Enzymic glucosylation of gibberellins

Starting from the well-known conversion of exogenously applied free gibberellic acid (GA₃) to its 3(O)-glucoside by intact immature fruits of runner beans (Phaseolus coccineus L.), a protein fraction has been prepared from this plant material possessing glucosylating activity towards GAs. This glucosyltransferase is located in the pericarp only and utilizes preferably UDP-glucose as a sugar donor. The product formed enzymically from GA₃ and UDP-glucose could be identified by derivatization and comparison with the authentic compound to be GA₃-3(O)-glucoside. Among 15 native or chemically modified GAs, the enzyme glucosylates only GA₃ and to a lower extent GA₇ and GA₃₀, indicating a high enzyme specificity with regard to the A ring of gibberellins. The physiological significance of the enzymic GA₃-3(O)-glucoside formation inPhaseolus coccineus is not clear, since this glucoside is not known to be endogenous in this plant. The enzyme preparation did not glucosylate substances of phenolic structure, such as hydroquinone, aesculetin, and quercetin. Glucosylation of GA₃ was achieved also by enzyme preparations fromVigna sinensis and from cell suspension cultures ofDigitalis purpurea. A number of other plant materials showed no activity.Gibberellins 100. For part 99 see Liebisch et al. 1984a.     

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.     

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.     

Enzymic glucosylation of gibberellins

Starting from the well-known conversion of exogenously applied free gibberellic acid (GA₃) to its 3(O)-glucoside by intact immature fruits of runner beans (Phaseolus coccineus L.), a protein fraction has been prepared from this plant material possessing glucosylating activity towards GAs. This glucosyltransferase is located in the pericarp only and utilizes preferably UDP-glucose as a sugar donor. The product formed enzymically from GA₃ and UDP-glucose could be identified by derivatization and comparison with the authentic compound to be GA₃-3(O)-glucoside. Among 15 native or chemically modified GAs, the enzyme glucosylates only GA₃ and to a lower extent GA₇ and GA₃₀, indicating a high enzyme specificity with regard to the A ring of gibberellins. The physiological significance of the enzymic GA₃-3(O)-glucoside formation inPhaseolus coccineus is not clear, since this glucoside is not known to be endogenous in this plant. The enzyme preparation did not glucosylate substances of phenolic structure, such as hydroquinone, aesculetin, and quercetin. Glucosylation of GA₃ was achieved also by enzyme preparations fromVigna sinensis and from cell suspension cultures ofDigitalis purpurea. A number of other plant materials showed no activity.     

Effect of Different Gibberellins on the Growth of the Hypocotyl

It has been stated earlier that hypocotyls of different plants show different growth response to added GA₃. It was suggested that this difference may be due to the requirement of some specific gibberellin. Hence hypocotyl growth response of three groups of plants has been studied with different gibberellins: group one showing no or insignificant growth response, group two showing 150–200 per cent growth response and group three showing 300–500 per cent growth response to added GA₃. Eight gibberellins were used, viz., GA₁, GA₂, GA₃, GA₄, GA₅, GA₇, GA₈ and GA₉, to test if this varying response is connected with the requirement of some specific gibberellin. In general, the results obtained do not favour this view. Iberis amara, a plant showing no response to added GA₃, Dianthus sp., a plant showing 150 to 200 per cent response and Lactuca satwa, Antirrhinum majus and Nicotiana tabacum, plants showing 300 to 500 per cent response, were promoted by all the gibberellins tested to a similar extent as by GA₃, with the exception of GA₈ which was inactive in most of the cases.     

