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1.
Changes in the contents of phytate (IP6) and other phosphorus(P)-compoundsin germinating seeds of a huskless barley were investigatedin the embryo with scutellum (EM), the starchy endosperm (EN),and the aleurone layer with pericarp-testa (AL). More than 80%of the total P in the AL of 1-day germinated seeds was foundin acid-soluble organic P, most of which was IP6. During germination,the IP6 in AL decreased markedly with no accumulation of lessphosphorylated myo-inositols and Pi and acid-insoluble organicP increased in the EM. The total P in the EN of 1-day germinatedseeds was about one-third that in the AL, the greater part ofwhich was found in the acid-insoluble fraction and decreasedgradually during germination. Only a small amount of IP6 couldbe detected in the EM and EN during the early stage of germination. IP6 in AL of embryoless half-seeds incubated without gibberellicacid (GA3) decreased slightly even after 6 days. Incubationwith 10 ppm GA3 remarkably stimulated the IP6 degradation. Thisstimulation was reduced, with no change in the Pi content, byabout 8090% with 1 mM 6-methylpurine or 10 ppm cycloheximide.The addition of 0.1 M KH2PO4 caused a 4-fold increase in thePi content of AL in the presence of GA3. In addition, it suppressedthe GA3-dependent -amylase synthesis by about 20% and the GA3effect on IP6 degradation by about 50%. In light of these results, IP6 seems to be hydrolyzed completelyinto Pi and myo-inositol within the aleurone tissue, and gibberellinseems to control this process. (Received August 24, 1979; ) 相似文献
2.
Tannins as gibberellin antagonists in the synthesis of alpha-amylase and Acid phosphatase by barley seeds
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The tannins chebulinic acid or tara tannin were added to an incubation system in which GA3 induces enzyme synthesis in endosperm half seeds of barley (Hordeum vulgare L.). The activity of amylase and acid phosphatase in the incubation medium was reduced compared to the activity in the medium after incubation with GA3 alone. When embryo half seeds of barley were incubated with chebulinic acid or tara tannin in the absence of added GA3, the enzyme activity of the incubation medium was also reduced. The activity of preformed enzymes obtained from endosperm half seeds previously induced with GA3 was not reduced by the addition of tannin. Comparisons were made of the amount of enzyme activity from breis of aleurone layers incubated with GA3 in the presence and absence of tannins. The amounts of activity were relatively small and approximately equal in both cases, indicating that secretion from the aleurone was not blocked by the tannins. The reduction of enzyme activity caused by tannins in both endosperm and embryo half seeds could be completely reversed by the addition of GA3. 相似文献
3.
Summary When barley aleurone layers are treated with gibberellic acid (GA3) in the presence of increasing concentrations (0.2–0.8 M) of mannitol, the rate of 32Pi incorporation into phospholipids becomes progressively inhibited. Mannitol does not affect this process in aleurone layers not treated with GA3, nor does it appreciably inhibit GA3-effected increases of 32Pi incorporation into organic phosphates or the activities of the particulate enzymes of the CDP-choline pathway. These results suggest that some of the early events controlled by GA3 can be separated from later activities regulated by the hormone, including -amylase synthesis. 相似文献
4.
5.
Germination of whole barley seeds for 4 and 6 days followed by measurement of lysophospholipase (lysolecithin acyl hydrolase, LAH) in the embryo-containing and embryo-free halves revealed a gradient of activity between the two halves of the seed. Most of the activity appeared in the embryo-containing half. This gradient decreased slightly in the aleurone and dramatically in the starchy endosperm during the 2 day germination interval. Embryo-containing and embryo-free half seeds of surface sterilized barley were placed separately on sterile agar plates. After 4 and 6 days LAH was observed in both the aleurone and starchy endosperm of the embryo-containing halves. In the embryo-free halves, LAH appeared at low levels in the aleurone and was virtually absent in the starchy endosperm. The scutellum of germinating seeds contains LAH activity. Exposure of embryo-free half seeds to GA3 for 24 hr showed enhancement of acidic and alkaline LAH activities in the aleurone fraction and in the GA3-medium in which the half seeds were treated. The LAH activity of the starchy endosperm of these half seeds was little changed by GA3 treatment. Exposure of isolated aleurones to GA3 for 24 hr resulted in substantial enhancement of acidic and alkaline LAH activities in the bathing medium and in fractions prepared from the aleurone. The physiological significance of the influence of GA3 on LAH activity during barley germination is discussed. 相似文献
6.
