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1.
Extracts of mature silver fir (Abies alba Mill.) needles, current-year, and one-year old (A) and seven to nine-year old (B), were purified by reversed and normal phase HPLC. Gibberellin (GA)-like compounds were detected by the Tan-ginbozu dwarf rice micro-drop bioassay and corresponding fractions were analyzed by GC-MS. GA9 was present in small amounts, while a major component was a cellulase-hydrolysable GA9 conjugate which was assumed to be GA9 glucosyl ester. It is proposed that GA9 glucosyl ester plays a key role in the regulation of endogenous GA levels in silver fir needles.  相似文献   

2.
The level of gibberellin-like substances was determined in the cotyledons and axis of developing seedlings of dwarf (Little Marvel) and normal (Tall Telephone) cultivars of pea (Pisum sativum L.). The effect of cotyledon removal with GA3 application on growth was also examined. Greater levels of gibberellin-like substances were observed in the cotyledons of the normal cultivar than the dwarf. This was particularly evident in the cotyledons during the early stages of seedling growth. Subsequently there was a decline in GA levels in the cotyledons. This was coincidental with a rise in GA content in the axis with markedly greater levels in the normal than the dwarf cultivar. Decotyledonated dwarf and normal plants supplied with GA were much taller than the decotyledonated controls. This observation along with those of the gibberellin levels in the cotyledons and axis, provided circumstantial evidence that there may be translocation of gibberellins from the cotyledons to the axis.  相似文献   

3.
A previously unknown pathway for the biosynthesis of 12α-hydroxylated gibberellins was found in a cell-free system from Cucurbita maxima endosperm. The microsome fraction converts the gibberellin precursor GA12-aldehyde simultaneously to GA12 and 12α-hydroxy-GA12-aldehyde. The ratio of these products is pH-dependent: above pH 6.5, the production of GA12 is favoured, whilst below pH 6.5, 12α-hydroxy-GA12-aldehyde is the predominant product. 12α-Hydroxy-GA12-aldehyde is converted further by soluble enzymes to 12α-hydroxy-GA14, 12α-hydroxy-GA15, 12α-hydroxy-GA37 and several unidentified products. This conversion is optimal between pH 6.0 and 6.5 in contrast to the previously known conversion of GA12-aldehyde to GA43 by soluble enzymes, which is optimal at pH 7.5. GA58, a major 12α-hydroxylated endogenous constituent of C. maxima endosperm, was not obtained when 12α-hydroxy-GA12-aldehyde was used as a substrate, but it was obtained together with GA4 when GA9 was incubated with a preparation containing both microsomal and soluble enzymes.  相似文献   

4.
Gibberellin (GA)-like substances were analyzed in extracts from cotyledons and phloem exudate collected from cotyledons in photoinduced and vegetative seedlings of the short-day plant Pharbitis nil Chois. var. Violet, using high performance liquid chromatography (HPLC) and the dwarf rice bioassay, to see whether any specific GA-like substances were transported from the photoinduced cotyledons via phloem. Cotyledon extracts exhibited five peaks of free GA-like activity in HPLC, whereas only one or two active peaks were detected in phloem exudate extracts. The level of free GA-like activity was considerably lower in phloem exudate than in the cotyledons. In five out of six analyses of cotyledons and phloem exudate, there were substantially higher levels of free GA-like substances in photoinduced plants. Conjugated GA-like substances were present in much higher levels than free GA-like substances in the cotyledon extracts but the levels were not influenced by daylength. In phloem exudate extracts there was no conjugated GA-like substances. The free GA-like substances that are transported via phloem cochromatographed with GA5/20 and GA19 on HPLC. These were significantly higher in photoinduced plants and thus could have some influence on the photoperiodically-induced flowering in P. nil.  相似文献   

5.
《Phytochemistry》1986,25(4):817-822
Endosperm and cotyledons of Sechium edule at different stages of seed development were found to contain three novel GA conjugates. 3-propyl- or 3-acetyl- GA4/7 were characterized by mass spectral analysis and were found to be biologically active in contrast to synthetic GA4/7 propyl esters. An unusual GA glucoside showing biological activity was also isolated from both tissues and characterized by mass spectrometry and NMR analysis as 16,17-dihydro-16-hydroxy-GA15 alcohol glucoside. The functional significance of this novel GA conjugate is discussed.  相似文献   

