共查询到20条相似文献,搜索用时 15 毫秒
1.
Applications of the growth promotive gibberellins (GAs) GA4 and 2,2-dimethyl GA4, and of C-16,17 endo-dihydro GA5, which is known to promote flowering while inhibiting stem growth in the long-day grass Lolium temulentum, were made to micropropagated plants of Metrosideros collina cv. Tahiti, a highly ornamental cultivar with an intermittent flowering pattern. Gibberellin A4 and 2,2-dimethyl GA4 stimulated vegetative growth both in elongating shoots, and internodes of shoots developing from buds that were quiescent at the time of GA application. Abscission of the apices of expanding shoots, a feature of mature Metrosideros plants, was inhibited by these GAs, the rejuvenation of micropropagated plantlets being enhanced. However, C-16,17 endo-dihydro GA5 differed from GA4 and 2,2-dimethyl GA4 by having no promotive effects on vegetative growth, and no inhibition of apical abscission. Notwithstanding this contrasting effect on vegetative growth, high doses of GA4 or C-16,17 endo-dihydro GA5 similarly reduced flowering on shoots to which either GA was applied. Reduced flowering in response to applied GAs is common in many woody angiosperms, and in this instance was probably the combined result of abortion of developing floral structures in quiescent buds, and a preferential inhibition of bud break for floral buds relative to vegetative buds, particularly by GA4. Finally, both C-16,17 endo-dihydro GA5 and GA4 strongly inhibited bud break in this woody angiosperm, although GA4 could initially stimulate bud break when applied to vegetative buds close to the expansion stage. The above findings, in toto, highlight the sensitivity of Metrosideros to both classes of GA in a variety of growth and development processes. 相似文献
2.
Gibberellins, Endogenous and Applied, in Relation to Flower Induction in the Long-Day Plant Lolium temulentum 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Changes in endogenous gibberellin-like substances (GAs) and related compounds in the shoot apices of Lolium temulentum during and after flower induction by one long day was examined for plants grown in three consecutive years. The total GA level in the shoot apical tissue was high (up to 42 micrograms per gram dry weight, or 3 × 10−5 molar GA3 equivalents), increasing several-fold on the day after the long day and then declining. Of the many GA-like substances present, the putative polyhydroxylated components—with HPLC retention times between those of GA8 (three hydroxyls) and GA32 (four hydroxyls), and accounting for about a quarter of the total GA activity—were most consistent and striking in their changes. Their level in the apices increased 3- to 5-fold on the day after the long day and then subsided. When various GAs were applied to plants in noninductive short days, flower initiation was induced by several, most notably by GA32, GA5, 2,2-dimethyl GA4, GA3, and GA7. GA32 was most like one long day in eliciting a strong flowering response while having little effect on stem growth, whereas GA1 had the opposite effect. It is suggested that highly hydroxylated C-19 GAs may play a central role in the induction of flowering in this long-day plant. 相似文献
3.
In previous experiments with many gibberellins (GAs) and GA derivatives applied to Lolium temulentum L., quite different structural requirements were evident for stem elongation on the one hand and for the promotion of flowering on the other. Whereas hydroxylation at carbons 12, 13 and 15 enhanced flowering relative to stem growth, the reverse was the case at carbon 3 (L.T. Evans et al. 1990, Planta 182, 97–106). The significance of hydroxylation at carbon 3 is examined in this paper. The application of inhibitors of 3β-hydroxylation, including C/D-ring-rearranged GAs, reduced stem growth but, in the case of the two acylcyclohexanediones, increased the flowering response when applied on the inductive long day. Later applications of the acylcyclohexanediones, made after floral initiation had occurred, were inhibitory to flowering, suggesting that subsequent inflorescence development requires 3β-hydroxylated GAs. Applications of the 3α-hydroxy epimers of GA1, GA3 and GA4 gave slightly less promotion of flowering in comparison with the 3β-hydroxy GAs, but far less promotion of stem elongation, except in the case of 3-epi-GA4, which was comparable to GA4. The 3α-hydroxy epimer of 2,2-dimethyl GA4 gave less promotion of flowering than its 3β-hydroxy epimer but almost no promotion of stem elongation. The 3α-hydroxy epimers of GA3 and 2,2-dimethyl GA4 did not act as competitive inhibitors of the stem elongation elicited by GA3 and 2,2-dimethyl GA4, respectively. These results extend the differences in GA structure which favour flowering as opposed to stem elongation, and indicate that 3-hydroxylation and its epimeric configuration are of much greater importance to stem elongation than to flower initiation in Lolium. 相似文献
4.
