Induction of stem elongation on in vitro chicory root explants under unfavourable photoperiodic conditions by gibberellin A3

Flowering stems are formed under long-day conditions on root explants of chicory (Cichorium intybus L.) cultured in vitro while under short days, only vegetative growth is observed. Under short-day conditions (12 h), stem elongation is induced by treating newly formed shoot apices with GA₃ (1 l, 10^–3M). No flower buds were formed on the GA₃-induced stems. Long days seem to be indispensable for the induction of flower buds on the elongated stem.     

Comparison of de-novo flower-bud formation in a photoperiodic and a day-neutral tobacco

Regeneration of flower buds in thin tissue layers from pedicels of photoinduced short-day (SD) tobacco, Nicotiana tabacum L. cv. Maryland Mammoth, is described. Up to seven flower buds per explant were obtained in a medium containing Murashige and Skoog's macro- and microclements, 100 mg/l myoinositol, 0.1 mg/l thiamine-HCl, 6% glucose, 5 M N⁶-benzylaminopurine, and 0.5 M -naphthaleneacetic acid. Usually some vegetative buds were also formed in the pedicel thin tissue layers. Thin tissue layers from other positions in the induced SD tobacco regenerated vegetative buds only. A comparative study with a day-neutral (DN) tobacco, Samsun, showed that the capacity to form de-novo flower buds was more localized and less strongly determined in photoperiodic than in the DN tobacco. The differences between the photoperiodic and DN tobaccos in flower-bud regeneration capacity are thus quantitative and not qualitative. The basis for this quantitative difference is not known, but may depend on factors controlling production of floral stimulus (florigen) and competency of cells to respond to florigen, and-or stability of the determined state to form flower buds in vitro.Abbreviations BAP N⁶-benzylaminopurine - DN day-neutral - GA₃ gibberellic acid - LD long-day - MM Maryland Mammoth - NAA -naphthaleneacetic acid - SD short-day     

Effects of gibberellic acid and temperature on growth and root carbohydrates of Delphinium seedlings

Delphinium Blue Bird seedlings weregrown in heated (air temperature >15) and unheatedglasshouses in winter and treated with foliar sprays of gibberellic acid(GA₃) or drenched with uniconazole (UZ). The unheated seedlings wereexposed to temperatures as low as 5. Under bothheated and unheated growing conditions, leaf differentiation was retarded by theGA₃ application. Leaves of the unheated seedlings showed very littleexpansion, but the GA₃ application stimulated leaf expansion underchilled conditions. Root starch and mannitol decreased and root sucroseincreased during cold acclimation. These changes were less in theGA₃-treated seedlings than in the non-treated seedlings. The higherstarch and mannitol contents in GA₃-treated seedlings indicates thatthe GA₃ application inhibits starch and mannitol utilization orconversion to sucrose. Chilling hastened flowering but the GA₃application did not. GA₃ application during the chilling periodincreased spike volume, probably because under chilled conditions, the seedlingsto which GA₃ was applied expanded their leaves and were able toassimilate more than the seedlings not receiving GA₃. These results suggest that exogenous GA₃ apparently breaksthe rosette by means of rapid enlargement of already differentiated tissues andthat the action of exogenous GA₃ is, essentially, different from thatof the chilling treatment.     

Further studies on the metabolism of gibberellins (GAs) A9, A20 and A29 in immature seeds of Pisum sativum cv. progress No. 9

Seed maturation of Pisum sativum cv. Progress No. 9 proceeds more slowly in winter than in summer even when the parent plants are grown in greenhouse conditions with light-and heat-supplementation. For parent plants grown under summer and winter conditions the metabolism of [³H]GA₉ in cultured seeds is qualitatively different in seeds of equivalent age and qualitatively the same in seeds of equivalent weight. 13-Hydroxylation of [³H]GA₉[³H]GA₂₀ is restricted to early stages of seed development. 2-Hydroxylation of [³H]GA₉2-OH-[³H]GA₉ has only been observed at a stage of development after endogenous GA₉ has accumulated. 2-OH-GA₉ has been shown to be endogenous to pea and is named GA₅₁. H₂-GA₃₁ and its conjugate have not been shown to be present in pea and may be induced metabolites of [³H]GA₉. The metabolism of GA₂₀GA₂₉ is used to illustrate a technique of feeding [²H][³H]GAs in order to distinguish a metabolite from the same endogenous compound. The in vitro conversion of [³H]GA₂₀[³H]GA₂₉, and the virtual non-metabolism of [³H]GA₂₉ have been confirmed for seeds in intact fruits. These results are discussed in relation to the apparent absence of conjugated GAs in mature pea seeds.Abbreviations GA_n gibberellin A_n - GC gas chromatography - GC-MS combined gas chromatography-mass spectrometry - GC-RC combined gas chromatography-radio counting - Me methyl ester - R_T etention time - SICM selected ion current monitoring - TLC thin layer chromatography - TMS trimethyl silyl ether The author is née Frydman     

