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1.
This investigation was undertaken to study the effect of GA3on extension growth of Glycine max L. and on starch contentof its individual internodes at maturity. The effect on hydrolyticactivity of the extract of different internodes was also studied.GA3 stimulates the extension growth of stem by increasing theelongation of those internodes which are either in the processof elongation or being differentiated at the time of treatment.Starch content decreases with the position of the internode(from base upwards) on the intact plant. Corresponding internodeshave minimum starch content in 100 ppm GA3-treated plants andmaximum in the controls. Internodes which show the maximum elongationdue to GA3 treatment, show the least starch content and alsoshow maximum hydrolytic activity during the period of elongation.It is suggested that enhanced extension growth is brought aboutby enhanced mobilization of reserve food by GA3. (Received November 21, 1967; )  相似文献   

2.
The effects of low temperature and the Rht3 dwarfing gene onthe dynamics of cell extension in leaf 2 of wheat were examinedin relation to gibberellin (GA) content and GA-responsivenessof the extension zone. Leaf 2 of wild-type (rht3) wheat closelyresembled that of the Rht3 dwarf mutant when seedlings weregrown at 10C. The maximum relative elemental growth rate (REGR)within the extension zone in both genotypes was lower at 10Cthan at 20C, but the position with respect to the leaf basewas unaffected by temperature. The size of the extension zoneand epidermal cell lengths were similar in both genotypes at10C. Growth at 20C, instead of 10C, increased the lengthof the extension zone beyond the point of maximum REGR in thewild type, but not in the Rht3 mutant. Increasing temperatureresulted in longer epidermal cells in the wild type. Treatingwild-type plants at 10C with gibberellic acid (GA3) also increasedthe length of the extension zone, but the Rht3 mutant was GA-non-responsive.However, the concentrations of endogenous GA1 and GA3 remainedsimilar across the extension zone of wild-type plants grownat both temperatures, despite large differences in leaf growthrates. The period of accelerating REGR as cells enter the extensionzone, and the maximum REGR attained, are apparently not affectedby GA. It is proposed that GA functions as a stimulus for continuedcell extension by preventing cell maturation in the region beyondmaximum REGR and that low temperature increases the sensitivitythreshold for GA action. Key words: Cell extension, gibberellin, Rht3 dwarfing gene, temperature, wheat leaf  相似文献   

3.
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   

4.
The second leaf of wheat was used as a model system to examinethe effects of the Rht3 dwarfing gene on leaf growth. Comparedto the rht3 wild type, the Rht3allele decreased final leaf length,surface area and dry mass by reducing the maximum growth rates,but without affecting growth duration. Gibberellic acid (GA3)increased final leaf length and maximum growth rate in the rht3wild type, but was without effect on the Rht3 mutant, whichis generally regarded as being non-responsive to gibberellin(GA). Paclobutrazol, an inhibitor of GA biosynthesis, decreasedfinal leaf length and maximum growth rate in the rht3 wild typeto values similar to those in the untreated Rht3 mutant. NeitherGA3 nor paclobutrazol affected the duration of leaf growth.The decrease in leaf length was produced by reduction of celllength rather than cell number. The maximum relative elementalgrowth rate (REGR) for cell extension was essentially the samein all treatments, as was the time between the cells leavingthe meristem and achieving maximum extension rate. The differencesbetween the genotypes and treatments were all almost entirelydue to differences in the time taken from the attainment ofmaximum REGR of cell extension to the cessation of extension.This was reflected in the length of the extension zone, whichwas approximately 6–8 per cent of final leaf length. Theeffects of the Rht3 allele, GA3 and paclobutrazol all appearto be on the processes which promote the cessation of cell elongation. Key words: Cell extension, gibberellin, leaf growth, Rht3 gene, Triticum, wheat  相似文献   

5.
The application of GA3in aqueous solution to leaves or flowersof hermaphrodite cultivars of strawberry, Redgauntlet and Rabunda,prevented growth of the receptacle despite hand pollination.This inhibitory effect occurred only when GA3 was applied priorto anthesis. Although viable pollen was produced and germinatedto grow down the styles of treated plants, no seeds were formed.Receptacle growth failed underneath the unfertilized carpels,but the basal region devoid of carpels enlarged and ripened.The effect of GA3 was the same in vivo and for flowers grownin vitro. ABA and BAP also inhibited growth of pollinated flowersin vitro, but neither substance stimulated growth of the baseof the receptacle. 2-NOA stimulated receptacle growth of pollinatedflowers but did not overcome the inhibitory effect of GA3. Removal of fertile carpels 9 days after pollination preventedfurther receptacle growth. GA3 treatment of the bare receptaclere-started growth but was less effective than 2-NOA. No growth substance treatment induced parthenocarpic developmentin these cultivars when unopened buds were emasculated and culturedwithout pollination, although GA3 induced some swelling of thereceptacle base. Fragaria x ananassa Duch., strawberry fruit set, fruit growth, growth regulators  相似文献   