K. R. Foster I.-j. Lee R. P. Pharis P. W. Morgan 《Journal of Plant Growth Regulation》1997,16(2):79-87
Plants of early flowering mutant and wild type genotypes of Sorghum bicolor were treated with ring D-modified gibberellins (GAs), and the effects on endogenous GA levels were determined. The growth
and timing of floral initiation in 58M plants grown under 18-h days (which significantly delays floral initiation in this
short day plant) following treatment with these compounds, relative to GA3 and GA5 treatments, were also investigated. Application of the endo-isomer of C16,17-dihydro-GA5 (endo-DiHGA5), the exo-isomer of C16,17-dihydro-GA5 (exo-DiHGA5), and C16α,17-dichloromethanodihydro-GA5 (DMDGA5) altered GA levels in both genotypes. Each ring D-modified GA significantly inhibited shoot growth while significantly decreasing
levels of GA1 and increasing levels of its immediate precursor, GA20. Gibberellin A8 levels also decreased. Tillering was not affected by any treatment. For the early flowering genotype 58M, grown under noninductive
long days, both dihydro-GA5 isomers promoted floral initiation while shoot growth was strongly inhibited, and floral development was strongly advanced
beyond floral stage 4. Gibberellin A3 and GA5, applied under the same conditions, promoted shoot growth slightly and gave ``floral-like' apical meristems that did not
develop past floral stage 1. These results suggest that the reduced shoot growth of sorghum, which follows application of
those ring D-modified GAs, is due to their inhibiting the 3β hydroxylation of GA20 to GA1, thereby reducing the GA1 content. That floral initiation was hastened and floral development promoted in genotype 58M by application of both isomers
of DiHGA5 are in contrast to the effects of other GA biosynthesis inhibitors, which act earlier in the GA biosynthesis pathway, but
are consistent with results seen for long day grasses. This suggests that endo-DiHGA5 and exo-DiHGA5 may be acting directly in promoting floral initiation and subsequent floral apex development of this short day plant under
long day conditions.
Received October 3, 1996; accepted January 22, 1997 相似文献
5.
The restricted flowering of colored cultivars ofZantedeschia is a consequence of developmental constraints imposed by apical dominance of the primary bud on secondary buds in the tuber,
and by the sympodial growth of individual shoots. GA3 enhances flowering inZantedeschia by increasing the number of flowering shoots per tuber and inflorescences per shoot. The effects of gibberellin on the pattern
of flowering and on the developmental fate of differentiated inflorescences along the tuber axis and individual shoot axes
were studied in GA3 and Uniconazole-treated tubers. Inflorescence primordia and fully developed (emerged) floral stems produced during tuber
storage and the plant growth period were recorded. Days to flowering, percent of flowering shoots and floral stem length decreased
basipetally along the shoot and tuber axes. GA3 prolonged the flowering period and increased both the number of flowering shoots per tuber and the differentiated inflorescences
per shoot. Activated buds were GA3 responsive regardless of meristem size or age. Uniconazole did not inhibit inflorescence differentiation but inhibited floral
stem elongation. The results suggest that GA3 has a dual action in the flowering process: induction of inflorescence differentiation and promotion of floral stem elongation.
The flowering pattern could be a result of a gradient in the distribution of endogenous factors involved in inflorescence
differentialtion (possibly GAs) and in floral stem growth. This gradient along the tuber and shoot axes is probably controlled
by apical dominance of the primary bud.
Online publication: 7 April 2005 相似文献
6.
