QUANTITATIVE AND QUALITATIVE DIFFERENCES IN PLANT RESPONSE TO THE GIBBERELLINS

Wittwer , S. H., and M. J. Bukovac . (Michigan State U., E. Lansing.) Quantitative and qualitative differences in plant response to the gibberellins. Amer. Jour. Bot. 49(5): 524–529. Illus. 1962.—The comparative biological activities of gibberellins A₁ through A₉ were evaluated, over a wide concentration range and in several test systems. All gibberellins were effective in promoting stem elongation of dwarf peas (Pisum sativum), and, with the exception of A₈, epicotyl growth in Phaseolus vulgaris. Elongation of Cucumis sativus seedlings was strikingly greater with A₄, A₇, and A₉ than with the other gibberellins. With mutant dwarfs of Zea mays, A₅ and A₉ were the most active gibberellins for d₃ and d₅, and relatively ineffective compared to A₃ on d₁. Gibberellins A₂, A₇, and A₈ were less effective than A₃ on all dwarfs. Qualitative and quantitative differences among the gibberellins were noted on seedstalk elongation and flowering of Lactuca sativa, with A₃ the most active followed by A₁, A₇, A₄, and A₉. No flowering or seedstalk elongation occurred with A₂, A₆ or A₈. Parthenocarpic fruit growth in Lycopersicon esculentum was a function of dosage with all gibberellins. At the lowest levels, A₅ and A₇ were the most active, while at the highest levels all gibberellins with the exception of A₈ were equally effective. The results suggest a high degree of species and response specificity among the known fungal and higher plant gibberellins, and demonstrate the importance of utilizing a wide spectrum of plant responses and dosage levels in the biological assay of plant extracts for native gibberellins.     

Preparation of 2- and 3-substituted gibberellins A9 and A4 for bioassay

To test the effects of preventing enzymatic 2β- and 3β-hydroxylation on the biological activities of gibberellins, the preparation of the following compounds is described: 2β-methyl- and 2,2-dimethyl-gibberellins A₄ and A₉; 2α-fluoro-, 2β-fluoro- and 2β-methoxy-gibberellin A₉; and 3β-chloro-, 3β-fluoro-, 3β-methoxy- and 3-methylene A₉.     

Isolation and identification of the gibberellins of Cucumis sativus and Cucumis melo

Summary Thin-layer chromatography, gas-liquid chromatography, and mass spectrometry were used to identify gibberellins isolated from mature seeds of both Cucumis sativus (cucumber) and Cucumis melo (muskmelon). The gibberellins were extracted and purified by organic solvent fractionation, paper and thin-layer chromatography, and crystallization. Seeds of C. sativus were found to contain gibberellins A₁, A₃, A₄, and A₇ with A₁ the predominant species. Seeds of C. melo contained gibberellins A₁ and A₃ and a trace of A₅. Direct probe mass spectrometry of the gibberellins proved successful for identification purposes. Distinctive molecular ions and fragmentation patterns were obtained for each gibberellin.Journal Article No. 5664 from the Michigan Agricultural Experiment Station. This work was supported in part by a grant from the Herman Frasch Foundation.Portions were taken from a thesis submitted in partial fulfillment of the requirements for the Ph.D. degree, Michigan State University, 1971     

Gibberellins in developing fruits of Pisum sativum cv. Alaska: Studies on their role in pod growth and seed development

