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1.
Removal of the blade from the leaf subtending the first flowerbud on Cyclamen persicum ‘Swan Lake’ plants causedthe petiole of that leaf to senesce, but had no effect on thegrowth of the flower peduncle in the debladed petiole's axil.A 10 mg NAA l–1 application generally had no effect onpetiole senescence, peduncle elongation or flowering date whenapplied to the cut end of the petiole after blade removal. A25 mg GA3 l–1 application or a combination of 25 mg GA3l–1 application or a combination of 25 mg GA3 l–1plus 10 mg NAA l–1 delayed petiole senescence and enhancedpeduncle elongation and subsequent flowering. No treatment significantlyaltered peduncle length at the time of flowering. Cyclamen persicum Mill, ‘Swan Lake’, tissue receptivity, flowering, GA3, NAA  相似文献   

2.
Deoxygibberellin C (DGC), a C/D ring-rearranged isomer of GA20,was shown to inhibit the conversion of [2,3-3H2]GA9 to [2-3H]GA4by gibberellin 3ß-hydroxylase from immature seedsof Phaseolus vulgahs. Deoxygibberellin C inhibited the promotionof growth by exogenously applied GA20 of rice (Oryza sativaL.) seedlings. Evidence is also presented that DGC is a competitiveinhibitor of the 3ß-hydroxylase from P. vulgaris.However, DGC only weakly inhibited the conversion catalyzedby the 3ß-hydroxylase from Cucurbita maxima at highconcentrations, and it did not inhibit the promotion of growthby exogenously applied GA9 of cucumber (Cucumis sativus) seedlings.These results suggest that the 3ß-hydroxylases fromP. vulgaris and C. maxima have different structural requirementswith respect to their substrates. 16-Deoxo-DGC also inhibitedcatalysis of the same conversion by 3ß-hydroxylasefrom P. vulgaris, and it slightly inhibited the conversion catalyzedby the enzyme from C. maxima. Application of 16-deoxo-DGC causedthe promotion of the growth of seedlings of both rice and cucumber. 3 Present address: Genetic Engineering Center, Korea Instituteof Science and Technology, Daejeon 305–606, Korea 4 Present address: Department of Agricultural Chemistry, UtsunomiyaUniversity, Utsunomiya-shi, Tochigi, 321 Japan (Received September 25, 1990; Accepted December 17, 1990)  相似文献   

3.
The levels of purine and pyrimidine nucleotides in suspensioncultures of Catharanthus roseus were determined 24 h after stationary-phasecells were transferred to fresh complete (‘+Pi’)or phosphate-deficient (‘–Pi’) Murashige-Skoogmedium. The levels of ATP, GTP, UTP and CTP were from approx.3 to 5-fold greater in the cells grown in ‘+Pi’medium than in the cells grown in ‘–Pi’ medium.The levels of almost all other nucleotides were slightly higherin the cells in ‘+Pi’ medium. The rates of de novoand salvage biosynthesis of purine and pyrimidine nucleotideswere estimated from the rates of incorporation of radioactivityfrom [14C]formate, [2–14C]glycine, NaH14CO3, [6–14C]orotate,[8–14C]adenine, [8–14C]adenosine, [2–14C]uraciland [2–14C]uridine. The results indicated that the activityof both the de novo and the salvage pathway was higher in thecells in ‘+Pi’ medium than in the cells in ‘–Pi’medium. The rate of degradation estimated from the rate of releaseof 14CO2 from labelled purines and pyrimidines indicated thatdegradation of uridine was significantly reduced in the cellsin ‘+Pi’ medium, but no significant difference wasfound in the degradation of adenine, adenosine and uracil. Thepossible role of Pi in the control of the biosynthesis of nucleotidesand in the degradation of uridine is discussed. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, nucleotides, purines, pyrimidines, biosynthesis, degradation  相似文献   

4.
5.
Activity curves are determined for gibberellins A1 to A0 bythe Avena first-leaf bioassay method. Gibberellins A1, A4 andA5 can be detected at 10-11 or 10-10 g/ml and give optimum activityof approximately 230 per cent elongation (water controls = 100per cent). Gibberellins A2A3, and A9 can be detected at 10-3g/mland give optimum activity of approximately 200 per cent. GibberellinsA6 and A7 can be detected at 10-5g/ml; GA7 gives optimum activityof around 190 per cent. All the gibberellins except GA8 canbe detected by this bioassay method after chromatography inn-butanol: 1.5 N ammonia (3: 1) and benzene: acetic acid: water(4: 2: 1) when applied to the paper at concentrations from O.Ito µg. The sensitivity of the method is compared withthat of other gibberellin bioassay methods.  相似文献   

