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1.
Chlorophyll loss in the leaves of cut flowering branches of Alstroemeria pelegrina L. cv. Stajello, placed in water in darkness at 20°, was inhibited by irradiation with red light and by the inclusion of gibberellic acid (GA3 ) in the water. The effects of red light were abolished when it was followed by far-red light. Effects of GA3 and red light were additive over a range of GA3 concentrations (0. 01–1 μ M ). Chlorophyll breakdown was increased by the inclusion of AMO-1618, ancymidol, or tetcyclasis in the water. The effect of these inhibitors of gibberellin synthesis was fully reversed by GA3 . The inhibition of chlorophyll breakdown by red light was absent when AMO-1618, ancymidol or tetcyclasis were included in the water. The results indicate that leaf yellowing is controlled by endogenous gibberellins and that the effect of phytochrome is mediated by gibberellin synthesis. 相似文献
2.
Acid sensitivity induction (ASI) at alkaline pH in Escherichia coli 1157 ( phoE ) is only fully mounted if protein synthesis occurs for the first 5 min of the 12–15 min induction period, but appreciable sensitization occurs in the presence of chloramphenicol indicating that there are protein synthesis-independent and -dependent components (components 1 and 2). Component 1 sensitization is in place after 10 min at pHo 9.0 but the dependent process is induced slightly more slowly. Collapsing ΔpH at pHo 9.0 did not prevent full ASI, indicating that component 1 and 2 induction does not depend on increased ΔpH. The two induction (or activation) processes responded differently to intermediate levels of external alkalinization; component 1 was induced at pHo 8.3 but component 2 needed pHo 8.4 or greater. Collapsing ΔpH at pHo 8.0 led to full induction of component 1 and appreciable induction of component 2, indicating that both processes are triggered if pHi rises to 8.0 or greater (presumably at pHo 8.3–8.4). Component 1 appears less important for ASI in 1157-4 ( phoE + ) than in 1157 ( phoE ). 相似文献
3.
Jan Kpczyski 《Physiologia plantarum》1986,67(4):584-587
The role of gibberellins in the germination of seeds of Amaranthus caudatus L. was examined. Tetcyclacis (BAS 106), an inhibitor of gibberellin biosynthesis, inhibited germination of the seeds. The inhibition caused by BAS 106 was antagonised by gibberellin A4+7 (GA4+7 ). Ethephon (2-chloroethylphosphonic acid) and 1-aminocyclopropane-1-carboxylic acid (ACC) could replace GA4+7 . Ethephon and ACC counteracted also the side effects of BAS 106 that are not reversible by GA4+7 . The rate of seed germination was not increased by gibberellin in the presence of aminoethoxyvinylglycine (AVG). AVG increased the effect of BAS 106. GA4+7 could not reverse the effect of BAS 106 when AVG was simultaneously applied. The results indicate that the biosynthesis of endogenous gibberellins may be required for germination of A. caudatus seeds and that main physiological effects of GA4+7 on seed germination may depend on ethylene biosynthesis. 相似文献
4.
Evidence was obtained by gas chromatography-mass spectrometry and gas chromatography-selected ion monitoring for the presence of gibberellin A20 ), GA1 , GA29 , GA8 and 2-epiGA29 in vegetative shoots of tall sweet pea, Lathyrus odoratus L. Both tall (genotype L –) and dwarf (genotype II ) sweet peas elongated markedly in response to exogenous GA1 attaining similar internode lengths at the highest dose levels. Likewise internode length in both genotypes was reduced by application of the GA biosynthesis inhibitor, PP333. The ratio of leaflet length to width was reduced by application of PP333 to tall plants and this effect was reversed by GA1 . When applied to plants previously treated with PP333, GA20 promoted internode elongation of L – plants as effectively as GA1 , but GA29 was not as effective as GA1 when applied to II plants. In contrast, GA20 and GA1 were equally effective when applied to the semidwarf lb mutant but GA-treated lblb plants did not attain the same internode length as comparable GA-treated Lb – plants. The difference in stature between the tall and dwarf types persisted in dark-grown plants. It is concluded that GA1 may be important for internode elongation and leaf growth in sweet pea. Mutant l may influence GA1 synthesis by reducing 3β-hydroxylation of GA20 whereas mutant lb appears to affect GA sensitivity. 相似文献
5.
