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1.
研究了CO2加富对丹尼斯凤梨(Guzmania`Denise’)和吉利凤梨(Guzmania `Cherry’)叶片光合速率、植株生长、开花和光合相关酶活性的 影响。结果表明,处理30 d期间,处理(600±40)、(900±40) μmol CO2&;#8226;mol-1的净光合速率分别比同期对照增加了6.24%~31.91%和11.92%~ 41.48%;CO2加富下促进了叶片中可溶性糖和淀粉的积累, 蒸腾速率和气孔导度下降,Rubisco活性增加,乙醇酸氧化酶活性则明显下降。(600 ±40)μmol CO2&;#8226;mol-1处理下的株高、叶面积分别比同期对照下增加了6.94%~14.63%和1.66%~7. 06%,而处理(900±40) μmol CO2&;#8226;mol-1下 分别增加了9.71%~20.85%和2.87%~11.62%;CO2加富下促进了干重和鲜重的积累。此外,CO2加富提前了吉利凤梨的花期。 相似文献
2.
为探究柠檬酸或EDTA-Na_2对Pb污染下黑麦草(Lolium perenne L.)吸收Pb和营养元素特性的影响,对水培黑麦草进行不同处理,研究黑麦草一些生理生化指标的变化。结果表明,与对照相比,Pb处理降低黑麦草干重,增加质膜透性和根系脱氢酶活性,且在叶和根中积累Pb,而叶和根中6种营养元素含量的变化不尽相同。与Pb处理同时加入低浓度的柠檬酸或EDTA-Na_2对其生长影响较小,且叶片的Pb积累量较低;而同时加入高浓度的柠檬酸或EDTA-Na_2,虽然强化Pb在叶片中的积累,但是加重了生长的抑制作用和营养元素的稳态失衡;1 mmol L~(–1)的柠檬酸强化叶片积累Pb的效应强于同浓度的EDTA-Na_2,而5和10 mmol L~(–1)柠檬酸的强化作用则弱于同浓度的EDTA-Na_2。因此,适当浓度的柠檬酸或EDTA-Na_2在治理Pb污染环境中具有一定作用。 相似文献
3.
Characterization and Induction of the Activity of 1-Aminocyclopropane-1-Carboxylate Oxidase in the Wounded Mesocarp Tissue of Cucurbita maxima 总被引:4,自引:0,他引:4
Hyodo Hiroshi; Hashimoto Chise; Morozumi Shingo; Hu Wenzhong; Tanaka Kuniaki 《Plant & cell physiology》1993,34(5):667-671
1-Aminocyclopropane-1-carboxylate (ACC) oxidase (ethylene-formingenzyme) was isolated from wounded mesocarp tissue of Cucurbitamaxima (winter squash) fruit, and its enzymatic properties wereinvestigated. The enzyme required Fe2+ and ascorbate for itsactivity as well as ACC and O2 as substrates. The in vitro enzymeactivity was enhanced by CO2. The apparent Km value for ACCwas 175 µM under atmospheric conditions. The enzyme activitywas inhibited by sulfhydryl inhibitors and divalent cationssuch as Co2+, Cu2+, and Zn2+. ACC oxidase activity was induced at a rapid rate by woundingin parallel with an increase in the rate of ethylene production.The exposure of excised discs of mesocarp to 2,5-norbornadiene(NBD),an inhibitor of ethylene action, strongly suppressed inductionof the enzyme, and the application of ethylene significantlyaccelerated the induction of the activity of ACC oxidase inthe wounded mesocarp tissue. These results suggests that endogenousethylene produced in response to wounding may function in promotingthe induction of ACC oxidase. (Received January 13, 1993; Accepted April 15, 1993) 相似文献
4.
Inactivation of 1-aminocyclopropane-1-carboxylate (ACC) oxidase 总被引:1,自引:0,他引:1
Smith Julian J.; Zhang Zhi Hong; Schofield Christopher J.; John Philip; Baldwin Jack E. 《Journal of experimental botany》1994,45(5):521-527
The enzyme 1-aminocyclopropane-1-carboxylate (ACC) oxidase,which catalyses the final step in the biosynthesis of ethylene,showed a non-linear time-course in vitro and activity decayedwith a half-life of around 14 min. This loss of activity wasstudied using tomato ACC oxidase purified from Escherichia coiltransformed with the cDNA clone pTOM13. Inactivation was notdue to end-product inhibition by dehydroascorbic acid or cyanide.Preincubatlon of enzyme in the combined presence of Fe2+ ascorbateand ACC, which together allowed catalytic turnover, resultedin almost total loss of ACC oxidase activity. Enzyme Inactivatedby catalysis could not be reactivated by passage through SephadexG-25 or by treating with combina tions of DTT and CO2 A non-lineartime-course and inactivation in the presence of all substratesand cofactors was also shown for the enzyme assayed in vivowith melon fruit discs. Using the purified tomato enzyme a distinctascorbate-dependent inactivation was also observed, which occurredIn the absence of catalysis and was prevented, although notreversed, by catalase. This ascorbate-dependent inactivationmay thus be due to H2O2 attack on ACC oxidase. Key words: 1-aminocyclopropane-1-carboxylate (ACC) oxidase, catalase, catalytic inactivation, ethylene 相似文献
5.
