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Gibberellins and Light Inhibition of Stem Growth in Peas

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... Indeed, since the pre-molecular era, it has been accepted (although with some controversy) that the control of hormone-triggered responses might be exerted by concentration changes, by alterations in tissue sensitivity, or by a combination of both (Cleland, 1983). Similarly, light treatments were postulated to alter hypocotyl/stem elongation by modifying these two aspects of hormone action: levels and sensitivity (Kende and Lang, 1964;Kamiya and Garcia-Martinez, 1999;Alabadi and Blazquez, 2009). However, the molecular basis of how changes in hormone sensitivity are instrumented after plant proximity perception remains almost unexplored. ...
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The shade avoidance syndrome (SAS) refers to a set of plant responses initiated after perception by the phytochromes of light enriched in far-red colour reflected from or filtered by neighbouring plants. These varied responses are aimed at anticipating eventual shading from potential competitor vegetation. In Arabidopsis thaliana, the most obvious SAS response at the seedling stage is the increase in hypocotyl elongation. Here, we describe how plant proximity perception rapidly and temporally alters the levels of not only auxins but also active brassinosteroids and gibberellins. At the same time, shade alters the seedling sensitivity to hormones. Plant proximity perception also involves dramatic changes in gene expression that rapidly result in a new balance between positive and negative factors in a network of interacting basic helix–loop–helix proteins, such as HFR1, PAR1, and BIM and BEE factors. Here, it was shown that several of these factors act as auxin- and BR-responsiveness modulators, which ultimately control the intensity or degree of hypocotyl elongation. It was deduced that, as a consequence of the plant proximity-dependent new, dynamic, and local balance between hormone synthesis and sensitivity (mechanistically resulting from a restructured network of SAS regulators), SAS responses are unleashed and hypocotyls elongate.
... Like Hyoscyamus niger (43) and Urtica pilulifera (47) spinach shows less inhibition at photoperiods of 3 h than at 8-10 h. From the investigations of LOCKHART (44), LOCKHART and GOTTSCHALL (46), GORTER (18), KENDE and LANG (31) and KOHLER (34,35), it seems that in peas light exercises an inhibiting effect on stem growth, which is overcome by the production of gibberellins. LOCKHART (45) showed that the light inhibition in dwarf peas is mediated by the phytochrome system, red light being most effective in causing suppression of stem growth. ...
Thesis
Influences of genotype (cultivar), temperature, light intensity, gibberellic acid (GA <sub>3</sub> ) and daylength on stem elongation and flowering of spinach were investigated. Most cultivars reacted quantitatively to long days (LD) both for stem and flower formation. Daylength requirements varied from almost dayneutral to LD. Cold, 2-8°C, decreased daylength requirement; 9-12° only accelerated stem growth. All cvs reacted similarly to temperature. Dimmer light decreased daylength requirement, especially in later cvs. GA <sub>3</sub> accelerated stem growth strongly, flower- formation only slightly. There was no juvenile stage for temperature or daylength response. Regression of flower formation may occur in a qualitatively LD cv after transfer to SD. Flower formation was most inhibited with photoperiods of 6-10 h; it increased with shorter or longer photoperiods. A qualitative LD cv as 'Nobel' remained vegetative only in SD, if stem growth was inhibited. In SD differentiation in axillary primordia and the consequent formation of flower clusters occurred much slower than in LD and stopped early unless caulescent tissue grew at low temperatures, dim light or GA <sub>3</sub> in accordance with the hypothesis of Chailakhyan that both gibberellins and floral stimulus were needed for stem growth and flower differentiation, respectively, of LD rosette plants. Formation of both hormones would depend on daylength. Cvs were earlier where they required shorter daylength and where they grew faster. By studying the influences of temperature, vernalisation, light intensity and GA <sub>3</sub> on yields, through their influence on developmental rate and growth rate, several practical conclusions could be drawn about optimum sowing date.
... It is useful to compare this suggestion with information available for the control of stem growth in pea plants, which are more readily available for extraction experiments. For that species, evidence is accumulating that the inhibitory effect of light on stem growth, and the genetic control of stem growth, are mediated through a control over the response of the tissue to gibberellin, rather than a control operating in the pathway of gibberellin synthesis (see, for example, Kende and Lang 1964;Jones and Lang 1968;McComb and McComb 1970). ...
Article
Shoots of the aquatic, Callitriche, form floating rosettes of leaves, the internodes of which elongate if the shoot is submerged, or treated at the water surface with gibberellic acid (McComb 1965; Wong and McComb 1967). It may therefore be tentatively proposed that submerged shoots synthesize more gibberellin than do floating shoots. To obtain further information concerning this hypothesis, investiga-tions have been carried out with the growth retardants Amo1618 and CCC, com-pounds which characteristically bring about dwarfing in higher plants, an effect reversed by gibberellin (e.g. McComb and McComb 1970), and which have been shown to inhibit gibberellin biosynthesis in certain systems (e.g. Baldev, Lang, and Agatep 1965; Dennis, Upper, and West 1965; Zeevaart 1966).
... To date, the functions of GA and BR associated with plant growth and development have been investigated intensively. Gibberellin is mainly concentrated on promoting the extension of stem, germination, seed dormancy, flowering, gender performance, root development, and aging suppression of leaf and fruit (Tyler et al. 2004;Kende and Lang 1964;Olszewski et al. 2002;Fu and Harberd 2003;Groot et al. 1987). In addition, BR plays important regulatory roles in seed dormancy and germination, organ differentiation, vascular tissue development, flowering and senescence, morphogenesis and other various important growth and development processes (Topping et al. 1997;Souter et al. 2002;Schlagnhaufer and Arteca 1985;Diener et al. 2000). ...
