Interaction of gibberellic acid and photoperiod on leaf sheath elongation in normal and gibberellin-insensitive genotype of wheat

Effect of gibberellic acid (GA₃) on leaf sheath elongation in a normal (cv. Møystad) and a gibberellin(GA)-insensitive (cv. Siete Cerros) genotype of wheat ( Triticum aestivum L.) were studied at 18 and 12°C under short (SD, 12 h) or long (LD, 24 h) photoperiod. Leaf sheath length in cv. Møystad was signficantly increased by exogenous GA₃ both under SD and LD. LD alone stimulated leaf sheath elongation and the combined effect of LD and GA₃ was additive, and there was no statistically signficant interaction between photoperiod and GA₃ concentrations. Leaf sheath length in cv. Siete Cerros was not significantly affected by GA₃ under any conditions. However, there was a highly significant stimulation of leaf sheath elongation by LD in cv. Siete Cerros as well. These results indicate that stimulation of elongation growth in wheat leaves by LD is not mediated by gibberellin.     

Interaction between ethylene,abscisic acid and gibberellic acid in elongation of rice mesocotyl

Summary Combined application of ethylene, abscisic acid and gibberellic acid produced marked partly synergistic stimulation of mesocotyl growth of japonica rice in darkness.     

Interaction of coumarin, gibberellic acid and abscisic acid in the translocation of auxin in bean seedlings

The effects of coumarin on the translocation of 2,4,5-trichlorophenoxyaceticacid (2,4,5-T) in bean (Phaseolus vulgaris L. cv. StringlessGreenpod) seedlings was determined. ¹⁴C-labeled 2,4,5-T wasinjected in the stem tissue at the cotyledonary node along withthe coumarin or the coumarin was added to the nutrient solutionprior to, or at the time of, 2,4,5-T treatment. The amount oftranslocation of radioactive 2,4,5-T to plant parts was thendetermined at various times after treatment. An immediate effectof coumarin was to enhance acropetal 2,4,5-T translocation tothe young shoots. This effect occurred at low 2,4,5-T treatmentlevels and appeared to be specific for 2,4,5-T since sucrosetranslocation was not affected. Prolonged treatment with coumarininhibited acropetal and basipetal 2,4,5-T translocation in amanner similar to prolonged treatment with abscisic acid (ABA).Gibberellin A₃ (GA) reversed the inhibitory effects of coumarinand ABA on 2,4,5-T acropetal translocation. ¹ Journal article 3244 of the Agricultural Experiment Station,Oklahoma State University. (Received December 6, 1976; )     

Nodulation and nitrogen fixation on vegetative soybean plants as affected by photoperiod and gibberellic acid

Long-day photoperiods and applications of gibberellic acid promoted shoot growth by stimulating leaf enlargement as a result of increasing avaliable photosynthates, which was also reflected in the higher leaf, stem and nodule plant dry weights. Short-day plants had more nodules, but they were smaller (by weight) than those of long-day plants. Gibberellic acid at 1.5×10^–6 m enhanced nodule growth without preventing nodule formation. Factors other than just gibberellic acid are concluded to be involved in the responses of nodulation and nitrogen fixation to day length.

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Résumé Des photopériodes de longue journée et l'application d'acide gibbérellique a promu la croissance des pousses en stimulant l'élargissement des feuilles. Celle-ci résuitalent d'un accroissement de photosynthates disponibles. Cet effet s'est aussi réflecté dans un accroissement de la masse de feullies, de tiges et de nodules chez la plante. Des plants soumis à des photopériodes de courte journée présentaient plus de nodules mais ceux-ci étaient plus petits et de masse moindre que ceux de plants soumis à des photopériode de longue journée. L'acide gibbérellique à la dose de 1.5 10^–6 m a accru la croissance des nodules sans empêcher la formation des nodules. On a conclu que des facteurs autres que le seul acide gibbérellique sont mêlés aux réponses de la nodulation et de la fixation d'azote à la longueur de la journée.

     

Effect of photoperiod and gibberellic acid on the plasma membrane H+ATPase activity of spinach leaves

Plasma membrane H⁺ATPase extracted from leaves of spinach plants induced to flower by gibberellic acid treatments or by a transfer to a photoperiod of 24 h had a lower Km_app than that from vegetative plants grown in short days. The Km_app obtained after inhibition by vanadate was decreased in vegetative plants and increased in induced ones showing a differential effect of this inhibitor on the kinetic properties of the enzyme between vegetative and induced plants. The phospholipid fatty acid analysis of the purified plasma membrane showed an increase of C18:1/C18:2 fatty acid ratio upon induction by light or by gibberellic acid treatments, whereas the saturated to unsaturated fatty acid ratio was kept constant. The decrease in the Km_app observed after induction may be thus interpreted in terms of the observed changes in lipid environment.     