6.
Segments excised from the upper and the lower parts of cowpea(Vigna unguiculata L.) hypocotyls were compared in terms oftheir responses to exogenous indole-3-acetic acid (IAA) in relationto their endogenous levels of gibberellin. Growth of the segmentswas measured continuously during xylem perfusion with a lineardifferential transformer. IAA induced a burst of elongationin the upper segments but only slight promotion of growth inthe lower segments. Treatment with uniconazole, a potent inhibitorof the biosynthesis of gibberellins, reduced the responsivenessof the upper segments to exogenous IAA to about one half ofthe control value. Pre-perfusion with GA3 of such segments fortwo hours prior to application of IAA, partially restored theresponsiveness to IAA. Analysis by GC/MS identified GA1, GA4,GA9 GA20 and GA51 as native gibberellins in the hypocotyls ofcowpea seedlings. Analysis by GC/SIM also showed that the physiologicallyactive gibberellins (GA1 and GA4) were located mainly in theupper part of the hypocotyl and the treatment with uniconazolemarketly reduced the endogenous level of gibberellins thereto less than 11% of the control level. These results suggestthat levels of endogenous gibberellins possibly control theresponse to IAA in these segments. (Received May 12, 1994; Accepted November 15, 1994)  相似文献   

7.
The change of endogenous gibberellin and ABA content was measuredduring the fruit development of Prunus persica. GA5, GA32 andtwo unidentified gibberellins, were found throughout the developmentalstages. GA5, GA32 and ABA showed maximum peaks in their contentsixty days after full bloom, which suggests that they play importantroles in fruit development. 1 To whom correspondence should be addressed. (Received December 12, 1975; )  相似文献   

8.
Inhibition of the biosynthesis of gibberellins by prohexadione,3,5-dioxo-4-propionylcyclo-hexanecarboxylic acid, was studiedwith cell-free systems derived from immature seeds of Cucur-bitamaxima, Phaseolus vulgaris and Pisum sativum. Prohexadione,at a concentration of 10–4 M, inhibited C-7 oxidationof GA12-aldehyde, C-20 oxidation of GA15, conversion of C20-gib-berellinsto C19-gibberellins, 3ß-hydroxylation, 2,3-dehydrogenationof GA20, 2,3-epoxidation of GA5 and 2ß-hydroxylationof GA9 and GA20. The 3ß-hydroxylase activity appearedto be more sensitive to prohexadione than were the C-20 oxygenaseand the 2ß-hydroxylase activities. The conversionof mevalonic acid to GA12-aldehyde and the 13-hydroxylationof GA12 were not affected by prohexadione at a concentrationof 3 ? 10–4 M. All of the steps inhibited by prohexadioneare oxidation steps catalyzed by soluble enzymes that require2-oxoglutarate, Fe2+ and oxygen, and all of them occur distalto the synthesis of GA12-aldehyde in the biosynthesis of gibberellins. (Received April 4, 1990; Accepted September 14, 1990)  相似文献   

9.
Endogenous levels of gibberellins in shoots and ears of twodwarf rice (Oryza sativa L.) cultivars, Tan-ginbozu (dx mutant)and Waito-C (dy mutant), were analyzed and compared with thoseof normal rice cultivar, Nihonbare. The endogenous levels of13-hydroxylated gibberellins in Tan-ginbozu were much lowerthan those in Nihonbare. In Waito-C, the levels of GA19 andGA20 in the shoots were higher but that of GA1 was lower thanthe levels of these gibberellins in Nihonbare. These resultssupport the hypothesis that the dy gene controls the 3ß-hydroxylationof GA20 to GA1 while the dx gene controls a much earlier stepin the gibberellin biosynthesis. Our results indicate that GA1is the active gibberellin that regulates the vegetative growthof rice. The endogenous levels of GA4 in the ears of the twodwarf cultivars of rice were higher than the level of GA4 inthe ears of the normal cultivar, Nihonbare suggesting that thebiosynthesis of gibberellin is not blocked in the anthers ofthe dwarf rice. (Received April 27, 1989; Accepted July 12, 1989)  相似文献   