6.
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   

7.
Endopeptidase activity in cotyledons of 5-day seedlings of Pisum sativum increased rapidly during germination. However, the increase of the activity in detached cotyledons was depressed. We examined whether a growth regulator can be substituted for the embryonic axis on the development of endopeptidase activity. As monitored by an assay with azoalbumin, the development of endopeptidase activity from crude extracts of detached cotyledons appeared to be slightly accelerated by incubation with 10–5 M GA3. However, the pattern after gelatin-polyacrylamide gel suggested that the activity induced in detached cotyledons during a 5-d incubation at 10–7 M GA3 was the same as that in attached ones during germination for 5 days and an even greater increase in activity was obtained with 10–5 M GA3. These results suggest that GA3 from the embryonic axis induces endopeptidase activity in attached cotyledons at the first stage of germination.Abbreviations ABA abscisic acid - IAA indole-3-acetic acid - GA gibberellic acid  相似文献   

8.
Identification of endogenous gibberellins from oilseed rape   总被引:6,自引:3,他引:3       下载免费PDF全文
Oilseed rape (Brassica napus, canola variety `Westar') plants were grown in greenhouse conditions and shoots were harvested during the final stages of shoot elongation. Leaves and immature pods were removed and the remaining stem tissue was extracted and purified. The extract was chromatographed on sequential, step-eluted silica gel partition and reverse-phase C18 HPLC columns, and gibberellin (GA)-like substances were detected using the `Tan-ginbozu' dwarf rice microdrop assay. Purified fractions showing GA-like activity were analyzed by capillary gas chromatography-mass spectrometry (GC-MS) and GC-selected ion monitoring (GC-SIM). Gibberellins A1, A3, and iso-A3 were identified by full spectrum GC-MS with GA1 being the most abundant GA in the stem tissue. Gibberellins A19 and A20 were identified by GC-SIM and are logical precursors of the GA1.  相似文献   

9.
J. L. Stoddart  E. J. Lloyd 《Planta》1986,167(3):364-368
High-resolution growth measurements were conducted using a linear variable displacement transformer in conjunction with a temperature-programmed meristem-cooling collar. Chilling and rewarming profiles were determined for a range of Gramineae, in the presence and absence of varying concentrations of gibberellic acid (GA3). In wheat (Triticum aestivum L.) seedlings, the growth-constraining temperature (Pe) was progressively lowered by increasing GA3 concentration, with a difference of-4.8°C between controls and material treated with 10–4 M GA3. Dwarf-5 maize (Zea mays L.) seedlings had a higher Pe than tall segregates and the difference was markedly reduced by exposure to a saturating concentration of GA3. A similar effect was observed with Tanginbozu dwarf rice (Oryza sativa L.). The growth ratetemperature responses of Rht3 gibberellin-insensitive dwarf wheat seedlings were unaffected by GA3 and the Pe values for these segregates were around 5° C higher than for normals. Slender (s1) barley (Hordeum vulgare L.) genotypes had Pe values of-7° C, compared with +4° C for wild-type material, and did not show positive hysteresis for growth rate during the rewarming phase. These studies indicate that GA3 modifies the thermal sensitivity of meristem function in Gramineae in a manner which enhances low-temperature growth.Abbreviations GA gibberellin - GA3 gibberellic acid - LVDT linear variable displacement transducer  相似文献   