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The ornamental Brassica oleracea var. acephala f. tricolor is a good winter and spring foliage plant. Plant architecture is an important agronomic trait of plants, especially for ornamental plants with high ornamental and economic value. In this study, three miniature-related genes, BoDWARF, BoGA20ox and BoSP (SELF-PRUNING), were cloned and their tissue-specific expression patterns were analyzed. The results showed that the three genes were all highly expressed in young leaves and flowers, followed by the lateral roots, seeds and stems. To further achieve the purpose of miniaturization of plants, an RNAi expression vector, jointly targeting BoDWARF, BoGA20ox and BoSP, was constructed and transformed into kale plants. Smaller plant size and slower growth and development speed of flowers and roots were observed in jointly silenced kales. Brassinosteroids and gibberellin contents in leaves and flower buds of transgenic plants were significantly decreased. Furthermore, the expressions of brassinolide-, gibberellin- and flowering-related genes were down-regulated by varying degrees in silenced plants. These results suggest that BoDWARF, BoGA20ox and BoSP play important roles in plant architecture, and that brassinolide and gibberellin are important hormones controlling plant growth and architecture. This miniaturization strategy of kale provides an efficient approach for cultivation of new varieties of ornamental plants and crops.
... The inhibition of stem growth by light has been studied for decades. Pioneering work on pea (Pisum sativum; Lockhart, 1956;Kende and Lang, 1964) indicated that the inhibition could be reversed by the application of exogenous gibberellic acid (GA 3 ), suggesting a role for GAs in mediating the light response. This work also suggested the involvement of phytochrome since the response to light was red (R)/far red (FR)-reversible (Lockhart, 1956). ...
Article
The level of gibberellin A1 (GA1) in shoots of pea (Pisum sativum) dropped rapidly during the first 24 h of de-etiolation. The level then increased between 1 and 5 d after transfer to white light. Comparison of the metabolism of [13C3H] GA20 suggested that the initial drop in GA1 after transfer is mediated by a light-induced increase in the 2β-hydroxylation of GA1 to GA8. A comparison of the elongation response to GA1 at early and late stages of de-etiolation provided strong evidence for a change in GA1 response during de-etiolation, coinciding with the return of GA1 levels to the normal, homeostatic levels found in light- and dark-grown plants. The emerging picture of the control of shoot elongation by light involves an initial inhibition of elongation by a light-induced decrease in GA1 levels, with continued inhibition mediated by a light-induced change in the plant's response to the endogenous level of GA1. Hence the plant uses a change in hormone level to respond to a change in the environment, but over time, homeostasis returns the level of the hormone to normal once the ongoing change in environment is accommodated by a change in the response of the plant to the hormone.
Article
'Alaska’ peas (Pisum sativum L.) grown under a 16-hr photoperiod at 20 ± 1 C and an 8-hr dark period at 16 ± 1 C in their ontogeny exhibit two periods of sensitivity to applied gibberellin (GA), namely, prior to and subsequent to but not during the linear phase of stem elongation. This paper describes experiments conducted primarily with seedlings. Growth-saturating doses of GA, applied to dry seeds before planting (10⁻³ m) and to the shoot tips of 3-day-old seedlings (10 μg), evoked growth rates equal to the growth rate of etiolated seedlings. Sensitivity of seedlings to applied GA decreased with age through the first 2 to 3 weeks of development; by the time seedlings were about 14 days of age and had four elongating internodes they no longer responded to applied GA. As endogenous growth rate diminished late in ontogeny, the plants again became sensitive to applied GA. Growth response was used as a criterion for determining apparent translocation of applied GA. ‘Alaska’ pea seedlings appeared to transport GA, both acropetally from the cotyledons and basipetally from the shoot tip, to all internodes with remaining extension potential. Excision of both cotyledons at any time during the first 9 days of development caused a significant reduction of growth rate, and applied GA did not restore normal growth rate. No evidence was found that the cotyledons supply endogenous GA to the shoot axis in normal seedling development. It is suggested that the normal growth rate of light-grown ‘Alaska’ peas is correlated with the rate of synthesis of GA and that GA is rate-limiting for stem elongation during early seedling development and during the period of decreasing growth rate and onset of apex senescence.
Article
The physiological basis of dwarfism in a single-gene, recessive mutant of Silene armeria L. was investigated through comparison with a normal strain. Exposure of the normal strain to long days led to stem growth and flower formation while similar exposure of the dwarf strain led only to flowering, with very little stem growth. Application of gibberellin A3 or A4+7 in short days promoted stem elongation in the normal strain, but had a much lesser effect in the dwarf strain. Upon extraction and chromatographic fractionation of the endogenous gibberellins (GAs) in the normal strain of S. armeria, three zones of GA activity were found. An increase in one zone of activity was found in both strains after 1 long day. Neither the quality nor the quantity of the extractable GAs differed greatly between the dwarf and the normal strain. Vegetative dwarf scions, grafted onto fully induced, normal stocks formed flowers, but their growth habit was not changed. Thus, the lack of stem growth in response to long days in the dwarf strain appears to result from a lack of GA sensitivity in the stem tissue of these plants. However, during flower formation dwarf plants did exhibit elongation of the peduncles. This response was suppressed by the growth retardant 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride (AMO-1618), and applied GA3 could partially overcome this inhibition. Thus, peduncle elongation in the dwarf strain appears to be regulated by endogenous GAs.