6.
Gibberellic acid (GA3), kinetin, and indol-3yl-acetic acid (IAA)contained in lanolin were applied in various combinations andconcentrations to decapitated stems and petioles and to budsof Phaseolus vulgaris L. GA3 applied alone usually promotedgrowth of main stems and laterals but this was by no means consistentand occasionally it acted in the opposite way. IAA applied alonereduced lateral bud extension slightly, but not consistently;however, when applied with GA3 or GA3 plus kinetin, it oftenmarkedly inhibited the promotion caused by these compounds.On occasions, however, GA3 and IAA acted synergistically topromote and sometimes to inhibit lateral shoot growth. Kinetinalone showed few significant effects on lateral shoot growthbut applied with GA3 it often dramatically increased GA3-inducedgrowth of main stems and laterals. The diversity of these results,which parallels that found in the literature, was shown to bepartly dependent on the point of hormone application and ageof the plant or bud, on concentration of hormone and on lightintensity or nutrition. However, no meaningful relationshipswere found and it is concluded that growth of laterals and mainstems is dependent on a hormone balance which can be criticallymodified by a wide range of internal and external factors thenature of which is still to be determined.  相似文献   

7.
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   

8.
Strain S1.2 of Silene armeria was grown under an 8h-photoperiodand treated with GA3 every day for 20 days. This growth substancecaused stem elongation, but no flowering in this long-day plant.Changes in the mitotic index and DNA content of cells in thevarious zones of the apical meristem before, during and afterGA3 treatment were described. Mitotic activity and increasein the proportion of nuclei at the 4C level (S+G2 phase of thecell cycle) were strongly stimulated in the rib-meristem, andto a lesser extent in the lateral zone, but not in the axialzone. This stimulation of apical activity reached a peak aftertwo GA3 treatments and then declined gradually, so that after20 days the activity in GA3-treated meristems was lower thanthat in untreated controls; at this point most cells were inthe G1 phase. When the GA3 treatment was discontinued, there was a gradualincrease in the mitotic activity which ultimately reached thesame level as that in controls. Stem elongation ceased and leavesformed aerial rosettes. It is concluded that in vegetative plants of strain S1.2 ofSilene armeria GA3 acts mainly on the rib-meristem cells whichresults in stem elongation. Lack of response in the axial cellsexplains why GA3 fails to induce flowering in this strain ofSilene armeria. (Received June 18, 1983; Accepted August 3, 1983)  相似文献   

9.
The effects of GA3 on weeping were examined in the Japanesecherry, Prunus spachiana. Current-year branches first elongateupward then gradually bend to elongate downward. GA3 appliedto apical buds promoted the upward elongation and inhibitedthe bending. Thus, GA3 changed the direction of branches duringtheir growth. (Received April 12, 1993; Accepted February 2, 1994)  相似文献   

10.
The kinetics of extension induced by GA31 in the hypocotyl ofintact seedlings of Lactuca sativa are similar in the dark andin the light, and differs fundamentally from the kinetics ofelongation in the dark without GA3. Both in continuous lightand in the dark, GA3-induced promotion starts 24 h after incubation.In the dark, even low concentrations of GA3, which do not affectthe length measured after 6 d when the extension of hypocotylalmost ceases, remove the lag period of 48 h which precedesextension, and prolong the high rate of elongation. FollowingGA3 supply the hypocotyl length in the dark and in the lightdoes not differ until 48 h; thereafter the rate of elongationin the light is less, so that the final length of the hypocotylis 40 per cent shorter than that of the dark-grown seedlingswithout GA3. IAA supplied apically to light-grown seedlings induces a weakpromotion at a concentration of 1 mg l–1 only. With anincreasing concentration of GA3 supplied simultaneously, theconcentration of IAA inducing a significant promotion decreases.A combined supply of both these regulators, however, does notrestore the light-mediated inhibition of hypocotyl elongationcompletely. The maximum decrease in hypocotyl length induced by the growthretardants AMO-1618, CCC, and B-9 supplied from the beginningin the dark does not exceed 70 per cent. Saturating doses ofGA3 supplied in combination with any one of the retardants compensateonly a fraction of the decrease. The results have been interpreted to show that native GAs arenot involved in extension growth in the dark.  相似文献   

