共查询到20条相似文献,搜索用时 31 毫秒
1.
Immature seeds of apricot (Prunus armeniaca L.) were fed the native gibberellin A5 (GA5) as 1- and 1,2-[3H]GA5 (5.3 Curies per millimole to 16 milliCuries per millimole) at doses (42 nanograms to 10.6 micrograms per seed) 2 to 530 times the expected endogenous level. After 4 days of incubation, seeds were extracted and free [3H]GA-like metabolites were separated from the highly H2O-soluble [3H]metabolites. For high specific activity feeds the retention times (Rts) of radioactive peaks were compared with Rts of authentic GAs on sequential gradient-eluted → isocratic eluted reversed-phase C18 high performance liquid chromatography (HPLC) -radiocounting (RC). From high substrate feeds (530 and 230 × expected endogenous levels) HPLC-RC peak groupings were subjected to capillary gas chromatography-selected ion monitoring (GC-SIM), usually six characteristic ions. The major free GA metabolites of [3H] GA5 were identified as GA1, GA3, and GA6 by GC-SIM. The major highly water soluble metabolite of [3H]GA5 at all levels of substrate GA5 had chromatographic characteristics similar to authentic GA1-glucosyl ester. Expressed as a percentage of recovered radioactivity, low substrate [3H]GA5 feeds (2 × expected endogenous level) yielded a broad spectrum of metabolites eluting at the Rts where GA1, GA3, GA5 methyl ester, GA6, GA22, GA29 (17, 14, 1.6, 7, 1.1, 0.5%, respectively) and GA glucosyl conjugates of GA1, GA3, GA5, and GA8 (33, 11, 1, 0.1%, respectively) elute. Metabolites were also present at Rts where GA glucosyl conjugates of GA6 and GA29 would be expected to elute (8 and 0.1%, respectively). Only 5% of the radioactivity remained as GA5. Increasing substrate GA5 levels increased the proportion of metabolites with HPLC Rts similar to GA1, GA6, and especially GA1 glucosyl ester, primarily at the expense of metabolites with HPLC Rts similar to GA3, GA3-glucosyl ester, and a postulated conjugate of GA6. There was evidence that high doses of substrate GA5 induced new metabolites which often, but not always, differed from GA1, GA3, and GA6 in HPLC Rt. These same metabolites, when analyzed by GC-SIM yielded m/e ions the same as the M+ and other characteristic m/e ions of the above GAs, albeit at differing GC Rt and relative intensities. 相似文献
2.
Rick C. Heupel Bernard O. Phinney Clive R. Spray Paul Gaskin Jake MacMillan Peter Hedden Jan E. Graebe 《Phytochemistry》1985,24(1):47-53
The native hormones from tassels of maize (Zea mays) were re-investigated. The previous identification by GC/SIM of GA1, GA8 and GA29 in normal tassels was confirmed by full GC/MS scans at the correct Kovats retention indices. In tassels of dwarf-1 mutants, GA44,?GA19, GA17, GA20 and the 16,17-dihydro, 7β,16α,17-trihydroxy derivative of ent-kaurenoic acid were identified by GC/MS. Gibberellin A1 was not found in the mutant tassels. [14C]Gibberellin A53 was fed to tassels of the dwarf-5 mutant. In the ethyl acetate-soluble acidic fraction from the feeds, [14C]GA44 was identified by GC/MS; [14C]GA19 and [14C]GA29 were identified by GC/SIM. The GA29 is probably a metabolite of the feeds because the dwarf-5 mutant is known to control the step copalyl pyrophosphate to ent-kaurene in the maize GA-biosynthetic pathway and because GA29 was not identified in a control experiment. The n-butanol fractions obtained from the feeds were shown, by GC/MS, to contain [14C]GA53 after hydrolysis, suggesting that conjugated [14C]GA53 is a major metabolite from GA53 feeds. [17-13C, 17-3H2]Gibberellin A20 was fed to normal, dwarf-1 and dwarf-5 tassels. In each case, analysis of the purified ethyl acetate-soluble acidic extracts by GC/MS led to the identification of [13C]GA29 and unmetabolized [13C]GA20 in which no 13C-isotope dilution was observed. 相似文献
3.