10.
Zoea I larvae of the brown shrimp Crangon crangon (Decapoda)were exposed to varying levels of UV radiation in a sunshinesimulator. ‘Short-term exposures’ (0–8 h)were used to determine the highest UV dose with no significanteffect (NOEC; defined by limit of detection) and the lethaldose of 10 and 50% mortality (LD10 and LD50). Crangon crangonshowed a relatively high sensitivity to UVB radiation (NOEC= 10 kJ m–2, LD10 = 15 kJ m–2, LD50 = 24 kJ m–2)compared to other crust-acean species. LD values (1997–1998)showed no adaptation to seasonal light regimes. ‘Long-termexposures’ (0–10 days) were carried out to assessthe range where the ‘law of reciprocity’ is valid.The larvae were exposed to UV levels of 0.2, 0.4 and 0.7 J m–2for appropriate time intervals, always cumulating in a sublethaldose of 5 kJ m–2 day–1. Results reflect a possiblethreshold (0.2–0.4 J m–2 UVB) in the effect of thedifferent UVB doses used; thus, a proportional relationshipof intensity and exposure time can only be shown at UVB levelsabove this threshold intensity.  相似文献   

11.
ZIESLIN  N.; GELLER  Z. 《Annals of botany》1983,52(6):849-853
Dormancy was induced during storage of Liatris spicata cormsgrown in Israeli summer conditions, but plants left in soilcontinued vegetative growth. Corms of winter-grown plants sproutedfreely. Treatment with GA3 restored both sprouting and floweringin summer-grown corms, but in winter corms GA2 was effectiveonly after corms were stored at low temperature. All the plantsflowered after 4 weeks at 2 °C and GA3 treatment. The content of gibberellins in the main bud of freshly excavatedcorms decreased during the first 18 d of storage but increasedto the initial level after 4 months of cold storage. The numberof flowering stems increased to 2.5 per corm when corms werecold-stored up to 75 d, but decreased with a longer storage. Liatris spicata, dormancy, flowering, gibberellin, sprouting  相似文献   

12.
The properties and mode of action of a new plant growth retardant,(E)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol(S-3307), were investigated. When a dipping method was used,S-3307 at 2.2 ? 10-7 M (0.064 ppm) retarded the growth of riceplants by 50% of the value found for the control. The retardationof growth was removed by a gibberellin application (8.7?10-5M). S-3307 had nearly no effect on the shoot elongation inducedby gibberellin. The amounts of gibberellin-like substances inrice shoots were decreased by S-3307 treatment in proportionto the degree of growth retardation. This observation was confirmedwith GA1 and GA19, the main gibberellins in the rice plant.Our results indicate that S-3307 inhibits gibberellin biosynthesisin rice plants. (Received November 7, 1983; Accepted March 21, 1984)  相似文献   

13.
The effects of exposure of up to 2 h with sulphur dioxide ona range of plant species was observed by measuring changes inthe rate of net photosynthesis under closely controlled environmentalconditions. Ryegrass, Lolium perenne ‘S23’ was thespecies most sensitive to SO2; significant inhibition was detectedat 200 nl l–1. Fumigations at 300 nl l–1 also inhibitedphotosynthesis in field bean (Vicia faba cv. ‘Three FoldWhite’ and ‘Blaze’) and in barley (Hordeumvulgare cv. ‘Sonja’). No effect was detected inwheat (Triticum aestivum cv. ‘Virtue’) at concentrationsup to 600 nl l–1 SO2, or in oil-seed rape (Brassica napuscv. ‘Rafal’) except at 800 nl l–1 SO2). Recoverycommenced immediately after the fumigation was terminated andwas complete within 2 h when inhibition had not exceeded 20%during the SO2 treatment. Key words: Sulphur dioxide, short-term fumigation, photosynthesis  相似文献   