Article
Gibberellin-like substances were present in cell-free culture medium of autotrophically grown Thiobacillus novellus. Dwarf-pea and cucumber-hypocotyl bioassays indicate presence of two gibberellin-like compounds.
Article
The gibberellin A1 (GA1)-like and GA5-like fractions from immature seeds of Pisum sativum cv. Progress No. 9 were identified by combined gas chromatography-mass spectrometry as GA29 and GA20 respectively.
Article
Inhibition of hypocotyl lengthening in Lupinus albus seedlings mediated through the high energy reaction was not reversed by 5 authentic gibberellins nor by extracted lupin "gibberellin-like" compounds. However, inhibition by continuous light was largely overcome by applying IAA (indole-3-acetic acid) to intact seedlings. In contrast, inhibition of lengthening mediated through phytochrome in its low energy mode was reversed by gibberellin. It is concluded that light antagonises hormone-regulated growth.
Article
Six authentic gibberellins marginally promoted hypocotyl lengthening of etiolated lupin seedlings whereas extracted lupin "gibberellin-like" compounds were ineffective. However, dwarfing by AMO-1618 [2'-isopropyl-4'-(trimethyl-ammonium chloride)-5'-methylphenyl piperidine carboxylate] was totally counteracted by co-application with GA3 and partially overcome by extracted lupin "gibberellins". Meaningful quantities of free extractable and diffusible gibberellins were detected; "bound" gibberellin activity was not found. The time-course of the decline in extractable gibberellin levels during the process of dwarfing showed a significant difference from 6 h after applying AMO-1618. It is suggested that axis growth is dependent on gibberellin in a system normally close to saturation for endogenous growth.
Article
Light inhibits the rate of stem elongation of Phaseolus coccineus L. seedlings. Gibberellin A4 (GA4), an endogenous component of Phaseolus seedlings (Bowen et al., Phytochem. 12, 2935-2941, 1973) promotes stem growth in the light but not in darkness. Dark-grown seedlings contain larger GA pools than light-grown plants. Apically applied [(3)H]GA4 in etiolated bolised more extensively in the light. The slower rate of metabolism of [(3)H]GA4 in etiolated seedlings is not a consequence of isotopic dilution by the endogenous GA4 pool or a lack of penetration of the labelled material. While it can be concluded that the capacity of seedlings to metabolise [(3)H]GA4 is greater in the light than in darkness, it does not necessarily follow that there is a more rapid rate of turnover of endogenous GA4 in light-grown tissues. The results are discussed in relation to the involvement of GAs in the inhibitory effects of ligh on stem elongation.
Article
When apical senescence in the genetic line of peas G2 was prevented by short days fruit development was also found to be retarded. The levels of GA20 and GA29 in cotyledons and pods grown under long or short days were measured by gas chromatography - mass spectrometry multiple ion monitoring using extracts derivatised with deuterated trimethylsilyl groups as internal standards. The levels of GA20 but not GA29, were increased by short days. Conventional gas chromatography - mass spectrometry showed that relative to GA29 the levels of GA19, the other GA identified in G2 cotyledons, were also increased in short days. The levels of GA20 in the pods were highest during the main phase of pod growth early in fruit development.
Article
The following seven gibberellins (GAs) have been identified by gas chromatography-mass spectrometry in shoots and leaves of the long-day plant Agrostemma githago: GA53, GA44, GA19, GA17, GA20, GA1, and 3-epi-GA1. The levels of these compounds were measured, using selected ion monitoring, during photoperiodic induction. The levels of GA44, GA19, GA17, and GA20 all increased to a peak at eight long days (LD), followed by a decline, while the levels of GA1 and 3-epi-GA1 did not reach a peak until 12 LD. The level of GA53 remained steady over the first 10-12 LD. Later in the LD treatment the levels of GA53, GA44, GA19, and GA17 increased again. The rate of metabolism of all GAs except GA53 was higher after 12-16 LD than under short days. These data thus provide indirect evidence for an effect of photoperiodic induction on GA turnover in A. githago.
Article
When radioactive gibberellin A5 (3H-GA5) was applied to the apices and surrounding young leaves of the long-day plant Silene armeria, it was partially converted to at least two other acidic substances. One of them was similar to GA3 in chromatographic, but not in biological properties. The other metabolite was more polar than GA3 and inactive in the dwarf d-5 corn assay. The rate of 3H-GA5 conversion was influenced by the photoperiod under which Silene plants were grown. Exposure to 2 long days significantly increased 3H-GA5 metabolism over that in control plants kept under short days. The increased conversion of 3H-GA5 persisted for at least a few days after transferring Silene plants back from long to short days. Likewise, stem growth induced by long photoperiods continued for a considerable period of time under subsequent short days. Application of the growth retardant AMO-1618 to Silene reduced the levels of two endogenous GA-like substances, one of them with GA5-like properties, more under long than under short days. These results indicate that long photoperiods, which induce flower formation and stem elongation in Silene, increase the turnover of endogenous gibberellins.