Metabolism of Tritiated Gibberellin A(20) in Immature Seeds of Dwarf Pea, cv. Meteor 总被引:3,自引:3,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tritium-labeled gibberellin A20 ([3H]GA20) was applied via the pedicel to immature pods and seeds of dwarf peas and three harvests were made at days 5, 10, and 23 (mature) after application. Of the five metabolites of [3H]GA20, the three in highest yield were GA29, an α,β-unsaturated ketone, and a compound (B), whose structure was only tentatively assigned. The metabolic sequence GA20 → GA29 → compound B → the ketone was indicated. The amount of [3H]GA29 in both seeds and pods was highest at day 5 and declined to its lowest level at maturity. The amount of the [3H]ketone in the seed increased with time to its highest level at maturity. It is suggested that compound B and the ketone represent the major pathway of catabolism of GA29, a 2β-hydroxylated GA of low biological activity, and that the ketone is not metabolized, or only slowly metabolized, during seed maturation. 相似文献
4.
Effect of Photoperiod on Metabolism of [H] Gibberellins A(1), 3-epi-A(1), and A(20) in Agrostemma githago L
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
To determine whether daylength influences the rate of metabolism of gibberellins (GAs) in the long-day (LD) rosette plant Agrostemma githago L., [3H]GA20 and [3H]GA1 were applied under short day (SD) and LD. Both were metabolized faster under LD than under SD. [3H]GA20 was metabolized to a compound chromatographically identical to 3-epi-GA1. [3H]GA1 was metabolized to two acidic compounds, the major metabolite having chromatographic properties similar to, but not identical with GA8. [3H]3-epi-GA1 applied to plants under LD was metabolized much more slowly than was [3H]GA1, and formed a very polar metabolite which did not partition into ethyl acetate at pH 2.5. Very polar metabolites were also formed after the feeds of [3H]GA20 and [3H]GA1. It was not possible to characterize these very polar compounds further because of their apparent instability. The results obtained suggest that in Agrostemma GA20 is the precursor of 3-epi-GA1, but there is at present no evidence indicating the precursor of GA1. 相似文献
5.
Metabolism of Gibberellin A(12) and A(12)-Aldehyde in Developing Seeds of Pisum sativum L 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Metabolism of [14C]gibberellin (GA) A12 (GA12) and [14C]gibberellin A12-aldehyde (GA12-aldehyde) was examined in cotyledons and seed coats from developing seeds of pea (Pisum sativum L.). Both were metabolized to only 13-hydroxylated GAs in cotyledons but to 13-hydroxylated and non-13-hydroxylated GAs in seed coats. The metabolism of [14C]GA12 was slower in seed coats than in cotyledons. [14C]GA12-aldehyde was also metabolized to conjugates in seed coats. Seed coat [14C]-metabolites produced from [14C]GA12-aldehyde were isolated by high-performance liquid chromatography (HPLC). Conjugates were base hydrolyzed and the free GAs reisolated by HPLC and identified by gas chromatography-mass spectrometry. [14C]GA53-aldehyde, [14C]GA12-aldehyde conjugate, and [14C]GA53-aldehyde conjugate were major metabolites produced from [14C]GA12-aldehyde by seed coats aged 20-22 days or older. The dilution of 14C in these compounds by 12C, as compared to the supplied [14C]GA12-aldehyde, indicated that they are endogenous. Feeding [14C]GA53-aldehyde led to the production of [14C]GA53-aldehyde conjugate in seed coats and shoots and also to 13-hydroxylated GAs in shoots. Labeled GAs, recovered from plant tissue incubated with either [14C]GA12, [14C]GA12-aldehyde, or [3H]GA9, were used as appropriate markers for the recovery of endogenous GAs from seed coats or cotyledons. These GAs were purified by HPLC and identified and quantified by gas chromatography-mass spectrometry. GA15, GA24, GA9, GA51, GA51-catabolite, GA20, GA29, and GA29-catabolite were detected in seed coats, whereas GA9, GA53, GA44, GA19, GA20, and GA29 were found in cotyledons. The highest GA levels were for GA20 and GA29 in cotyledons (783 and 912 nanograms per gram fresh weight, respectively) and for GA29 and GA29-catabolite in seed coats (1940 and > 1940 nanograms per gram fresh weight, respectively). 相似文献
6.