The role of gibberellins (GAs) during germination and early seedling growth is examined by following the metabolism and transport
of radiolabeled GAs in cotyledon, shoot, and root tissues of pea (Pisum sativum L.) using an aseptic culture system. Mature pea seeds have significant endogenous GA20 levels that fall during germination and early seedling growth, a period when the seedling develops the capacity to transport
GA20 from the cotyledon to the shoot and root of the seedling. Even though cotyledons at 0–2 days after imbibition have appreciable
amounts of GA20, the cotyledons retain the ability to metabolize labeled GA19 to GA20 and express significant levels of PsGA20ox2 message (which encodes a GA biosynthesis enzyme, GA 20-oxidase). The large pool of cotyledonary GA20 likely provides substrate for GA1 synthesis in the cotyledons during germination, as well as for shoots and roots during early seedling growth. The shoots
and roots express GA metabolism genes (PsGA3ox genes which encode GA 3-oxidases for synthesis of bioactive GA1, and PsGA2ox genes which encode GA 2-oxidases for deactivation of GAs to GA29 and GA8), and they develop the capacity to metabolize GAs as necessary for seedling establishment. Auxins also show an interesting
pattern during early seedling growth, with higher levels of 4-chloro-indole-3-acetic acid (4-Cl-IAA) in mature seeds and higher
levels of indole-3-acetic acid (IAA) in young root and shoot tissues. This suggests a changing role for auxins during early
seedling development. 相似文献
7.
CCC, uniconazol, ancymidol, prohexadione-calcium (BX-112), and CGA 163′935, which represent three groups of gibberellin (GA)
biosynthesis inhibitors, were applied as a soil drench to Sorghum bicolor cultivars 58M (phyB-1, phytochrome B-deficient mutant) and 90M (phyB-2, equivalent phenotypically to wild type, PHYB, except for small differences in flowering dates). The inhibitors that block
steps before GA12 (CCC, uniconazol, and ancymidol) lowered the concentrations of all endogenous early-C13α-hydroxylation pathway GAs found
in sorghum: GA12, GA53, GA44, GA19, GA20, GA1, and GA8. In contrast, the inhibitors that block the conversion of GA20→ GA1, (CGA 163′935 and BX-112) drastically reduced GA1 and GA8 levels, but they either did not change or caused accumulation of intermediates from GA12 to GA20. Combinations of pre-GA12 inhibitors and GA3 plus GA1 strongly reduced GAs other than GA1 and GA3. Each of these compounds inhibited shoot growth in both cultivars and delayed floral initiation in 90M. Floral initiation
of 58M was also delayed by CCC, uniconazol, and ancymidol but not by CGA 163`935 and BX-112. This separation of shoot elongation
from floral initiation in sorghum is novel. Both inhibition of shoot growth and delayed floral initiation were almost completely
relieved by a mixture of GA3 and GA1 in both 58M and 90M. This observation, plus the much lower levels of endogenous GA3 than of GA1 observed in these experiments, implies that GA1 is the major endogenous GA active in shoot elongation. CGA 163′935 and BX-112 also failed to promote tillering in 58M, whereas
inhibitors active before GA12 did so. The possibility that the GA20→ GA1 inhibitors fail to block flowering and promote tillering in 58M because biosynthetic intermediates between GA12 and GA20 accumulate and/or because 58M is altered in GA metabolism in this same region of the biosynthetic pathway is discussed.
Received April 7, 1998; accepted July 31, 1998 相似文献
8.
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. 相似文献
9.