CONSTANS delays flowering and affects tuber yield in potato

CONSTANS (CO) has a central role in the photoperiodic regulation of flowering in Arabidopsis thaliana. We show here that potato (Solanum tuberosum ssp. andigena) plants constitutively expressing Arabidopsis CO (pACo plants) flower late under all photoperiodic conditions tested. Exogenous application of gibberellic acid to pACo plants corrected their short stem phenotype but not their late flowering. To further understand the effect of CO in potato, we used three photoperiodic conditions: short days (SD), which strongly induce tuberisation of wild type plants, SD supplemented with a night break (SD+NB), which are moderately inductive, and tuberisation-inhibiting long days. Tuberisation of pACo plants was delayed under SD and very strongly delayed or completely inhibited under SD+NB, suggesting that CO affects an autonomous pathway controlling potato tuberisation. In addition, tuber yield, a trait of high agronomic relevance, was significantly increased in pACo plants expressing moderate CO levels. Our results indicate that CO affects flowering and stem elongation through distinct mechanisms and suggest that its effects on flowering and tuberisation in potato are photoperiod-independent.     

Studies on the Transmission of Floral Effects of Photoperiod and Gibberellin from One Branch to the Other inImpatiens balsamina

In two branched plants ofImpatiens balsamina with intact apex and leaves floral buds are induced only in the branch which is either exposed to 8-h (inductive) photoperiods or receives GA₃ treatment if maintained under 24-h (non-inductive) photoperiods. GA₃ induces floral buds on the treated branch even if the leaves on that branch are removed, showing that while leaves are essential for photoperception, these are not neoessary for GA₃ to cause induction. The effect of the inductive photoperiods or GA₃ treatments to a branch is not transmitted to the other branch which is treated with water and is maintained under non-inductive photoperiods even when the latter is defoliated but is transmitted if the apioal or both the apical and axillary buds on the branch receiving inductive photoperiods or GA₃ treatment are excised. It, therefore, appears that the existence of strong sinks in the form of axillary and apical buds on the treated branch prevents the transmission of photoperiodic as well as GA₃ effects to the other branch in this plant.     

Distribution of endogenous gibberellins in dwarf and giant off-types banana (Musa AAA,cv.‘Grand nain’) plants from in vitro propagation

GA₃ and GA₂₀ were quantified in leaf extracts from true-to-type and somaclonal variants (dwarf and giant) of Musa AAA cv. Grand nain by GC-MS-SIM after purification on reverse- and normal-phase HPLC and detection by ELISA with GA₃ antibodies and by a dwarf rice bioassay. GA₃ concentration in dwarf plants was 811 ng g^–1 dry weight. For normal and giant plants, the endogeneous GA₃ levels were respectively 3.6 and 4.6 times higher. The GA₂₀ concentration in the giant plant was 68 ng g^–1 of dry weight. This concentration was, respectively, 4.6 and 7.3 times higher than those of normal and dwarf plants. These results suggest that the somaclonal variations affecting banana plant height are associated with modifications in GA metabolism.Abbreviations HPLC High Performance Liquid Chromatography - GC-MS Gas Chromatography-Mass Spectrometry - SIM Selected Ion Monitoring - GA Gibberellin - BSA Bovine Serum Albumin - PB Phosphate Buffer     

The Effects of Photoperiod, Glucose and Gibberellic Acid on Growth In Vitro and Flowering of Chenopodium Murale