Interaction between the effects of phytochrome and gibberellic acid on the senescence of Alstroemeria pelegrina leaves

Chlorophyll loss in the leaves of cut flowering branches of Alstroemeria pelegrina L. cv. Stajello, placed in water in darkness at 20°, was inhibited by irradiation with red light and by the inclusion of gibberellic acid (GA₃) in the water. The effects of red light were abolished when it was followed by far-red light. Effects of GA₃ and red light were additive over a range of GA₃ concentrations (0. 01–1 μ M ). Chlorophyll breakdown was increased by the inclusion of AMO-1618, ancymidol, or tetcyclasis in the water. The effect of these inhibitors of gibberellin synthesis was fully reversed by GA₃. The inhibition of chlorophyll breakdown by red light was absent when AMO-1618, ancymidol or tetcyclasis were included in the water. The results indicate that leaf yellowing is controlled by endogenous gibberellins and that the effect of phytochrome is mediated by gibberellin synthesis.     

Regulation of lettuce hypocotyl elongation by gibberellic acid. Interaction of gibberellic acid and gibberellin synergists - dihydroconiferyl alcohol, pestalotin and a triazinone compound

The effect of three gibberellin synergists on lettuce hypocotylelongation was studied. Dihydroconiferyl alcohol isolated fromlettuce plants and (–)-(6S, 1'S)-pestalotin isolated fromPestalotia cryptomeriaecola enhanced the promoting effect ofgibberellic acid on hypocotyl elongation of lettuce seedlingswith and without the cotyledons. On the other hand, TA, a triazinonecompound, did not enhance the gibberellin effect. The actionof (–)-(6S, 1'S)-pestalotin was strongly inhibited bycompetitive inhibitors of dihydroconiferyl alcohol such as caffeic,ferulic and trans-cinnamic acids. Of the two stereoisomers ofpestalotin, (+)-(6R, 1'R)-pestalotin enhanced the gibberellineffect but (+)-(6R, 1'S)-epipestalotin did not. (+)-(6R, 1'S)-Epipestalotinstrongly inhibited the action of (–)-(6S, 1'S)-pestalotinand dihydroconiferyl alcohol. TA did not affect the action ofdihydroconiferyl alcohol. Stress-relaxation analysis of the mechanical properties of thelettuce hypocotyl cell wall demonstrated that gibberellic acidcaused cell wall loosening and dihydroconiferyl alcohol andpestalotin did not influence this gibberellin effect. The action mechanism of gibberellin synergists is discussedbased on these results. (Received December 22, 1978; )     

Dormancy in bulbils of several herbaceous plants: Effects of photoperiod,light, temperature,oxygen and gibberellic acid

Effects of some environmental conditions (photoperiod, white and colored lights, temperature, partial oxygen pressure) and growth regulators (gibberellic acid, 2-chloroethyltrimethylammonium chloride) on induction and release of dormancy of the bulbils ofDioscorea batalas, Laportea bulbifera, Elatostema involucratum andSedum bulbiferum were investigated. Bulbils were formed under short-day conditions inLaportea andElatostema, under long-day conditions inSedum, and irrespective of photoperiods inDioscorea. In all species exceptSedum, immature bulbils required light, particularly blue or far red, for sprouting (photo-sprouting stage), and mature bulbils required a cold treatment (thermo-sprouting stage). The duration of photo-sprouting and thermo-sprouting stages and the degree of dependency on light or low temperature of sprouting differed from species to species. Sprouting of chilled mature bulbils of these species was promoted by light, especially by red or green light. Both immature and mature bulbils ofSedum sprouted under short-day conditions. Continuous irradiation with blue, far-red and green light markedly inhibited their sprouting. Oxygen at high concentration inhibited the sprouting of immature bulbils inDioscorea; in the other species it promoted sprouting regardless of the maturation of the bulbils. Applications of gibberellic acid caused the sprouting of bulbils the absence of light, chilling or photoperiodic treatment in all species exceptDioscorea, in which gibberellic acid inhibited sprouting. Polyphenol oxidase activity was very high in the homogenates ofDioscorea bulbils, and increased further when the bulbils had been treated with gibberellic acid. In the other species, little or no such activity was observed.     