The effects of differential photoperiodic treatments applied to shoot tips and mature leaves of the long-day (LD) plant Silene armeria L. on growth and flowering responses, and on the levels of endogenous gibberellins (GAs), were investigated. Gibberellins were analyzed by gaschromatography-mass spectrometry and the use of internal standards. Exposure of mature leaves to LD, regardless of the photoperiodic conditions of the shoot tips, short days (SD), LD, or darkness, promoted elongation of the stems and of the immature leaves. Long-day treatment of the mature leaves modified the levels of endogenous GAs in shoot tips kept under LD, SD, or darkness. In shoot tips kept in LD or darkness the levels of GA53 were reduced, whereas the levels of GA19 and GA20 were increased. The contents of GA1 were increased in all three types of shoots: SD twofold, LD fivefold, and darkness eightfold. Dark treatment of the shoot tips on plants of which the mature leaves were grown in SD promoted elongation of the immature etiolated leaves and increased the GA1 content of the shoot tips threefold. However, this treatment did not cause stem elongation. The different photoperiodic treatments applied to the shoot tips did not change the levels of GAs in mature leaves. These results indicate that both LD and dark treatments result in an increase in GA1 in shoot tips. In addition, it is proposed that LD treatment induces the formation of a signal that is transmitted from mature leaves to shoot tips where it enhances the effect of GA on stem elongation.Abbreviations GAn
gibberellin An
- LD
long day(s)
- SD
short day(s)
We thank Dr. L.N. Mander, Australian National University, Canberra, for providing [2H]-gibberellins and Dr. D.A. Gage, MSU-NIH Mass Spectrometry Facility, East Lansing, for advice with mass spectrometry. This work was supported, in part, by a fellowship from the Spanish Ministry of Agriculture (Instituto Nacional de Investigaciones Agrarias) to M.T., by the U.S. Department of Energy grant No. DE-FG02-91ER20021, and by the U.S. Department of Agriculture grant No. 88-37261-3434 to J.A.D.Z. 相似文献
10.
The gibberellins GA1, GA3, GA4, GA7, GA9 and GA20 were quantified in vegetative and pollen cone buds of juvenile and mature trees of Pinus radiata by combined gas chromatography-mass spectrometry and selected ion monitoring (GC-MS-SIM) using deuterated GAs as internal standards. Higher levels of GA7 and GA9 and lower levels of GA4 were detected in juvenile vegetative buds compared to mature buds, and there were no differences in relation to age for GA1, GA3 and GA20. Conversely, when differences between vegetative and pollen cone buds from a mature tree were studied, the highest levels of GA1 and GA4 were found in pollen cone buds, similar levels of GA3, GA7 and GA9 were observed in both, and ten fold lower levels of GA20 were found in pollen cone buds as compared with vegetative buds. These results indicate a difference in GA metabolism in relation to both the tree age as well as the physiological status of buds: vegetative or reproductive in this conifer. 相似文献
11.
Gillian M. Boolher Michael D. Gale Paul Gaskin Jake MacMiilan Valerie M. Sponsel 《Physiologia plantarum》1991,81(3):385-391
The gibberellin (GA) content of barley (Hordeum vulgare L.) cv. Triumph was analysed by full scan gas chromatography-mass spectrometry. Developing grain contained several di-, tri-, and tetra-hydroxylated GAs, with the most abundant ones being hydroxylated at C-2, C-3, C-12β, and/or C-18. In contrast, the only GAs to be detected in shoots of 9-day old dark- and light-grown seedlings of Triumph were 13-hydroxylated C19-GAs, namely GA1, GA8, GA20, and GA29, (all of which are components of the early 13-hydroxylation GA biosynthetic pathway) and GA3. Feeds of [13C.3H2GA20, confirmed that GA20 is a precursor of GA1, GA8, and GA29 in barley shoots. From these results it is suggested that stem growth of barley, in common with that of several other mono- and dicotyledons, is controlled by GA,. Homozygous gal and gal lines were obtained after backcrossing to Triumph. These were then compared to Triumph with respect to their GA content and response to applied GAs and GA precursors. Shoots of the homozygous gal gal plants contained ca 6-fold less GA1, than Triumph. These plants responded to all ent-kaurenoids and 13-hydroxylated C20- and C19-GAs tested. It is concluded that the gal locus impairs the GA biosynthetic pathway prior to ent-kaurene, most probably at ent-kaurene synthetase. In contrast, shoots of homozygous gal gal line contained ca 10-fold higher levels of GA, than Triumph, but failed to respond to applied GA, or GA3. The gal locus therefore confers insensitivity to both exogenous and endogenous GAs, possibly by perturbing the reception or transduction of the GA1 signal. 相似文献
12.