Natural and post-harvest ethylene-induced pigment changes in the rind of Satsuma mandarin ( Citrus unshiu Marc.) fruits respond differently to the exogenous application of growth regulators. Both gibberellin A3 and the synthetic cytokinins N6 -benzyladenine and kinetin opposed the ethylene-induced chlorophyll destruction, while the loss of chlorophyll during natural maturation was retarded by the gibberellin but not by the cytokinins. This different behaviour suggests that ethylene may not be playing a central role in the endogenous control of ripening. Carotenoid accumulation during natural maturation is apparently controlled through a different mechanism than chlorophyll loss since it is reduced both by the cytokinins and gibberellin A3 .
Kinetin and gibberellin A3 increased to a similar extent the accumulation of reducing sugars and free amino acids, and reduced that of non-reducing sugars in the peel during natural maturation. Their differential effect on chlorophyll loss may not be explained through their effects on sugar accumulation. 相似文献
Kinetin and gibberellin A
6.
Photoinhibition at chilling temperatures and effects of freezing stress on cold acclimated spinach leaves in the field. A fluorescence study 总被引:5,自引:0,他引:5
The role of high light stress in a natural environment was studied on spinach plants ( Spinacia oleracea L. cv. Wolter) grown in the field during the winter season. Fluorescence induction (at 293 K and 77 K) of leaves was used to characterize the stress effects. Night frost with minimum temperatures between – 1.5°C and –7.5°C (i.e. above the'frost killing point'at ca. –11.5°C) led to impaired photosynthesis. This was seen as increased initial fluorescence (Fo ), decreased ratio of variable to maximum fluorescence (FV /FM ) and lowered rates of O2 evolution. The freezing injury was reversible within several frostless days. Exposure to high light (about 900 mol m–2 s–1 ) at chilling temperatures in the field caused photoinhibition, manifested as decreased variable fluorescence (FV ) and FV /FM ratio without changes in FO . The photoinhibitory fluorescence quenching was not stronger after frost than after frostless nights; synergism between light stress and preceding freezing stress was not observed. Fluorescence induction signals at 77 K showed that FV of photosystems I and II decreased to the same extent, indicating increased thermal deactivation of excited chlorophyll. Photoinhibition was fully reversible at +4°C within 1 h in low light, but only partially in moderate light. Preceding night frosts did not affect the recovery. The photoinhibition observed here is regarded as a protective system of thermal dissipation of excess light energy. 相似文献
7.
Hormonal regulation of sex expression in Momordica charantia 总被引:1,自引:0,他引:1
Sex expression in a monoecious cucurbit, Momordica charantia L. (long–fruited variety 'Karela') can be regulated by application of gibberellin A3 (GA3 ), indole-3-acetic acid (IAA) and 3-hydroxymethyl oxindole (HMO), an oxidation product of IAA, all of which promote female flowering. Both IAA and HMO accelerated ethylene evolution in the seedlings of this plant. While a low concentration of Ethrel promotes flowering, the effect was reversed with increased concentrations. Surprisingly, GA3 was the most effective growth regulator in increasing, femaleness. In untreated plants, levels of endogenous GA-like substance increased progressively up to the age of 60 days, at which the ratio of male to female flowers was minimum. 相似文献
8.
Growth and development of Brassica genotypes differing in endogenous gibberellin content. II. Gibberellin content, growth analyses and cell size 总被引:2,自引:0,他引:2
Three rapid cycling Brassica rapa genotypes were grown in greenhouse conditions to investigate the possible relationships between endogenous gibberellin (GA) content and shoot growth. Endogenous GA1 GA3 and GA20 were extracted from stem samples harvested at 3 weekly intervals and analyzed by gas chromatography-mass spectrometry with selected ion monitoring, using [2 H2 ]-GA1 and [2 H2 ]-GA20 as quantitative internal standards. During the first 2 weeks, GA levels of the dwarf, rosette ( ros ), averaged 36% of levels in normal plants (on a per stem basis). Levels in the tall mutant, elongated internode (ein) , were consistently higher, averaging 305% of levels in normal plants.