R. L. Jones 《Protoplasma》1987,138(2-3):73-88
Summary The cytochemical localization of adenosine triphosphatase (ATPase) was studied in the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya). Isolated barley aleurone layers secrete numerous enzymes having acid phosphatase activity, including ATPase. The secretion of these enzymes was stimulated by incubation of the aleurone layer in gibberellic acid (GA3). ATPase was localized using the metal-salt method in tissue incubated in CaCl2 with and without GA3. In sections of tissue incubated without GA3, cytochemical staining was confined to a narrow band of cytoplasm adjacent to the starchy endosperm and to the cell wall of the innermost tier of aleurone cells. Cytochemical staining was absent from the organelles of tissues not treated with GA3. In tissue incubated in the presence of GA3, cytochemical staining was evident throughout the cytoplasm and cell walls of the tissue. In the cell wall, electron-dense deposits were found only in digested channels. The cell-wall matrix of GA3-treated aleurone did not stain, indicating that it does not permit diffusion of enzyme. In the cytoplasm of GA3-treated aleurone, all organelles except microbodies, plastids, and spherosomes stained for ATPase activity; endoplasmic reticulum (ER), Golgi apparatus, and mitochondria showed intense deposits of stain. The ER of the aleurone is a complex system made up of flattened sheets of membrane, which may be associated with both the Golgi apparatus and the plasma membrane. The dictyosome did not stain uniformly for ATPase activity; rather there was a gradation in staining of the cisternae from thecis (lightly stained) to thetrans (heavily stained) face. Vesicles associated with dictyosome cisternae also stained intensely as did the protein bodies of GA3-treated aleurone cells. 相似文献
7.
Dormancy of the barley grain is correlated with gibberellic Acid responsiveness of the isolated aleurone layer 总被引:1,自引:0,他引:1
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The relationship between barley grain dormancy and gibberellic acid (GA3) responsiveness of aleurone layers has been investigated. Barley (Hordeum distichum L. cvs Triumph and Kristina) grains were matured under defined conditions in a phytotron. Grains of Triumph plants grown under long-day/warm conditions had lower dormancy levels than grains of plants grown under short-day/cool conditions. Aleurone layers isolated from grains of long-day Triumph plants secreted more α-amylase and had a higher responsiveness to GA3 as measured by α-amylase secretion. Storage of the grains increased both the percentage of germination and the responsiveness of the aleurone to GA3. Use of different sterilization methods to break dormancy confirmed the correlation between germination percentage and aleurone layer GA3 responsiveness. The response of embryoless Triumph grains to GA3 was lower than that of the isolated aleurone layers, suggesting a role of the starchy endosperm in regulating the GA3 response of the aleurone layer. Grains of the cultivar Kristina harvested from short day- and long day-grown plants lacked dormancy, and their isolated aleurone layers had a similar responsiveness to GA3 as measured by α-amylase secretion. The data indicate that the physiological state of the aleurone layers contributes to the percentage germination of the grains. 相似文献
8.