In vitro culture of long-day plant Chenopodium murale L was established. The effects of photoperiod, glucose and gibberellic acid (GA₃) on flowering and growth in vitro were investigated. Oscillatory changes of photoperiodic sensitivity were noticeable with regard to plant age. The plants induced at the phase of the 1^st and the 3^rd pair of leaves flowered to higher degree than those induced at the phase of 2^nd pair. Plants induced at the phase of the 1^st pair of leaves flowered to 17 % on 5 % glucose-containing medium and the addition of 5 mg dm^-3 GA₃ resulted in maximum flowering (43 %). Neither glucose nor GA₃ were able to compensate for photoperiodic requirements for flowering. Hypocotyl growth was decreased and the 1^st internode elongation and development of leaves were increased due to inductive photoperiodic conditions, as compared to non-inductive ones.     

Identification of gibberellins in the rice plant and quantitative changes of gibberellin A19 throughout its life cycle

The major endogenous gibberellin (GA) in shoots, roots and ears of the rice plant, Oryza sativa L. japonica cv. Nihonbare, was identified as GA₁₉ by combined gas liquid chromatography-mass spectrometry (GC-MS) and GC-selected ion current monitoring (GC-SICM). Another GA present in these tissues in small quantity was tentatively identified as GA₁ by GC-SICM, and GA₄ may be present in the seeds (kernels) of 3rd-leaf-stage seedlings. Using GC-SICM, the GA₁₉ content was quantified throughout the life cycle of rice plants. It was found to reach high levels (ca. 10–15 g/kg fresh weight) in 3rd-leaf seedlings, at panicle initiation (shoots), and during heading and anthesis (ears). The levels of GA₁₉ in Oryza sativa indica cv. T-136 underwent changes closely similar to those found in Nihonbare. The growth-promoting activity in rice of exogenous GA₁₉ is generally considerably less than that of GA₁. It therefore seems possible that GA₁₉ functions as a pool GA. The level of active GAs such as GA₁ may be regulated by the rate of biosynthesis of GA₁₉ or its metabolic conversions.Abbreviations GA(s) gibberellin(s) - GA_n gibberellin A_n - GA_n-MeTMS trimethylsilyl ether of GA_n methyl ester - GC-MS combined gas liquid chromatography-mass spectrometry - GC-SICM combined gas liquid chromatography-selected ion current monitoring - TLC thin-layer chromatography     

The control of bud dormancy in potato tubers. Measurement of the seasonal pattern of changing concentrations of zeatin-cytokinins

A radioimmunoassay, combined with high-performance liquid chromatography, has been used to analyse the zeatin-type cytokinins of potato (Solanum tuberosum L. cv. Majestic) tubers and tuber buds throughout growth and storage. During tuber growth, zeatin riboside was the predominant cytokinin detected in all tissues. Immediately after harvest, the total cytokinin concentration fell dramatically in the storage tissue, largely as a consequence of the disappearance of zeatin riboside. During storage, levels of cytokinins in the storage tissue remained relatively constant, but increased in the tuber buds. In the buds of tubers stored at 2°C there was a 20-to 50-fold increase in total cytokinin over six weeks, coinciding with the natural break of innate dormancy. At 10°C the rise in the level of bud cytokinins was slower, correlating with the longer duration of innate dormancy. Injecting unlabelled cytokinins into tubers in amounts known to induce sprouting gave rise to increases in cytokinin concentrations in the buds of the same order as the increase associated with the natural break of dormancy. Metabolism of injected cytokinins was greater in non-dormant than in dormant tubers. The roles of cytokinin concentration and the sensitivity of the buds to cytokinin in the control of dormancy are discussed.Abbreviations CK cytokinin - FW fresh weight - HPLC high-performance liquid chromatography - RIA radioimmunoassay - tio⁶ade 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-purine=zeatin - tio⁶adeglc⁹ 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-glucopyranosyl purine=zeatin-9-glucoside - tio⁶ado 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-ribofuranosyl purine=zeatin riboside - tio⁶ado-[³H]-diol a radioactive derivative of zeatin riboside, synthesised by periodate-oxidation followed by [³H]NaBH₄-reduction - tio⁶AMP 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-5-phosphoribofuranosyl purine=zeatin riboside 5-monophosphate - t(ioglc⁴)⁶ade 6-(4-O--D-glucopyranosyl-3-methylbut-trans-2-enylamino)-purine=zeatin-O-glucoside     

