珍稀濒危植物珙桐胚的萌发与快速繁殖

首次采用均匀设计和回归分析方法对影响珙桐(Davidia involucrata)胚萌发的3种因素(基本培养基、赤霉素和活性炭)进行优化, 并利用萌发胚建立了珙桐的高效再生体系。 利用回归方程得出胚萌发的最优条件为: 在含有0.5 mg.L^{- 1} IBA和1 mg.L^-1 6-BA的1/2MS培养基中添加2.85 mg.L^-1 GA3和0.25 g.L^-1活性炭。在验证实验中珙桐胚萌发率为87.72%, 与预测值无显著差异。 最优的芽诱导与增殖条件为: 添加0.1 mg.L^-1 NAA和2.0 mg.L^-1 6-BA 的WPM培养基, 增殖系数为4.34。在生根培养基中增殖的芽生根率高达90%, 移栽成活率为71%。     

Effects of gibberellic acid and some diphenols on the flowering of Impatiens balsamina L., a qualitative short day plant

Res, DOPA and CA resemble GA₃ in inducing floral buds in Impatiensbalsamina under strictly non-inductive photoperiods, while Catdoes not do so. 1 mg/liter Res and 100 mg/liter CA in combinationwith 100 mg/liter GA₃ even hastened the initiation of floralbuds. All the tested phenols, in combination with 100 mg/literGA₃, caused a synergistic increase in the number of floral buds. (Received November 24, 1977; )     

Effect of sucrose, auxins and gibberellic acid on rooting of stem segments of Populus nigra under varying light conditions

This paper deals with the effects of sucrose, IAA, IBA and GA₃on rooting stem segments of Populus in a sterile culture whenexposed to varying periods of continuous dark. The results demonstrate that segments shorter than 3.5 cm inlength, root only when exposed to 3 or more days of darkness,the number of roots increasing with the number of days in dark.The dark requirement for rooting can be substituted both byIAA and IBA, as rooting occurred with auxins even under continuouslight. The failure of control segments to root under continuouslight is ascribed to low auxin content due either to inadequatesynthesis or its inactivation by light. This deficiency canbe met either by exogenous application of auxins or by increasingthe size of the segments. GA₃inhibits rooting under favourablelight conditions although it stimulates sprouting of buds andsubsequent elongation. Sucrose increases the effectiveness ofauxins. (Received July 15, 1968; )     

Effect of some Metabolic Inhibitors on Rooting Cuttings of Phaseolus mungo under Varying Light Conditions and its Relationship with Auxin and Nutrition

Water and 1 mg1^–1 each of IAA and IBA completely inhibitedon the cuttings of Phaseolus mungo obtained from the seedlingsraised under far-red light but rooting took place in the darkand under white and red lights. Sucrose, however, caused rootingunder far-red light and its effectiveness increased with theaddition of IAA and IBA to the sucrose medium IBA being moreeffective. Culturing in 1 and 5 mg 1^–1 each of FudR, actinomycin-D,cycloheximide and chloramphenicol after pre-treatment with water,IAA, IBA, sucrose and IAA/IBA + sucrose inhibited rooting. Theeffect increased with the concentration of each inhibitor. Incontrast to this, the culturing in water, IAA, IBA, sucroseand IAA/IBA + sucrose after pre-treatment with these metabolicinhibitors produced varying effects. While the inhibition persistedin water, IAA and IBA and even in 5 mg 1^–1 of each inhibitorthat in sucrose stimulated rooting and the effect increasedwith the addition of IAA and IBA to sucrose, the effect of IBA+ sucrose being more pronounced. This stimulation was irrespectiveof the inhibitor and light condition except that 1 mg 1^–1actinomycin-D inhibited rooting in the dark and under far-redlight.     