Gibberellin-induced delay of leaf senescence of Alstroemeria cut flowering stems is not caused by an increase in the endogenous cytokinin content

The effects of various chemically pure gibberellins and cytokinins on leaf yellowing of Alstroemeria were described. The loss of chlorophyll was measured both in leaves of cut flowering stems and in a model system consisting of detached leaf tips. It was demonstrated that plant growth substances affected chlorophyll loss in both systems to the same extent. Leaf senescence was delayed by various gibberellins and cytokinins. The results demonstrated that some of the gibberellins (GA₄ and GA₇) are far more effective in delaying chlorophyll loss than GA₃, which is commonly used as a postharvest treatment for Alstroemeria cut flowering stems. Immunoassays were used to demonstrate that the effect of gibberellins on leaf yellowing does not involve an increase in the endogenous cytokinin concentrations in the leaves as an intermediate step.Abbreviations GA gibberellin A - HPLC high performance liquid chromatography - GA_3Mc GA₃-methyl ester - ZR zeatin riboside - IPAR isopentenyl adenine riboside.     

Stimulatory effect of ethephon,ACC, gibberellin A3 and A4+7 on germination of methyl jasmonate inhibited Amaranthus caudatus L. seeds

Methyl jasmonate (JA-Me) inhibited or retarded germination of Amaranthus caudatus seeds in darkness at 24°C, Ethephon, ACC and gibberellins (GA₃ or GA₄₊₇) partially or completely reversed this inhibition depending on the concentration of JA-Me applied. Both ethephon and the gibberellins were more effective than ACC. Both GA₃ and GA₄₊₇ enhanced the stimulatory effect of ethephon or ACC on germination of seeds inhibited by JA-Me.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - JA jasmonic acid - JA-Me methyl jasmonate     

Three Novel Gibberellins Produced by Gibberella fujikuroi

Three novel gibberellins, GA₅₄ (ent-1α, 3α, 10-trihydroxy-20-norgibberell-16-ene-7, 19-dioic acid 19, 10-lactone), GA₅₅ (ent-1α, 3α, 10, 13-tetrahydroxy-20-norgibberell-16-ene-7, 19-dioic acid 19, 10-lactone) and GA₅₆ (ent-2β, 3α, 10, 13-tetrahydroxy-20-norgibberell-16-ene-7, 19-dioic acid 19, 10-lactone) were shown to occur in the culture broth of Gibberella fujikuroi. Their structures were determined mainly by mass spectrometrical comparison of the derivatives with those of authentic compounds prepared from known gibberellins.     

Endogenous gibberellins in clover broomrape,a parasitic plant,and its host,clover: Dependency of the parasite on the host for gibberellin production

Endogenous gibberellins were analyzed from a parasitic plant, clover broomrape (Orobanche minor Smith), and its host, clover (Trifolium repens L.). Members of both the early-13- and the early-non-hydroxylation pathways were identified from both the parasite and the host (GA₁₂, GA₂₄, GA₉ GA₄, GA₄₄, GA₁₉, GA₂₀, and GA₁ from clover broomrape; GA₉, GA₄, GA₄₄, GA₁₉, GA₂₀, and GA₁ from clover). Quantitative analyses showed that GA₄₄ was present at high levels in both host and parasite. The similarity in the gibberellins suggests the possibility that the major gibberellins in clover broomrape are transported from clover. However gibberellins such as GA₅₈, GA₃₈, and notably GA₄₇ which was identified from a plant for the first time were detected only from clover broomrape, suggesting that the parasite may have the ability to produce at least those gibberellins     

Dormancy of <Emphasis Type="Italic">Nicotiana benthamiana</Emphasis> seeds can be broken by different compounds

The influence of after-ripening, sodium nitroprusside, potassium ferricyanide, cyanide, paclobutrazol and nitrite on germination of seeds of Nicotiana benthamiana was investigated as well as the influence of plant hormones such as gibberellins and abscisic acid. Dormancy of N. benthamiana seeds was broken by all treatments except treatments with abscisic acid, paclobutrazol and gibberellic acid (GA₃). Gibberellins had an interesting effect on dormancy breakage of studied seeds which was dependent on use of particular gibberellin: GA₃ or GA₄₊₇. Unlike GA₃, GA₄₊₇ had broken seed dormancy.     