Differences in shoot height across the genotypes resulted from varying internode length which resulted from epidermal cell length and number being increased in ein and decreased in ros relative to the normal genotype. The exogenous application of GA3 to normal plants increased cell length while the application of paclobutrazol (PP333), a triazole plant growth retardant, reduced cell size. Thus, exogenous GA manipulations mimicked the influence of the mutant genes ros and ein. The dwarf, ros , had reduced shoot dry weights and relative growth rates compared to the other genotypes. Total dry weights were similar in ein and the normal genotype but stem weights were increased in ein , compensating for decreased leaf weights. Thus, the gibberellin-deficiency of ros resulted in generally reduced shoot growth. The overproduction of endogenous GA by ein did not result in enhanced shoot growth but rather a specific enhancement of internode elongation and stem growth at the expense of leaf size. 相似文献
Differences in shoot height across the genotypes resulted from varying internode length which resulted from epidermal cell length and number being increased in ein and decreased in ros relative to the normal genotype. The exogenous application of GA
9.
Behavioural and metabolic reactions of Pomatoschistus minutus (Pallas) exposed to various degrees of hypoxia were studied. At 15°C and 20‰ mortality was 50% at 15.2% oxygen saturation. Avoidance and oxygen saturation showed a linear inverse relationship. At levels lower than 60% saturation increased activity occurred; avoidance was significant at 30% saturation. Active, routine and standard MO2 correlated linearly with weight at 6 and 15°C (salinity = 19‰). During hypoxia at 15°C routine MO2 rose significantly at 60–50% and 40–30% saturation expressed either as MO2 during longer periods at night or MO2 at shorter intervals during the day. Standard MO2 was unaffected by hypoxia at 15°C. Haemoglobin concentration was significantly increased when P. minutus was acclimatized to 35% saturation. 相似文献
10.
The Second Messenger, Cyclic AMP, Is Not Sufficient for Myelin Gene Induction in the Peripheral Nervous System 总被引:1,自引:0,他引:1
Joseph F. Poduslo Randall S. Walikonis Marie-Christine Domec Carole T. Berg Carrie J. Holtz-Heppelmann 《Journal of neurochemistry》1995,65(1):149-159
Abstract: The adenylyl cyclase-cyclic AMP (cAMP) second messenger pathway has been proposed to regulate myelin gene expression; however, a clear correlation between endogenous cAMP levels and myelin-specific mRNA levels has never been demonstrated during the induction or maintenance of differentiation by the myelinating Schwann cell. Endogenous cAMP levels decreased to 8–10% of normal nerve by 3 days after crush or permanent transection injury of adult rat sciatic nerve. Whereas levels remained low after transection injury, cAMP levels reached only 27% of the normal values by 35 days after crush injury. Because P0 mRNA levels were 60% of normal levels by 14 days and 100% by 21 days after crush injury, cAMP increased only well after P0 gene induction. cAMP, therefore, does not appear to trigger myelin gene induction but may be involved in myelin assembly or maintenance. Forskolin, an activator of adenylyl cyclase, increased endoneurial cAMP levels only in the normal nerve, and in the crushed nerve beginning at 16 days after injury, but at no time in the transected nerve. Only by treating transected nerve with 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of cAMP phosphodiesterases, in combination with forskolin was it possible to increase cAMP levels. No induction of myelin genes, however, was observed with short- or long-term treatment with IBMX and forskolin in the transected nerve. A three-fold increase in phosphodiesterase activity was observed at 35 days after both injuries, and a nonmyelinated nerve was shown to have even higher activity. These experiments, therefore, suggest an important role for phosphodiesterase in the inactivation of this second messenger-dependent stimuli when Schwann cells are non-myelinating, such as after sciatic nerve injury or in the nonmyelinated nerve, which again implies that cAMP may be required for the maintenance of the myelin sheath. 相似文献
11.
