer, while the cambium ceased activity, the genome size did not change in the WS, WL and natural environments, whereas it decreased in the CS and CL conditions. The results indicate that increasing temperature and lengthening photoperiod in the spring induce the loss of the extra DNA. However, the environmental conditions that promote DNA synthesis in the fall remain unknown. Genome size varied independently of cambial growth potential and frost hardiness measured previously in the same experimental trees, indicating that the regulation of these processes does not directly involve the extra DNA. However, the finding that cambial cells cycled in the CS and CL environments only in the spring, when their genome size was large, suggests that the extra DNA is important for cambial growth at low temperatures.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 95 (1995), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gibberellin A4/7 (GA4/7) was applied in lanolin or ethanol around the circumference at the midpoint of the previous-year terminal of dormant Pinus sylvestris seedlings. After cultivating the seedlings under environmental conditions favorable for growth for up to 10 weeks, cambial growth was measured as the radial widths of xylem and phloem, and the level of indole-3-acetic acid (IAA) was determined by combined gas chromatography-mass spectrometry using [136](IAA) as the internal standard. In intact seedlings, both 1 mg GA4/7 g−1 lanolin and 50 mg GA4/7 I−1 ethanol increased phloem production and the cambial region IAA level in the current-year terminal, without significantly altering its longitudinal growth. In the previous-year terminal, 1 mg GA4/7 g−1 lanolin promoted phloem production at the application point and increased the cambial region IAA level above this point, whereas 50 mg GA4/7 I−1 ethanol stimulated the production of both xylem and phloem at the treatment site and elevated the cambial region IAA level beneath it. Laterally applied GA4/7 at 50 mg I−1 ethanol stimulated xylem and phloem production in debudded previous-year terminals treated at the apical cut surface with 1 mg IAA g−1 lanolin, but not in those treated with plain lanolin. However, the promotion of cambial growth in debudded terminals treated apically with 1 mg IAA g−1 lanolin and laterally with 50 mg GA4/7 I−1 ethanol was not associated with an elevated IAA content in the cambial region. The results indicate that exogenous GA4/7 can promote xylem and phloem production provided an IAA source is present, and that it or a metabolic product acts directly, rather than indirectly by stimulating longitudinal growth and/or raising the cambial region IAA level.
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  • 9
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The application of gibberellin A4/7 (GA4/7) to the stem of previous-year (1-year-old) terminal shoots of Scots pine (Pinus sylvestris) seedlings has been observed to stimulate cambial growth locally, as well as at a distance in the distal current-year terminal shoot, but the distribution and metabolic fate of the applied GA4/7, as well as the pathway of endogenous GA biosynthesis in this species, has not been investigated. As a first step, we analysed for endogenous GAs and monitored the transport and metabolism of labelled GAs 4, 9 and 20. Endogenous GAs from the elongating current-year terminal shoot of 2-year-old seedlings were purified by column chromatography and high-performance liquid chromatography and analysed by combined gas chromatography-mass spectrometry (GC-MS). GAs 1, 3, 4, 9, 12 and 20 were identified in the stem, and GAs 1, 3 and 4 in the needles, by full-scan mass spectrometry (GAs 1, 3, 4, 9 and 12) or selected-ion monitoring (GA20) and Kovats retention index. Tritiated and deuterated GA4, GA9 or GA20 were applied around the circumference at the midpoint of the previous-year terminal shoot, and metabolites were extracted from the elongating current-year terminal shoot, the application point, and the 1-year-old needles and the cambial region above and below the application point. After purification, detection by liquid scintillation spectrometry and analysis by GC-MS, it was evident that, for each applied GA, unmetabolised [2H2]GA and [3H]radioactivity were present in every seedling part analysed. Most of the radioactivity was retained at the application point when [3H]GA9 and [3H]GA20 were applied, whereas the largest percentage of radioactivity derived from [3H]GA4 was recovered in the current-year terminal shoot. It was also found that [2H2]GA9 was converted to [2H2]GA20 and to both [2H2]GA4 and [2H2]GA1, [2H2]GA4 was metabolised to [2H2]GA1, and [2H2]GA20 was converted to [2H2]GA29. The data indicate that for Pinus sylvestris shoots (1) GAs applied laterally to the outside of the vascular system of previous-year shoots not only are absorbed and translocated extensively throughout the previous-year and current-year shoots, but also are readily metabolised, (2) the GA metabolic pathways found are closely related to the endogenous GAs identified, and (3) GA9 metabolism follows two distinctly different routes: in one, GA9 is converted to GA1 through GA4, and in the other it is converted to GA20, which is then metabolised to GA29. The results suggest that the late 13-hydroxylation pathway is an important route for GA biosynthesis in shoots of Pinus sylvestris, and that the stimulation of cambial growth in Scots pine by exogenous GA4/7 may be due to its conversion to GA1, rather than to it being active per se.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Trees 13 (1999), S. 173-177 
    ISSN: 0931-1890
    Keywords: Key words Abies balsamea ; Cambial growth ; Compression wood formation ; Ethylene ; N-1-naphthylphthalamic acid (NPA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The terminal (1-year-old) shoot of dormant, 2-year-old balsam fir [Abies balsamea (L.) Mill.] seedlings was either left vertically oriented or tilted to an angle of 60° from the vertical (tilting experiment), or was ringed with N-1-naphthylphthalamic acid (NPA), an inhibitor of indole-3-acetic acid transport, at a concentration of 0, 1 or 10 mg g−1 lanolin (NPA experiment). After 6 weeks of growth, ethylene evolution from the cambial region was measured by gas chromatography – flame ionization detection, and tracheid production and compression wood formation were determined by microscopy. In vertical seedlings of the tilting experiment and in 0 mg g−1-treated seedlings of the NPA experiment, compression wood was not formed and neither ethylene evolution nor tracheid production varied longitudinally or circumferentially within the stem. Tilting induced compression wood formation and increased ethylene evolution and tracheid production on the lower side of the stem, while decreasing tracheid production on the upper side. Compression wood formation was induced and tracheid production and ethylene evolution were stimulated at and above the point where 1 or 10 mg NPA g−1 was applied, whereas below this point compression wood was not formed and tracheid production was inhibited. In both tilting and NPA experiments, there was a positive correlation between ethylene evolution and tracheid production when data from all seedlings were analyzed, but not when data from seedlings forming compression wood were excluded. The results indicate that cambial region ethylene evolution is enhanced when compression wood is being formed, and that the enhancement is related to compression wood formation per se rather than the associated increase in tracheid production.
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