Gibberellins A₁, A₈, A₂₀ and A₂₉ were identified by capillary gas chromatography-mass spectrometry in the pods and seeds from 5-d-old pollinated ovaries of pea (Pisum sativum cv. Alaska). These gibberellins were also identified in 4-d-old non-developing, parthenocarpic and pollinated ovaries. The level of gibberellin A₁ within these ovary types was correlated with pod size. Gibberellin A₁, applied to emasculated ovaries cultured in vitro, was three to five times more active than gibberellin A₂₀. Using pollinated ovary explants cultured in vitro, the effects of inhibitors of gibberellin biosynthesis on pod growth and seed development were examined. The inhibitors retarded pod growth during the first 7 d after anthesis, and this inhibition was reversed by simultaneous application of gibberellin A₃. In contrast, the inhibitors, when supplied to 4-d-old pollinated ovaries for 16 d, had little effect on seed fresh weight although they reduced the levels of endogenous gibberellins A₂₀ and A₂₉ in the enlarging seeds to almost zero. Paclobutrazol, which was one of the inhibitors used, is xylem-mobile and it efficiently reduced the level of seed gibberellins without being taken up into the seed. In intact fruits the pod may therefore be a source of precursors for gibberellin biosynthesis in the seed. Overall, the results indicate that gibberellin A₁, present in parthenocarpic and pollinated fruits early in development, regulates pod growth. In contrast the high levels of gibberellins A₂₀ and A₂₉, which accumulate during seed enlargement, appear to be unnecessary for normal seed development or for subsequent germination.Abbreviations GA_(a) gibberellin A_n - GC-MS combined gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - PFK perfluorokerosene - PVP polyvinylpyrrolidone     

The Effect of the Plant Growth Retardants Amo 1618 and CCC on Gibberellin Production in Fusarium monili-forme: Light Stimulated Biosynthesis of Gibberellins

Through the use of a single gene dwarf mutant of Zea mays L., dwarf-1, the interaction of growth retardants with gibberellin biosynthesis was studied in Fusarium monitiforme. It was demonstrated that the growth retardants 2-isopropyl-4-dimcthylamine-5-methyphenyl-1-piperidine-cai'boxylate methyl chloride (Amo 1618) and (2-chloroethyl) trimethylammonium chloride (CCC) are more effective inhibitors of gibberellin biosynthesis in cultures maintained under continuous illumination. Light grown cultures produced significantly more biologically active gibberellin-like materials than dark grown cultures. Stock cultures exposed to light also promoted the subsequent biosynthesis of gibberellins in the dark. Chromatographical analysis of the soluble gibberellins extracted from the culture medium revealed that large amounts of chromatographically detectable A₃ and A₇ were produced in light cultures with only A₇ produced in the dark. Light also induced a greater incorporation of acelate-2-¹⁴C into the gibberellins A₇, A₃ and an unidentified gibberellin. Growth returdants occasionally caused a complete disappearance of chromatographically detectable gibberellins in the dark; however, in the light at no concentration tested was it possible to detect the complete disappearance of gibberellin-like material. A₃ was always detectable. Like higher plants, different strains of F. moniliforme exhibit variation which makes them more or less sensitive to the growth retardants. This variation is interpreted to mean that there may be more than one pathway leading to the synthesis of the gibberellins.     

Endogenous Gibberellins in the Xylem Exudate from Apple Trees

In the xylem exudate extracted from the current-year stems of apple (Malus domestica Borkh.), gibberellins A₁₅, A₁₇, A₁₈, A₁₉, A₂₃, A₄₄, and A₅₃ were identified, and 16,17-dihydro-17-hydroxy GA₁₉ was presumed from full-scan mass spectra and Kovats retention indices.     

Gibberellins and the Legume-Rhizobium Symbiosis : I. Endogenous Gibberellins of Lima Bean (Phaseolus lunatus L.) Stems and Nodules

The content of gibberellin-like substances in nodules formed by Bradyrhizobium species strain 127E14 on roots of lima bean (Phaseolus lunatus L.) has been previously found to be relatively high. The objectives of the present study were to purify and identify the endogenous gibberellins from the stems and nodules of lima bean. By sequential silica gel partition column chromatography, C₁₈ reverse-phase high performance liquid chromatography, and combined gas chromatography-mass spectrometry, the gibberellins A₁, A₃, A₁₉, A₂₀, A₂₉, and A₄₄ were identified from root nodules. Gibberellins A₁, A₃, A₁₉, A₂₀, and A₄₄ were also identified from lima bean stem tissue. These data provide the first mass spectral-based evidence that gibberellins are present in leguminous root nodules. The presence of the gibberellins identified indicates that the early 13-hydroxylation gibberellin biosynthetic pathway predominates in stem and nodule tissue. However, it is not known if the gibberellins within the nodules are produced in situ, or if they are imported from some remote host plant tissue.     