Article
Agrostemma githago is a long-day rosette plant in which transfer from short days (SD) to long days (LD) results in rapid stem elongation, following a lag phase of 7-8 d. Application of gibberellin A20 (GA20) stimulated stem elongation in plants under SD, while 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride (AMO-1618, an inhibitor of GA biosynthesis) inhibited stem elongation in plants exposed to LD. This inhibition of stem elongation by AMO-1618 was overcome by simultaneous application of GA20, indicating that GAs play a role in the photoperiodic control of stem elongation in this species. Endogenous GA-like substances were analyzed using reverse-phase high-performance liquid chromatography and the d-5 corn (Zea mays L.) assay. Three zones with GA-like activity were detected and designated, in order of decreasing polarity, as A, B, and C. A transient, 10-fold increase in the activity of zone B occurred after 8-10 LD, coincident with the transition from lag phase to the phase of rapid stem elongation. After 16 LD the activity in this zone had returned to a level similar to that under SD, even though the plants were elongating rapidly by this time. However, when AMO-1618 was applied to plants after 11 LD, there was a rapid reduction in the rate of stem elongation, indicating that continued GA biosynthesis was necessary following the transient increase in activity of zone B, if stem elongation was to continue under LD. It was concluded that control of stem elongation in A. githago involves more than a simple qualitative or quantitative change in the levels of endogenous GAs, and that photoperiodic induction alters both the sensitivity to GAs and the rate of turnover of endogenous GAs.
Article
Gibberellins (GAs) A17, A19, A20, A29, A44, 2βOH-GA44 (tentative) and GA29-catabolite were identified in 21-day-old seeds of Pisum sativum cv. Alaska (tall). These GAs are qualitatively similar to those in the dwarf cultivar Progress No. 9 with the exception of GA19 which does not accumulate in Progress seeds. There was no evidence for the presence of 3-hydroxylated GAs in 21 day-old Alaska seeds. Dark-grown shoots of the cultivar Alaska contein GA1, GA8, GA20, GA29, GA8-catabolite and GA29-catabolite. Dark-grown shoots of the cultivar Progress No.9 contain GA8, GA20, GA29 and GA29-catabolite, and the presence of GA1 was strongly indicated. Quantitation using GAs labelled with stable isotope showed the level of GA1 in dark-grown shoots of the two cultivars to be almost identical, whilst the levels of GA20, GA29 and GA29-catabolite were significantly lower in Alaska than in Progress No. 9. The levels of these GAs in dark-grown shoots were 10(2)- to 10(3)-fold less than the levels in developing seeds. The 2-epimer of GA29 is present in dark-grown-shoot extracts of both cultivars and is not thought to be an artefact.
Article
The stem growth in darkness or in continuous red light of two pea cultivars, Alaska (Le Le, tall) and Progress No. 9 (le le, dwarf), was measured for 13 d. The lengths of the first three internodes in dark-grown seedlings of the two cultivars were similar, substantiating previous literature reports that Progress No. 9 has a tall phenotype in the dark. The biological activity of gibberellin A20 (GA20), which is normally inactive in le le geno-types, was compared in darkness and in red light. Alaska seedlings, regardless of growing conditions, responded to GA20. Dark-grown seedlings of Progress No. 9 also responded to GA20, although red-light-grown seedlings did not. Gibberellin A1 was active in both cultivars, in both darkness and red light. The metabolism of [(13)C(3)H]GA20 has also been studied. In dark-grown shoots of Alaska and Progress No. 9 [(13)C(3)H]GA20 is converted to [(13)C(3)H]GA1, [(13)C(3)H]GA8, [(13)C]GA29, its 2α-epimer, and [(13)C(3)H]GA29-catabolite. [(13)C(3)H] Gibberellin A1 was a minor product which appeared to be rapidly turned over, so that in some feeds only its metabolite, [(13)C(3)H]GA8, was detected. However results do indicate that the tall growth habit of Progress No. 9 in the dark, and its ability to respond to GA20 in the dark may be related to its capacity to 3β-hydroxylate GA20 to give GA1. In red light the overall metabolism of [(13)C(3)H]GA20 was reduced in both cultivars. There is some evidence that 3β-hydroxylation of [(13)C(3)H]GA20 can occur in red light-grown Alaska seedlings, but no 3β-hydroxylated metabolites of [(13)C(3)H]GA20 were observed in red light-grown Progress. Thus the dwarf habit of Progress No. 9 in red light and its inability to respond to GA20 may be related, as in other dwarf genotypes, to its inability to 3β-hydroxylate GA20 to GA1. However identification and quantification of native GAs in both cultivars showed that red-light-grown Progress does contain native GA1. Thus the inability of red light-grown Progress No. 9 seedlings to respond to, and to 3β-hydroxylate, applied GA20 may be due to an effect of red light on uptake and compartmentation of GAs.
Article
In order to correlate the role of endogenous inhibitors of growth of soybean plants with the inhibition of such growth by red light (R), a search for specific growth inhibitors was undertaken in the neutral and acidic fractions of acetone extracts from R- and dark-grown hypocotyls of soybean seedlings (Glycine max L.). Two neutral and two acidic inhibitors were isolated. They were named N-I and N-II (neutral inhibitors) and A-I and A-II (acidic inhibitors), respectively, based on the order of their increasing Rf values during chromatography. Variations in the activity of the inhibitors in the hypocotyls of dark-grown seedlings after the onset of R irradiation were determined in terms of «cress units» which were defined as the activity that causes 50 % inhibition in the cress-root bioassay. The inhibitory activity of N-I and N-II tripled after exposure of plants to R for 24 h, whereas the activity of A-I and A-II remained almost unchanged. These results suggest that R-induced inhibition of growth of soybean hypocotyls may be controlled by variations in the levels of the neutral inhibitors, N-I and/or N-II, in the hypocotyls rather than by the acidic inhibitors.