Hormonal regulation of the development of protease and carboxypeptidase activities in barley aleurone layers 总被引:13,自引:6,他引:7
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Carboxypeptidase and protease activities of hormone-treated barley (Hordeum vulgare cv Himalaya) aleurone layers were investigated using the substrates N-carbobenzoxy-Ala-Phe and hemoglobin. A differential effect of gibberellic acid (GA3) on these activities was observed. The carboxypeptidase activity develops in the aleurone layers during imbibition without the addition of hormone, while the release of this enzyme to the incubation medium is enhanced by GA3. In contrast, GA3 is required for both the production of protease activity in the aleurone layer and its secretion. The time course for development of protease activity in response to GA3 is similar to that observed for α-amylase. Treating aleurone layers with both GA3 and abscisic acid prevents all the GA3 effects described above. Carboxypeptidase activity is maximal between pH 5 and 6, and is inhibited by diisopropylfluorophosphate and p-hydroxymercuribenzoate. We have observed three protease activities against hemoglobin which differ in charge but are all 37 kilodaltons in size on sodium dodecyl sulfate polyacrylamide gels. The activity of the proteases can be inhibited by sulfhydryl protease inhibitors, such as bromate and leupeptin, yet is enhanced by 2-fold with 2-mercaptoethanol. In addition, these enzymes appear to be active against the wheat and barley storage proteins, gliadin and hordein, respectively. On the basis of these characteristics and the time course of GA3 response, it is concluded that the proteases represent the GA3-induced, de novo synthesized proteases that are mainly responsible for the degradation of endosperm storage proteins. 相似文献
9.
A cytochemical investigation has been made of nucleotide pyrophosphatase activity in dry and germinated seeds of Triticum, and its distribution compared to that of general acid phosphatase reactions seen with naphthol AS-BI phosphate and p-nitrophenylphosphate as substrates. Acid phosphatase activity was present in the cytoplasm and in channels through the walls of the aleurone cells in both dry and germinated seeds. The cytoplasmic activity was even more marked with nucleotide pyrophosphatase which was almost entirely absent from the cell walls. Nucleotide pyrophosphatase was active in all endosperm cells but particularly in some cells adjacent to the aleurone layer. In addition, all cells of the scutellum and embryo were positive for nucleotide pyrophosphatase activity, especially the developing fibres and xylem elements of leaves and coleoptiles, mature leaf xylem and phloem elements, scutellar provascular and vascular tissues and the epidermis of dark grown coleoptiles.Abbreviation GA3
gibberellic acid 相似文献
10.
Aleurone layers, with testa attached, were prepared from degermed, decorticated barley with the aid of a fungal enzyme preparation. The preparations appeared intact under the scanning electron microscope. By using antibiotics only in an early stage preparations were obtained uncontaminated by micro-organisms and which, when incubated under optimal conditions with gibberellic acid, GA3, produced near-maximal amounts of α-amylase. The enzyme accumulated in the tissue before it was released into the incubation medium. Daily replacement of the incubation medium, containing GA3, depressed the quantity of α-amylase produced. α-Amylase was also produced in response to gibberellins GA1, GA4 and GA7 and, to a much lesser extent, helminthosporol and helminthosporic acid. A range of other substances, reported elsewhere to induce α-amylase formation, failed to do so in these trials. At some concentrations, glutamine marginally enhanced the quantity of enzyme formed during prolonged incubations. It is confirmed that α-glucosidase occurs in the aleurone layer and embryo of ungerminated barley, and increases in amount during germination. GA3 is shown to enhance this increase. When embryos arc burnt, to prevent gibberellin formation, no rise in α-glucosidase levels occurs unless GA3 is supplied to the grains. As the activity of α-glucosidase and other enzymes have been determined as ‘α-amylase’ by some assay methods, their alterations in activity in response to GA3 necessitates a re-evaluation of the evidence for de novo) synthesis of α-amylase in aleurone tissue. 相似文献
11.
Richard Hooley 《Planta》1984,161(4):355-360
In the presence of gibberellic acid (GA3) aleurone layers and isolated aleurone protoplasts of Avena fatua accumulate specific isozymes of acid phosphatase (EC 3.1.3.2). Some of these may be involved in mobilizing aleurone-grain phosphate reserves during germination. The hormone also controls secretion of other specific molecular forms of the enzyme that probably assist in endosperm hydrolysis. The accumulation and secretion of putative cell-wall-associated isozymes are stimulated by the action of GA3 in isolated protoplasts. This effect however, is apparently over-ridden in the intact tissue, possibly by a cell-wall-based feedback mechanism.Abbreviations GA3
gibberellic acid
- pI
isoelectric point(s) 相似文献
12.
13.