Isolation of gibberellins A26 and A27 and their glucosides from immature seeds of Pharbitis nil

Summary Two new gibberellins, gibberellins A₂₆ and A₂₇ (GA₂₆ and GA₂₇), and their glucosides have been isolated from immature seeds of Japanese morning-glory (Pharbitis nil), together with GA₈ and its glucoside. GA₂₆, GA₂₇ and their glucosides showed only slight growth-promoting activities on seedlings of rice, dwarf maize and cucumber.     

Gibberellins inCitrus sinensis: A comparison between seeded and seedless varieties

The gibberellin (GA) content of the reproductive organs ofCitrus sinensis (L.) Osb., cv. Bianca Comuna and the seedless variety, Salustiana, were examined by combined gas chromatography-mass spectrometry (GC/MS) at different stages of development. Gibberellins A₁, A₂₀, and A₂₉ were identified in the reproductive buds of both cultivars 21 days prior to anthesis and in fruits 35 days after anthesis by comparison of their mass spectra and Kovats retention indices with those of standards. In addition, three uncharacterized isomers of GA₁ were detected, one in buds and two in fruits. The presence of GA₄ in both tissues, and of GA₈ in the reproductive buds, was indicated by the occurrence of characteristic ions at the expected retention times, although their spectra were too weak for full identification. Vegetative shoots of cv. Salustiana contained gibberellins A₁, A₁₉, A₂₀, and A₂₉, and the unidentified isomer of GA₁ present in reproductive buds. The presence of trace amounts of gibberellins A₈ and A₁₇ was also indicated. Although the two varieties did not differ qualitatively in the GAs present during flower and fruit development, the seedless variety contained slightly greater amounts. The concentrations of gibberellins A₁, A₄, and A₂₀ were determined by gas chromatography-selected ion monitoring (GC/SIM) throughout ovary development and early fruit growth. In both varieties, the maximum GA₁ concentration occurred at anthesis. Highest concentrations of gibberellins A₂₀ and A₄ were found in fruit 35 days after anthesis, although the GA₁ concentration at this stage remained low.     

Promotory effect of GA13 on flowering ofAmaranthus — a short day plant

Abstact The three plant types ofAmaranthus namely,A. caudatus f.albiflorus, A. caudatus f.caudatus andA. tricolor var.tristis are qualitative short day plants with critical photoperiods 16.0, 15.5 and 15.0 h, respectively. Gibberellins A₃, A₄₊₇ and A₁₃ affect extension growth, leaf differentiation and floral induction differently. Thus, in all the three plant types ofAmaranthus, whereas, GA₃ and G₄₊₇ enhanced extension growth, GA₁₃ was completely ineffective under both, 24- and 8-h photoperiods. None of the three gibberellins could affect the leaf differentiation. In all the three plant types, flowering was promoted by GA₁₃ and not by other gibberellins tried. GA₁₃ caused promotion was manifested in two manners, firstly by lowering the critical dark period requirement in each inductive cycle, and secondly by shortening the total period taken for the initiation of inflorescence primordia under inductive photoperiods. The floral induction by gibberellins inAmaranthus is contrary to the gibberellin-anthesin concept of Chailakhyan. It is suggested that gibberellins other than GA₃ may be playing an important role in floral morphogenesis of short day plants.     