Article
In order to clarify the role of endogenous inhibitors of growth in dwarf and tall bean plants, a search for specific inhibitors of growth was undertaken using the neutral fractions of acetone extracts from the hypocotyls of dwarf (cv. Morocco) and tall (cv. Kentucky Wonder) bean seedlings (Phaseolus vulgaris L. Three inhibitors were isolated from both cultivars and they were named N-1, N-2 and N-3, respectively, on the basis of the order of their elution from a silica-gel column. Variations in the activity of the inhibitors in hypocotyls of both cultivars after the onset of red-light irradiation were determined by use of a bean bioassay, and results were compared with those of red-light-induced inhibition of growth. The difference in the activity of N-1 between the two cultivars was particularly great, and the changes with time in levels of N-1 in hypocotyls of each cultivar matched the time course of the red-light-induced inhibition of growth of hypocotyls of the same cultivar. No such correlation was found with N-2 and N-3. These results suggest that red-light-induced inhibition of growth of bean hypocotyls may be controlled by variations in the levels of N-1. N-2 was spectroscopically identified as a mixture of xanthoxins.
Article
The free acid gibberellins in extracts from young second internodes of dwarf and tall Phaseolus vulgaris seedlings were bioassayed with the tall pea assay. Tall plants contain more gibberellin-like substances than dwarf ones; amounts found correspond with fresh-weights of extracted internodes. Since dwarfs grow like tails after application of a bean gibberellin, it is concluded, that the low gibberellin-content of dwarf shoots is the cause and not the consequence of dwarfism in beans. The gibberellin deficit of the dwarf shoot seems to be the consequence of the low gibberellin content in cotyledons of dwarfs, which was found by Goto and Esashi.
Article
Gibberellin A14-[17-3H] applied to seedlings of dark grown dwarf pea (Pisum sativum L. cy. Meteor) was converted to GA1, GA8, GA18, GA23, GA28, and GA38. The sequence of interconversion of GA14→ GA18 → GA38 → GA23 → GA1 → GA8 is indicated. Identifications were made by gas-liquid radiochromatography using three liquid stationary phases.
Article
Tritium labelled gibberellin A20 ([3H]-GA20) applied to etiolated shoots and germinating seeds of dwarf pea (Pisum sativum L. cv. Meteor) was converted to gibberellin A29. Identifications were made by GLRC and GC-MS.
Article
The regulation of ribulose-1,5-bisphosphate carboxylase (RuBPCase) by light and hormones has been studied in excised cotyledons of Cucumis sativus L. to determine the relationship between photomorphogenetic and hormonal control. Both content and activity of the enzyme are increased by light, this effeet being mediated by phytochrome, and can be stimulated by external application of 6-benzylaminopurine (BAP) and gibberellic aeid (GA3). With increasing cytokinin concentration the effectiveness of light decreases and saturation by BAP is reached at lower concentrations in the light than in darkness, indicating interactions between photocontrol and cytokinin regulation. However, even at saturating and optimal BAP concentrations light retains a promoting influence which is supposed to be a cytokinin-independent component of light effect. Finally, a two-factor-analysis concerning BAP and GA3 was performed. A positive correlation between GA3 concentration and enzyme activity in the absence of BAP and an inhibition of cytokinin-mediated stimulation of RuBPCase by GA3 indicate interactions between the two hormones.
Article
[3H]-Gibberellin A5 ([3H]-GA5) applied to seedlings of dark-grown dwarf pea (Pisum sativum L. cv. Meteor), was converted to two acidic compounds, GA3 and a chromatographically similar unknown. Identification of GA3 was made by gas-liquid radiochromatography using three stationary phases.
Article
The main gibberellin in immature seed of Pisum sativum L., cv. Alaska, is identified as GA20 by GC-MS. GA9 may also be present.
Article
An extract from 6000 dark-grown Phaseolus coccineus seedlings was purified by countercurrent distribution and G-10 Sephadex followed by gradient elution from a silicic acid partition column with increasing amounts of ethyl actetate in n-hexane. 25 fractions were collected and tested with the barley-aleurone, ‘Tan-ginbozu’ dwarf-rice, lettuce, cucumber, dwarf-pea, d-1, d-2, d-3 and d-5 maize, oat first-internode, and sugarcane-spindle bioassays. Major gibberellin (GA)-like activity was detected in fractions 4 (500μg GA3-equivalents) and 12–13 (270 μg GA3-equivalents) with smaller amounts in fractions 6, 8–9, 15–16, 18, 20, 23 and 25. The extracts were also applied to AMO-1618=dwarfed Ph.-coccineus seedlings. Fractions 4, 8 and 12 promoted the growth of both light- and dark-grown seedlings. GA1, GA3, GA4 and GA8 were active in the Phaseolus bioassay but GA8-glucoside was inactive. The biological and chromatographic properties of fractions 4, 8–9 and 12–13 correspond with those of GA4, GA19 and GA1. The identity of GA4 in fraction 4 was conclusively established by combined gas chromatography-mass spectrometry (GC-MS) of the methyl ester and the trimethylsilyl ether of the methyl ester. Gasliquid-chromatography peaks corresponding to these derivatives of GA19 and GA1 were detected on QF-1 and SE-33 columns but their intensities were too weak to permit conclusive identification by GC-MS.
Article
Lettuce and barley endosperm bioassays of successive eluates from a phosphate-buffered celite column detected two gibberellin-like compunds, Phaseolus I and Phaseolus II, in extracts of both light-and dark-grown seedlings of Phaseolus multiforus. There were differences in the gibberellin content of light-and dark-grown seedlings, the former containing more Phaseolus I but less Phaseolus II than the latter. An examination of the gibberellin content of leaves and apical buds, stems, cotyledons, and roots of light-and dark-grown seedlings revealed distinct qualitative and quantitative differences in the distribution of Phaseolus I and Phaseolus II.
