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1.
Exposure of Avena coleoptile sections to 8% O2 brought aboutrespiration decrease, resulting in a decrease of ATP production.The pH at the cell wall surface slightly rose in sections exposedto 8% O2, while their growth was greatly accelerated. Moreover,this growth acceleration was observed even in sections treatedwith CCCP known to make membranes permeable for protons. Weconcluded that the growth acceleration with reduction of O2concentration is probably not the result of secretion of H+ions into cell wall compartments. Results of this study provided evidence to support the hypothesisthat there is an inverse relationship between hydroxyproline-proteinlevel and the ability of a cell to undergo rapid cell elongation.Total labeling of the cell wall fraction with 14C-proline wasunaffected by 8% O2 treatment, although the radioactivitiesof hydroxyproline incorporated into this fraction during thetreatments fell to about 45% of the control. Moreover, the radioactivitiesof hydroxyproline incorporated into the SLS-insoluble cell wallfraction of sections exposed to 8% O2 decreased to about 30%of the control. This decrease of hydroxyproline was also observedin sections treated with cycloheximide, which inhibits the secretionof H+ ions into the cell wall compartment. Reduction of O2 concentrationin the surrounding atmosphere affects not only the hydroxylationof peptidyl proline, but also the binding of hydroxyproline-protein(s)to cell wall polysaccharides, and the resulting decrease ofthe protein rigidly bound to them may induce cell elongation. (Received December 5, 1975; ) 相似文献
2.
The distribution of exogenously-supplied radioactive labelledindol-3-yl-acetic acid (IAA) and gibberellin A1 (GA1) in geotropicallystimulated roots of Norway spruce (Picea abies (L.) Karst.)has been demonstrated. Seedlings were positioned with theirroot tips in 2.1 x 106 M [14C]IAA or 1.3 x 108m 3H-GA1 for 4 and 20 h, respectively. After geotropic stimulationfor 90 min in the horizontal position the root tips were cutlongitudinally in 50 µm thick sections, using a freeze-microtome.The radioactivity in the 14C-IAA treated roots occurred in higherconcentration in the lower than in the upper halves (ratio 1.25:1). A similar trend was observed in the [3H]GA1-treated rootswhere the ratio lower: upper halves was 2.04: 1. The ratio ofradioactivity in right and left halves of vertical roots wasapproximately the same in roots supplied with [14C]IAA and [3H]GA1(1.09: 1). The supplied radioactive compounds were analysed chromatographicallyafter extraction in methanol of 6 mm apical root segments. Onlya small fraction (78 per cent) of the supplied [14C]IAAwas revealed unchanged in the segments. The major part of thechromatographed, labelled compound has not been identified,but on basis of its RF value it is suggested that it may beindol-3-acetyl-aspartic acid (IAAasp). The chromatographic analysis of the [3H]GA,-treated segmentsshowed that only small fractions of this gibberellin has beenconverted to other compounds. These results have been discussed and correlated with knowledgeof plant growth regulators and their participation in root geotropism. Picea abies, spruce, geotropism, gibberellin A1, indol-3-yl-acetic acid, growth regulators, redistribution in roots 相似文献
3.
IAA-induced growth of light-grown cucumber hypocotyl sectionsis markedly enhanced by GA3-pretreatment of the sections; thereis a distinct synergism between IAA and GA3. Water pretreatmentalso enhances IAA-induced growth. On the other hand, IAA-pretreatedsections showed practically no further growth in response topost treatment with GA3. The enhancing effect of GA3 is obtainedwith only 30 min pretreatment, the maximum effect occuring with2 hr pretreatment. Pretreatment longer than 8 hr is less effective.This enhancing effect of GA3 can be observed soon after posttreatment with IAA. The response of GA3-pretreated sectionsto IAA is greater in pretreatment with higher concentrationsof GA3, and higher degrees of synergism between IAA and GA3are obtained at IAA concentrations less than 10-4 M. This synergisticinteraction between GA3 and IAA is more marked in aged hypocotylsections than in young sections. From these results we concludedthat gibberellin sensitizes hypocotyl cells to the subsequenteffect of auxin on cell elongation. (Received October 6, 1973; ) 相似文献
4.