Effects of Gibberellic Acid and Naphthaleneacetic Acid on Petiole Senescence and Subtended Peduncle Growth of Cyclamen persicum Mill

Removal of the blade from the leaf subtending the first flowerbud on Cyclamen persicum ‘Swan Lake’ plants causedthe petiole of that leaf to senesce, but had no effect on thegrowth of the flower peduncle in the debladed petiole's axil.A 10 mg NAA l^–1 application generally had no effect onpetiole senescence, peduncle elongation or flowering date whenapplied to the cut end of the petiole after blade removal. A25 mg GA₃ l^–1 application or a combination of 25 mg GA₃l^–1 application or a combination of 25 mg GA₃ l^–1plus 10 mg NAA l^–1 delayed petiole senescence and enhancedpeduncle elongation and subsequent flowering. No treatment significantlyaltered peduncle length at the time of flowering. Cyclamen persicum Mill, ‘Swan Lake’, tissue receptivity, flowering, GA₃, NAA     

Metabolism and Translocation of Gibberellins in the Seedlings of Pharbitis nil (II). Photoperiodic Effects on Metabolism and Translocation of Gibberellins Applied to Cotyledons

We investigated the metabolism and translocation of two gibberellins(GAs), [³H]GA₂₀ and [³H]GA₁, which were applied at low concentrationto the cotyledons of Pharbitis nil (cv. Violet). Seedlings weregrown under three different photoperiodic conditions: continuouslight (CL-CL), continous light followed by short day conditions(CL-DT) and long day conditions followed by short day conditions(DT-DT). Translocation of the applied [³H]GAs from cotyledonsto hypocotyls was promoted by DT for all GAs examined. Whilethe conversion of the translocated [³H]GA₁ to [³H]GA₈ and itsconjugates was rapid in hypocotyl, the conversion of translocated[³H]GA₂₀ to [³H]GA₂₉ was slow. Radioactivity in epicotyls wasdetected much more rapidly on application of [³H]GA₂₀ than of[³H]GA₁, [³H]GA₈ and [³H]GA₂₉ and their conjugates. The conversionof [³H]GA₂₀ to [³H]GA₁ in the epicotyl was more rapid underCL-CL conditions. This result in consistent with the higherlevel of endogenous GA₁ existing in epicotyls under CL-DT thanDT-DT conditions. However, when [³H]GA₁ was applied to the cotyledon,only small amounts of [³H]GA₈ and its conjugates were detectedin the epicotyl regardless of the photoperiodic conditions.This result may suggest that the translocation and metabolismof [³H]GA₂₀ from cotyledons to epicotyl was faster under CL-CLthan DT-DT conditions and may correlate with the increased epicotylelongation of GA₂₀ treated plants under CL-DT than DT-DT conditions. (Received June 28, 1995; Accepted November 2, 1995)     

Abscisic acid and the accumulation, biological activity and metabolism of four derivatives of [3H]gibberellin A1 in barley aleurone layers

Tritiated GA₁ and four of its synthetic derivatives were studiedin relation to their biological activity, uptake and metabolismby barley aleurone layers. Incubation was done in the presenceand absence of ABA. Tentative identification of some of themetabolites was made by TLC and GLC radiocounting of the metaboliteand its acid hydrolyzed derivative. Only GA₁ promoted -amylase synthesis. Uptake ranged from 20to 42%, varying with the derivative. ABA enhanced uptake of[³H]GA₁ and [³H]pseudoGA₁ and inhibited uptake of [³H]ketoGA₁the Wagner-Meerwein rearrangement product of [³H]GA₁ Uptakeof [³H]GA₁ methyl ester ([³H]GA₁-Me) and [³H]dihydroGA₁ wasunaffected by ABA. [³H]GA₁ was converted to an amphoteric GA₁ derivative ([³H]amphoGA₁)and [³H]GA₁-glycosyl ester. GA₁-Me was metabolized to four products,all of them GA₁ derivatives, including an apparent amphotericGA₁ derivative. DihydroGA₁ was quite stable; only one metabolitewas produced in sufficient yield to analyze. This product didnot cochromatograph with either of the expected acid hydrolyzedepimers of [³H]dihydroGA₁. [³H]ketoGA₁ was readily metabolizedto one product, probably the glycoside. [³H]pseudoGA₁ remainedessentially unmetabolized. Metabolism of all compounds testedwas not dramatically affected by ABA. Surprisingly, no metabolitesfrom hydroxylation at the 2-position were found. ¹ Present address: Monsanto Agricultural Co., 800 N. LindberghBlvd., St. Louis, MO 63166, U.S.A. (Received January 31, 1977; )     