A highly-sensitive rice seedling bioassay for the detection of femtomole quantities of 3β-hydroxylated gibberellins

A very sensitive and specific bioassay using prohexadione calcium [BX-112, which blocks 2- and 3-hydroxylation of gibberellins (GAs)] with uniconazole (which blocks oxidation of ent-kaurene, ent-kaurenol and ent-kaurenal) in a microdrop assay was developed for several rice (Oryza sativa L.) varieties, including cv. Waito-C, which is already specific to 3-hydroxylated GAs. The sensitivity and specificity of cvs. Waito-C, Tan-ginbozu and Koshihikari to 3-hydroxylated GAs was greatly enhanced by treatment of the seeds with a combination of 40 mM prohexadione calcium and 80 M uniconazole. The minimum detectable doses of 3-hydroxylated GAs (GA₁, GA₃, GA₄ and GA₇) in the three cultivars treated with both chemicals were 1 to 10 fmol (i.e. ca. 350 fg to 3.5 pg) per plant. This is equal to 30-fold more sensitive than Waito-C treated with uniconazole alone, and 30 to 1000-fold more sensitive than Waito-C with no growth retardant soak. Minimum detectable doses of 3-nonhydroxylated GAs (GA₉, GA₁₉ GA₂₀) and GAs with very low biological activity (GA₈ and GA₁₇) were equal to or more than 1000 fmol per plant. This is about equal to the activity in Waito-C treated with uniconazole alone. Application of this assay to an extract from Raphanus sativus was compared with the data by gas chromatography/mass spectrometry (GC/MS), confirming the conclusions reached using authentic test GAs, namely that use of uniconazole plus BX-112 appreciably enhanced the detection sensitivity to fractions shown by GC/MS to contain GA₁ and GA₄, both 3-hydroxylated GAs.Abbreviations GA gibberellin - BX-112 prohexadione calcium     

The control of bud dormancy in potato tubers

Potato (Solanum tuberosum L.) tuber buds normally remain dormant through the growing season until several weeks after harvest. In the cultivar Majestic, this innate dormancy persisted for 9 to 12 weeks in storage at 10° C, but only 3 to 4 weeks when the tubers were stored at 2° C. At certain stages, supplying cytokinins to tubers with innately dormant buds induced sprout growth within 2 d. The growth rate was comparable to that of buds whose innate dormancy had been lost naturally. Cytokinin-treatment did not accelerate the rates of cell division and cell expansion in buds whose innate dormancy had already broken naturally. Gibberellic acid did not induce sprout growth in buds with innate dormancy. We conclude that cytokinins may well be the primary factor in the switch from innate dormancy to the non-dormant state in potato tuber buds, but probably do not control the subsequent sprout growth.Abbreviations tio ⁶ade 6-(4-hydroxy-3-methylbut-trans-2-enyl amino)purine, zeatin - tio⁶ado 6-(4-hydroxy-3-methylbut-trans-2-enyl amino)-9--D-ribofuranosyl purine, zeatin riboside     

Inhibition of stem growth and gibberellin production in Agrostemma githago L. by the growth retardant tetcyclacis

The effects of the new growth retardant tetcyclacis (TCY) on stem growth and endogenous gibberellin (GA) levels were investigated in the long-day rosette plant Agrostemma githago. Application of TCY (10 ml of a 5·10^-5M solution daily) to the soil suppressed stem elongation in Agrostemma grown under long-day conditions. A total of 10 g GA₁ (1 g applied on alternate days) per plant overcame the growth retardation caused by TCY.Control plants and plants treated with TCY were analyzed for endogenous GAs after exposure to nine long days. The acidic extracts were fractionated by high-performance liquid chromatography. Part of each fraction was tested in the d-5 maize bioassay, while the remainder was analyzed by combined gas chromatography-selected ion monitoring. The bioassay results indicated that the GA content of plants treated with TCY was much lower than that of untreated plants. The data obtained by gas chromatography-selected ion monitoring confirmed that the levels of seven GAs present in Agrostemma were much reduced in TCY-treated plants when compared with the levels in control plants: GA₅₃ (13%), GA₄₄ (0%), GA₁₉ (1%), GA₁₇ (33%), GA₂₀ (15%), GA₁ (4%), and epi-GA₁ (13%). These results provide evidence that TCY inhibits stem growth in Agrostemma by blocking GA biosynthesis and thus lowering the levels of endogenous GAs.Abbreviations AMO-1618 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine-carboxylate methyl chloride - GA(s) gibberellin(s) - HPLC high-performance liquid chromatography - TCY Tetcyclacis (5-[4-chlorophenyl]-3,4,5,9,10-pentaaza-tetracyclo-5,4,1,0^2,6,0^8,11-dodeca-3,9-diene)     