Article
Reciprocal grafts between plants of the tall variety Alaska and the dwarf Progress No. 9 show that neither roots nor mature leaves determine shoot phenotype. It is demonstrated that differences in stem growth between the two varieties are essentially controlled by a single Mendelian factor, and the effect of this Le locus is not graft transmissible. Combined with published data for gibberellin content this confirms that the Le locus does not control shoot phenotype by regulating gibberellin synthesis. Growth of slender plants (Le la cry s ) and early growth of microcryptodwarfs (le la cry c lm) is not inhibited by AMO-1618 at concentrations which greatly reduce growth of tall plants. This is consistent with the suggestion that rapid growth in these varieties, in the absence of the inhibitory effect of La and Cry, is not dependent on endogenous gibberellin.
Chapter
Over two millenia, observers of plants have noticed that one part of a plant may influence or control the activities of another part (see, e.g., Wiesner 1871, Dostal 1967). There are diverse examples, such as axillary buds growing out when the main bud has been removed (Goebel 1900, Snow 1925), excision of seeds from fleshy fruit promoting their germination (Albertus Magnus, thirteenth century, see Wareing 1965), cutting off the coleoptile tip preventing coleoptile tropisms (Darwin and Darwin 1880), removal of the embryo blocking starch degradation in grains (Brown and Morris 1890), partial defoliation altering bud growth (Loeb 1918) and removal of reproductive structures delaying the senescence of leaves and stems (Molisch 1928).
Chapter
In dem vorliegenden Abschnitt werden Primärreaktionen und biochemische Folgeprozesse von Photoreaktionssystemen behandelt, die nicht zur Photosynthese gehören. Lichtwirkungen auf Entwicklungs- und Bewegungsprozesse (einschließlich Photoperiodismus u. a.) werden in den Abschnitten „Entwicklungsphysiologie“ bzw. „Bewegungen“ besprochen.
Chapter
All research on the gibberellins (GAs) actually stems from the work of E. Kurosawa, a Japanese plant pathologist working in Formosa, who generally is credited with having discovered GA in 1926. However, the gibberellin story actually had its beginning in the last decade of the nineteenth century.
Chapter
All research on the gibberellins (GAs) actually stems from the work of E. Kurosawa, a Japanese plant pathologist working in Formosa, who generally is credited with having discovered GA in 1926. However, the gibberellin story actually had its beginning in the last decade of the nineteenth century.
Chapter
During the 30 years since its initial isolation, a great body of information has accumulated concerning the structure of phytochrome, the physiological responses it controls, and the genes whose expression it affects, yet little is known about the molecular mechanisms of phytochrome action. The recent advent of technologies allowing the expression of heterologous phytochrome genes in transgenic plants provide an important new method for research into the mechanisms of phytochrome action (Keller et al., 1989; Boylan and Quail, 1989; Kay et al., 1989). In the first report of this approach, Keller et al. (1989) described the expression of a functional oat phytochrome in tobacco. Transgenic plants expressing the oat protein have a radically altered phenotype characterized by decreased stem elongation, increased leaf chlorophyll content, reduced apical dominance, and delayed leaf senescence. Exploiting this “light-exaggerated” phenotype as an assay, it is now possible to identify and examine domains involved in phytochrome structure and function by in vitro mutagenesis.
Chapter
Alteration of the growth and form of plants by light is certainly one of the most notable and important ways in which the environment affects plants. Plants growing in complete darkness take on a peculiar appearance: stems become long and spindly, leaves remain folded and are usually small, and the apical part of the stem often forms a hook (Fig. 1). Such appearance is referred to as etiolated. Other characteristics of etiolation include suppressed chloroplast development, reduced pigmentation (both photosynthetic and non-photosynthetic pigments), and reduced levels of many enzymes and other substances. In this chapter we will concentrate on the control of plant size and shape by light.
Chapter
Als einfach sollen solche Indolderivate bezeichnet werden, die außer dem Indolring (s. Tab. 88, A) keine zusätzlichen Ringsysteme aufweisen. Ihnen stehen komplizierter gebaute Indolalkaloide (S. 428) und Indolfarbstoffe gegenüber.
Chapter
Light, perceived and transduced by a number of photoreceptors, is known to regulate or modify many aspects of plant growth and development. Beginning with seed germination and ending with fruiting and senescence, light can regulate processes which can also be modified by plant hormones. This has been taken as circumstantial evidence that light may be exerting its influence via plant hormones, and considerable research effort has been directed toward elucidating the role of plant hormones in light-mediated processes. The two areas of light and plant hormone research that have received the most attention are de-etiolation and photoperiodism (see Vince-Prue, Chap. 9 this Vol.). While the emphasis, by necessity, of this chapter is on plant hormones in de-etiolation, we include relevant work on other aspects of photomorphogenesis and plant hormones.
Chapter
Gibberellins (GAs) are well known for their spectacular effects in intact plants. They were first discovered in the secretory products of Gibberella fujikuroi, a fungus infecting rice seedlings (for an historical account see 47). Diseased plants grow tall and spindly and tend to fall over under their own weight. In 1926, Kurosawa showed that fungal extracts applied to plants could induce the same symptoms as the pathogen. After, two compounds were crystallized from extracts and given the names Gibberellin A and B. It was not until the 1950s that the first chemical structure of GA was characterized. During that period, a number of laboratories reported that extracts of higher plants could induce similar biological responses as those obtained with fungal GA. This opened the way to intensive analytical research and GAs were eventually detected in various taxa of lower and higher plants. The notion that GAs are in fact genuine plant growth regulators gradually emerged. Chemical identification was pursued vigorously: more than 70 different GAs have been discovered so far. The principal metabolic pathways have also been extensively documented (see chapter B2). Besides its effect on stem elongation GAs affect a number of physiological processes such as fruit and flower formation, dormancy of vegetative organs as well as seed germination (23).