Rapid propagation of Holostemma ada-kodien Schult., a rare medicinal plant, through axillary bud multiplication and indirect organogenesis

Efficient protocols of axillary bud multiplication and indirect organogenesis were established for Holostemma ada-kodien Schult. (Asclepiadaceae). Murashige and Skoog (MS) medium supplemented with 2.0 mg l^-1 N⁶-benzylaminopurine (BAP) and 0.5 mg l^-1 indole-3-butyric acid (IBA) induced an average of eight shoots per node and was the best for axillary bud proliferation. Subsequent cultures enhanced the number of shoots. The explant source of callus and the growth regulator inducing the callus exhibited significant influence on organogenesis. Callus developed from the basal cut end of the node explants differentiated more than 15 shoots on MS medium fortified with 1.5 mg l^-1BAP. Callus from internode explants developed fewer shoots than callus from the basal cut ends of node explants. Leaf-derived callus did not undergo organogenesis. The abscission of leaves and shoot tips of the developed shoots was prevented by the addition of AgNO₃ or CoCl₂, but with a concomitant significant reduction in the number of shoots. Half-strength solid MS or liquid medium with 0.05 mg l^-1 IBA exhibited the best in vitro rooting. Ninety percent of the rooted shoots survived in the field.     

Gibberellic-Acid-Promoted Transport of Assimilates in Stems of Phaseolus vulgaris. Effects on Assimilate Accumulation by the Sink

Under conditions of apoplastic unloading from the sieve element-companioncell (se-cc) complexes in fully-elongated stems of Phaseolusvulgaris plants, gjbberellic acid (GA₃ stimulated in vitro uptakeof [¹⁴C]sucrose by the stem tissues. The GA₃, response dependedupon the incubate containing calcium ions and being bufferedat pH 6. The GA₃ action could be accounted for by a reductionin the Michaelis-Menten constant of the uptake process. Promotedtransport by GA₃ in the decapitated stems resulted in all thetissues accumulating higher levels of [¹⁴C]photosynthates. Comparisonof this response with that for in vitro uptake of [¹⁴C]sucroseindicated that GA₃ stimulation of the sucrose uptake processcontributed significantly to the accumulation of photosynthatesby the pith alone. The bulk of enhanced photosynthate accumulationby the remaining stem tissues can be accounted for by a GA,-inducedelevation of the apoplast sucrose concentration. In terms ofonset and change in rate, the time-course kinetics of GA₃ stimulationof [¹⁴C]photosynthate transport and of in vitro [¹⁴CJsucroseuptake were found to be similar. It is proposed that GA₃ promotionof photosynthate accumulation by the pith tissues is a minorcontributing factor to GA₃ regulation of phloem translocation Phaseolus vulgaris L., french bean, stem, assimilate transport, gibberellic acid, rink accumulation     

Effects of a Plant-Growth Regulator, Prohexadione, on the Biosynthesis of Gibberellins in Cell-Free Systems Derived from Immature Seeds

Inhibition of the biosynthesis of gibberellins by prohexadione,3,5-dioxo-4-propionylcyclo-hexanecarboxylic acid, was studiedwith cell-free systems derived from immature seeds of Cucur-bitamaxima, Phaseolus vulgaris and Pisum sativum. Prohexadione,at a concentration of 10–⁴ M, inhibited C-7 oxidationof GA₁₂-aldehyde, C-20 oxidation of GA₁₅, conversion of C₂₀-gib-berellinsto C₁₉-gibberellins, 3ß-hydroxylation, 2,3-dehydrogenationof GA²⁰, 2,3-epoxidation of GA₅ and 2ß-hydroxylationof GA₉ and GA₂₀. The 3ß-hydroxylase activity appearedto be more sensitive to prohexadione than were the C-20 oxygenaseand the 2ß-hydroxylase activities. The conversionof mevalonic acid to GA₁₂-aldehyde and the 13-hydroxylationof GA₁₂ were not affected by prohexadione at a concentrationof 3 ? 10^–4 M. All of the steps inhibited by prohexadioneare oxidation steps catalyzed by soluble enzymes that require2-oxoglutarate, Fe²⁺ and oxygen, and all of them occur distalto the synthesis of GA₁₂-aldehyde in the biosynthesis of gibberellins. (Received April 4, 1990; Accepted September 14, 1990)     