Gibberellin Biosynthesis: Genetic Studies in Gibberella fujikuroi

Biochemical genetic studies on the production of gibberellins by the fungus Gibberella fujikuroi have identified two genes which control different steps in the biosynthetic pathway. One gene (g₁) controls the production of all of the gibberellins: the second gene (g₂) controls the production of GA₁ and GA₃ only. Ascospores are not ordered in the ascus of this fungus. This apparent spore slippage precludes mapping of these genes to their respective centromeres.     

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.     

The levels of GA3 and GA20 may be associated with dormancy release in Onopordum nervosum seeds

Endogenous levels of two gibberellins, GA₃ andGA₂₀, were quantified in unimbibed Onopordumnervosum seeds collected from two different populations, whichshoweddifferences in their germination capacity. After purifying the seed extracts,gibberellin levels were evaluated by gas chromatography mass spectrometry byusing selected ion monitoring (GC-MS-SIM) adding deuterated gibberellins asinternal standards. The intraspecific differences in germination capacity wereassociated with differences in the endogenous levels of both gibberellins. Thecontents of GA₃ and GA₂₀ in seeds with high germinationrate were twice and five times higher, respectively, than those from seeds witha low germination rate, indicating a possible role of gibberellins in dormancyrelease in this plant species.     

Preussia sp. BSL-10 producing nitric oxide,gibberellins, and indole acetic acid and improving rice plant growth

Preussia sp. have been least known to improve plant growth and produce phytohormones. The current study investigated the production of nitric oxide (NO), indole-3-acetic acid (IAA), and gibberellins (GA₄, GA₇, GA₁₅, and GA₅₃) by a novel endophytic-fungal strain Preussia sp. BSL-10 using advanced chromatographic and spectroscopic techniques. Production of these phytohormones were validated by RT–PCR analysis, which indicated the expression of genes encoding tryptophan synthase (TRP), indole-3-acetamide hydrolase (IAAH), tryptophan-2-monooxygenase (IAAM), aldehyde dehydrogenase (ALD), GA₄ desaturase (DES), geranylgeranyl-diphosphate synthase (GGS2), ent-desaturase oxidase (P450-4), GA₁₄ synthase (P450-1) and nitrite reductase (NIRK/NIRS), cytochrome P450 (P450nor), nitrate reductase (NR), NOS-like (NOL), and nitric oxide reductase (QNOR/CNOR). In plant growth-promoting effects, the inoculation of Preussia sp. BSL-10 significantly increased the growth of dwarf mutant Waito-C and wild-type rice cultivars. In conclusion, utilizing new endophytic with the ability to produce NO, IAA, and gibberellins can be used to promote growth and yield of marginalized crops.     

In vitro morphogenetic responses of Ilex paraguariensis nodal segments treated with different gibberellins and Prohexadione-Ca

One-bud nodal segments of Ilex paraguariensis (yerba mate) were cultured in vitro in a sugar-rich medium with different gibberellins or an inhibitor of their synthesis. Bud sprouting, shoot length (assessed as shoots of less or more than 5 mm) and bud abscission were evaluated after 45 d of culture in a growth chamber at 27±2 °C, with a 14 h photoperiod of white fluorescent light. There was a differential effect of the two types of gibberellins used; the double bond ring-A gibberellins (GA₃ and GA₇) inhibited shoot length, while the non double bond-ring A gibberellins (GA₁ and GA₄) stimulated shoots with a length of more than 5 mm. Prohexadione-Ca (Bx-112; a late step gibberellin biosynthesis inhibitor), at high doses, restrained bud sprouting up to 75%, but lower doses promoted shoot lengthening.     

