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1.
In Schizaeaceae ferns, including Anemia phyllitidis, formation of antheridia is known to be induced by exogenously applied gibberellic acid. Also present studies show that GA3 (10−5 mol·dm−3) modifies the development of gametophytes of Anemia phyllitidis. Simultaneously with formation of antheridia, they exhibit lower number of cells but only slightly lowered profile areas and lengths of prothalli. Growth in size of individual cells compensates for lowered division frequency. Cytophotometric measurements reveal no essential changes in the DNA content in vegetative cells of the control and GA3-stimulated gametophytes. It remains at haploid level and therefore it is assumed that cell cycle is blocked at G1 phase. Application of GA3 increases the total amount of proteins. CZE (Capillary Zone Electrophoresis) separation of peptides extracted from control and GA3-treated prothalli indicates the differences in the ratio of their particular forms. In GA3-treated gametophytes the activities of acid and basic phosphatases, contents of carbohydrates (glucose, starch), chlorophyll, the number of chloroplasts and dry mass of prothalli are increased. GA3-intensified metabolism, evidenced in gametophytes of A. phyllitidis, may be interpreted as a stimulatory mechanism which influences metabolic pathways involved in forming, developing and maturing of male sex organs.  相似文献   

2.
Cytomorphological studies of the development of young fern gametophytes (Anemia phyllitidis) have been used to investigate combined effects of gibberellic acid and ethylene on male sex expression. ACC (the key by-product in ethylene biosynthesis pathway) was found to exert a synergetic effect on the gibberellic acid-induced antheridia formation, and this phenomenon could be related with the specific stimulation of cell growth and activity of their differentiation. To complete and verify those observations male sex expression in the fern gametophytes treated with ACC-biosynthesis inhibitor was reinvestigated. Aminooxyacetic acid (AOA) restrained antheridia formation via inhibition of cell divisions. AOA influenced the arrangement and flexibility of cellulose microfibrils in the antheridial zone cells, thus affecting cell expansion. On the other hand, the level of DNA synthesis was not reduced. Transient increase in the number of S-phase cells, followed by the accumulation of G2-phase cells led to the enhancement of cell polyploidization. All these findings correspond with the previous observations and support participation of ethylene in gibberellic acid-induced male sex expression in ferns.Abbreviations AOA Aminooxyacetic acid - CPA Cell profile area - GA Gibberellin - GA3 Gibberellic acid  相似文献   

3.
An antheridiogen of Anemia mexicana Klotzsch has been partially characterized by combined gas chromatography-mass spectrometry and gas chromatography-Fourier transform/infra-red spectrometry. It is a C19-gibberellin(GA)-like compound with one carboxyl group, an exocyclic methylene group and a lactone ring. It also has one hydroxyl-group and one double-bond equivalent which has not been determined. On the basis of its mass spectrum, it is not identical to previously identified monohydroxy GAs with one ring double bond such as GA5, GA7, GA31 and GA62. By direct comparison of mass spectra, the antheridiogen of A. mexicana was also determined to be different from the antheridiogens of Anemia phyllitidis (L.) Swartz, Anemia hirsuta (L.) Swartz and Lygodium japonicum (Thunb.) Sw.Abbreviations GA(s) gibberellin(s) - GAa gibberellin An - GC-FT/IR combined gas chromatography-Fourier transform/infra-red spectrometry - GC-MS combined gas chromatography-mass spectrometry - IR intra-red spectrometry - KRI Kovats Retention Index - m/z mass/charge - TLC thin-layer chromatography - TMSi trimethylsilyl  相似文献   