Metabolism of Steviol and Its Derivatives by Gibberella fujikuroi

Steviol (ent-13-hydroxykaur-16-en-19-oic acid)* is metabolized by Gibberella fujikuroi in the presence of inhibitors of gibberellin biosynthesis, such as quaternary ammonium salt-type growth retardants, to afford 7β-Miydroxy- and 6β,7β-dihydroxysteviol, gibberelhns A₁, A₁₈, A₁₉, A₅₃ and 7β,13-dihydroxykaurenolide. Steviol acetate (ent-13-acetoxykaur-16-en-19-oic acid) is also metabolized to the 6β,7β-dihydroxy-derivative and to the 13-acetyl derivatives of gibberellins A₁₇ and A₂₀ and steviol methyl ester (methyl ent-13-hydroxykaur-16-en-19-oate) into the monohydroxy-, dihydroxy- and hydroxyoxo-derivatives. These results indicate a low substrate specificity of the enzymes in the fungus and provide a useful preparative methodology of several important plant gibberellins carrying the 13-hydroxyl group.     

Effect of nine different gibberellins on stem elongation and flower formation in cold-requiring and photoperiodic plants grown under non-inductive conditions

Summary The effect of gibberellins A₁ through A₉ on stem elongation and flower formation in five plants was tested. The plants wereMyosotis alpestris and a biennial strain ofCentaurium minus (cold-requiring plants),Silene armeria andCrepis parviflora (long-day plants), andBryophyllum crenatum (a long-short-day plant). The two former plants were maintained on non-inductive temperatures and long days, the three latter on short days, InMyosotis, flower formation was only obtained with GA₇ and GA₁, the latter being relatively less active. InCentaurium GA₃ was the most effective, followed by GA₁, GA₄ and GA₇ and perhaps GA₅ and GA₉. InSilene, flower formations was induced only by GA₇. InCrepis, the most effective gibberellins were GA₄ and GA₇, inBryophyllum, GA₃, GA₄ and GA₇. Thus, the different gibberellins exhibited considerable differences in their activity with respect to flower induction, and different plants exhibited in this respect certain specific differences in their sensitivity to the various gibberellins. Except inCrepis, flower initiation as a result of gibberellin treatment was always preceded by substantial stem or internode elongation; however, the correlation between the effect of the different gibberellins on stem elongation and flower induction was not in all cases complete. No correlation of the flower-inducing and elongation-promoting activity with the chemical structure of the different gibberellins could be recognized.With 2 Figures in the TextWork in part supported by the National Science Foundation, grants G-16408 and G-17483.     

Effect of ínductive photoperiod and gibberellin treatment on peroxidase enzyme system in relation to floral induction inImpatiens balsamina L

Gibberellins A₃ and A₁₃ cause floral induction inImpatiens balsamina, a qualitative short day plant, under non-inductive 24-h photoperiods (continuous illumination). However, the influence of the two inductive factors,i.e. gibberellins and short days (8-h photoperiods) on the peroxidase enzyme system is different. The total peroxidase activity decreases under both inductive and non-inductive photoperiods, with or without gibberellin treatment. The electrophoretic pattern of isoperoxidases changes only in response to gibberellin treatment. Under 24-h photoperiods, treatment with gibberellins A₃ and A₁₃ causes the appearance in the stem of three additional isoenzymes of peroxidase (Rm 0.50, 0.71 and 0.76). These bands do not appear in the leaves, which are non-essential for gibberellin-caused floral induction in this plant. Under 8-h photoperiods also, gibberellins induce the appearance of new isoenzyme bandsi.e. two in the stem (Rm 0.50 and 0.76) and one in the leaves (Rm 0.05). These may be correlated with the synergistic increase in the number of floral buds in these plants in response to simultaneous exposure to two inductive factors.     