Structural requirements for florigenic activity among gibberellins (GAs) and GA derivatives, including several new ones, applied once to leaves of Lolium temulentum, were examined. The compounds were applied to plants kept either in non-inductive short days (SD) or exposed to one inductive long day (LD). Inflorescence initiation and stem-elongation responses were assessed three weeks later. Among the GAs used, the range in effective dose for inflorescence initiation was more than 1000-fold, but substantially less for stem elongation. Some GAs promoted both stem elongation and inflorescence initiation, some promoted one without the other, and some affected neither. The structural features enhancing florigenic activity were often different from those enhancing stem elongation. Except in the case of 2,2-dimethyl GA4, a double bond in the A ring at either C-1,2 or C-2,3 was essential for high florigenic activity, though not for stem elongation. A free carboxy group was needed for both. Inflorescence initiation in Lolium was enhanced by hydroxylation at C-12, ?13 and ?15, whereas hydroxylation at C-3 reduced the effect on inflorescence initiation but increased that on stem elongation. A 12β-hydroxyl was more effective than the α epimer for inflorescence initiation whereas the reverse was true for stem elongation. Although such differential effectiveness of GAs for inflorescence initiation and for stem elongation could reflect differences in uptake, transport or metabolism, we suggest that it is indicative of specific structural requirements for inflorescence initiation. 相似文献
13.
Prohexadione, a gibberellin (GA) biosynthesis inhibitor, was applied in ethanol around the circumference at the midpoint of the previous year terminal shoot of dormant Pinus sylvestris seedlings. After cultivating the seedlings under environmental conditions favorable for growth for 10 weeks, longitudinal and cambial growth were measured, and the endogenous levels of GA1, GA3, GA4, GA9, and indole-3-acetic acid (IAA) were determined by combined gas chromatography-mass spectrometry, using deuterated GAs and [13C6]IAA as internal standards. Prohexadione application inhibited elongation and xylem and phloem production in the current year terminal shoot and xylem production in the previous year terminal shoots. Concomitantly, in both ages of shoots the cambial region contents of GA1; GA3, and GA4 were decreased, whereas the level of GA9 was increased. However, the IAA content was not altered in the terminal bud on the current year terminal shoot or in the cambial region of the current year or previous year terminal shoots. The results provide additional evidence that: (1) GAs are involved in the regulation of cambial growth, as well as longitudinal growth, in Pinus sylvestris shoots; (2) they act directly, rather than indirectly, by altering the IAA level; and (3) the GA9 GA4 GA1 pathway is a major route of GA biosynthesis in conifer species.Abbreviations GA
gibberellin
- IAA
indole-3-acetic acid
- HPLC
high performance liquid chromatography
- GC
gas chromatography
- SIM
selected ion monitoring
- MS
mass spectrometry 相似文献
14.
Endogenous gibberellins (GAs) were extracted from safflower (Carthamus tinctorius L.) stems and detected by capillary gas chromatography-mass spectrometry from which GA1, GA3, GA19,, GA20, GA29, and probably, GA44 were detected. The detection of these GAs suggests that the early 13-OH biosynthetic pathway is prevalent in safflower shoots. Deuterated GAs were used as internal standards and GA concentrations were determined in stems harvested at weekly intervals. GA1 and GA19 levels per stem increased but concentrations per gram dry weight decreased over time. GA20 was only detected in young stem tissue.Gibberellic acid (GA3) was also applied in field trials and both GA3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests. GA3 increased epidermal cell size, internode length, and increased internode cell number causing stem elongation. Conversely, paclobutrazol reduced stem height, internode and cell size, cell number and overall shoot weight. In field tests, GA3 increased total stem weight, but decreased leaf weight, flower bud number and seed yield. Thus, GA3 promoted vegetative growth at the expense of reproductive commitment. These studies collectively indicate a promotory role of GAs in the control of shoot growth in safflower, and are generally consistent with gibberellin studies of related crop plants.
Author for correspondence 相似文献
15.