枣花芽分化过程中营养物质和内源激素含量及抗氧化酶活性变化研究

以新疆主栽品种灰枣和骏枣的花芽为材料,测定不同分化时期花芽的可溶性糖、还原糖、淀粉、可溶性蛋白含量,SOD、POD、PPO、CAT活性以及内源GA3、IAA、ABA、ZT水平的变化,并分析它们与花芽分化的关系,为枣花芽分化调控提供理论参考.结果表明:(1)灰枣和骏枣花芽可溶性糖、还原糖和淀粉含量在花芽分化过程的变化趋势...     

Gibberellins and bud break,vegetative shoot growth and flowering in Metrosideros collina cv. Tahiti

Applications of the growth promotive gibberellins (GAs) GA₄ and 2,2-dimethyl GA₄, and of C-16,17 endo-dihydro GA₅, which is known to promote flowering while inhibiting stem growth in the long-day grass Lolium temulentum, were made to micropropagated plants of Metrosideros collina cv. Tahiti, a highly ornamental cultivar with an intermittent flowering pattern. Gibberellin A₄ and 2,2-dimethyl GA₄ stimulated vegetative growth both in elongating shoots, and internodes of shoots developing from buds that were quiescent at the time of GA application. Abscission of the apices of expanding shoots, a feature of mature Metrosideros plants, was inhibited by these GAs, the rejuvenation of micropropagated plantlets being enhanced. However, C-16,17 endo-dihydro GA₅ differed from GA₄ and 2,2-dimethyl GA₄ by having no promotive effects on vegetative growth, and no inhibition of apical abscission. Notwithstanding this contrasting effect on vegetative growth, high doses of GA₄ or C-16,17 endo-dihydro GA₅ similarly reduced flowering on shoots to which either GA was applied. Reduced flowering in response to applied GAs is common in many woody angiosperms, and in this instance was probably the combined result of abortion of developing floral structures in quiescent buds, and a preferential inhibition of bud break for floral buds relative to vegetative buds, particularly by GA₄. Finally, both C-16,17 endo-dihydro GA₅ and GA₄ strongly inhibited bud break in this woody angiosperm, although GA₄ could initially stimulate bud break when applied to vegetative buds close to the expansion stage. The above findings, in toto, highlight the sensitivity of Metrosideros to both classes of GA in a variety of growth and development processes.     

Changes in jasmonate and gibberellin levels during development of potato plants (Solanum tuberosum)

Among the multiple environmental signals and hormonal factors regulatingpotato plant morphogenesis and controlling tuber induction, jasmonates (JAs)andgibberellins (GAs) are important components of the signalling pathways in theseprocesses. In the present study, with Solanum tuberosum L.cv. Spunta, we followed the endogenous changes of JAs and GAs during thedevelopmental stages of soil-grown potato plants. Foliage at initial growthshowed the highest jasmonic acid (JA) concentration, while in roots the highestcontent was observed in the stage of tuber set. In stolons at the developmentalstage of tuber set an important increase of JA was found; however, in tubersthere was no change in this compound during tuber set and subsequent growth.Methyl jasmonate (Me-JA) in foliage did not show the same pattern as JA; Me-JAdecreased during the developmental stages in which it was monitored, meanwhileJA increased during those stages. The highest total amount of JAs expressed asJA+Me-JA was found at tuber set. A very important peak ofJA in roots was coincident with that observed in stolons at tuber set. Also, aprogressive increase of this compound in roots was shown during the transitionof stolons to tubers. Of the two GAs monitored, gibberellic acid(GA₃) was the most abundant in all the organs. While GA₁and GA₃ were also found in stolons at the time of tuber set, noothermeasurements of GAs were obtained for stolons at previous stages of plantdevelopment. Our results indicate that high levels of JA and GAs are found indifferent tissues, especially during stolon growth and tuber set.     