Indole-3-acetic acid (IAA) induced the accumulation of 14C-hydroxyprolinein the endoplasmic reticulum (ER)- and Golgi-rich fractions;especially in the ER fraction. It inhibited the incorporationof hydroxyproline in the cell wall fraction. In addition, IAAhad no effect on the ratio of hydroxyproline to proline in eachfraction. The decrease in hydroxyproline content per sectiontreated with IAA was very little. Based on these results wepropose that IAA inhibits the transport of hydroxyproline-proteinin the cell wall, but the resulting decrease in hydroxyproline-proteinrigidly bound to the cell wall may not be the main factor thatinduces cell elongation. (Received July 13, 1981; Accepted February 15, 1982) 相似文献
5.
Kato Ryoichi; Takatsuna Sachiko; Wada Tsuyoshi; Narihara Yumi; Suzuki Takashi 《Plant & cell physiology》1996,37(5):667-672
Five-mm sections of elongation zones of Zea mesocotyls wereincubated for designated periods with various concentrationsof IAA. In vitro protein phosphorylation in the soluble fraction(85,000 x g supernatant) prepared from the sections was analyzedby sodium dodecyl sulfate-polyacrylamide gel electrophoresis.The phosphorylation of proteins in the soluble fraction thathad been prepared from sections incubated for 20 min in thepresence of 10{small tilde}s M IAA was greater than that inthe sections incubated for 20 min without IAA. The amount ofphosphorylation of proteins per protein became higher when higherconcentrations increased (10{small tilde}810{small tilde}5M).The growth of sections incubated in the presence of 10{smalltilde}8 M IAA or higher concentrations was greater than thatof sections incubated in the absence of IAA. The promotion ofgrowth by IAA was greater at higher concentrations of IAA. Proteinsin the soluble fraction, prepared from sections incubated for20 min in the presence of 10{small tilde}5 M IAA, were phosphorylatedin the presence of either 10 fM cAMP, 10 µM cGMP, 100µM W-7, 100 µM W-5, 20 µM H-7 or 20 µMHA1004. The calmodulin antagonist, W-7, and the inhibitor ofprotein kinase C, H-7, inhibited the phosphorylation of proteinsstimulated by incubation with IAA. These results suggest thatIAA promotes cell elongation via protein phosphorylation thatdepends on calmodulin-dependent protein kinase and protein kinaseC. (Received November 29, 1995; Accepted May 20, 1996) 相似文献
6.
Photosynthetic carbon metabolism was studied with Chroomonassp. cells in which the rate of photosynthesis was inhibitedunder both an anaerobic condition and high concentrations ofoxygen. The time course of 14C-incorporation into photosyntheticproducts showed that 3-phosphoglycerate was the initial productof photosynthetic CO2 fixation in Chroomonas sp. cells. During5-min photosynthesis, a considerable amount of 14C was incorporatedinto the insoluble fraction (mostly cryptomonad starch), andoxygen predominantly affected 14C-incorporation into this fraction.Although 14C-incorporation into intermediates of the photorespiratorypathway increased with increasing O2 concentration, the amountswere much less than expected from the degree of oxygen inhibition.It is noteworthy that 14C-dihydroxyacetone phosphate accumulatedduring photosynthesis only under the anaerobic condition, whereasthe levels of the other phosphate esters were scarcely affectedby the oxygen concentration. Ribulose-1,5-bisphosphate carboxylase from Chroomonas sp. wascompetitively inhibited by oxygen, and its Km(CO2) value wassimilar to those of terrestrial C3 plant enzymes. (Received November 19, 1984; Accepted May 20, 1985) 相似文献
7.