10.
Gibberellins (GAs) A1, A5, and A29 were identified, and also GA32 was confirmed, as endogenous GAs of immature seeds (3-4 weeks after anthesis, 0.25-0.5 gram fresh weight) of apricot (Prunus armeniaca L.) based on capillary gas chromatography (GC), retention time (Rt), and selected ion monitoring (SIM), in comparison with authentic standards. Fractions subjected to GC-SIM were purified and separated using sequential solvent partitioning → paper chromatography → reverse phase C18 high performance liquid chromatography (HPLC) → bioassay on dwarf rice cv Tan-ginbozu. Two other peaks of free GA-like bioactivity (microdrop and immersion dwarf rice assays) were eluted from C18 HPLC at Rts where GA4/7 and GA8 (or other GAs with similar structures) would elute. Also, three unidentified GA glucoside-like compounds (based on bioactivity on the immersion assay, and no bioactivity on the microdrop assay) were noted. There were very high amounts of GA32 (112 ng of GA3 equivalents per gram fresh weight), and minor amounts (0.5 ng of GA3 equivalents) for each of GA1 and GA5, respectively, based on the microdrop assay.  相似文献   

11.
Liu Y  Xu Y  Xiao J  Ma Q  Li D  Xue Z  Chong K 《Journal of plant physiology》2011,168(10):1098-1105
The A20/AN1 zinc-finger proteins (ZFPs) play pivotal roles in animal immune responses and plant stress responses. From previous gibberellin (GA) microarray data and A20/AN1 ZFP family member association, we chose Oryza sativa dwarf rice with overexpression of gibberellin-induced gene (OsDOG) to examine its function in the GA pathway. OsDOG was induced by gibberellic acid (GA3) and repressed by the GA-synthesis inhibitor paclobutrazol. Different transgenic lines with constitutive expression of OsDOG showed dwarf phenotypes due to deficiency of cell elongation. Additional GA1 and real-time PCR quantitative assay analyses confirmed that the decrease of GA1 in the overexpression lines resulted from reduced expression of GA3ox2 and enhanced expression of GA2ox1 and GA2ox3. Adding exogenous GA rescued the constitutive expression phenotypes of the transgenic lines. OsDOG has a novel function in regulating GA homeostasis and in negative maintenance of plant cell elongation in rice.  相似文献   

12.
Six 3-methylgibberellin analogs were synthesized, and their effects on the GA 3β-hydroxylases from immature seeds of Phaseolus vulgaris and Cucurbita maxima, and/or on the growth of dwarf rice (Oryza sativa L. cv. Tan-ginbozu) and cucumber (Cucumis sativus L. cv. Spacemaster) were investigated. 3-Methyl-GA5 and 2, 3-didehydro-3-methyl-GA9· inhibited the conversion of [2, 3-3H2]GA9 to [2-3H]GA4 by GA 3β-hydroxylases from both P. vulgaris and C. maxima at 3 μM and higher. Their C/D-ring-rearranged isomers, 2, 3-didehydro-3-methyl-DGC and 16-deoxo-2, 3-didehydro-3-methyl-DGC, inhibited 3β-hydroxylation by the enzyme from P. vulgaris threefold more strongly than the non-C/D-ring-rearranged compounds, but exhibited no effect on 3β-hydroxylation by the enzyme from C. maxima. In a dwarf rice seedling assay, 3-methyl-GA5 and 2, 3-didehydro-3-methyl-GA9 promoted shoot elongation at doses of 300 ng/plant and higher, and 3α-methyl-GA1 and 3α-methyl-GA4 at doses of 30 ng/plant and higher. In contrast 2, 3-didehydro-3-methyl-DGC inhibited shoot growth to half that of the control at a dose of 300 ng/plant, and 16-deoxo-2, 3-didehydro-3-methyl-DGC showed no effect on growth. In a cucumber seedling assay, 3α-methyl-GA4 promoted hypocotyl elongation at doses of 300 ng/plant and higher. The other C-3 methyl compounds showed no effect on the hypocotyl elongation of cucumber seedlings.  相似文献   