Endogenous Gibberellins in Elongating Shoots of Clones of Salix dasyclados and Salix viminalis
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Elongating shoots of rapidly growing clones of Salix viminalis L. (clone 683-4) and Salix dasyclados Wimm. (clone 908) harvested in early August were analyzed for endogenous gibberellins (GA). Distribution of GA-like activity, determined by Tan-ginbozu dwarf rice microdrop bioassay after reverse phase C18 high performance chromatography, was similar for both species. For S. dasyclados, combined gas chromatography-selected ion monotoring (GC-SIM) yielded identifications of GA1, GA8, GA19, GA20, and GA29. Identifications of GA4 and GA9 were also made using co-injections of known amounts of [17, 17-2H2]GAs. By bioassay, the main activity was GA19-like in both species. Gibberellin A1, GA19, and GA20 concentrations were approximated by GC-SIM using co-injections of known amounts of [17,17-2H2]GAs. Both bioassay and GC-SIM results indicated very high concentrations of GA19 and GA20 (about 6000 nanograms per kilogram fresh weight shoot tissue using GC-SIM: 800 ng using bioassay), compared to the concentration of GA1 (about 130 nanograms per kilogram fresh weight using either GC-SIM or bioassay). 相似文献
7.
Masaji Koshioka Richard P. Pharis Rod W. King Noboru Murofushi Richard C. Durley 《Phytochemistry》1985,24(4):663-671
The native gibberellin A5 (GA5), as [1-3H]GA5 (3.2 Ci/mmol) was fed to seed capsules (0.58 μCi/capsule) of Pharbitis nil cv Violet at the 2-week stage of development, and its metabolism in the seeds was investigated after 43 hr. Extractable radioactivity in free GA metabolites was 38%, with 56% in GA glucosyl conjugate-like substances. Only 2.5% of the extractable radioactivity remained as [3H]GA5. Tentative identifications, based on comparisons with authentic standards after sequential chromatography on silica gel partition column → gradient-eluted C18 HPLC → isocratic-eluted C18 HPLC-radiocounting (RC), showed that [3H]GA5 was converted to at least six free GAs, GA1, GA3, GA6, GA8, GA22, GA29, a GA5 methyl ester-like metabolite, and at least twelve GA glucosyl conjugate-like substances, GA5-glucoside (GA5-G), GA5-glucosyl ester (GA5-GE), GA1-O(3)-G, GA1-O(13)-G, GA1-GE, GA3-O(3)-G, GA3-O(13)-G, GA3-GE, GA6-G or GE, GA8-O(2)-G, GA22-G or GE and GA29-O(2)-G. After lower specific activity feeds of [1,2-3H]GA5 (74 mCi/mmol; 0.1 μCi/capsule) at approximately the same stage of development, the presence of GA1, GA3, GA5, GA6, GA8 and GA29 was further confirmed by sequential (after C18 HPLC-RC) capillary gas chromatography-selected ion monitoring (GC-SIM), using six characteristic ions. However, for GA22 only a trace of the parent ion was present at the appropriate retention time. 相似文献
8.
After the application of 2.36 Curies per millimole [2,3-3H]gibberellin A20 (GA20) to 21-day-old maize (Zea mays L., hybrid CM7 × CM49) plants, etiolated maize seedlings, or maturing maize cobs, a number of 3H-metabolites were observed. The principal acidic (pH 3.0), ethyl acetate-soluble metabolite was identified as [3H]GA1 on the basis of co-chromatography with standard [3H]GA1 on SiO2 partition, high resolution isocratic elution reverse phase C18 high performance liquid chromatography and gas-liquid chromatography radiocounting. Two other acidic metabolites were identified similarly as [3H]GA8 and C/D ring-rearranged [3H]GA20, although gas-liquid chromatography radiocounting was not performed on these metabolites. Numerous acidic, butanol-soluble (e.g. ethyl acetate-insoluble) metabolites were observed with retention times on C18 high performance liquid chromatography radiocounting similar to those of authentic glucosyl conjugates of GA1 and GA8, or with retention times where conjugates of GA20 would be expected to elute. Conversion to [3H]GA1 was greatest (23% of methanol extractable radioactivity) in 21-day-old maize plants. In etiolated maize seedlings, the C/D ring-rearranged [3H]GA20-like metabolite was the major acidic product, while conversion to [3H]GA1 was low. 相似文献
9.