4.
In a carrot (Daucus carota L.) cell line lacking the ability to undergo somatic embryogenasis, and in carrot and anise (Pimpinella anisum L.) cell lines in which embryogenesis could be regulated by presence or absence of 2,4-dichlorophen-oxyacetic acid (2,4-D), in the medium (+2,4-D=no embryogenesis,-2,4-D=embryo differentiation and development), the levels of endogenous gibberellin(s) (GA) were determined by the dwarfrice bioassay, and the metabolism of [3H]GA1 was followed. Embryos harvested after 14 d of subculture in-2,4-D had low levels (0.2–0.3 g g-1 dry weight) of polar GA (e.g. GA1-like), but much (3–22 times) higher levels of less-polar GA (GA4/7-like); GA1, GA4 and GA7 are native to these cultures. Conversely, the undifferentiated cells in a non-embryogenic strain, and proembryos of an embryogenic strain (+2,4-D) showed very high levels of polar GA (2.9–4.4 g g-1), and somewhat reduced levels of less-polar GA. Cultures of anise undergoing somatic embryo development (-2,4-D) metabolized [3H]GA1 very quickly, whereas proembryo cultures of anise (+2,4-D) metabolized [3H]GA1 slowly. The major metabolites of [3H]GA1 in anise were tentatively identified as GA8-glucoside (24%), GA8 (15%), GA1-glucoside (8%) and the 1(10)GA1-counterpart (2%). Thus, high levels of a GA1-like substance and a reduced ability to metabolize GA1 are correlated with the absence of embryo development, while lowered levels of GA1-like substance and a rapid metabolism of GA1 into GA8 and GA-conjugates are correlated with continued embryo development. Exogenous application of GA3 is known to reduce somatic embryogenesis in carrot cultures; GA4 was found to have the same effect in anise cultures. Thus, a role (albeit negative) in somatic embryogenesis for a polar, biologically active GA is implied.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - GA gibberellin(s) or gibberellin-like substances - GC-RC gas chromatography-radiochromatogram counting - HPLC high-presare liquid chromatography - Rt retention time - TLC thinlaver chromatography  相似文献   

5.
Fei H  Zhang R  Pharis RP  Sawhney VK 《Planta》2004,219(4):649-660
Earlier, we reported that mutation in the Male Sterile33 (MS33) locus in Arabidopsis thaliana causes inhibition of stamen filament growth and a defect in the maturation of pollen grains [Fei and Sawhney (1999) Physiol Plant 105:165–170; Fei and Sawhney (2001) Can J Bot 79:118–129]. Here we report that the ms33 mutant has other pleiotropic effects, including aberrant growth of all floral organs and a delay in seed germination and in flowering time. These defects could be partially or completely restored by low temperature or by exogenous gibberellin A4 (GA4), which in all cases was more effective than GA3 Analysis of endogenous GAs showed that in wild type (WT) mature flowers GA4 was the major GA, and that relative to WT the ms33 flowers had low levels of the growth active GAs, GA1 and GA4, and very reduced levels of GA9, GA24 and GA15, precursors of GA4. This suggests that mutation in the MS33 gene may suppress the GA biosynthetic pathway that leads to GA4 via GA9 and the early 13-H C20 GAs. WT flowers also possessed a much higher level of indole-3-acetic acid (IAA), and a lower level of abscisic acid (ABA), relative to ms33 flowers. Low temperature induced partial restoration of male fertility in the ms33 flowers and this was associated with partial increase in GA4. In contrast, in WT flowers GA1 and GA4 were very much reduced by low temperature. Low temperature also had little effect on IAA or ABA levels of ms33 flowers, but did reduce (>2-fold) IAA levels in WT flowers. The double mutants, ms33 aba1-1 (an ABA-deficient mutant), and ms33 spy-3 (a GA signal transduction mutant) had flower phenotypes similar to ms33. Together, the data suggest that the developmental defects in the ms33 mutant are unrelated to ABA levels, but may be causally associated with reduced levels of IAA, GA1 and GA4, compared to WT flowers.Abbreviations ABA Abscisic acid - GA Gibberellin - GC-MS-SIM Gas chromatography-mass spectrometry-selected ion monitoring - IAA Indole-3-acetic acid - ms33 Male sterile33 mutant - PP333 Paclobutrazol - WT Wild type  相似文献   

6.
Valerie A. Smith 《Planta》1993,191(2):158-165
The physiological and biochemical consequences of treating Le (tall) and le (dwarf) pea seedlings with varying quantities of the gibberellins [3H]GA20 and GA1 have been investigated. Although the percentage uptake of these compounds from the site of application on the 3 stipules was low and most of the applied GA remained unmetabolised in situ, the quantitative relationship between GA translocation and GA dosage was found to be linear for GA1 but saturating for GA20. The movement of the GAs and their subsequently produced metabolites was mainly acropetal. They accumulated in greatest quantity in the apical extremities of the shoot. Overall, the extent to which GA20 was metabolished in le seedlings was considerably less than in Le pea seedlings. Although all le tissues contained significantly less [3H]GA1 than their Le counterparts, phenotypic effects of the le mutation were apparent only on internode and tendril development. Increased tissue growth, consequent upon GA treatment, was also apparent only in the internodes and tendrils of le plants. For internodes, GA1 content determined the mid-logarithmic-phase growth rate and, consequently, final length. For tendrils, GA20 rather than GA1 may be the primary stimulatory agent.Abbreviations GA gibberellin - HPLC high-performance liquid chromatography - 1–6 consecutive developmental numbering system for plant tissues/organs as shown in Fig. 1 The author gratefully acknowledges financial support from Imperial Chemical Industries, Plant Protection, Jealott's Hill, Bracknell, Berks., UK and the Science and Engineering Research Council.  相似文献   