Auxin induced growth and decreased the hexosamine content ofthe cell walls of rice coleoptile sections. Indole-3-aceticacid (IAA) at 105 M inhibited the incorporation of 14C-glucosamineinto the cell walls. IAA did not affect the 14C-incorporationinto the cytoplasm, while inhibitors of glycoprotein synthesis,unicamycin and monensin, suppressed the incorporation into boththe cytoplasm and the cell walls. The radioactivity due to labeledglucosamine in the cell walls increased during the chase, butthis increase was inhibited by IAA. Among the cell wall fractions,the increase in radioactivity and its inhibition by IAA wereconspicuous in the hemicellulose I fraction. The inhibitoryeffect of IAA on glucosamine incorporation into the cell wallswas observed even in the presence of 0.15 M mannitol solutionwhich completely suppressed the IAA-induced growth. These resultssuggest that auxin induces growth at least partly by inhibitingthe transport of asparagine-linked glycoproteins from the cytoplasmto the cell walls.
1 Present address: Department of Biology, Faculty of Science,Osaka City University, Sumiyoshi-ku, Osaka 558, Japan (Received July 23, 1986; Accepted December 22, 1986) 相似文献
8.
The effect of morphactin (methyl 2-chloro-9-hydroxyfluorene-9-carboxylate)on basipetal transport of auxin (Indol-3-ylacetic acid-2-14C)was studied in bean (Phaseolus vulgaris) hypocotyl with thedonor-receiver block method. Morphactin (5 x 106m) reduced IAA (5 x 106m) transportintensity by an average of 83 per cent and auxin transport capacityby 90 per cent, but transport velocity was not affected. Morphactin did not inhibit uptake of IAA into hypocotyl tissue,but it did prevent transfer of IAA from the tissue into receiverblocks. Chromatographic analysis of the tissue after 4 h IAA-2-14Ctransport showed that 54 per cent of the total activity wasin the form of IAA in the control and 42 per cent in the morphactintreated tissue. No difference was found in the rate of decarboxylationof IAA-1-14C between control and morphactin treated tissue sections.Nor could any difference between control and morphactin be shownin the radioactivity associated with a TCA ppt fraction. Ina study of the transportable auxin pool, morphactin decreasedthe size of the pool and increased the half-life of decay ofauxin transport from 122 h to 385 h. In a kineticanalysis of the reversal of morphactin (5 x 106m) inhibitionby increasing concentration of IAA-2-14C (5 x 106m to2 x 105m), it was shown that IAA transport resemblesMichaelis-Menten enzyme reaction kinetics, and that inhibitionby morphactin fitted a mixed type model. IAA hada dissociation constant of 85 x 106m and morphactinthat of 43 x 107m with a Km for the transport processof 85 x 106m. 相似文献
9.
When 14CO2 was administered to a fully expanded leaf (12th leaf)of tobacco plant at the stage just before flower budding, about30% of 14C assimilated was translocated to other organs after3 hours. After 21 hours, 20{small tilde}30% of the radioactivitywas translocated to the roots, about 20% to upper stem, 10%to lower stem, and 10% to the 17th leaf located directly abovethe 12th leaf. The amount of 14C translocated to other leaveswas small after 31 hours. When 14CO2 was applied to the 17th leaf, radioactivity in otherorgans was negligible. Judging from the time course of 14C-incorporation into organicsubstances, it was inferred that sucrose imported into the rootsfrom the 12th leaf was converted into compounds of cationicfraction and sugar esters. 14C imported into the 17th leaf was mostly incorporated into80% ethanol-soluble fraction, especially into sucrose. On theother hand, 14C fixed photosynthetically by the 17th leaf wasmostly recovered in starch and protein fraction after 8 hoursof 14CO2 assimilation.
1A part of this paper was presented at the Japanese Societyof Plant Physiologists, in April, 1965.
2Present address: Central Research Institute, Japan MonopolyCorporation, Shinagawa-ku, Tokyo. 相似文献
10.