14.
Comparative Potency of Nine Gibberellins   总被引:1,自引:0,他引:1  
Gibberellins A1 to A9 have been compared, each at several doselevels, in bioassays based on extension of stems of dwarf gardenpea (Pisum sativum), dwarf bean (Phaseolus vulgaris) and Lunariaannua, of hypocotyls of cucumber (Cucumis sativus) and lettuce(Lactuca sativa), and of leaf sheaths of three dwarf mutants(d–1, d–3, d–5) of maize (Zea mays). GibberellinsA3 (gibberellic acid) and A7 are of high potency in most bioassays.A8 is of negligible potency in all and is probably not a functionalhormone. The other gibberellins show a more or less marked tendencyto specificity. The plants used as bioassay material also differin the specificity of their response. Some, for example, maizedwarfs d–3 and d–5 and lettuce, respond well tomost gibberellins; others, for example, cucumber, respond onlyto a few; extreme specificity is shown by Lunaria annua which,in the unvernalized condition, responds by stem elongation onlyto gibberellin A7. Dose/response curves of the various gibberellinsare usually parallel, but certain exceptions to this have beenfound. Possible explanations of specificity are discussed inrelation to the results obtained, and it is concluded that insufficientevidence is available to make it possible to draw any validconclusions. Current definitions of gibberellins, whether basedon chemical structure or biological activity, are unsatisfactory.  相似文献   

15.
The role of gibberellins in regulating the growth of tomatoroots was investigated by comparing various cellular parametersin cultured roots of the gibberellin-deficient mutant gib-l/gib-lwith those in roots of the near-isogenic wild-type. In addition,wild-type roots treated with 0?1 µM 2S,3S paclobutrazol,an inhibitor of gibberellin biosynthesis, and mutant roots treatedwith 0?1 µM GA3 were also compared: the former roots constitutea phenocopy of the mutant, whereas the latter roots appear tobe ‘normalized’ and similar to wild-type. The elongationof mutant and phenocopied roots were similar, their maximumelongation rates being about half or two-thirds that of wild-typeor GA3-treated mutant roots, respectively. These rates wereinterpreted in terms of the numbers and lengths of cells withinthe meristematic and non-meristematic portions of the elongationzone. Mean meristem length tended to be shorter in both themutant and the 2S,3S paclobutrazol-treated wild-type roots thanin the other two types of root. A major difference between thetwo pairs of mutant and normal roots was their mean final celllengths: mean lengths of cortical cells of the mutant and 2S,3Spaclobutrazol-treated roots were, respectively, 39% and 25%shorter than the mean length of wild-type roots. Final celllength in the GA3-treated mutant roots were similar to wild-type.By contrast, the diameters of mature cortical cells of the mutantand phenocopy were about 20% greater than the diameters of equivalentwild-type or ‘normalized’ mutant cells. The meanvolumes of cortical cells in all four types of roots showedno significant differences. Knowledge of the distribution ofcortical cell lengths, widths and volumes along the root axis,together with information about the rate of root elongation,permitted comparisons of the relative elemental growth ratesof each of these three cellular parameters. The available evidence suggests that the level of endogenousgibberellins in mutant roots is lower than in wild-type roots.The present results, therefore, suggest that endogenous gibberellinsare necessary for normal growth of cultured tomato roots andthat they regulate the relative amounts of growth at the longitudinaland transverse walls of the cells which, in turn, affects theshape of the elongating cells. Key words: Cell growth, cultured roots, gibberellin, gib-l mutant, Lycopersicon esculentum, 2S,3S paclobutrazol, relative elemental growth rate, root meristem  相似文献   

16.
Gibberellin 3/ß-hydroxylase,a 2-oxoglutarate-dependentdioxygenase that catalyzes the hydroxylation of GA20 to GA1,was purified 313-fold from immature seeds of Phaseolus vulgarisL. The mol wt of the enzyme was estimated to be 42,000 by gelfiltration HPLC and SDS-polyacrylamide gel electrophoresis.The enzyme exhibited maximum activity at pH 7.7. The Km valuesfor [2,3-3H]GA20 and [2,3-3H]GA, were 0.29µu and 0.33µm, respectively. The enzyme requires 2-oxoglutarate asa cosubstrate; the Km value for 2-oxoglutarate was 250µMusing [3H]- GA20 as a substrate. Fe2+ and ascorbate significantlyactivated the enzyme at all purification steps, while catalaseand BSA activated the purified enzyme only. The enzyme was inhibitedby divalent cations Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+.3ß-Hydroxylation of [3H]- GA20 was also inhibitedby non-radioactive GA5, GA9,GA15, GA20 and GA44. The possiblesite of 3ß-hydroxylation in gibberellin biosynthesisis discussed in terms of the substrate specificity of partiallypurified gibberellin 3ß-hydroxylase. (Received February 29, 1988; Accepted June 3, 1988)  相似文献   