Characterization of the increased lysophospholipase activity in gibberellic Acid-treated barley aleurone layers
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A lysophospholipase (LPL) activity appears in the aleurone of barley (Hordeum vulgare L. cv Himalaya) half seeds during imbibition on moist agar. Secretion of LPL by half seeds is promoted by GA3; the increase in secretory rate is almost linear from 10−10 to 10−6 molar GA3. LPL activity is likewise promoted in isolated aleurone layers by GA3. Its secretion into the incubation medium requires the continued presence of GA3 and commences after a 10 to 14 hour lag period when 10 millimolar Ca2+ is present. In the absence of Ca2+, the lag period remains unchanged but attainment of the maximum secretory rate is delayed. Ca2+ alone has very little effect either on LPL activity accumulated in the aleurone layer or in the surrounding medium. However, 50 millimolar Ca2+ together with GA3 dramatically increase the level of secreted activity and of total (accumulated and secreted) activity.
The metabolic inhibitors cycloheximide and actinomycin D inhibit the accumulation of LPL activity in the aleurone and also the secreted activity. Actinomycin D added after the lag period results in a much lower inhibition. The increase in LPL activity in response to GA3 occurs as a result of de novo synthesis; LPL activity from barley half seeds incubated in 80% D2O in the presence of GA3 undergoes a shift to higher density compared with the activity from similar controls incubated in H2O. The characteristics of the GA3 enhancement of LPL activity are compared specifically with α-amylase and generally with other GA3-controlled hydrolases.
相似文献14.
15.
During germination the aleurone layer of barley grains becomes progressively less able to form more α-amylase in response to a dose of gibberellic acid (GA3). This decline appears to be linked to the presence of a growing embryo. In whole grains the embryo ‘modulates’ the response (α-amylase formation) to controlled external applications of GA3 in a dose-dependent manner. Sugars, and some other metabolites, repress α-amylase formation in transected grains, apparently by reducing levels of endogenously produced gibberellins. This effect is partly, but not completely, reversed by additions of GA3. External applications of GA3 augment the levels of several gibberellin fractions within the grain. The nature of the gibberellin material remaining on the surface of the grains alters with time. Grains treated with GA3 contain a conjugate of low biological activity, possibly a glycoside, that is hydrolysed by a mixed glycosidase preparation to release a biologically-active gibberell in resembling GA3. 相似文献
16.
17.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1586-1588
Changes in the kind and level of endogenous gibberellins (GAs) in the developing liquid endosperm of tea (Camellia sinensis L.) were investigated. Gibberellin A1 (GA1), GA8, GA19, GA20, and GA44 were identified by GC-MS or GC-SIM. Besides these early C-13 hydroxylated GAs, GA3, iso-GA3, and GA38 were also identified. Of these GAs, GA1 and GA3 were the major gibberellins. The levels of these GAs were at a maximum in the globular embryo stage and then decreased rapidly during embryo maturation. 相似文献
18.
Phytase (EC 3.1.3.–) hydrolyzes phytate (IP6) present in cereals and grains to release inorganic phosphate (Pi), thereby making it bioavailable. The most commonly used method to assay phytase, developed nearly a century ago, measures the Pi liberated from IP6. This traditional endpoint assay is time-consuming and well known for its cumbersomeness in addition to requiring extra caution for handling the toxic regents used. This article reports a simple, fast, and nontoxic kinetic method adaptable for high throughput for assaying phytase using IP6–lysozyme as a substrate. The assay is based on the principle that IP6 forms stable turbid complexes with positively charged lysozyme in a wide pH range, and hydrolysis of the IP6 in the complex is accompanied by a decrease in turbidity monitored at 600 nm. The turbidity decrease correlates well to the released Pi from IP6. This kinetic method was found to be useful in assaying histidine acid phytases, including 3- and 6-phytases, a class representing all commercial phytases, and alkaline β-propeller phytase from Bacillus sp. The influences of temperature, pH, phosphate, and other salts on the kinetic assay were examined. All salts, including NaCl, CaCl2, and phosphate, showed a concentration-dependent interference. 相似文献
19.