de S. WAIDYANATHA U. P.; KEYS A. J.; WHITTINGHAM C. P. 《Journal of experimental botany》1975,26(1):27-32
Segments of wheat leaves were supplied in the light with 14C-labelledserine or glucose in atmospheres containing different concentrationsof O2 and zero or 350 parts/106 CO2. Some O2 was necessary forsucrose synthesis from either serine or glucose but sucrosesynthesis from glucose depended on reactions with a high affinityfor O2 whereas sucrose synthesis from serine depended both onreactions with high and low affinities for O2. In the presenceof CO2 sucrose synthesis from serine was decreased when theO2 concentration was increased from 20 to 80% by volume andCO2 was liberated; sucrose synthesis from glucose was almostunaffected by the same change in conditions. Also, in an atmospherecontaining 80% O2 and 350 parts/106 CO2, radioactivity from[14C]serine, was incorporated into glycine. This was not truefor glucose feeding. Hence glucose provides a substrate forsucrose synthesis but not for photorespiration whereas serineis used for both processes in the presence of CO2; in the absenceof CO2 glucose provides substrate for both sucrose synthesisand photorespiration and serine metabolism to sucrose is restricted. 相似文献
11.
The effect of oxygen on photosynthetic 14CO2 fixation in theair-grown freshwater flagellate Chroomonas sp. (Cryptophyta)was studied. Considerable inhibition by anaerobiosis was observedonly under light-saturated conditions with no effect from theCO2 concentration. This inhibition was reversed by 2% O2. With,more than 2% O2, the rate of 14CO2 fixation was inhibited; 100%O2 caused about 20% inhibition which could be reversed by 2%O2. The degree of inhibition was only slightly higher at lowconcentrations (less than 0.43 mM NaHCO3) than at high CO2 concentrations,indicating that photorespiration is not a main cause of thisinhibition. Possible causes of the inhibitions by anaerobiosisand by oxygen are discussed. (Received June 29, 1983; Accepted January 23, 1984) 相似文献
12.
The effects of a number of growth-promoting and growth-inhibitingsubstances, including two fungal toxins, were studied on theextension of segments of etiolated tomato seedling hypocotyls.The bioassay was sensitive to small quantities of NaF, coumarinand 2, 4-DNP and inhibition was observed at all concentrations.2, 4-DNP or Iodoacetate stimulated growth at concentrationsbetween 1? 104 and 5 ? 106M. or 1 ? 106and 1 ? 107M. respectively. Inhibitor experiments inbuffered nutrient solution were approximately 10 per cent. moresensitive than those in deionized water. By means of paper partition chromatography small quantitiesof two fungal toxins, fusaric and alternaric acid were chromatographedand bioassayed. The effect of fussric acid (5, n-butyI picolinicacid) on hypocoty1 growth was detected at concentrations aslow as 1 ? 105M. Experiments with recongnized growth-promoting substances showedthat Kinetin inhibited growth at concentrations up to 1 ?108M.in both light and dark. IAA inhibited growth up to 1 ? 106M.At 1 ? 107 and 1 ? 108 only small increases occurredwith IAA and the effect of light was negligible. Gibberellicacid (GA2)stimulated growth at concentrations from 103to 107M. and significant increases up to 17 per cent.were recorded in the light. Since the light induced inhibitionwas only partly restored, the existence of some other naturallight sensitive growth substance is suggested. The value ofthe bioassay as a method for estimating natural growth-inhibitingand growth-promoting substances is discussed. 相似文献
13.
Germination and sprouting tests were used to demonstrate thatperoxydisulfate ion, S2O82, reversibly inhibits turnipsprout growth but does not prevent germination. Peroxydisulfateion is kinetically inert to most organic compounds but readilyoxidizes IAA. Activation energy and rate constants for the reactionwere measured and the pH effect studied. Hormone oxidation isproposed as the effective mechanism of growth inhibition. (Received April 28, 1979; ) 相似文献
14.