Gibberellin metabolism in cell-free extracts from spinach leaves in relation to photoperiod 总被引:19,自引:12,他引:7
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Cell-free extracts capable of converting [14C]-labeled gibberellins (GAs) were prepared from spinach (Spinacia oleracea L.) leaves. [14C]-labeled GAs, prepared enzymically from [14C]mevalonic acid, were incubated with these extracts, and products were identified by gas chromatography-mass spectrometry. The following pathway was found to operate in extracts from spinach leaves grown under long day (LD) conditions: GA12 → GA53 → GA44 → GA19 → GA20. The pH optima for the enzymic conversions of [14C]GA53, [14C]GA44 and [14C]GA19 were approximately 7.0, 8.0, and 6.5, respectively. These three enzyme activities required Fe2+, α-ketoglutarate and O2 for activity, and ascorbate stimulated the conversion of [14C]GA53 and [14C]GA19. Extracts from plants given LD or short days (SD) were examined, and enzymic activities were measured as a function of exposure to LD, as well as to darkness following 8 LD. The results indicate that the activities of the enzymes oxidizing GA53 and GA19 are increased in LD and decreased in SD or darkness, but that the enzyme activity oxidizing GA44 remains high irrespective of light or dark treatment. This photoperiodic control of enzyme activity is not due to the presence of an inhibitor in plants grown in SD. These observations offer an explanation for the higher GA20 content of spinach plants in LD than in SD. 相似文献
10.
Internode Length in Pisum: Gene na May Block Gibberellin Synthesis between ent-7alpha-Hydroxykaurenoic Acid and Gibberellin A(12)-Aldehyde
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The elongation response of the gibberellin (GA) deficient genotypes na, ls, and lh of peas (Pisum sativum L.) to a range of GA-precursors was examined. Plants possessing gene na did not respond to precursors in the GA biosynthetic pathway prior to GA12-aldehyde. In contrast, plants possessing lh and ls responded as well as wild-type plants (dwarfed with AMO-1618) to these compounds. The results suggest that GA biosynthesis is blocked prior to ent-kaurene in the lh and ls mutants and between ent-7α-hydroxykaurenoic acid and GA12-aldehyde in the na mutant. Feeds of ent-[3H]kaurenoic acid and [2H]GA12-aldehyde to a range of genotypes supported the above conclusions. The na line WL1766 was shown by gas chromatography-mass spectrometry (GC-MS) to metabolize [2H]GA12-aldehyde to a number of[2H]C19-GAs including GA1. However, there was no indication in na genotypes for the metabolism of ent-[3H]kaurenoic acid to these GAs. In contrast, the expanding shoot tissue of all Na genotypes examined metabolised ent-[3H]kaurenoic acid to radioactive compounds that co-chromatographed with GA1, GA8, GA20, and GA29. However, insufficient material was present for unequivocal identification of the metabolites. The radioactive profiles from HPLC of extracts of the node treated with ent-[3H]kaurenoic acid were similar for both Na and na plants and contained ent-16α,17-dihydroxykaurenoic acid and ent-6α,7α,16β,17-tetrahydroxykaurenoic acid (both characterized by GC-MS), suggesting that the metabolites arose from side branches of the main GA-biosynthetic pathway. Thus, both Na and na plants appear capable of ent-7α-hydroxylation. 相似文献
11.
Metabolism of Tritiated Gibberellins in d-5 Dward Maize: II. [H]Gibberellin A(1), [H]Gibberellin A(3), and Related Compounds
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
After 30 minutes of incubation of young leaf sections of d-5 maize (Zea mays L.) in [3H]gibberellin A1 ([3H]GA1), the metabolite [3H]GA8 was present in significant amounts, with a second metabolite, [3H]GA8-glucose ([3H]GA8-glu), appearing soon after. A third [3H]GA1 metabolite, the polar uncharacterized conjugate [3H]GA1-X, took more than 1 hour to appear. The protein synthesis inhibitor cycloheximide inhibited the production of all [3H]GA1 metabolites, indicating a possible protein synthesis requirement for [3H]GA1 metabolism. 相似文献
12.