The Effect of Gibberellins on Flowering in Roses 总被引:1,自引:0,他引:1
Roberts AV Blake PS Lewis R Taylor JM Dunstan DI 《Journal of Plant Growth Regulation》1999,18(3):113-119
The gibberellins A1, A3, A5, A8, A19, A20, and A29 were identified in vegetative shoot tips of Rosa canina by comparing their mass spectra and Kovats retention indices with those of standards. Most wild roses have a short flowering
season of 2–4 weeks in spring, whereas most modern cultivars flower recurrently. `Félicité et Perpétue' is a short-season
hybrid from a cross between a wild rose and a recurrent-flowering rose, whereas its sport, `Little White Pet,' flowers recurrently.
The concentrations of gibberellins (GAs) were measured in shoot apices of both cultivars. In March (before floral initiation
in spring) the concentrations of GA1 and GA3 were respectively threefold and twofold higher in `Félicité et Perpétue' than in `Little White Pet.' In April (after floral
initiation) the concentrations of both gibberellins were substantially greater than in March, and concentrations of GA1 and GA3 were, respectively, 17-fold and 12-fold greater in `Félicité et Perpétue' than in `Little White Pet.' It is postulated that,
in `Félicité et Perpétue,' floral initiation occurs when concentrations of GAs are low and is inhibited when concentrations
of GAs are high, whereas in `Little White Pet' concentrations of GAs remain at permissive levels throughout the growing season.
Applications of GA1 and GA3 to axillary shoots in March inhibited floral development in `Félicité et Perpétue' but not in `Little White Pet.' This suggests
that the combined concentration of exogenous and endogenous gibberellins might have been raised to inhibitory levels in the
former but not in the latter cultivar.
Received January 10, 1999; accepted June 16, 1999 相似文献
16.
Flowering can be modified by gibberellins (GAs) in Pharbitis nil Chois. in a complex fashion depending on GA type, dosage, and the timing of treatment relative to a single inductive dark period. Promotion of flowering occurs when GAs are applied 11 to 17 hours before a single inductive dark period. When applied 24 hours later the same GA dosage is inhibitory. Thus, depending on their activity and the timing of application there is an optimum dose for promotion of flowering by any GA, with an excessive dose resulting in inhibition. Those GAs highly promotory for flowering at low doses are also most effective for stem elongation (2,2-dimethyl GA4 GA32 > GA3 > GA5 > GA7 > GA4). However, the effect of GAs on stem elongation contrasts markedly with that on flowering. A 10- to 50-fold greater dose is required for maximum promotion of stem elongation, and the response is not influenced by time of application relative to the inductive dark period. These differing responses of flowering and stem elongation raise questions about the use of relatively stable, highly bioactive GAs such as GA3 to probe the flowering response. It is proposed that the `ideal' GAs for promoting flowering may be highly bioactive but with only a short lifetime in the plant and, hence, will have little or no effect on stem elongation. 相似文献
17.
G. L. Steffens J. T. Lin A. E. Stafford J. D. Metzger J. P. Hazebroek 《Journal of Plant Growth Regulation》1992,11(3):165-170
Seeds from heavily fruiting (on-year), mature untreated, and paclobutrazol-treated apple trees (Malus domestica Borkh. cv. Spartan) were sampled in mid-June 1987, mid-July 1987, and mid-July 1990. After seeds were freeze-dried, gibberellins (GAs) were extracted, purified, and fractionated via C18 reversed-phase high-performance liquid chromatography (HPLC). Nine GAs (GA1, GA3, GA4, GA7, GA8, GA9, GA19, GA20, and GA53) were quantified by the use of deuterated GA internal standards. Paclobutrazol trunk drench treatments reduced vegetative shoot elongation in the seasons that seeds were sampled by 55% or more. Between June 17, 1987 and July 15, 1987, the dry weight of seeds from both untreated and treated trees increased about 2.5 times and there were reductions, on a per seed basis, of GA4 in seeds from both untreated and treated trees, of GA7 in seeds from treated trees, and of GA9 in seeds from untreated trees. However, GA9 increased in seeds from treated trees. Changes in levels of some of the early-13-hydroxylation pathway GAs (GA15 GA3, GA8, GA19, GA20, and GA53) also occurred during the month. For mid-July harvested seeds, the pattern, with some exceptions, was that 2 years after paclobutrazol treatment (1987), levels of early-13-hydroxylation pathway GAs in seeds from treated trees were lower compared to controls but after 5 years (1990) their levels tended to increase. For the non-13-hydroxylated GAs (GA4, GA7, and GA9), 2 years after paclobutrazol treatment, GA4 levels were equal in seeds from untreated and treated trees, GA7 decreased in seeds from treated trees compared with controls, but GA9 levels increased. Levels of these three GAs were higher in seeds from treated trees 5 years after treatment (1990) but levels of GA4, GA7, and GA9 dramatically increased in seeds from treated trees 4 years after treatment (1989), as we previously reported. 相似文献
18.