Atwell, B. J. and Green way, H. 1987. The relationship betweengrowth and oxygen uptake in hypoxic rice seedlings.J.exp. Bot. 38: 454465. Rice seedlings (Oryza saliva L.) were grown in the dark forup to 4 d in solutions containing various concentrations ofO2. Compared with seedlings grown at 0·250 mol O2 m3,the dry weight of the growing seedling was 14% lower at 0·110mol O2 m3 and 60% lower at 0 mol O2 m3. Decreasesin fresh weight were similar but not identical to decreasesin dry weight, possibly because leaf growth was suppressed evenabove 0·110 mol O2 m3. Oxygen deficiency inhibitedroot growth more severely than coleoptile growth. Coleoptiles from seedlings grown in aerated solution were exposedto an atmosphere of pure N2 for 30 min. Anoxia caused a declinein ATP content and energy charge, suggestive of decreased oxidativephosphorylation. It is not clear whether the decline in oxidativephosphorylation was solely responsible for impaired growth inhypoxia. In seedlings growing at O2 concentrations less than 0·110mol O2 m3, significant amounts of ethanol were synthesized.The rate of O2 uptake decreased markedly below 0·06 molO2 m3; this was presumably near the external O2 concentrationat which oxidative phosphorylation became limited by the supplyof O2. The stage of development of the seedlings appeared toinfluence O2 uptake, possibly through changes in conductanceof the tissue to O2. Uncouplers were used to confirm that thecritical O2 concentration was dependent on O2 diffusion ratherthan enzyme kinetics. Impaired growth above 0·110 molO2 m3 may have been due to a decreased activity of oxygenasesof relatively low affinity for O2, which in turn altered cellmetabolism. Key words: Growth, oxygen uptake, rice seedlings, hypoxia 相似文献
15.
Hormone-directed Transport of Assimilates in Decapitated Internodes of Phaseolus vulgaris L. 总被引:1,自引:0,他引:1
Application of ethylene, indole-3yl-acetic acid (IAA), 6-(benzylamino)-9-(2tetrahydropyranyl)-9-Hpurine (SD8339), or mixtures of IAA, gibberellic acid (GA),and cytokinins, increased the accumulation of 14C-activity indecapitated internodes of Phaseolus vulgaris seedlings. Differencesbetween treated and untreated tissues with respect to importof labelled assimilate were detected 3 h after application ofa mixture of IAA, GA, and SD8339. In longer-term experimentseffects of the growth-regulator mixture on translocation oflabel were greater than those of IAA alone. Inhibitory effectsof abscisic acid on import of assimilate were counteracted bySD8339. The ability of internode tissues to import 14C-photosynthatedeclines with time from decapitation, and a decrease in incorporationof 14C-leucine into protein was detected after 24 h. There wasan increase in protein and RNA synthesis in internodal tissuesfollowing a 2.5-h pre-treatment of decapitated internodes withIAA, GA, and SD8339. Concentrations of 2, 3, 5-triiodobenzoicacid which inhibit 14C-IAA translocation stimulate protein synthesisin decapitated internodes, and augment the IAA-effect on importof 14C-photosynthate. Hormone-directed assimilatetransport is discussed in relation to confounding effects ofgrowth responses and differential senescence of treated anduntreated tissues. It is suggested that accumulation of labelledassimilate in treated tissues results from effects of growthregulators on synthetic activities at the point of application. 相似文献
16.
In "air-grown" Chroomonas sp. cells, low concentrations of DCMU(less than 0.1 µM) could prevent the inhibition of 14CO2fixation by anaerobiosis under light-saturating conditions (morethan 40 W.m2), with phenazine methosulfate showing asimilar effect. Antimycin A, carbonyl cyanide m-chlorophenylhydrazone(CCCP), and N,N'-dicyclohexylcarbodiimide strongly inhibitedanaerobic photosynthesis at concentrations which did not significantlyinhibit the rate under 2% O2 at high light intensity (200 W.m2),although 0.2 µM CCCP stimulated the rate under 2% O2 tosome extent. On the other hand, KCN inhibited the rate muchmore strongly under 2% O2 than N2, although it inhibited therate very strongly at concentrations above 5 µM both underN2 and 2% O2. These results suggest that the inhibition of photosynthetic14CO2 fixation by anaerobiosis in this alga result from ATPdeficiency caused by over-reduction of electron carriers ofthe cyclic electron flow and that oxygen can prevent the over-reduction.Cyclic electron flow seems to be necessary to provide additionalATP for CO2 reduction under anaerobic conditions, although itseems to be less necessary under aerobic conditions. (Received July 21, 1983; Accepted January 23, 1984) 相似文献
17.