Effect of ABA and GA3 on tuberization and some chemical constituents of potato

The effects of abscisic acid (ABA) and gibberellic acid (GA₃)on the chemical composition of and tuberization in the potatowere studied. GA₃ at 10^–6 M inhibited and ABA at an equimolarconcentration promoted tuberization. The inhibitory effect ofGA₃ was relieved by the addition of ABA. The fresh weight ofthe shoot, chlorophyll content and the total glycoalkaloidslevel were increased by GA₃ treatment, but decreased by ABAtreatment. In contrast, total proteins were increased by ABA,but decreased by GA₃ treatment. ¹This work was supported by a PL-480 research grant (FG-Pa-262)from the United States Department of Agriculture widi co-ordinationby the Agriculture Research Council, Pakistan. (Received August 29, 1980; )     

Effects of a Plant-Growth Regulat or, Prohexadione-Calcium (BX-112), on the Endogenous Levels of Gibberellins in Rice

The effects of the plant-growth regulator, prohexadione-calcium,on the levels of the endogenous gibberellins in rice shootswere measured by GC-SIM using ²H-labeled gibberellins as internalstandards. The compound was applied at the 4-leaf stage andshoots were harvested 5 and 12 days after treatment. Plant lengthwas reduced to 78% and 66%, respectively, relative to controlby application of the compound at 1 and 30 mg m^–2, whenplant length was measured 12 days after treatment. The levelof GA, was reduced to 36% and 18%, respectively, relative tocontrol in the treated plants. The levels of GA₁₉and GA₂₀ increasedbut that of GA₄₄ was reduced in the treated plants. The levelof GA₅₃ was unchanged. These results suggest that primary modeof action of the compound in vivo is the inhibition of the 3ß-hydroxylationof GA₂₀ to GA₁ and further support the hypothesis that GA₁ notGA₁₉ nor GA₂₀ is active in promoting shoot elongation in rice. ³Present address: Frontier Research Program, RIKEN, Wakoshi,Saitama, 351-01 Japan.     

Effect of ABA and GA3 on tuberization and some chemical constituents of potato

The effects of abscisic acid (ABA) and gibberellic acid (GA₃)on the chemical composition of and tuberization in the potatowere studied. GA₃ at 10^–6 M inhibited and ABA at an equimolarconcentration promoted tuberization. The inhibitory effect ofGA₃ was relieved by the addition of ABA. The fresh weight ofthe shoot, chlorophyll content and the total glycoalkaloidslevel were increased by GA₃ treatment, but decreased by ABAtreatment. In contrast, total proteins were increased by ABA,but decreased by GA₃ treatment. ¹This work was supported by a PL-480 research grant (FG-Pa-262)from the United States Department of Agriculture widi co-ordinationby the Agriculture Research Council, Pakistan. (Received August 29, 1980; )     

Partial Purification and Characterization of Gibberellin 3{beta}-hydroxylase from Immature Seeds of Phaseolus vulgaris L.

Gibberellin 3/ß-hydroxylase,a 2-oxoglutarate-dependentdioxygenase that catalyzes the hydroxylation of GA₂₀ to GA₁,was purified 313-fold from immature seeds of Phaseolus vulgarisL. The mol wt of the enzyme was estimated to be 42,000 by gelfiltration HPLC and SDS-polyacrylamide gel electrophoresis.The enzyme exhibited maximum activity at pH 7.7. The Km valuesfor [2,3-³H]GA20 and [2,3-³H]GA, were 0.29µu and 0.33µm, respectively. The enzyme requires 2-oxoglutarate asa cosubstrate; the K_m value for 2-oxoglutarate was 250µMusing [³H]- GA₂₀ as a substrate. Fe²⁺ and ascorbate significantlyactivated the enzyme at all purification steps, while catalaseand BSA activated the purified enzyme only. The enzyme was inhibitedby divalent cations Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Hg²⁺.3ß-Hydroxylation of [³H]- GA₂₀ was also inhibitedby non-radioactive GA₅, GA₉,GA₁₅, GA₂₀ and GA₄₄. The possiblesite of 3ß-hydroxylation in gibberellin biosynthesisis discussed in terms of the substrate specificity of partiallypurified gibberellin 3ß-hydroxylase. (Received February 29, 1988; Accepted June 3, 1988)     