Identification of gibberellin A4 in Pisum sativum L. and the effects of applied gibberellins A9, A4, A5 and A3 on the le mutant

Gibberellin A₄ (GA₄) was identified for the first time in the garden pea (Pisum sativum) L.), by gas chromatography-mass spectrometry. However, in wild-type shoots the level of GA₄ was only about 6% of the level of GA₁, and it is therefore unlikely that GA₄ plays a major role per se in the control of pea stem elongation. In shoots of the le mutant, GA₄ was not detected, while the level of GA₉ was approximately twice that found in the wild-type. The le mutation also markedly reduced the elongation response to applied GA₉. It appears, therefore, that in Pisum the le mutation blocks the 3-hydroxylation of GA₉ to GA₄, in addition to the 3-hydroxylation of GA₂₀ to GA₁. In contrast, the le mutation did not reduce the response to applied GA₅, suggesting the step GA₅ to GA₃ is not catalysed by the enzyme controlled by the Le gene. The step GA₅ to GA₃ was confirmed in peas by metabolite analysis after treatment with deuterated GA₅.     

Specific proteins in stem meristems during transition to flowering

Immunodiffusion tests were used for studying protein composition of apical buds ofRudbeckia bicolor andPerilla nankinensis during their transition from vegetative to reproductive state under inductive photoperiodic conditions or GA₃ treatment. In both species the induced buds differ from the vegetative ones in the presence of specific proteins (P): P1, P2, P3 appear inRudbeckia apical buds 2, 8, 16 d after the start of inductive treatment; P4 appears inPerilla apical buds 6 d after inductive treatment. P1, P2, P4 are revealed in induced buds in the early period of apex development when morphogenetic changes are not yet present. The similarity between antigenic spectra of induced buds and of those treated by GA₃ appears only inRudbeckia. These observations support the hypothesis of a change in gene expression at floral evocation. Presented at the International Symposium “Plant Growth Regulators” held on June 18–22, 1984 at Liblice, Czechoslovakia.     

Ultrastructure ofDigitalis lanata tissue cultures

Summary The anatomy of twoDigitalis lanata tissue culture strains, S-1 and S-2, has been studied. The cardenolide accumulating cell aggregates consisted of highly vacuolated cells with very lobed nuclei in the periphery and a central part of meristematic cells. Sieve tube elements and companion cells and tracheids were observed in some of the cultures. The effect of gibberellic acid (GA₃) and SAN 9789 on the ultrastructure of the cultures was most apparent as regards the plastids and the amounts of mitochondria and ER. The content of starch seemed to be highest in the cardenolide accumulating strain S-2 grown in darkness (S-2 D) with or without GA3, but considerable amounts were also found in S-1 grown in darkness (S-1 D) with or without GA₃, which did not accumulate cardenolides. The amount of plastoglobuli was increased in S-1 by SAN treatment. It was also higher in S-2 D and S-2 D+GA₃ than in S-1 D and S-1 D+GA₃; i.e., it was high in tissues with blocked carotene synthesis. Many large plastoglobuli were also observed in apparently degenerating cells. The amount of ER seemed relatively high in cardenolide producing cultures. The amount of mitochondria was highly variable, but no correlation with cardenolide accumulation could be found.Abbreviations D dictyosome - ER endoplasmic reticulum - M mitochondrion - N nucleus - P plastid - PG plastoglobule - S starch grain - SC sieve cell - V vacuole - W cell wall - GA₃ gibberellic acid - S-1D strain S-1 cultured in darkness - S-1 L strain S-1 cultured in light - S-2 D strain S-2 cultured in darkness - S-2L8 strain S-2 previously cultured in darkness followed by 8 days in light in the present study - SAN SAN 9789 (Norflurazon) 4-chloro-5-(methylamino)-2-(,,,-trifluoro-m-tolyl)-3(2H)-pyridazinone