A mixture of tritiated and deuterated gibberellin A9 (GA9 ) was injected into elongating shoots of Norway spruce [ Picea abies (L.) Karst.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or noninductive (cool and wet, CW) for flowering. The shoots were divided into needles and shoot stems. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography-mass spectrometry (GC-MS). Deuterated GA9 was converted to deuterated GA4 in both treatments. The major metabolite in the CW-treated material was GA51 . The HD-treated material did not convert GA9 to GA51 , but a cellulase-hydrolysable GA9 -conjugate was formed. The same metabolites were found in the shoot stems, though in smaller amounts. The amounts of detected metabolites were higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. The estimated amounts of endogenous GAs show that the HD-treated material contained higher amounts of GA9 but no differences in the amounts of GA4 were found. 相似文献
12.
Relation between relative growth rate, endogenous gibberellins, and the response to applied gibberellic acid for Plantago major 总被引:4,自引:0,他引:4
Relationships between relative growth rate (RGR), endogenous gibberellin (GA) concentration and the response to application of gibberellic acid (GA3 ) were studied for two inbred lines of Plantago major L., which differed in RGR. A4, the fast-growing inbred line, had a higher free GA concentration than the slow-growing W9, as analyzed by enzyme immunoassay. GA3 application increased total plant weight and RGR3 particularly for the slow-growing line. Chlorophyll a content and photosynthetic activity per unit leaf area were decreased, while transpiration rate was unaffected by GA3 application. The increase in RGR by GA3 application was associated with an increased leaf weight ratio; specific leaf area and percentage of dry matter in the leaves were only temporarily affected. Root respiration rate per unit dry weight was unaffected.
The correlation between low RGR, low GA concentration and high responsiveness to applied GA3 supports the contention that gibberellins are involved in the regulation of RGR. However, the transient influence of GA3 application on some growth components suggests the involvement of other regulatory factors in addition to GA. 相似文献
The correlation between low RGR, low GA concentration and high responsiveness to applied GA
13.
Abstract: The amyloid protein (βA4 ) is found in the CNS of patients with Alzheimer's disease; however, the pathogenic role of this protein is not known. In the present study, a peptide fragment of βA4 βA4 25–35; Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-NH2 ), which contains the conserved C-terminal sequence of substance P (X-Gly-Leu-Met-NH2 ), and the neuropeptide substance P (SP) were examined for their ability to modulate nicotine-evoked secretion from cultured bovine adrenal chromaffin cells. Secretion of the released endogenous catecholamines was monitored by electrochemical detection after separation by HPLC. Secretion induced by 10−5 M nicotine was inhibited by SP and βA4 25–35. The IC50 of SP and βA4 25–35 was 3 × 10−6 and 3 × 10−5 M , respectively. SP and βA4 25–35 both protected against nicotinic receptor desensitization. However, βA4 25–35 was ∼ 10-fold less effective than SP in its protective effect. The present work shows that βA4 25–35 can mimic the modulatory actions of SP on the nicotinic response of cultured bovine chromaffin cells, i.e., inhibition of the nicotinic response and protection against nicotinic desensitization. These modulatory actions may be associated with changes in nicotinic receptor levels reported to occur in Alzheimer's disease. 相似文献
14.
Administration of 17β-oestradiol (E2 ) to rainbow trout, in the form of hydrogenated coconut oil implants produced a stable, long-term elevation in plasma E2 levels. The elevation was doserelated (over the range 1–10mg kg-1 body weight) both 4 and 8 weeks after implantation. Dose-related increases were also observed with respect to liver weight-body weight ratios and plasma protein levels. Plasma T3 and total calcium levels were depressed and elevated, respectively, by E2 treatment but the responses were not linearly related to the dose of E2 administered; there was no significant effect of E2 on plasma T4 levels.