Metabolism and Translocation of Gibberellins in Seedlings of Pharbitis nil. (I) Effect of Photoperiod on Stem Elongation and Endogenous Gibberellins in Cotyledons and Their Phloem Exudates

Gibberellin A₁, (GA₁), GA₁₉, and GA₂₀ in phloem exudates andcotyledons of seedlings of Pharbitis nil cv. Violet, grown underdifferent photoperiodic conditions, were qualitatively and semi-quantitativelyanalyzed by a combination of high performance-liquid chromatography(HPLC) and radioimmunoassays (RIA). The levels of GA₁₉ and GA₂₀were higher in cotyledons from plants grown under dark treatment(DT) conditons of 16 h-light/8 h-dark for 6 days followed by8 h-light/16 h-dark for 3 days than in those grown under continuouslight (CL) for 9 days. This relationship was also observed forthe GAs in phloem exudates, although the levels were much lowerthan in the cotyledons. When GAs were applied to the cotyledons,elongation of the epicotyl was promoted more by GA₂₀ than byGA₁ or GA₁₉, especially under the CL treatment. The relativeeffect of GA₁ and GA₂₀ on the epicotyl elongation was reversedwhen these GAs were applied to epicotyls pre-treated with prohexadione,an inhibitor of 2-oxoglutarate-dependent dioxygenases. ³Present address: Frontier Research Program, The Institute ofPhysical and Chemical Research (RIKEN), 2-1 Hirosawa, Wakoshi,Saitama, 351-01 Japan ⁴Present address: Laboratory of Horticulture, Faculty of Agriculture,Nagoya University, Nagoya, 464-01 Japan     

Auxin-gibberellin relationships in their effects on hypocotyl elongation of light-grown cucumber seedlings VI. Promotive and inhibitory effects of kinetin

The interaction of kinetin with IAA and GA₃ on the elongationof hypocotyl sections of Cucumis sativus L. cv. National Picklingwas studied. Kinetin in the concentration range of 10^–7M to 10^–4 M markedly inhibited IAA-induced elongation,while in a lower range from 10^–10 M to 10^–8 M, itsynergistically enhanced IAA-induced elongation. Kinetin alonein this range had no effect. A 5-to 15-min pulse treatment seemsenough to induce the maximum effect for both inhibition andpromotion. Since the magnitude of the maximum inhibition dependedon the concentration and not on the duration of treatment, thereaction in the cell caused by kinetin seemed to be completedwithin a short period. Washing of the sections with distilledwater after kinetin treatment (30 min) did not significantlyeliminate the kinetin effect. This probably indicates that thebinding of kinetin molecules to a supposed acceptor is not reversible.Interaction of kinetin with GA₃ in their pretreatment effectson IAA-induced elongation shows that in the inhibitory concentrationrange, the kinetin effect was partly overcome by GA₃, and thatin the promotive range, the magnitude of the enhancement wasdetermined by kinetin regardless of the presence of GA₃. Theeffect of kinetin seems to dominate over that of GA₃ indicatingthat the modes of their pretreatment effects differ from oneanother. (Received June 24, 1977; )     

Interaction of auxin, cytokinin, and gibberellin on cell division and xylem differentiation in cultured explants of Jerusalem artichoke.