Induction of fruit set and development in pea ovary explants by gibberellic acid

The response of unpollinated ovary explants ofPisum sativum L. cv. Alaska No. 7 to several plant growth regulators and nutrients has been studied. Explants consisted of a segment of stem and an emasculated flower with or without the adjacent leaf. They were made on the day equivalent to anthesis and were cultured in a liquid medium. Growth regulators were applied either in the solution or directly to the ovaries. Giberellic acid (GA₃) in the presence of sucrose, but not indole-3-acetic acid or N⁶-(Δ²-isopentenyl)-adenine (2iP), induced fruit set and development of parthenocarpic fruits, the final length of these being a function of the intensity of the GA₃ treatment. The capacity of ovaries to respond fully to GA₃ was not lost after incubation of explants in water or 50 mM sucrose for 1 day and was similar in explants made between the day of anthesis and 3 days later. Limited growth was obtained with 100 mM sucrose alone but this effect was counteracted by 2′-isopropyl-4′-(trimethyl ammonium chloride)-5′-methylphenyl piperidine-1-carboxylate (AMO-1618). This inhibitor was ineffective when GA₃ was applied to the ovary. The development of the fruit was proportional to the length of the segment of stem up to 5 cm. The presence of the leaf in the explant enhanced the development of the fruit. These results indicate that a gibberellin is necessary for setting and development of fruits from cultured ovaries and that this effect depends on an appropriate source of nutrients. The course of development of parthenocarpic fruits on explants was similar to that of seeded fruits on the intact plant. The cultured pea ovary systemoffers convenient means to investigate the role of gibberellins and nutrients in fruit set and development.     

Induction of fruit set and development in pea ovary explants by gibberellic acid

The response of unpollinated ovary explants ofPisum sativum L. cv. Alaska No. 7 to several plant growth regulators and nutrients has been studied. Explants consisted of a segment of stem and an emasculated flower with or without the adjacent leaf. They were made on the day equivalent to anthesis and were cultured in a liquid medium. Growth regulators were applied either in the solution or directly to the ovaries. Giberellic acid (GA₃) in the presence of sucrose, but not indole-3-acetic acid or N⁶-(²-isopentenyl)-adenine (2iP), induced fruit set and development of parthenocarpic fruits, the final length of these being a function of the intensity of the GA₃ treatment. The capacity of ovaries to respond fully to GA₃ was not lost after incubation of explants in water or 50 mM sucrose for 1 day and was similar in explants made between the day of anthesis and 3 days later. Limited growth was obtained with 100 mM sucrose alone but this effect was counteracted by 2-isopropyl-4-(trimethyl ammonium chloride)-5-methylphenyl piperidine-1-carboxylate (AMO-1618). This inhibitor was ineffective when GA₃ was applied to the ovary. The development of the fruit was proportional to the length of the segment of stem up to 5 cm. The presence of the leaf in the explant enhanced the development of the fruit. These results indicate that a gibberellin is necessary for setting and development of fruits from cultured ovaries and that this effect depends on an appropriate source of nutrients. The course of development of parthenocarpic fruits on explants was similar to that of seeded fruits on the intact plant. The cultured pea ovary systemoffers convenient means to investigate the role of gibberellins and nutrients in fruit set and development.     

Abscisic acid and gibberellic acid as factors in the translocation of auxin

The effects of abscisic acid (ABA) and gibberellic acid (GA)on the translocation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)in beans (Phaseolus vulgaris L. cv. Stringless Greenpd) seedlingswere determined. ¹⁴C-labeled 2,4,5-T was injected in the stemtissue at the cotyledonary node in 1-µl amounts alongwith the AB or GA. ABA caused an enhancement of 2,4,5-T translocationto the lower hypocotyl and roots and promoted a decrease inthe accumulation of 2,4,5-T in the young expanding shoots andprimary leaves. GA promoted the accumulation of 2,4,5-T in youngshoots. The enhanced basipetal translocation of 2,4,5-T wasmeasurable after a few hours of treatment and was partiallyeffective even in the presence of the protein synthesis inhibitorcychloheximide. The GA effects on 2,4,5-T translocation werenullified by cycloheximide and were also noted after only afew hours of treatment. ¹Journal Article 2618 of the Agricultural Experiment Station,Oklahoma State University. (Received October 1, 1973; )     

Effect of gibberellic acid on carnation flower senescence: evidence that the delay of carnation flower senescence by gibberellic acid depends on the stage of flower development