E2 induced a shift in the binding of T3 to plasma proteins, with T3 binding to smaller molecular weight proteins; neither T4 nor T3 bound to vitellogenin which was present at high levels in the plasma of E2 -treated fish. 相似文献
E
15.
Regulation of the germination of Rhus coriaria, a post-fire pioneer, by heat, ash, pH, water potential and ethylene 总被引:1,自引:0,他引:1
Germination of the post-fire pioneer species Rhus coriaria , in Pinus halepensis forests on Mount Carmel, Israel, is restricted to the ash covered microsites under large burned pine trees, where the germination of other species is strongly inhibited. The aim of this study was to examine the effect of heat, ash cover, pH, water potential (Ψ Π ) and ethylene on germination of R. coriaria seeds, in order to identify the causes of this unique germination pattern. Pre-heating to 120–140°C for 15 min was essential for the induction of seed germination. Germination percentage was increased by ash cover of 1.2 and 2.4 kg m−2 (1 and 2 cm, respectively) but inhibited by ash cover of 6.0 kg m−2 (5 cm). Wet pine ash from a recently burned forest had pH of 10 and Ψ Π of −0.26 MPa. Under such conditions the germination of R. coriaria was reduced by ca 80%. On the other hand, germination was stimulated by 0.03–0.10 p.p.m. ethylene which was released by wet ash. The post-fire germination of R. coriaria is regulated by the balance between the stimulating effects of fire heat and the ethylene released by the ash, and the inhibition caused by the high pH and the low Ψ Π caused by the ash. Its mode of dispersal by birds and these ecophysiological attributes direct germination of R. coriaria to preferred microsites under the burned canopies of large pine trees. These microsites are characterized by improved nutrition and low competition. 相似文献
16.
Developmental changes in tomato fruit composition in response to water deficit and salinity 总被引:6,自引:0,他引:6
Processing tomato ( Lycopersicon esculentum Mill. cv. UC82B) plants were subjected to moderate levels of water deficit and salinity (Na2 SO4 /CaCl2 ) in sand culture. Fruit water content and the relative contributions of organic and inorganic constituents to fruit solute potential (Ψ ) and soluble solids content were determined throughout development. Fruit Ψ averaged –0.63, –0.86 and –0.77 MPa in the control, salinity and water deficit plants, respectively. Reduced net water import and maintenance of solute accumulation, irrespective of water import, accounted for the reductions in Ψ of stressed fruits. Mineral ions (Na+ , K+ , Ca2+ , Mg2+ , Cl− and SO2- 4 ) contributed –0.31 MPa to Ψ in salinized fruit, compared with –0.19 MPa in control and water deficit treatments. Changes in net carbon accumulation were not observed among treatments, despite considerable differences in fruit K+ status. Starch accumulation in immature fruit was increased and hexose accumulation was decreased by both salinity and water deficit. Maximum starch levels were negatively correlated with total fruit Ψ , but were independent of fruit K+ . Organic acid levels were generally higher throughout development in salinized plants, relative to control plants, and correlated with increased inorganic cation rather than anion accumulation in these fruits. 相似文献
17.
After the application of [13 C3 H]-gibberellin A20 to wild-type (tall) sweet peas ( Lathyrus odoratus L.) labelled gibberellin A1 (GA1 ), GA8 , GA29 and 2-epiGA29 were identified as major metabolities by gas chromatography-mass spectrometry after high performance liquid chromatography. By contrast in genetically comparable dwarf ( II ) plants only labelled GA29 and 2-epiGA29 were produced in significant amounts, although evidence was obtained for trace amounts of labelled GA1 and GA8 . The apical portions of dwarf plants contained 8–10 times less GA1 than those of tall plants but at least as much GA20 (measured using di-deuterated internal standards). In conjunction with previous data these results strongly indicate that in genotype ll internode length is reduced and leaf growth altered by a reduction in GA1 levels attributable to a partial block in the 3β-hydroxylation of GA20 to GA1 .