11.
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   

12.
The synergistic effects of 2-ethyl-3-methoxycarbonyl-l-(p-tolylcarbamoyl)-isoureaand 4-ethoxy-l-(p-tolyl)-s-triazine 2,6(1H,3H)-dione on GA1,3,4,7,8,9,17,19,20ana 53 in rice seedlings were investigated. Each synergist showeda very high effect when combined with GA1,3,9 or 17, a higheffect with GA4,7,19 or 20, little effect with GA53, and noeffect with GA8. (Received July 22, 1981; Accepted October 2, 1981)  相似文献   

13.
The effects of a novel plant growth regulator (PGR) prohexadionecalcium (BX-112; calcium 3,5-dioxo-4-propionylcyclohexanecarboxylate)on shoot elongation caused by exogenously applied GA1, GA3,GA4) GA19 and GA20 were investigated in rice (Oryza sativa L.cv. Nihonbare and cv. Tan-ginbozu) seedling test. Dependingon the dose, BX-112 reduced shoot elongation in both cultivarscaused by GA19 and GA20, but not by GA1. When a high dose ofBX-112 (e.g. 250 ng/plant and over) was applied with GA1, orGA4, shoot elongation was even promoted. This promotive effect,however, was not observed with GA3. These results suggest thatBX-112 inhibits gibberellin (GA) biosynthesis in the rice plantat the 3ß- and 2ß-hydroxylation of GAs,namely steps of activation and inactivation, respectively. (Received September 6, 1989; Accepted November 27, 1989)  相似文献   

14.
A critical stage in flower bud growth in the spike of Gladioluswhich is initiated by gibberellic acid (GA3) and sustained bysucrose has been identified. This corresponds to the stage atwhich separation of the outer bract occurs. In buds at differentdevelopmental stages isolated and held in water, it is the samebud stage that first shows increased growth. Buds not inducedby light were shown to respond more significantly to GA3 andsucrose than those induced by light. Since the separation ofthe outer bract results in light-induced amylase productionand starch hydrolysis leading to petal growth, it is proposedthat growth promotion by GA3 is related to light-induced petalgrowth at this specific stage. flower bud growth, Gladiolus natalensis, gibberellic acid, sucrose  相似文献   

15.
A 10-min irradiation with red light (R) of ‘Grand Rapids’lettuce (Lactuca sativa L.) seeds increased respiratory rates(QO2 and QCO2) over those of far red (FR)-irradiated seeds within2 to 3 hr. Differences in respiration between R- and FR-irradiatedseeds became more pronounced with time. The respiration, indarkness at 25?C, of seeds air dried after germination promotingimpregnation treatments with 1.0 mM GA3+0.5 mM kinetin in acetonewas stimulated slightly by the 6th hour after planting and markedlyby the 12th and 24th hour. Results with seeds in GA3+kinetindissolved in water were similar. ABA, which inhibits germinationand seedling growth, prevented stimulation in respiration oflight-induced seeds. ABA also repressed respiration when usedwith GA3+kinetin. The germination and growth retardant, isopropylN-(3-chlorophenyl) carbamate (CIPC), did not affect the respirationof either R- or FR-treated seeds. A comparison of the effectsof chemical and light treatments on respiration indicate thatchemical and photocontrol mechanisms are not identical. (Received May 17, 1976; )  相似文献   

16.
The metabolism of GA12 and its precursors was investigated incultured cells of seven cell lines of Nicotiana tabacum andthree cell lines of Catharanthus roseus using l4C-labeled substrates.The presence of a metabolic pathway from ent-7-hydroxykaurenoicacid to GA53 via GA12-aldehyde and GA12 was demonstrated inthe cultured cells. GA12 was effectively converted to GA53 incells of BY-2, 2b-4, 2b-13 and CG from N. tabacum. By contrast,GA53 was not converted to any other GAs in all of the linesof cells examined. The metabolism of C19-GAs was also examinedusing 3H-labeled substrates. The conversion of GA20 to GA29and GA, and of GA4 to GA34 occurred more efficiently in cellsfrom C. roseus than in cells from N. tabacum. However, 13-hydroxylationof GA4 and GA9 was not observed in any of the cell culturesexamined. Among the various metabolites, GA53, GA29 and GA34were identified by full-scan GC/MS. (Received December 20, 1990; Accepted May 27, 1991)  相似文献   