Article
When shoots of 6-day-old, dark-grown peas were excised 30 mm below the apex and floated on a solution of radioactive gibberellin A 1 (3H-GA1) or radioactive gibberellin A5 (3H-GA5), more radioactivity accumulated in the apical part of the stem which responds to GA than in the basal, unresponsive region. The accumulation of 3H-GA1 was, however, less pronounced than the accumulation of 3H-GA5. GA derivatives of very low biological activity were not taken up preferentially by the apical region of the stem. Light, which lowers the responsiveness of dwarf peas to GA1 and particularly to GA5, also reduced the accumulation of these GAs in the apical part of the stem. Sections from the GA-responsive region were able to retain a higher level of GA5 than sections from the non-responsive, basal region. The accumulation and retention of GA in the hormone-responsive tissue may be due to binding of the hormone to specific GA receptors.
Article
Indole derivatives possessing no ring system in addition to the indole ring (see Table 88A) may be entitled “simple”, in contrast to the more complex-structured indole alkaloids (p. 446) and indole dyes.
Article
Two gibberellin-like compounds, Phaseolus I and Phaseolus II, were detected in extracts of etiolated Phaseolus multiflorus seedlings. Phaseolus I shows activity in the barley endosperm and lettuce bioassays. Phaseolus II also is active in the barley endosperm assay but induces only a marginal response in the lettuce bioassay. Both Phaseolus I and II have thin-layer chromatographic properties similar to gibberellins A1 and A3 from which they can be separated by column partition chromatography. Although it is impossible at this time to identify either Phaseolus I or Phaseolus II, it appears that they are different from at least nineteen of the twenty-three gibberellins at present characterized.
Chapter
This chapter presents the aspects of the metabolism and physiology of gibberellins (GAs). The GAs are a group of diterpenoid acids, which function as endogenous regulators of the growth and development of higher plants. General acceptance of their hormonal role is based on the observation that GAs are natural components of the vast majority of higher plants, and that exogenous application of μg quantities of it can induce a wide range of plant growth responses. The concentration of GAs in the acidic ethyl acetate soluble fraction is usually very low so a multistep analytical procedure has to be employed to attain a degree of purity that facilitates an accurate determination of GA content. In most instances, extracts that have been subjected to a range of group purification procedures will still require further purification before successful attempts can be made at GA analysis. This is achieved through the use of analytical methods, which separate the GAs to some degree. The chapter explains the separatory techniques for GAs.
Chapter
This chapter discusses the microbial production of gibberellins. Gibberellins (GAS), a large family of closely related diterpenoid acids biologically derived from tetracyclic diterpenoid hydrocarbon, represent an important group of potent plant growth hormones. This chapter discusses the chemistry and biosynthetic pathways of GAS. It illustrates the mode of action, structure–activity relationship of GAS. The uses of GA are also discussed. GA is a high-value industrially important biochemical in the international market, depending on the purity and potency. Therefore, its use at present is limited to high-premium crops. The industrial process currently used for fermentative production of GA3 is based on submerged fermentation (SmF) techniques. This chapter critically examines the existing as well as the potential techniques of fermentation and product recovery in the production of GAS.
Article
Chrysanthemums (Dendranthema morifolium) are one of the most economically important perennial flowering plants, with floricultural (cut flowers), ornamental crop (pot and garden flowers) and, for some cultivars, medicinal uses. Plant architecture is an important agronomic trait for plants with a high ornamental and economic value. In this study, two miniature-related genes, DmCPD and DmGA20ox, were cloned and their tissue-specific expression patterns were analyzed. The results showed that the two genes were both highly expressed in stems, mature leaves, and flowers, and that DmCPD was also highly expressed in pedicels. To generate miniature plants, an RNAi expression vector targeting both DmCPD and DmGA20ox was constructed and transformed into chrysanthemum plants. Smaller plant size and slower growth and development of flowers were observed in dual-silenced chrysanthemums. Brassinosteroid and gibberellin contents in leaves and flower buds of transgenic plants were significantly decreased. Furthermore, the expressions of brassinolide-, gibberellin-, and flowering-related genes were down-regulated by varying degrees in dual-silenced plants. These results suggest that DmCPD and DmGA20ox play important roles in plant architecture, and brassinolide and gibberellin are important hormones in controlling plant architecture. This miniaturization strategy provides an efficient approach for generating new varieties of ornamental plants and crops.