The Effect of Gibberellins on Flowering in Roses

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     

Interactions of Abscisic Acid, Cytokinin and Gibberellin in the Control of Betacyanin Synthesis in Seedlings of Amaranthus caudatus

In de-rooted seedlings of Amaranthus caudatus L., betacyanin synthesis induced by white light or cytokinin was inhibited by abscisic acid (ABA) or a mixture of gibberellins A₄ and A₇ (GA_4/7). The GA_4/7 and ABA effects were additive. Thus ABA inhibited the cytokinin action but had no effect on the gibberellin response.     

3-hydroxylation of gibberelin A,12-aldehyde in Gibberella fujikuroi strain rec-193A

When grown on PDL medium for 11 days the strain REC-193A of Gibberella fujikuroi produces the usual range of gibberellins and ent-kaurenoid metabolites. After 3–5 days under the same conditions of culture, this slow growing strain produces virtually none of these metabolites. These short term cultures were found to convert gibberellin A₁₂-aldehyde into gibberellins A₁₂ (8.3 % A₁₄ (45%), A₄ (ca. 17%) and A₇ (ca. 6%). Under identical conditions of culture gibberellin A₁₂ was largely unmetabolised. These results show that 3-hydroxylation is the first step in the conversion of gibberellin A₁₂-aldehyde into gibberellins A₁₄, A₄ and A₇.     

Flowering and gibberellins in a mutant red clover (Trifolium pratense L.)

Relationships between gibberellins and floral initiation were investigated in a conditional non-flowering mutant of red clover, Trifolium pratense. Untreated mutant plants will not flower under long-days, but will do so when certain GAs are applied. Gibberellins, A₃, A₁, A₇, and A₅ all resulted in both stem elongation and flowering whilst GA₄ produced the elongation only. Applications of GA₂₀, GA₈ and GA₁₃ under long-days had no detectable effect. Thus, by combining the use of the mutant with the application of different GAs, the correlation between the processes of stem elongation and floral initiation, which is normally strongly expressed in this species, was broken. Endogenous gibberellins shown to be present in normal plants were also found in the mutant genotype. Gibberellins alone were not sufficient to initiate floral development in the mutant, there being an essential element of interaction with long-days. These results are discussed in relation to the nature of the lesion in the mutant and the signal provided by the applied gibberellin.     

The endogenous gibberellins of vegetative and reproductive tissue of G2 peas

The gibberellins (GAs) of both vegetative (leaves and stems) and reproductive (pods and seeds) tissue of the G2 strain of peas Pisum sativum L. were characterized in purified extracts by a combination of sequential silicic-acid partition column chromatography, and gas chromatography-mass spectrometry. Gibberellins A₁₉, A₂₀, A₂₉ and an A₂₉ catabolite were identified in both types of tissue. Gibberellins A₉, A₁₇ and A₄₄ were also found in pods and seeds.Abbreviations FID Ilame ionization detector - GA(s) gibberellin(s) - GC gas chromatograph(y) - HPLC high performance liquid chromatograph(y) - LD long day - MS mass spectrum(a) or mass spectrometer(ry) - SD short day     

Two New Gibberellins A50 and A52 in Seeds of Lagenaria leucantha

Two new gibberellins A₅₀ and A₅₂ were isolated from seeds of Lagenaria leucantha Rusby var. clavata Makino. Their structures were shown to be ent-2α,3α,10,llα-tetrahydroxy-20-norgibberell-16-ene-7,19-dioic acid 19,10-lactone (1) and ent-2α,3α,11β20-tetrahydroxy-gibberell-16-ene-7,19-dioic acid 19,20-lactone (10), respectively.     

Expression Pattern of the Coparyl Diphosphate Synthase Gene in Developing Rice Anthers

Rice anthers contain high concentrations of gibberellins A₄ and A₇. To understand their physiological roles, we examined the site of their biosynthesis by analyzing the expression pattern of a gene (OsCPS) encoding coparyl diphosphate synthase in developing rice flowers. Expression was apparent in the anthers 1–2 days before flowering, and CPS mRNA accumulated in the maturing pollen.