Spray Clive Phinney Bernard O. Gaskin Paul Gilmour Sarah J. MacMillan Jake 《Planta》1984,160(5):464-468
[13C, 3H]Gibberellin A20 (GA20) has been fed to seedlings of normal (tall) and dwarf-5 and dwarf-1 mutants of maize (Zea mays L.). The metabolites from these feeds were identified by combined gas chromatography-mass spectrometry. [13C, 3H]Gibberellin A20 was metabolized to [13C, 3H]GA29-catabolite and [13C, 3H]GA1 by the normal, and to [13C, 3H]GA29 and [13C, 3H]GA1 by the dwarf-5 mutant. In the dwarf-1 mutant, [13C, 3H]GA20 was metabolized to [13C, 3H]GA29 and [13C, 3H]GA29-catabolite; no evidence was found for the metabolism of [13C, 3H]GA20 to [13C, 3H]GA1. [13C, 3H]Gibberellin A8 was not found in any of the feeds. In all feeds no dilution of 13C in recovered [13C, 3H]GA20 was observed. Also in the dwarf-5 mutant, the [13C]label in the metabolites was apparently undiluted by endogenous [13C]GAs. However, dilution of the [13C]label in metabolites from [13C, 3H]GA20 was observed in normal and dwarf-1 seedlings. The results from the feeding studies provide evidence that the dwarf-1 mutation of maize blocks the conversion of GA20 to GA1.Abbreviations GAn
gibberellin An
- GC-MS
combined gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
- RP
reverse phase 相似文献
13.
Stewart B. Rood 《Plant Growth Regulation》1995,16(3):271-278
The correlation between gibberellin (GA) metabolism and growth rate was investigated using two Sorghum bicolor inbred lines, Hegari and AT×623, and their heterotic F1 hybrid. Previous studies have demonstrated that this hybrid is taller and has substantially greater shoot dry weights and leaf areas than either parental inbred. [3H]GA20 was applied to the leaf whorl of seedlings and after 24 hours, plants were harvested and separated into roots, shoot cylinders containing the apical meristems, and leaf blades. Chromatographic analyses of metabolites indicated the conversions of [3H]GA20 to [3H]GA1,8 and 29. The conversion of [2H]GA20 to [2H]GA1 was demonstrated by gas chromatography-selected ion monitoring (GC-SIM). Putative glucosyl conjugates of all of the [3H]GAs were also produced and GA8 was identified by GC-SIM following enzymic cleavage of the putative [3H]GA8 glucosyl conjugate fraction. Comparing the genotypes, [3H]GA20 metabolism was more rapid in the shoot cylinders of the hybrid than in the shoot cylinders from inbreds. In the hybrid samples, there was a three-fold increase in the putative conjugate(s) of [3H]GA1 which was the principal metabolite, and increased production of [3H]GA8 and the putative conjugates of [3H]GA29 and [3H]GA8. Conversely, levels of the remaining precursor, [3H]GA20, and its putative conjugate(s) were reduced in the hybrid. The rate of GA20 metabolism was thus positively correlated with growth rate across these sorghum genotypes. This correlation supports a promotive role of GA in the regulation of shoot growth and in the expression of heterosis (hybrid vigor) in sorghum. 相似文献
14.
Metabolism of ent-Kaurene to Gibberellin A(12)-Aldehyde in Young Shoots of Normal Maize 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Young shoots of normal maize (Zea mays L.) were used to determine both the stepwise metabolism of ent-kaurene to gibberellin A12-aldehyde and the endogenous presence of the members in this series. Each of the five steps in the sequence was established by feeds of 17-13C, 3H-labeled kauranoids to cubes from the cortex of elongating internodes, to homogenates from the cortex of elongating internodes, and/or to homogenates from dark-grown seedlings. The 13C-metabolites were identified by Kovats retention indices (KRI) and full-scan capillary gas chromatography-mass spectrometry (GC-MS). Five substrates and the final product in this sequence were shown to be native by the isotopic dilution of 17-13C, 3H-labeled substrates added as internal standards to extracts obtained from elongating internodes. Evidence for the isotopic dilution was obtained by KRI and full-scan capillary GC-MS. Thus, we document the presence in young maize shoots of the metabolic steps, ent-kaurene → ent-kaurenol → ent-kaurenal → ent-kaurenoic acid → ent-7 α-hydroxykaurenoic acid → gibberellin A12-aldehyde. 相似文献
15.