In contrast to dwarf plants, semidwarf plants (genotype lblb ) contained more GA1 in the apical portion than wild-type counterparts. This is consistent with the suggestion that lb alters some aspect of GA sensitivity. 相似文献
In contrast to dwarf plants, semidwarf plants (genotype lblb ) contained more GA
18.
The NO− 3 -triggered induction of nitrate reductase (NR; EC 1.6.6.2) in the bryophyte Sphagnum magellanicum Brid. has been studied, using in vivo and in vitro assays as well as immunological methods. The time-course of induction was triphasic with maximal NR activity after 6–8 h. Results obtained from Western blots show that NR is synthesized de novo after NO− 3 application. The inhibitory effect of cycloheximide on NR induction corroborated this conclusion. Light enhanced the NO− 3 -triggered NR induction. The enzyme activity, measured in vivo, increased more than the in vitro activity. No evidence for phytochrome control of NR was found. Nitrate uptake, in contrast to NR activity, showed no lag period after NO− 3 application and, under the experimental conditions used, was not rate limiting for NR induction. Neither light nor a NO− 3 pretreatment significantly affected NO− 3 uptake. 相似文献
19.
Francisco Javier Gutiérrez-Mañero Beatriz Ramos-Solano Agust´n Probanza Jalel Mehouachi Francisco R. Tadeo Manuel Talon 《Physiologia plantarum》2001,111(2):206-211
The plant-growth-promoting rhizobacteria (PGPR), Bacillus pumilus and Bacillus licheniformis, isolated from the rhizosphere of alder ( Alnus glutinosa [L.] Gaertn.) have a strong growth-promoting activity. Bioassay data showed that the dwarf phenotype induced in alder seedlings by paclobutrazol (an inhibitor of gibberellin [GA] biosynthesis) was effectively reversed by applications of extracts from media incubated with both bacteria and also by exogenous GA3 . Full-scan gas chromatography-mass spectrometry analyses on extracts of these media showed the presence of GA1 , GA3 , GA4 and GA20 , in addition to the isomers 3- epi -GA1 and iso -GA3 . Isotope dilution analysis indicated that epi -GA1 was an artefact. Likewise, iso -GA3 is also probably an artifact spontaneously formed during extraction and/or analysis. In both culture media, GA1 was present in higher concentrations (130–150 ng ml−1 ) than GA3 (50–60 ng ml−1 ), GA4 (8–12 ng ml−1 ) and GA20 (2–3 ng ml−1 ). The data indicated that culture of both bacteria accumulate bioactive C19-gibberellins in relative high amounts and that these GAs appear to be physiologically active in the host plant. The evidence suggests that the promotion of stem elongation induced by the PGPR could be mediated by bacterial GAs. 相似文献
20.
Regulation of alcohol dehydrogenase gene expression in barley aleurone by gibberellin and abscisic acid 总被引:4,自引:0,他引:4
The expression of the Adh1 gene (alcohol dehydrogenase, EC 1.1.1.1) was studied in the aleurone layer of barley ( Hordeum vulgare cv. Himalaya). Expression increased markedly during grain development at the levels of activity, enzyme protein and mRNA. mRNA content, but not enzyme activity, could be increased further by exogenous abscisic acid (ABA) when isolated, de-embryonated developing grains were pre-treated with gibberellic acid (GA3 ) or fluridone. In isolated mature aleurone layers incubated with exogenous hormones, ADH mRNA was strongly up-regulated by ABA and down-regulated by GA3 within 6 h. With ABA, this increase in mRNA was followed by an increase in ADH protein and activity, peaking at 18 h. With GA3 , the decrease in mRNA was accompanied by simultaneous decreases in protein and activity. In general, GA3 counteracted the effect of ABA and vice versa. In the aleurone of germinating grain, ADH activity decayed in a distal direction from the embryo, consistent with down-regulation by gibberellin(s) diffusing from it. It was concluded that ADH gene expression in the aleurone of the intact grain is regulated by an ABA/gibberellin interaction. 相似文献