13.
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   

14.
The frequencies of adventitious root formation in vitro of isolated shoots from bud cultures of apple (Malus pumila cv. Jonathan) after 1, 7 and 31 subcultures (weeks 5, 29 and 109 after the initial culture) were 5, 78 and 95% respectively. Endogenous gibberellin-like substances (GA) were extracted, chromatographed on SiO2 partition columns, and assayed on dwarf rice (Oryza sativa cv. Tan-ginbozu). The levels of GA in shoots from the 1st, 7th and 31st subcultures were 40, 19 and 14 ng GA3 eq./g dry weight of tissue, respectively, a trend which suggests an inverse relationship between endogenous GA level and rooting ability. This is consistent with the fact that applied GA3 inhibits rooting in apple and many other species. The major peak of GA activity eluted coincidentally with GA1/GA3/GA19. Endogenous cytokinin-like substances (CK) were chromatographed on paper and assayed with soybean hypocotyl sections. In contrast to the decrease in GA activity, CK activity increased 1.5–2.7 fold in the later subcultures (cytokinin activity per shoot, however, declined).  相似文献   

15.
Several gibberellins (GAs) and kauranoids were identified in extracts of barley (Hordeum vulgare) by combined capillary gas chromatography-mass spectrometry (GC-MS). A partially purified acidic ethyl acetate extract from 21-day postanthesis developing barley grain (cv. Proctor) contained GA1 (trace), GA4 (trace), GA8 (trace), GA12, GA17, GA20 (tentative) (trace), GA25, GA34, GA48, 18-hydroxy-GA4, 12-hydroxy-GA9, and 18-hydroxy-GA34 (tentative). A hydrolyzed butanol extract contained GA17, GA20, GA48, and 18-hydroxy-GA34 (tentative). An acidic ethyl acetate extract from 3-day-old germinating barley grain (cv. Maris Otter) contained GA1, GA3 (possibly a contaminant), GA17, GA19, GA20, GA34, GA48, and 18-hydroxy-GA34 (tentative). A hydrolyzed butanol extract contained GA34, GA48, and 18-hydroxy-GA34 (tentative). In germinating grain, levels of all GAs were very low. Two hydroxylated kauranoic acids and a number of other kauranoids were also detected in the above extracts. 1-Hydroxylated GAs previously found in wheat were not found in barley in this study.This work has been reported in a poster demonstration (Gaskin et al. 1982).  相似文献   

16.
Seed quality is a key critical component to produce well established and vigorous seedlings under cool soil (<10°C) conditions experienced in Western Canada. A simple, relatively quick germination assay is required to separate small differences in seed germination which can have a significant impact on seedling growth. It has long been established that phytohormones regulate seed germination: abscisic acid inhibits germination whereas gibberellins enhance germination. We investigated the effects of ABA, GA, ethylene and inhibitors of these phytohormones alone and in combination on the germination rate of a black and a yellow seed canola (Brassica napus) imbibed at 8°C. The effects of either saline solutions, osmotic solutions, fusicoccin or testa on the germination of canola seeds imbibed at 8°C were also investigated. This temperature is representative of the soil temperatures experienced in the early spring of Western Canada. The two canola seed lines, especially the yellow seed line, were very sensitive to increasing concentration of saline solutions at 8°C, but not at 23°C; however, iso-osmotic solutions that reduced water potential were more inhibitory. The seed coat (testa) including the endosperm was a major factor affecting the germination rate of the yellow seed line at 8°C, however, GA4+7 overcame the inhibitory effect of the testa, whereas ABA exacerbated it. Fusicoccin was more stimulatory to germination than GA4+7, however, unlike GA4+7, it was unable to overcome the inhibitory effect of paclobutrazol, a GA biosynthesis inhibitor. Fluridone, an ABA biosynthesis inhibitor, was unable to overcome the inhibitory effects of a saline solution suggesting that the inhibitory effect was not due to elevated ABA levels. Ethylene, a stimulator of germination did not appear to be involved in the germination of these two lines. Controlled deterioration at 35°C, 85% RH could be either partially or completely overcome by exogenous GA4+7. This study demonstrated the effect of hormones, salinity and testa on the germination of canola seeds under less than ideal environmental conditions.  相似文献   