Germination of Tagetes minuta L. II. Role of gibberellins

The effect of the application of gibberellins to Tagetes minuta L. achenes (seeds) was determined at both 25°C, the optimal germination temperature, and 35°C, at which temperature the achenes are thermoinhibited. Both GA₃ and GA₄₊₇ accelerated germination at 25°C. Seed germination at 25°C was inhibited by paclobutrazol, but on subsequent application of GA₄₊₇ rapid germination was induced. Following application of GA₃ or GA₄₊₇ to thermoinhibited seeds, a significantly higher final germination percentage was observed than in the distilled water control. However, endogenous gibberellin levels in germinating and thermoinhibited seeds did not differ significantly.     

The effect of exogenous and endogenous phytohormones on the in vitro development of gametophyte and sporophyte in <Emphasis Type="Italic">Asplenium nidus</Emphasis> L.

The fern Asplenium nidus L. is in great demand as an ornamental plant. The aim of this work was to investigate the influence of phytohormones in promoting a gametophytic and sporophytic growth in homogenized sporophytes tissue. Exogenous application of 0.5 and 5 μM N ⁶-benzyladenine, 0.05 and 0.5 μM indole-3-acetic acid (IAA), and 0.3 and 3 μM gibberellic acid (GA₃) favoured sporophyte regeneration, whereas gametophyte regeneration took place when plant material was cultured in a hormone-free liquid MS medium. The endogenous contents of the auxin IAA, the cytokinins trans-zeatin, trans-zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyladenine and isopentenyladenosine, and the gibberellins GA₁, GA₃, GA₄, GA₇, GA₉ and GA₂₀ in growing gametophytes and sporophytes were evaluated. Similar levels of the auxin and cytokinins and qualitative differences in the gibberellins were found between both generations.     

Exogenous and endogenous growth regulators on apogamy in Dryopteris affinis (Lowe) Fraser-Jenkins sp. affinis

This work showed for the first time the relationship between the effect of exogenous auxins and gibberellins on apogamy in Dryopteris affinis (Lowe) Fraser-Jenkins sp. affinis and its endogenous contents during early apogamic events. The addition of NAA (0.53 and 5.37 μM) or GA₃ 2.8 μM to an MS solid medium significantly increased apogamous sporophyte formation. BA induced brown callus that regenerated sporophytes in a hormone-free medium. The endogenous contents of GA₁, GA₃, GA₄, GA₇, GA₉ and IAA were determined by GC–MS in gametophytes cultured on MS solid medium, before and during early stages of apogamous embryo development. The accumulation of both GA₉ and IAA before embryo development was evident as high levels of GA₄ in the earliest analysed stage of embryo development and high levels of GA₃ in elongating shoots were found. The role of gibberellins on apogamy was also supported by data showing a decrease in the percentage of gametophytes developing embryos because of the addition of flurprimidol to the culture medium.     

The Biotechnology of Bacillus Thuringiensis

Abstract

Gibberellins are a classic example of the production of plant growth regulators by microorganisms. They are important biotechnological products and are increasingly used in agriculture and horticulture.

This article intends to assemble information on the history of the identification of gibberellins (GA) and producing microorganisms, especially Gibberella fujikuroi (Saw.) Wr. Furthermore, the biosynthesis of gibberelins through the isoprenoid biosynthetic pathway will be described. The main product of GA biosynthesis in Gibberella fujikuroi is gibberellic acid (GA₃), which is formed from GA₄ via GA₇. Both the amount and the type of gibberellins produced by the fungus are dependent on the genetic constitution of the strain and the fermentation conditions.

Mutation and selection for increased product formation are probably the most important factors in improving the yield of gibberellins. Some publications concerning methods of parasexual recombination will also be summarized. Beside strain improvement of wild strains, medium development and appropriate cultivation techniques (batch, fed-batch-, continuous-, and solid state-fermentation) are very important prerequisites for successful economy of gibberellin production. Furthermore, the most important ways of gibberellin recovery and purification are described. Continuing reductions in the costs make gibberellins more attractive for existing applications and open possibilities for further applications of GA₃ and some other active gibberellins like GA₄, Ga₇, and GA₉     

Gibberellins and antheridiogen on sex in Blechnum spicant L.

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 GA_1, 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.