Dark-cultured explants of parenchymatous cells isolated fromJerusalem artichoke tubers were induced to divide and differentiateas tracheary elements on Murashige and Skoog medium containingdifferent combinations of plant growth-hormones such as auxin(IAA), cytokinin (zeatin), and gibberellin (GA₃). Addition ofauxin to the growth-medium induced after a short lag period,very rapid cell division which was followed by differentiationof some of the divided cells as tracheary elements. At the optimallevel of IAA (5.0 mg/liter), the percentage of tracheids differentiatedwith respect to the total number of cell population was 13.54.When the explants were cultured in the presence of both auxin(IAA 5.0 mg/liter) and one cytokinin (zeatin 0.1 mg/liter),not only a strong interaction on cell division and trachearyelement formation was observed but also an increase in the percentageof tracheids differentiated in relation to the total cell population.Auxin-gibberellin and auxin-gibberellin-cytokinin treatmentsalso produced interaction on cell division and cytodifferentiation.In explants treated with the three growth-hormones about 20%of the total cell population differentiated as tracheary elements.Further, all the hormonal treatments gave different patternsof cytodifferentiation which reflected meristematic patterns. ¹ This research was supported by a grant from C. N. R. Italy. (Received April 18, 1973; )     

Hormonal Regulation of Hypocotyl Elongation in Lactuca sativa L.: I. EVIDENCE AGAINST THE INVOLVEMENT OF GIBBERELLINS IN THE ELONGATION OF HYPOCOTYL IN SEEDLINGS GROWN IN THE DARK

The kinetics of extension induced by GA₃¹ in the hypocotyl ofintact seedlings of Lactuca sativa are similar in the dark andin the light, and differs fundamentally from the kinetics ofelongation in the dark without GA₃. Both in continuous lightand in the dark, GA₃-induced promotion starts 24 h after incubation.In the dark, even low concentrations of GA₃, which do not affectthe length measured after 6 d when the extension of hypocotylalmost ceases, remove the lag period of 48 h which precedesextension, and prolong the high rate of elongation. FollowingGA₃ supply the hypocotyl length in the dark and in the lightdoes not differ until 48 h; thereafter the rate of elongationin the light is less, so that the final length of the hypocotylis 40 per cent shorter than that of the dark-grown seedlingswithout GA₃. IAA supplied apically to light-grown seedlings induces a weakpromotion at a concentration of 1 mg l^–1 only. With anincreasing concentration of GA₃ supplied simultaneously, theconcentration of IAA inducing a significant promotion decreases.A combined supply of both these regulators, however, does notrestore the light-mediated inhibition of hypocotyl elongationcompletely. The maximum decrease in hypocotyl length induced by the growthretardants AMO-1618, CCC, and B-9 supplied from the beginningin the dark does not exceed 70 per cent. Saturating doses ofGA₃ supplied in combination with any one of the retardants compensateonly a fraction of the decrease. The results have been interpreted to show that native GAs arenot involved in extension growth in the dark.     

Effects of Gibberellins and Prohexadione on the Activities of Oryzain and {alpha}-Amylase in Rice Seeds

Oryzains, cysteine proteinases of rice seeds, are induced byGA₃ in germinating rice seeds [Abe et al. (1987) Agric. Biol.Chem. 51: 1509]. The effects of GA₁, GA₃, GA₄, GA₉, and GA₂₀on the production of oryzain and -amylase were investigatedin embryoless half- and whole-seeds of rice (cv. Nipponbare).When gibberellins (GAs) were incubated with embryoless half-seeds,GA₁, GA₃ and GA₄ induced oryzain and -amylase, but GA₉, andGA₂₀ did not. GA₉ and GAM induced oryzain and -amylase productionin whole seeds, but this production was inhibited by the simultaneousapplication of prohexadione, an inhibitor of 2ß- and3ß-hydroxylation of GAs. Prohexadione did not inhibitthe activities of oryzain and -amylase induced by GA₁. Theseresults suggest that GAs possessing the 3ß-hydroxylgroup induce activities of oryzain and -amylase in rice seedsand that GA₉ and GA₂₀ have activity only after they are convertedmetabolically to active GAs, probably GA₄ and GA₁, respectively.GA₁, was more active than GA₄ in both half seeds and wholeseeds incubation. Oryzain and -amylase activities induced byGA₄ were significantly inhibited in the presence of 10^–4M prohexadione. This suggests that the conversion of GA₁, toGA₄ (13-hydroxylation) might be inhibited at a high dose ofprohexadione in whole seeds. ⁴Present address: Institute of Food Development, Kyung Hee University,Suwon 449-701, Korea