17.
Oryzains, cysteine proteinases of rice seeds, are induced byGA3 in germinating rice seeds [Abe et al. (1987) Agric. Biol.Chem. 51: 1509]. The effects of GA1, GA3, GA4, GA9, and GA20on the production of oryzain and -amylase were investigatedin embryoless half- and whole-seeds of rice (cv. Nipponbare).When gibberellins (GAs) were incubated with embryoless half-seeds,GA1, GA3 and GA4 induced oryzain and -amylase, but GA9, andGA20 did not. GA9 and GAM induced oryzain and -amylase productionin whole seeds, but this production was inhibited by the simultaneousapplication of prohexadione, an inhibitor of 2ß- and3ß-hydroxylation of GAs. Prohexadione did not inhibitthe activities of oryzain and -amylase induced by GA1. Theseresults suggest that GAs possessing the 3ß-hydroxylgroup induce activities of oryzain and -amylase in rice seedsand that GA9 and GA20 have activity only after they are convertedmetabolically to active GAs, probably GA4 and GA1, respectively.GA1, was more active than GA4 in both half seeds and wholeseeds incubation. Oryzain and -amylase activities induced byGA4 were significantly inhibited in the presence of 10–4M prohexadione. This suggests that the conversion of GA1, toGA4 (13-hydroxylation) might be inhibited at a high dose ofprohexadione in whole seeds. 4Present address: Institute of Food Development, Kyung Hee University,Suwon 449-701, Korea  相似文献   

18.
Maize (Zea mays L., hybrid Cargill 147) seedlings, grown inaseptic conditions, were inoculated with three strains of Azospirillumlipoferum (Al op 33, Al iaa 320, and ATCC 29708) or culturedin different concentrations of indol-3-acetic acid (IAA) orgibberellin A3 (GA3). After 48 h, root length, root surfacearea, root dry weight, and shoot dry weight were measured inall treatments. Gibberellin content was evaluated in selectedroots of control and Azospirillum inoculated seedlings by gaschromatography-mass spectrometry-selected ion monitoring withthe use of deuterated gibberellins as internal standards. Thethree strains of A. lipoferum, IAA (2 ng ml–1), and GA3(40 to 400 pg ml–1) significantly enhanced root growth.Improvement of root hair growth and density was obtained mainlywith A. lipoferum strain Al op 33 and GA3 40 pg ml–1.GA3 was identified by gas chromatography-mass spectrometry (byboth, full scan and selected ion monitoring) in a free acidfraction from roots of the seedlings inoculated with A. lipoferum.In the roots of the non inoculated seedlings GA3 was found afterhydrolysis of a fraction expected to contain glucosyl conjugates. (Received April 26, 1993; Accepted September 27, 1993)  相似文献   

19.
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   

20.
Experiments were carried out to explore the involvement of gibberellins(GAs) in the light-induced germination of Arabidopsis thaliana(L.) Heynh, using wild type (WT) and phytochrome-deficient mutants(phyA, phyB and phyAphyB deficient in phytochrome A, B and Aplus B, respectively). Seed germination of WT and phytochrome-deficientmutants was inhibited by uniconazole (an inhibitor of an earlystep in biosynthesis of GA, the oxidation of ent-kaurene) andprohexadione (an inhibitor of late steps, namely, 2rß-and 3rß-hydroxylation). This inhibition was overcomeby simultaneous application of 10-5 M GA4. The relative activityof GAs for promoting germination of uniconazole-treated seedswas GA4>GA1=GA9>GA20. The wild type and the phyA and phyBmutants had an increased response to a red light pulse in thepresence of GA1, GA4, GA9, GA20 and GA24 but there were no significantdifferences in activity of each GA between the mutants. Therefore,neither phytochrome A nor hytochrome B appears to regulate GAbiosynthesis from GA12 to GA4 during seed germination, sincethe conversion of GA12 to GA9 is regulated by one enzyme (GA20-oxidase). However, GA responsiveness appears to be regulatedby phytochromes other than phytochromes A and B, since the phyAphyBdouble mutant retains the photoreversible increased responseto GAs after a red light pulse. (Received February 13, 1995; Accepted July 11, 1995)  相似文献   

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