Masaji Koshioka Shigeru Hisajima Richard P. Pharis Noboru Murofushi 《Bioscience, biotechnology, and biochemistry》2013,77(9):2627-2631
Gibberellin A5 (GA5), a native GA of immature seeds of Pharbitis nil, was fed to Pharbitis nil cell suspension cultures as [C-l, 3H] GA5 (3.1 Ci/mmol), and its metabolism over a 48 hr period was investigated. Radioactivity in free GA metabolites was 13.1%, with 79.9% in GA glucosyl conjugate-like metabolites. Only 7.0% of the radioactivity remained as [3H] GA5. Tentative identifications were based on comparison with retention times of authentic free GAs and/or glucosyl conjugates after sequential chromatography on Si gel partition column → gradient-eluted C18 HPLC-radiocounting (RC) → isocratic-eluted C18 HPLC-RC, and showed that [3H] GA5 was converted to [3H] GA1 (2%), [3H] GA3 (4%), [3H] GA6 (2%), [3H] GA22 (1%) and their glucosyl conjugates, and also to [3H] GA8 glucoside, and [3H] GA5 glucosyl conjugates. The major conjugate-like substances were [3H] GA1 and [3H] GA3 glucosyl esters, at 15% and 34%, respectively, of the total extractable radioactivity. 相似文献
16.
Gibberellins and Gravitropism in Maize Shoots : Endogenous Gibberellin-Like Substances and Movement and Metabolism of [3H]Gibberellin A20 总被引:4,自引:2,他引:2
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
[3H]Gibberellin A20 (GA20) of high specific radioactivity (49.9 gigabecquerel per millimole) was applied equilaterally in a ring of microdrops to the internodal pulvinus of shoots of 3-week-old gravistimulated and vertical normal maize (Zea mays L.), and to a pleiogravitropic (prostrate) maize mutant, lazy (la). All plants converted the [3H]GA20 to [3H]GA1− and [3H]GA29-like metabolites as well as to several metabolites with the partitioning and chromatographic behavior of glucosyl conjugates of [3H]GA1, [3H]GA29, and [3H]GA8. The tentative identification of these putative [3H]GA glucosyl conjugates was further supported by the release of the free [3H]GA moiety after cleavage with cellulase. Within 12 hours of the [3H]GA20 feed, there was a significantly higher proportion of total radioactivity in lower than in upper halves of internode and leaf sheath pulvini in gravistimulated normal maize. Further, there was a significantly higher proportion of putative free GA metabolites of [3H]GA20, especially [3H]GA1, in the lower halves of normal maize relative to upper halves. The differential localization of the metabolites between upper and lower halves was not apparent in the pleiogravitropic mutant, la. Endogenous GA-like substances were also examined in gravistimulated maize shoots. Forty-eight hours after gravistimulation of 3-week-old maize seedlings, endogenous free GA-like substances in upper and lower leaf sheath and internode pulvini halves were extracted, chromatographed, and bioassayed using the `Tanginbozu' dwarf rice microdrop assay. Lower halves contained consistently higher total levels of GA-like activity. The qualitative elution profile of GA-like substances differed consistently, upper halves containing principally a GA20-like substance and lower halves containing mainly GA1-like and GA19-like substances. Gibberellins A1 (10 nanograms per gram) and A20 (5 nanograms per gram) were identified from these lower leaf sheath pulvini by capillary gas chromatography-selected ion monitoring. Results from all of these experiments are consistent with a role for GAs in the differential shoot growth that follows gravitropism, although the results do not eliminate the possibility that the redistribution of GAs results from the gravitropic response. 相似文献
17.
Gibberellin A(1) Biosynthesis in Pisum sativum L. : II. Biological and Biochemical Consequences of the le Mutation 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Smith VA 《Plant physiology》1992,99(2):372-377
A comparative study of the metabolism of radiolabeled gibberellin (GA) 1, 19, and 20 in isolated vegetative tissues of isogenic Le and le pea (Pisum sativum) plants incubated in vitro with the appropriate GA substrate is described. The results of this study provide evidence that the enzymes involved in the latter stages of GA biosynthesis are spatially separated within the growing pea plant. Apical buds were not apparently involved in the production of bioactive GA1 or its immediate precursors. The primary site of synthesis of GA20 from GA19 was immature leaflets and tendrils, and the synthesis of bioactive GA1 and its inactive catabolite GA8 occurred predominantly in stem tissue. GA29, the inactive catabolite of GA20, was produced to varying extents in all the tissues examined. Little or no difference was observed in the ability of corresponding Le and le tissues to metabolize radiolabeled GA1, GA19, or even GA20. During a fixed period of 24 hours, stems of plants carrying the le mutation produced slightly more [3H]GA1 (and [3H]GA29) than those of Le plants. It has been concluded that the le mutation does not lie within the gene encoding the GA20 3β-hydroxylase protein. 相似文献
18.