Localization of phytase and acid phosphatase isoenzymes in aleurone layers of barley 总被引:1,自引:0,他引:1
The localization of acid phosphatase (EC 3.1.3.2) in aleurone layers of barley (Hordeum vulgare L. cv. Himalaya) grains was studied. Phosphatase (EC 3.1.3.26) activity, assayed with phytic acid as the substrate, is present in the dry grain at low leveis and increases during incubation in H2O at 25°C for three days. When aleurone layers are isolated from imbibed grain and incubated for 18 h in buffer with or without 50 μM gibberellic acid (GA3), the level of extractable phosphatase activity increases two- to threefold, and phosphatase is released into the medium. GA, promotes the release of phosphatase activity: aleurone layers incubated in GA, release twice as much phosphatase as layers incubated in buffer. Nine isoenzymes of phosphatase are found in aleurone layers of barley by non-denaturing polyacrvlamide gel electropho-resis. Six of these forms, isoenzymes 1,2,3,5,6 and 8, can be extracted from dry tissue, and after three days of imbibition in H2O an additional isoenzyme, isoenzyme 9, is found in aleurone extracts. When isolated aleurone layers are incubated for a further 22 h in buffer with or without GA3, isoenzyme 7 is found and yet another form, isoenzyme 4, is found in layers incubated in GA3. Eight isoenzymes are released from aleurone layers into the incubation medium. Isoenzymes 5 and 6 are released in buffer both with and without GA3, even when cycloheximide is present; cycloheximide inhibits the release of the other isoenzymes. Isoenzymes 1-4, 7 and 8, on the other hand, are secreted into the incubation medium only when GA3, is present. Isoenzyme 9 is not released into the incubation medium. Acid phosphatase activity was localized in aleurone tissue using cytochemical, cell fractionation, and enzymatic methods. Cytochemical localization of ATPase (EC 3.6.1.8) in aleurone tissue showed the presence of enzyme activity in cell wall, protein bodies, endoplasmic reticulum, Golgi apparatus, and mitochondria. Analysis of organelle fractions isolated by density gradient centrifugation showed that the activity of acid phosphatase isoenzymes 1, 2 and 3 was prominently associated with the phytin globoid of protein bodies, and analysis of the activity released from the cell wall by enzymatic digestion showed that it was almost exclusively isoenzymes 5 and 6. 相似文献
20.
Belay T. Ayele Volker Magnus Snježana Mihaljević Tatjana Prebeg Rozelinda Čož-Rakovac Jocelyn A. Ozga Dennis M. Reinecke Lewis N. Mander Yuji Kamiya Shinjiro Yamaguchi Branka Salopek-Sondi 《Journal of Plant Growth Regulation》2010,29(2):194-209
Gibberellins (GAs) were identified and quantified during flower and fruit development in the Christmas rose (Helleborus niger L.), a native of southeastern Europe with a long international horticultural tradition. Physiologically, the plant differs from popular model species in two major respects: (1) following anthesis, the initially white or rose perianth (formed in this species by the sepals) turns green and persists until fruit ripening, and (2) the seed is shed with an immature embryo, a miniature endosperm, and a prominent perisperm as the main storage tissue. GA1 and GA4 were identified by full-scan mass spectra as the major bioactive GAs in sepals and fruit. LC-MS/MS system in accord with previously verified protocols also afforded analytical data on 12 precursors and metabolites of GAs. In the fruit, GA4 peaked during rapid pericarp growth and embryo development and GA1 peaked during the subsequent period of rapid nutrient accumulation in the seeds and continued pericarp enlargement. In the sepals, the flux through the GA biosynthetic pathway was highest prior to the light green stage when the photosynthetic system was induced. Unfertilized, depistillated, and deseeded flowers became less green than the seed-bearing controls; chlorophyll accumulation could be restored by applying GA1, GA4, and, less efficiently, GA3 to the deseeded fruit. The sepals of unfertilized and depistillated flowers indeed contained very low levels of GA4 and gradually decreasing levels of GA1. However, the concentrations of their precursors and metabolites were less affected. These data suggest that a signal(s) from the fruit stimulates GA biosynthesis in the sepals resulting in greening. The fruit-derived GAs appear to be mainly involved in pericarp growth and seed development. 相似文献