17.
TAUTVYDAS  K. J. 《Annals of botany》1979,44(4):503-509
The interaction of light, gibberellic acid (GA3), and phlorizinin the growth of lettuce (Lactuca sativa L. cv. ‘GrandRapids’) hypocotyls was investigated. At all concentrationsof GA3, phlorizin enhanced GA3-induced growth at luminous intensitiesabove 50 ft-c (continuous light). Without GA3, phlorizin hadno effect on hypocotyl growth in the light but it inhibitedgrowth in the dark. Both seedlings and hypocotyl sections respondedto phlorizin in the presence of GA3. There was no iteractionbetween phlorizin and KCl. Water-growth was severly inhibitedby light. GA3,-induced growth was slightly inhibited by light,and then only at luminous intensities above 50 ft-c. Thus, relativeto H2O-growth, GA3-induced growth increased with increasingluminous intensity up to 450 ft-c, where it reached saturation.It seems that a synergism may exist between light and GA3 aswell as between phlorizin and GA3. Lactuca sativa L, lettuce, hypocotyl elongation, gibberellic acid, phlorizin, light  相似文献   

18.
LORD  E. M. 《Annals of botany》1979,44(6):757-766
Plants of Lamium amplexicaule, grown under short-day field conditionsin Northern California produce predominantly closed flowers.Under long-day field conditions, plants may produce up to 50per cent open flowers, the same total number of flowers beingproduced under each daylength regime. A 20 ml drop of GA3 or GA7 (100µM) was applied to themain shoot apex of plants growing under short-day conditions,and all subsequently produced flowers opened. CCC, an inhibitorof gibberellin synthesis, was applied (0.06 per cent) to thesoil of seedlings grown under long-day conditions. The CCC-treatedplants were dwarfed and bore only closed flowers. With GA7 appliedexogenously to the CCC-treated shoots, inhibition was released,resulting in elongated internodes and open flower production.The timing of flower production and internodal extension inLamium amplexicaule are positively correlated. When floral primordiawere removed from main shoots, the average internode lengthsdecreased. The number of nodes produced in treated plants wasincreased as a result of flower removal. Exogenous GA7 (10 µM)applied to the nodes from which flowers were removed resultedin internodal extension but had no effect on node number. Twoprocesses that may contribute to the control of the productionof open and closed flowers in Lamium amplexicaule are: (1) anincreasing anther sac size from lower to upper node flowersthat may exert control locally, via GN production, on corollaexpansion, and (2) a photoperiodic control. Lamium amplexicaule L, henbit, cleistogamy, chasmogamy, gibberellins, gibberellic acid (GA3), (2 chloroethyl) trimethylammonium chloride (cycocel)  相似文献   

19.
Normal, terminal inflorescences of Cordyline terminalis, a woodymonocotyledon, appeared 4–6 weeks after apical buds weretreated with gibberellin A3 (GA3) or GA4+7. There was no responseto GA13. Large plants, newly rooted cuttings, and seedlingsall responded, although there were clonal differences. Floweringwas induced under natural day lengths throughout the year. Untreatedcontrol plants in all experiments remained vegetative. Dracaenaspp. did not respond to the three gibberellins.  相似文献   

20.
In the fern Lygodium japonicum, the effect of the exogenousapplication of two gibberellin methyl esters, gibberellin A4methyl ester (GA4Me) and gibberellin A20 methyl ester (GA20Me)on spore germination in the dark and uptake of GA4Me and GA20Meby spores was investigated. Tritiated GA4Me and GA20Me wereprepared and used as radioactive tracers. The activity of GA4Mewas more than 100-fold that of GA20Me for the induction of sporegermination. When treated for 24 h, the activity for inducingspore germination remained after removal of the gibberellinmethyl esters from the medium. The amount of GA4Me taken upby spores was more than three times that of GA20Me throughoutthe 24 h time course of treatment. The uptake of both gibberellinmethyl esters was proportional to the external concentrationfor the range of concentrations between 10–9 M and 10–6M. When treated with the tritiated gibberellin methyl estersat 10–6 M and 10–7 M for 24 h, most of the gibberellinmethyl esters taken up by the spores were not metabolized. Althoughthe uptake of the two gibberellin methyl esters differed by3- to 5- fold, their abilities to induce spore germination differedby more than 100-fold. Therefore, the difference in the activityof the two gibberellin methyl esters regarding the inductionof spore germination could not be explained solely by the differencein their uptake. (Received January 11, 1988; Accepted May 26, 1988)  相似文献   

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