Endogenous gibberellins (GAs) were extracted from flushing (expanding) vegetative buds of river alder (Alnus tenuifolia), European white birch (Betula pendula), and aspen (Populus tremuloides) and identified by gas chromatography-mass spectrometry with full scans and/or selected ion monitoring. Five 13-hydroxylated GAs were detected from the three trees: GA1, 8, and 20 from alder, GA1, 8, 19 and 20 from aspen and GA1, 8, 19, 20, and 29 from birch. Thirteen other GAs previously detected in Salix or common in other plants were specifically investigated but not detected. The presence of GA1, its probable precursors GA19 and GA20, and its probable metabolite, GA8, suggests that the early 13-hydroxylated GA biosynthetic pathway is dominant in vegetative buds of these trees. Abundant endogenous GAs of these trees are similar to the principal GAs of willows (various Salix spp.) and poplars (various Populus spp.). This suggests similarities in the GA physiology and is consistent with a common role of GA1 as a regulator of shoot growth in woody angiosperms. 相似文献
19.
Combinations of far-red light (FR) (4 min) and gibberellic acid (GA3), given at the beginning of a daily 12-h dark period in a growth room, were used to study floral induction in four maturity genotypes of the milo group of sorghum (Sorghum bicolor (L.) Moench). The 12-h dark period without GA3 application or FR induced flowering in only the early genotype; FR hastened initiation in the early genotype, while GA3 hastened floral initiation in the two intermidiate-flowering genotypes. GA3 and FR together had a strong synergistic effect, hastening floral initiation by 30 to more than 80 d in the early and intermediate genotypes. Red light (R) did not hasten flowering; FR preceded by R gave the same effect as FR alone. GA3 promoted stem elongation equally whether floral initiation occurred or not; thus, its effect on stem elongation was independent of floral initiation. The capacity of GA3 to induce flowering in sorghum, a short-day plant, seems to be enhanced by phytochrome being in the PR form at the beginning of the night when GA3 was applied.Abbreviations FR
far-red light
- GA(s)
gibberellin(s)
- GA3
gibberellic acid
- R
red light 相似文献
20.
The role of gibberellins (GAs) in determining sex in the gametophyte of the fern Blechnum spicant L. was studied through (a) the effect of exogenous GA4+7 and GA3 (b) quantitation of the endogenous levels of GA1, GA3, GA4, GA7, GA9, and GA20 in male and female gametophytes, and (c) the effect of flurprimidol, a GAs biosynthesis inhibitor of the steps of oxidation of ent-kaureno to ent-kaurenoic acid. Our results show that GA4+7 had a slight effect of inducing either male or female sexual organs, antheridia and archegonia, respectively. The endogenous GAs content was not significantly different between sexes, but the GA4, GA7, and GA20 levels were raised above those of the other GAs in both sexes. Neither antheridiogen biosynthesis nor antheridia formation was inhibited by flurprimidol. Gametophytes regenerated from homogenized mature gametophytes (HG) show a different physiological behavior than spore-derived gametophytes. In the first case, gametophytes are males and synthesize antheridiogen before they attain maturity, in contrast to what occurs in spore-derived gametophytes which are females and synthesize antheridiogen when mature. 相似文献