The first and second leaf sheaths of Zea mays L. cv Golden Jubilee were extracted and the extract centrifuged at 100,000g to yield a supernatant or cytosol fraction. Binding of [3H]gibberellin A1 (GA1) to a soluble macromolecular component present in the cytosol was demonstrated at 4°C by Sephadex G-200 chromatography. The binding component was of high molecular weight (HMW) and greater than 500 kilodaltons. The HMW component was shown to be a protein and the 3H-activity bound to this protein was largely [3H]GA1 and not a metabolite. Binding was pH sensitive but only a small percentage (20%) appeared to be exchangeable on addition of unlabeled GA1. Both biologically active and inactive GAs and non-GAs were able to inhibit GA1 binding. [3H]GA1 binding to an intermediate molecular weight (IMW) fraction (40-100 kilodaltons) was also detected, provided cytosol was first desalted using Sephadex G-200 chromatography. Gel filtration studies suggest that the HMW binding component is an aggregate derived from the IMW fraction. The HMW binding fraction can be separated into two components using anion exchange chromatography. 相似文献
19.
Gibberellin (GA) metabolism from GA12-aldehyde was studied in cell-free systems from 2-d-old germinating embryos of barley. [14C]- or [17-2H2]Gibberellins were used as substrates and all products were identified by combined gas chromatography-mass spectrometry. Stepwise analysis demonstrated the conversion of GA12-aldehyde via the 13-deoxy pathway to GA51 and via the 13-hydroxylation pathway to GA29, GA1 and GA8. In addition, GA3 was formed from GA20 via GA5. We conclude that the embryo is capable of producing gibberellins that can induce -amylase production in the aleurone layer. There was no evidence for 12- or 18-hydroxylation and GA4 was neither synthesised nor metabolised by the system. All metabolically obtained GAs, with the exception of GA3, were also found as endogenous components of the cell-free system in spite of ammonium-sulfate precipitation and desalting steps.Abbreviations GAn
gibberellin An
- GC-MS
combined gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
We thank Mrs. G. Bodtke and Mrs. B. Schattenberg for preparing the barley embryos and the Deutsche Forschungsgemeinschaft for supporting this work. 相似文献
20.
Effects of Chilling and ABA on [H]Gibberellin A(4) Metabolism in Somatic Embryos of Grape (Vitis vinifera L. x V. rupestris Scheele)
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Previous work has indicated that changes in gibberellin (GA) metabolism may be involved in chilling-induced release from dormancy in somatic embryos of grape (Vitis vinifera L. × V. rupestris Scheele). We have chilled somatic embryos of grape for 2, 4, or 8 weeks, then incubated them with [3H]GA4 (of high specific activity, 4.81 × 1010 becquerel per millimole) for 48 hours at 26°C. Chilling had little effect on the total amount of free [3H]GA-like metabolites formed during incubation at 26°C, but did change the relative proportions of individual metabolites. The amount of highly water-soluble [3H] metabolites formed at 26°C decreased in embryos chilled for 4 or 8 weeks. The concentration of endogenous GA precursors (e.g., GA12 aldehyde-, kaurene-, and kaurenoic acid-like substances) increased in embryos chilled for 4 or 8 weeks. Treatment with abscisic acid (ABA) (known to inhibit germination in grape embryos) concurrent with [3H]GA4 treatment at 26°C, reduced the uptake of [3H] GA4 but had little effect on the qualitative spectrum of metabolites. However, in the embryos chilled for 8 weeks and then treated with ABA for 48 hours at 26°C, there was a higher concentration of GA precursors than in untreated control embryos. Chilled embryos thus have an enhanced potential for an increase in free GAs through synthesis from increased amounts of GA precursors, or through a reduced ability to form highly water-soluble GA metabolites (i.e., GA conjugates or polyhydroxylated free GAs). 相似文献