7.
Capillary electrophoresis revealed that the endogenous level of ACC (1-aminocyclopropane-1-carboxylic acid) in the gametophytes of Anemia phyllitidis was elevated during GA3-induced male determination, whereas AOA (aminooxyacetic acid, specific inhibitor of ACC synthase) in untreated as well as in the GA3-treated gametophytes decreased concentration of ACC. The mechanism of ethylene involvement in controlling antheridiogenesis reflected at the level of ACC, which is supposed to mediate interactions between ethylene and gibberellins, is proposed.  相似文献   

8.
Effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) on the development and expression of male sex were tested using the model of the three-zonal structure of 12-day-old (15-celled) Anemia phyllitidis gametophyte. ACC at 10 M concentration enhanced the number of antheridia induced by gibberellic acid. Cytomorphological measurements showed that this effect was limited to only the antheridial region of gametophytes and depended on transverse expansion of antheridial mother cells. Time-course cytophotometrical measurements showed that this promotive effect of ACC was preceded by reorganization of nuclear chromatin and induction of DNA synthesis in nuclei in the antheridial region cells of fern gametophytes.Abbreviations ACC: 1-Aminocyclopropane-1-carboxylic acid. - CPA: Cell profile area. - GA: Gibberellin. - GA3: Gibberellic acid. - NPA: Nuclear profile area. - TE: Tris-EDTA buffer.Communicated by D. Bartels  相似文献   

9.
Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod and fix mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation.The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue.Abbreviations EIA enzyme immunoassay - GAn gibberellin An - GC-MS gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - IAA indole-3-acetic acid - Me methyl ester - RIA radioimmunoassay - TLC thin-layer chromatography  相似文献   

10.
John L. Stoddart 《Planta》1984,161(5):432-438
Growth parameters were determined for tall (rht3) and dwarf (Rht3) seedlings of wheat (Triticum aestivum L.). Plant statures and leaf length were reduced by 50% in dwarfs but root and shoot dry weights were less affected. Leaves of dwarf seedlings had shorter epidermal cells and the numbers of cells per rank in talls and dwarfs matched the observed relationships in overall length. Talls grew at twice the rate of dwarfs (2.3 compared with 1.2 mm h-1). [3H]Gibberellin A1 ([3H]GA1) was fed to seedlings via the third leaf and metabolism was followed over 12 h. Immature leaves of tall seedlings transferred radioactivity rapidly to compounds co-chromatographing with [3H]gibberellin A8 ([3H]GA8) and a conjugate of [3H]GA8, whereas leaves of dwarf seedlings metabolised [3H]GA1 more slowly. Roots of both genotypes produced [3H]GA8-like material at similar rates. Isotopic dilution studies indicated a reduced 2-hydroxylation capacity in dwarfs, but parallel estimates of the endogenous GA pool size, obtained by radioimmunoassay, indicated a 12–15 times higher level of GA in the dwarf immature leaves. Dwarfing by the Rht3 gene does not appear to operate through enhanced, or abnormal metabolism of active gibberellins and the act of GA metabolism does not bear an obligate relationship to the growth response.Abbreviations GAn gibberellin An - HPLC high-performance liquid chromatography  相似文献   

11.
One of the prime precursor for ethylene synthesis — L-methionine and the inhibitor of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) — Co2+-were tested for their effects on sex expression and development of Anemia phyllitidis fern gametophytes. Five concentrations of both chemicals (0, 10, 25, 50, 100 μM) were analysed with reference to antheridia and archegonia formation, number and size of cells as well as thalli length using the three-zone model of gametophyte structure. Both substances, however at different concentrations, enhanced the number of GA3-induced antheridia and similarly stimulated the cell number and inhibited thalli length. Both of them at 100 μM concentrations without GA3 induced meristematic area formation while methionine also induced archegonia in the apical parts of gametophytes. These findings correspond with the previous observations concerning the important role of ethylene synthesis precursor (ACC) in controlling gibberellic acid-induced male sex expression in ferns and broaden the knowledge about the mechanisms of fern gametophyte development.  相似文献   