Radioactive starch, glucose and fructose have been preparedfrom tobacco leaves after assimilation of C14O2. The apparatusused for photosynthesis consisted of a shallow Perspex leafchamber connected to a closed gas system, in which C14O2 wasgenerated from BaC14O2. Six leaves, area 14 to 18 sq. dm. whenexposed to bright sunlight with an initial CO2 concentrationof 8 to 10 per cent., assimilated 3.35 g. of C14O2 in 8 to 10hours. At least 80 per cent. of the C14O2 supplied appearedin the leaves as starch and sugar and over 80 per cent. of theradioactivity was accounted for in these carbohydrates. Thespecific activity per m. atom of carbon of the isolated productswas 85 to 90 per cent. of that of the C14O2. Small amounts ofradioactive carbon were also incorporated in the leaf proteinand in the celluose, hemicellulose and polyuronides. 相似文献
18.
Gibberellic acid (GA3) at 58 µM, indoleacetic acid (IAA)at 29 µM, and (2-chloroethyl) phosphonic acid (Ethephon)at 70 µM promoted pollen tube growth in Crotalaria junceapollen suspension cultures both in water and basal medium. GA3stimulated [ l-14C]acetate incorporation into total lipids inboth media, whereas IAA enhanced incorporation in water culturesonly. On the contrary, Ethephon reduced the label in total lipidswhen supplemented in basal medium. Based on [l-14C lacetateincorporation into different phospho- and glycolipids, it isproposed that these growth regulators have a definite role inthe biosynthesis of lipid components of the membranes. 相似文献
19.
Methionine sulfoximine (MSO) greatly reduced the carbon dioxideexchange rate (CER) of detached wheat (Triticum aestivvm L.cv Roland) leaves in 21% O2, but only slightly reduced it in2% O2. A supply of 50 mM NH4Cl had little effect on the CERirrespective of the O2 concentration. A simultaneous additionof glutamine and MSO protected against the inhibition of photosynthesisto a considerable extent and caused the accumulation of moreNH3 than did the addition of MSO alone. Fixation of 14CO2 in wheat leaves was inhibited by MSO treatmentin 22% O2, and there was decreased incorporation of 14G intoamino acids and sugars and increased label into acid fractions.The addition of MSO and glutamine together eliminated the effectof MSO on the photosynthetic 14CO2 fixation pattern. NH4Cl stimulatedthe synthesis of amino acids from 14CO2, especially the synthesisof serine in 22% O2. Our observations show that factors other than the uncouplingof photophosphorylation by accumulated NH3 may be responsiblefor the early stage of photosynthesis inhibition by MSO underphotorespiratory conditions.
1Present address: Department of Agricultural Chemistry, KyushuUniversity, Fukuoka 812 Japan.
2Also at U.S. Department of Agriculture, Agricultural ResearchService, Urbana, Illionois 61801, U.S.A. (Received September 13, 1983; Accepted February 2, 1984) 相似文献
20.
Nucleic acid was extracted by the SLS-phenol method from Phaseolusaureus hypocotyl treated with IAA-2-14C. Radioactivity in thenucleic acid fraction was found at the positions of sRNA andrRNA on an MAK column. IAA-14C was released from the radioactivecompound(s) in the sRNA fraction, by alkaline hydrolysis, butnot by ethanol extraction, or by dialysis to 2 M NaCl, 8 M urea,and 0.1 M EDTA. When the radioactive compound at the positionof sRNA on an MAK column was further re-chromatographed on aDEAE-cellulose column and on a BD-cellulose column, it was alwayslocalized only in a settled part of the fraction of each column.From this fraction IAA-14C was released by alkaline hydrolysis.Also, IAA-14C was released from the radioactive compound insRNA fraction, by RNase digestion, but not by pronase treatment.Results of these experiments suggest the existence of some kindsof sRNA binding IAA. The genesis of this sRNA binding IAA-14Cwas observed within 30 min after the supply of IAA-14C, andthe sRNA became saturated with IAA-14C about 2 hr after thebeginning of incubation. The behavior of sRNA binding IAA, representedby sRNA binding IAA-14C, may have a role in IAA induced growthof mung bean hypocotyl sections. (Received July 6, 1971; ) 相似文献