17.
We examined the gibberellin (GA) and ethylene regulation of submergence-induced elongation in seedlings of the submergence-tolerant lowland rice (Oryza sativa L.) cvs Senia and Bomba. Elongation was enhanced after germination to facilitate water escape and reach air. We found that submergence-induced elongation depends on GA because it was counteracted by paclobutrazol (an inhibitor of GA biosynthesis), an effect that was negated by GA3. Moreover, in the cv Senia, submergence increased the content of active GA1 and its immediate precursors (GA53, GA19 and GA20) by enhancing expression of several GA biosynthesis genes (OsGA20ox1 and -2, and OsGA3ox2), but not by decreasing expression of several OsGA2ox (GA inactivating genes). Senia seedlings, in contrast to Bomba seedlings, did not elongate in response to ethylene or 1-aminocyclopropane-1-carboxylic-acid (ACC; an ethylene precursor) application, and submergence-induced elongation was not reduced in the presence of 1-methylcyclopropene (1-MCP; an ethylene perception inhibitor). Ethylene emanation was similar in Senia seedlings grown in air and in submerged-grown seedlings following de-submergence, while it increased in Bomba. The expression of ethylene biosynthesis genes (OsACS1, -2 and -3, and OsACO1) was not affected in Senia, but expression of OsACS5 was rapidly enhanced in Bomba upon submergence. Our results support the conclusion that submergence elongation enhancement of lowland rice is due to alteration of GA metabolism leading to an increase in active GA (GA1) content. Interestingly, in the cv Senia, in contrast to cv Bomba, this was triggered through an ethylene-independent mechanism.  相似文献   

18.
2,6-Diisopropylphenoxyacetic acid (DIPA), a promoter of growth and flowering of Sagittaria species, was found to improve the shoot growth of rice plants treated with uniconazole, an inhibitor of gibberellin (GA) biosynthesis. In a modified micro-drop bioassay using semi-dwarf rice, Oryza sativa L. cv. Tan-ginbozu, in which uniconazole had been incorporated into the agar medium, a significant recovery from growth inhibition was observed for both the 3rd and the 4th leaf sheaths but not for the 2nd sheath. In greenhouse experiments, uniconazole-treated rice plants partially recovered from growth inhibition when DIPA was applied after uniconazole treatment, whereas DIPA applied with, or before, uniconazole treatment did not improve growth. The levels of GA1 and GA20 in the rice plants treated with uniconazole plus DIPA were almost equal to those of the untreated controls, indicating that the observed growth recovery is attributable to the restoration of GA biosynthesis by DIPA.  相似文献   

19.
The role of gibberellins (GAs) during germination and early seedling growth is examined by following the metabolism and transport of radiolabeled GAs in cotyledon, shoot, and root tissues of pea (Pisum sativum L.) using an aseptic culture system. Mature pea seeds have significant endogenous GA20 levels that fall during germination and early seedling growth, a period when the seedling develops the capacity to transport GA20 from the cotyledon to the shoot and root of the seedling. Even though cotyledons at 0–2 days after imbibition have appreciable amounts of GA20, the cotyledons retain the ability to metabolize labeled GA19 to GA20 and express significant levels of PsGA20ox2 message (which encodes a GA biosynthesis enzyme, GA 20-oxidase). The large pool of cotyledonary GA20 likely provides substrate for GA1 synthesis in the cotyledons during germination, as well as for shoots and roots during early seedling growth. The shoots and roots express GA metabolism genes (PsGA3ox genes which encode GA 3-oxidases for synthesis of bioactive GA1, and PsGA2ox genes which encode GA 2-oxidases for deactivation of GAs to GA29 and GA8), and they develop the capacity to metabolize GAs as necessary for seedling establishment. Auxins also show an interesting pattern during early seedling growth, with higher levels of 4-chloro-indole-3-acetic acid (4-Cl-IAA) in mature seeds and higher levels of indole-3-acetic acid (IAA) in young root and shoot tissues. This suggests a changing role for auxins during early seedling development.  相似文献   

20.
Summary Two new gibberellins, gibberellins A26 and A27 (GA26 and GA27), and their glucosides have been isolated from immature seeds of Japanese morning-glory (Pharbitis nil), together with GA8 and its glucoside. GA26, GA27 and their glucosides showed only slight growth-promoting activities on seedlings of rice, dwarf maize and cucumber.  相似文献   

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