12.
The levels of the biologically active gibberellin (GA), GA1, and of its precursor, GA20, were monitored at several stages during ontogeny in the apical portions of isogenic tall (Le) and dwarf (le) peas (Pisum sativum L.) using deuterated internal standards and gas chromatography-selected ion monitoring. The levels of both GAs were relatively low on emergence and on impending apical arrest. At these early and late stages of development the internodes were substantially shorter than at intermediate stages, but were capable of large responses to applied GA3. Tall plants generally contained 10–18 times more GA1 and possessed internodes 2–3 times longer than dwarf plants. Further, dwarf plants contained 3–5 times more GA20 than tall plants. No conclusive evidence for the presence of GA3 or GA5 could be obtained, even with the aid of [2H2]GA3 and [2H2]GA5 internal standards. If GA3 and GA5 were present in tall plants, their levels were less than 0.5% and 1.4% of the level of GA1, respectively. Comparison of the effects of gene le on GA1 levels and internode length with the effects of ontogeny on these variables shows that the ontogenetic variation in GA1 content was sufficient to account for much of the observed variation in internode length within the wild-type. However, evidence was also obtained for substantial differences in the potential length of different internodes even when saturating levels of exogenous GA3 were present.Abreviations GAn gibberellin An We thank Noel Davies, Omar Hasan, Leigh Johnson, Katherine McPherson and Naomi Lawrence for technical help, Professor L. Mander (Australian National University, Canberra) for deuterated GA standards and the Australian Research Council for financial assistance.  相似文献   

13.
Douglas S. Bush 《Planta》1996,199(1):89-99
Gibberellins (GAs) control a wide range of physiological functions in plants from germination to flowering. The cellular mechanisms by which gibberellic acid (GA3) acts have been most extensively studied in the cereal aleurone. In this tissue, alterations in cellular calcium are known to be important for the primary response to GA, which is the production and secretion of hydrolytic enzymes. The extent to which cytosolic Ca2+ mediates the early events in GA action, however, is not known. In order to address this question, changes in cytosolic Ca2+ in wheat (Triticum aestivum L. cv. Inia) aleurone cells that occur rapidly after treatment with GA were characterized. In addition, GA-induced changes were compared with changes induced by three environmental stimuli that are known to modify the GA response: osmotic stress, salt (NaCl), and hypoxia. The Ca2+-sensitive dye fluo-3 was used to photometrically measure cytosolic Ca2+. It was found that GA3 induced a steady-state increase in cytosolic Ca2+ of 100–500 nM. This increase was initiated within a few minutes of treatment with GA and was fully developed after 30–90 min. The changes in cytosolic Ca2+ that were induced by GA were distinct from those induced by mannitol, NaCl, or hypoxia. Mannitol caused a steady-state decrease whereas NaCl and hypoxia both increased cytosolic Ca2+. In the case of NaCl this increase was transient but for hypoxia the increase was prolonged as long as hypoxic conditions were maintained. Gibberellin-induced changes in cytosolic Ca2+ were not induced by the inactive GA, GA8, nor did the GA-insensitive wheat mutant, D6899, respond to active GA3 with altered cytosolic Ca2+. It is concluded that changes in cytosolic Ca2+ are an early and integral part of the GA response in aleurone cells. The data also indicate, however, that changes in Ca2+ are not sufficient, by themselves, to induce the GA response of aleurone cells.Abbreviations AM acetoxymethyl ester - GA gibberellin - GA3 gibberellic acid - Mes 2-[N-morpholino]ethanesulfonic acid - PM plasma membrane The author is very grateful to Dr. T-h. D. Ho for his gift of D6899 grain and to Dr. R. Hooley for supplying the inactive GA8. This work was supported by National Science Foundation Grant DCB-9206692.  相似文献   

14.
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  相似文献   

15.
The properties of the water-soluble metabolites of [3H]gibberellin A1 ([3H]GA1) from lettuce (Lactuca sativa L.) hypocotyls were compared with those of authentic samples of gibberellin (GA) glucosyl esters and ethers. Partitioning against l-butanol at high and low pH was not an efficient method of differentiating between ester and ether conjugates of GA1 or GA3. Extraction into l-butanol at pH 2.5 was, however, useful as a group purification step. Gel-filtration on acrylamide indicated a mean molecular weight of ca. 600 for the polar material and high-voltage electrophoresis separated two compounds (LH 1 and LH 2) with differing charge properties. Both metabolites incorporated 14C from glucose and 3H from GA1. Subsequent enzymatic hydrolysis of LH 1 released material with identical properties to [14C]glucose together with a second uncharacterised component. Feeding with [3H]GA1 methyl ester greatly reduced the formation of LH 1 but not LH 2. The metabolites were provisionally identified as GA1-glucosyl ester (LH 1) and GA1-glucosyl ether (LH 2).Abbreviations GA gibberellin - LH1 GA3-glucosyl ester - LH2 GA1-glucosyl ether - HVE high voltage paper electrophoresis - TLC thin-layer chromatography  相似文献   