Gibberellic acid at concentrations of 10^–5 M and 10^–4 M delayed the senescence of cut carnation flowers, when applied continuously via the stem, to flowers between the closed brush and fully open stages of development. Older flowers with reflexed petals were unresponsive. Treatment with paclobutrazol, an inhibitor of GA biosynthesis, prevented tight buds from opening fully, reduced the longevity of partially open flowers, but was ineffective when applied continuously to fully open flowers. Gibberellic acid-treated flowers did not show simultaneous petal inrolling, a known indicator of senescence, and the time to complete petal drying was extended. Gibberellic acid modified the climacteric ethylene rise in a manner consistent with the extension of longevity. These results provide evidence for a correlative role of gibberellins in flower development.Abbreviations GA₃ gibberellin A₃ - GLC gas liquid chromatography     

Laboratory fermentation of gibberellic acid

При изучении условий ферментации пригодные для gibberellic кислоты 6 коллекция штаммов Fusarium moniliforme и Gibberella fujikuroi были использованы Используется штамм имеет решающее значение за урожайностью и состав эффективный метаболит. После проверки методов, описанных в литературе нового средства массовой информации для gibberellic кислоты был разработан, которые будут использоваться для брожения на шейкер и в лабораторных fermentors, средних содержащие сахарозы и кукуруза крутых спиртными напитками. С помощью взаимных шейкер, максимум производство gibberellic кислота была получена после 14 дней, используя три этапа propagations по истечении 12 дней после брожения Максимальные значения, достигнутые в ходе ферментации из наиболее подходящие штаммы составил 150-240 μ g. / мл. Максимум производства в лаборатории fermentors достигло 212 μ g. / мл Метаболит изолированных после брожения в рамках описанных условиях определены в качестве gibberellic кислота     

Cyclization and hydroxylation stereochemistry in the biosynthesis of gibberellic acid

In Gibberella fujikuroi cultures, ent-[3β-³H,17-¹⁴C]kaurene is converted to gibberellic acid with retention of the tritium label at the 3α-position. This evidence for the stereochemistry of 3-hydroxylation also permits the stereochemistry of the ‘proton-initiated’ cyclization step in gibberellic acid biosynthesis to be deduced.     

Inositol phosphate signaling and gibberellic acid

To respond to physical signals and endogenous hormones, plants use specific signal transduction pathways. We and others have previously shown that second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P₃] is used in abscisic acid (ABA) signaling, and that some mutants with altered Ins(1,4,5)P₃ have altered responses to ABA. Specifically, mutants defective in the myo-inositol polyphosphate 5-phosphatases (5PTases) 1 and 2 genes that hydrolyze 5-phosphates from Ins(1,4,5)P₃ and other PtdInsP and InsP substrates, have elevated Ins (1,4,5)P₃, and are ABA-hypersensitive. Given the antagonistic relationship between ABA and gibberellic acid (GA), we tested the response of these same mutants to a GA synthesis inhibitor, paclobutrazol (PAC). We report here that 5ptase1, 5ptase2 and 5ptase11 mutants are hypersensitive to PAC, suggesting a relationship between elevated Ins(1,4,5)P₃ and decreased GA signal transduction. These data provide insight into signaling cross-talk between ABA and GA pathways.Key words: inositol, phosphatidylinositol phosphate, paclobutrazol, gibberellic acid, inositol trisphosphate, paclobutrazol     

Decomposition of gibberellic acid in aqueous solutions

Исследовалось влияние рН и температуры на гидролитическое разложение гибберелевой кислоты в бу?ерных водных растворах. Отдельные продукты гидролиха определяли с помощью хроматогра?ии на бумаге при одновременной спектро?отометриче ской оцерке концентрации образующейся гиббереленовой кислоты. Было установлено, что разложение гибберелевой кислоты в кислой, нейтральной и щелочной среде начинается с образования 1-карбокси-2,3,7-тригидрок си-1-метил-8-метиленгиб б-4-ен 1–3лактон 10 карбоно войкислоты. Это вещес твоприсутствует так же в?ерментационных средах и на различных этапах выделения гибберелевой кислоты. Дальнейшее разложение в растворах с рН 2–8 проходит потом через гиббереленовую кислоту до аллогибберовой кислоты. Следующее превращение аллогибберовой кислоты в гибберовую наблюдалось только в растворе с рН 2 иосле 24-часового прогревания при при 100° С. В растворе с рН 9 процесс разложения приводие к образованию 2,3,7-тригидрокси-1-метил-8-м етиленгибб-4-ен 1,10 дикарбоновой кислоты, которая возникает как главный окончательный продукт гидролиза, наряду с небольшим количеством гиббереленовой кислоты, при данном рН также уже не подвергающейся дальнейшим изменениям. Наибольшей устойчивостью гиььерелевая кислота отличается в растворах с рН 3–4. В нейтральной, а в особенности в слабо щелочной среде ее устойчивость резко понижается. Разложение гибберелевой кислоты в водных растворах значительно ускозяется также при повышении температуры.