Article
The ability of gibberellic acid (GA3) to prevent the light inhibition of stem elongation in peas was examined for several varieties under a wide range of irradiation conditions. A saturating dose of GA3 largely prevented the inhibitory effect of red light on total stem height in “Duke of Albany” (tall), “Alaska” (medium) and “Meteor” (dwarf) although a small, but statistically significant, effect persisted in all varieties after 3 days of light. The growth of the second internode was, however, markedly inhibited by red light even with a saturating dose of GA3. With gibberellin there was no difference between the effects of continuous red light and 15 minutes per day on height but the second internode was much shorter in the former treatment. The number of internodes present was the same in both cases and, therefore, the upper internodes in continuous light were as long or longer than in the 15-minute treatment. The number of internodes was only slightly fewer in darkness than in light so that, with GA3, the effect of red light was transient and only the growth of the lower internodes was inhibited. Without GA3 overall height was less in both red light treatments than in darkness for all three varieties. In blue light, on the other hand, there was no difference depending on whether height or internode length is considered, and even with a saturating dose of GA3 the growth rate remained depressed in continuous blue light. There was, however, some interaction between blue light and GA3. Red/far-red reversal experiments showed that in the varieties “Alska” and “Duke of Albany” the far-red stimulation of elongation persisted in the presence of a saturating dose of GA3 while for the dwarf variety “Meteor” there was a significant interaction between far-red and GA3. At least a quantitative difference was found between tall and dwarf peas in their response to light. Tall varieties showed a much greater effect of a prolonged exposure to blue and a smaller effect of a short exposure to red than dwarf varieties. Increasing the duration of exposure to red increasingly inhibited the growth of tall varieties. The medium variety “Alaska” grew to approximately the same height in continuous red and blue light.
Article
Responses of dark-grown pea seedlings of a dwarf (Progress No. 9) and a tall (Alaska) cultivar to red light have been compared 24 hours after irradiation. Identical percentage inhibition of elongation in 10-mm sub-apical segments of intact third internodes, identical dose-response curves and similar reversal of the inhibition by far-red light were observed. The time courses of the growth inhibition were quantitatively dissimilar in that seedlings of Alaska showed greater inhibition soon after light treatment, but greater recovery at later stages. Small varietal differences in phytochrome concentrations in comparable parts of the apical region correlate with early varietal differences in the growth response. Seedlings of Progress showed considerable far-red reversal of the red-light effect even with an extended time lapse between red and far-red irradiations, while decay of far-red reversibility was comparatively rapid in Alaska seedlings. It is concluded that there is no difference in energies required to activate the phytochrome system in the two varieties, but that the Pfr form of phytochrome probably remains stable and active in Progress but decays rapidly in Alaska seedlings.
Article
Aqueous buffers were used to extract gibberellin-like substances from pea tissue. The method possesses several distinct advantages when compared with extraction methods using organic solvents. Aqueous buffer extracts can be prepared more rapidly and produce extracts which are free of pigments and other alcohol soluble materials. Extraction of pea with aqueous buffer has indicated the presence of two gibbrellin-like substances in addition to those previously described.
Article
Gibberellins A3, A4+7 and A13 and (−)-kaurene delay floral-bud initiation and flowering and decrease the number of floral-buds and flowers in Impatiens balsamina under 4-hr photoperiods. They do not have any marked effect under 8-hr photoperiods. Under 16- and 24-hr photoperiods they hasten floral-bud initiation and flowering and increase the number of flowers, the effect being greater under 16- than under 24-hr days and the order of effectiveness being GA4+7>GA3>GA13>(−)-kaurene. While GA3 and GA4+7 promote extension growth, the effect being greater with the former, GA13 and (−)-kaurene do not promote it under any photoperiod. The magnitude of stem elongation in different treatments prior to floral-bud initiation increases from 4- to 8-hr photoperiods but decreases under 16- and 24-hr periods, the effect being more under 24-hr although both 16-and 24-hr photoperiods are noninductive for flowering.
Article
Gibberellin A1 is a dihydro-derivative of gibberellic acid since one of two dihydro-derivatives obtained by controlled hydrogenation of methyl gibberellate is shown to be identical with gibberellin A1 methyl ester. The isolation of some additional metabolites of Gibberella fujikuroi is described.
Article
PAPER chromatography of the gibberellins has been investigated by many investigators but no comprehensive study of all the known gibberellins has been reported. MacMillan, Seaton and Suter1 described four solvent systems which separate gibberellins A5, A6, A8 and A9 but not the pairs gibberellin A1 and gibberellic acid (A3) or gibberellins A4 and A7. The solvent systems used by Takahashi et al.2 and Phinney et al.3 do not separate gibberellins A1, A2 and A3. Gibberellins A1 and A3 can be separated on paper which is developed by overflow elution with benzene/acetic acid/water (4 : 1 : 2); this method is lengthy when conducted under gravity as described by Bird and Pugh4 and resolution is poor when development is hastened by centrifugal force5.
Article
The crude mixture of gibberellins produced in the pilot plant by the fungus Fusarium moniliforme (Gibberella fujikuroi)NRRL 2284 was shown to be separable, by means of buffer partition chromatography, into a gibberellin ([α]D + 36°) of composition C19H24O6, and gibberellic acid (C19H22O6).
Article
Gibberellin A (isolated by Yabuta and Hayashi(1)) and gibberellic acid (isolated by Cross(2)) represent a group of compounds which are rapidly coming to be recognized as of major importance in the physiology of higher plants. Phinney(3) has shown that the application of gibberellins will restore single-gene dwarf mutants of Maize to the normal phenotype, extending the results of Brian and Hemming,(4) who found that the application of gibberellic acid to dwarf varieties of Pisum resulted in growth rates equivalent to that of normal varieties. Lang(5) has shown that gibberellin will replace the vernalization requirement of biennial Hyoscyamus niger and, at higher doses, will replace the long-day requirement for flowering in this plant as well. Thus the gibberellins are active in promoting a response to at least two separate physiological phenomena which have, in the past, been inaccessible to chemical regulation.
Isolation of gibberellin A1 and gibberellin A5 from Phaseolius muiltifloruts
  • J C Seaton
  • And P J Suter
MACMILLAN, P., J. C. SEATON, AND P. J. SUTER. 1960. Isolation of gibberellin A1 and gibberellin A5 from Phaseolius muiltifloruts. Tetrahedron 11: 60- 66.