16.
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 GA1, 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.  相似文献   

17.
Endogenous gibberellins (GAs) were extracted from safflower (Carthamus tinctorius L.) stems and detected by capillary gas chromatography-mass spectrometry from which GA1, GA3, GA19,, GA20, GA29, and probably, GA44 were detected. The detection of these GAs suggests that the early 13-OH biosynthetic pathway is prevalent in safflower shoots. Deuterated GAs were used as internal standards and GA concentrations were determined in stems harvested at weekly intervals. GA1 and GA19 levels per stem increased but concentrations per gram dry weight decreased over time. GA20 was only detected in young stem tissue.Gibberellic acid (GA3) was also applied in field trials and both GA3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests. GA3 increased epidermal cell size, internode length, and increased internode cell number causing stem elongation. Conversely, paclobutrazol reduced stem height, internode and cell size, cell number and overall shoot weight. In field tests, GA3 increased total stem weight, but decreased leaf weight, flower bud number and seed yield. Thus, GA3 promoted vegetative growth at the expense of reproductive commitment. These studies collectively indicate a promotory role of GAs in the control of shoot growth in safflower, and are generally consistent with gibberellin studies of related crop plants. Author for correspondence  相似文献   

18.
The effect of auxin, GA and BAP on potato shoot growth and tuberization was investigated under in vitro condition. The shoot length of potato explants increased with the increasing of concentrations (0.5 – 10 mg dm−3) of IAA treatment especially with the addition of GA3 (0.5 mg dm−3), but was inhibited by BAP (5 mg dm−3). The root number and root fresh weight of potato explants increased with the increasing of IAA levels either in the presence of GA3 (treatment IAA+GA) or not (IAA alone). However, no root was observed in the treatment IAA+BAP, instead there were brown swollen calli formed around the basal cut surface of the explants. The addition of GA3 remarkably increased the fresh weight and diameter of calli. Microtubers were formed in the treatments of IAA+BAP and IAA + GA + BAP but not observed in the treatments of IAA alone or IAA + GA. IAA of higher concentrations (2.5 – 10 mg dm−3) was helpful to form sessile tubers. With the increasing of IAA levels, the fresh weight and diameter of microtubers increased progressively. At 10 mg/L IAA, the fresh weight and diameter of microtubers in the treatment of IAA + GA + BAP were 409.6 % and 184.4 % of that in the treatment of IAA + BAP respectively, indicating the interaction effect of GA and IAA in potato microtuberization.  相似文献   

19.
Endogenous pools of presumptive gibberellin (GA) glucosyl conjugates of Phaseolus coccineus were metabolically labelled by feeding of [3H]GA1 to immature fruits. The [3H]GA1 glucoside fraction was isolated and the main constituent tentatively identified by enzymic hydrolysis, ion exchange chromatography and elution volume on HPLC-RC as GA1-3-0--D-glucopyranoside.  相似文献   

20.
The kinetics of the uptake of [3H]gibberellin A1 (GA1) by light- and dark-grown suspension-cultured cells of Spinacia oleracea (spinach) have been studied. Use of nonradioactive GA1 and gibberellic acid (GA3) show that the uptake has a saturable and a nonsaturable component. The nonsaturable component increases as the pH is lowered at a fixed concentration of [3H]GA1 and is probably caused by non-mediated diffusion of the uncharged protonated species of GA1. The saturable component is not the result of metabolic transformation or to GA1 binding to the cell wall and is suggested to represent the operation of a transport carrier for which GA1 and GA3 are substrates. Auxin, abscisic acid and a cytokinin did not alter the GA1 uptake. The Km is approx. 0.3 mol dm-3 at pH 4.4 in light- and dark-grown cells. The Vmax of the carrier is higher in the light-grown cells. The optimum pH for the carrier at a physiological GA1 concentration (3 nmol dm-3) was pH 4.0, with no activity detectable at pH 7.0. Both saturable and nonsaturable components were decreased by protonophores indicating that the pH gradient between the cells and the medium may be a component of the driving forces for both types of transport. Both the permeability coefficient for the undissociated GA1 and the ratio V max/K m for the carrier are lower than the corresponding values for the indole-3-acetic acid and abscisic acid carriers studied in other species.Abbreviations and symbols ABA abscisic acid - DMO 5,5-dimethyloxazolidine-2,4-dione - GA gibberellin - GA3 gibberellic acid - IAA indole-3-acetic acid - P permeability coefficient  相似文献   

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