Lambert IH 《American journal of physiology. Cell physiology》2007,293(1):C390-C400
Hypotonic exposure provokes the mobilization of arachidonic acid, production of ROS, and a transient increase in taurine release in Ehrlich Lettre cells. The taurine release is potentiated by H2O2 and the tyrosine phosphatase inhibitor vanadate and reduced by the phospholipase A2 (PLA2) inhibitors bromoenol lactone (BEL) and manoalide, the 5-lipoxygenase (5-LO) inhibitor ETH-615139, the NADPH oxidase inhibitor diphenyl iodonium (DPI), and antioxidants. Thus, swelling-induced taurine efflux in Ehrlich Lettre cells involves Ca2+-independent (iPLA2)/secretory PLA2 (sPLA2) plus 5-LO activity and modulation by ROS. Vanadate and H2O2 stimulate arachidonic acid mobilization and vanadate potentiates ROS production in Ehrlich Lettre cells and NIH3T3 fibroblasts under hypotonic conditions. However, vanadate-induced potentiation of the volume-sensitive taurine efflux is, in both cell types, impaired in the presence of BEL and DPI and following restoration of the cell volume. Thus, potentiation of the volume-sensitive taurine efflux pathway following inhibition of tyrosine phosphatase activity reflects increased arachidonic acid mobilization and ROS production for downstream signaling. Vanadate delays the inactivation of volume-sensitive taurine efflux in NIH3T3 cells, and this delay is impaired in the presence of DPI. Vanadate has no effect on the inactivation of swelling-induced taurine efflux in Ehrlich Lettre cells. It is suggested that increased tyrosine phosphorylation of regulatory components of NADPH oxidase leads to increased ROS production and a subsequent delay in inactivation of the volume-sensitive taurine efflux pathway and that NADPH oxidase or antioxidative capacity differ between NIH3T3 and Ehrlich Lettre cells. organic osmolytes; reactive oxygen species; vanadate; H2O2; tyrosine phosphatases; arachidonic acid mobilization 相似文献
6.
BARAT GOPAL KRISHNA; HIRATA HIROSHI; KUMAZAWA KIKUO; MITSUI SHINGO 《Plant & cell physiology》1969,10(3):545-553
Distribution of iron-containing oxidases in aging nodal rootsof rice and wheat was studied. Activities of cytochrome c oxidase(1.9.3.1
[EC]
, cytochrome c : O2 oxidoreductase), catalase (1.11.1.6
[EC]
,H2O2: H2O2 oxidoreductase) and peroxidase (1.11.1.7
[EC]
, donor:H2O2 oxidoreductase) in wheat roots were comparatively higherthan were those in rice roots at corresponding stages. Cytochromec oxidase in roots remained active throughout the lives of therice and wheat crops. In rice roots, catalase seemed to playa distinct role around the panicle formation stage. Decay ofcatalase activity took place earlier than did that of peroxidaseand cytochrome c oxidase activities. In wheat roots similarenzyme activity changes were not observed. Data may suggestthat the high activity of iron containing oxidases at the panicleformation stage (I) may be chiefly due to catalase activityin rice roots.
1Paper presented at the 14th Annual Meeting of the Society ofthe Science of Soil and Manure, Japan (1968). (Received November 21, 1968; ) 相似文献
7.
Esaka Muneharu; Imagi Jun; Suzuki Kanichi; Kubota Kiyoshi 《Plant & cell physiology》1988,29(2):231-235
Ascorbate oxidase activity rapidly increased during callus formationfrom pumpkin fruit tissue. The activity reached a maximum at5 days after transfer and then declined. In callus which hadbeen subcultured at about 4-week intervals for more than oneyear, the activity also increased after transfer to fresh mediumand reached a maximum in the early logarithmic phase of growth.Light had little effect on the appearance of ascorbate oxidaseactivity in pumpkin callus. In the callus grown in the presenceof 10µM CuSO4, the activity was about 10 times that inthe presence of 0.1 µM CuSO4, suggesting that the formatonof ascorbate oxidase in pumpkin callus is stimulated by copper,a prosthetic metal of the enzyme. From 45 to 75% of the totalascorbate oxidase activity in pumpkin cell suspension cultureswas found in the medium. Ascorbate oxidase activity in the medium,as well as that in the cells, increased soon after transferto fresh medium, and reached a maximum at about 5 days. (Received July 2, 1987; Accepted November 21, 1987) 相似文献
8.
Two Phaseolus vulgaris L. cultivars were grown at 20/15, 25/20,and 30/25 °C day/night temperatures in growth chambers witha 16 h thermoperiod corresponding to the photoperiod. When thefirst trifoliolate leaf was fully expanded rates of CO2 exchange(CER) were measured at 27 °C and saturating light usinginfrared gas analysis. Stomatal (rs) and mesophyll resistances,CO2 compensation points, activities of the enzymes ribulosebisphosphate carboxylase (RuBPCase), glycolate oxidase (GAO),malate dehydrogenase (MDH), and fructose-1, 6 diphosphate (FDP),chlorophyll content, Hill activities, and leaf anatomy at boththe light and electron microscope level were also investigatedin these leaves. Rates of CO2 exchange in the light, transpiration rate, andchlorophyll content increased with increasing growth temperaturewhile leaf thickness, specific leaf weight, RuBPCase activity,compensation point, and stomatal resistance decreased. Mesophyllresistance also decreased when calculated assuming zero chloroplastCO2 concentration (rm, o), but not when calculated assuminga chloroplast CO2 concentration equal to the CO2 compensationconcentration (rm, g). Average leaf size was maximal in 25/20°C plants while dark respiration, MDH activity, stomataldensity, and starch were minimal. The activities of GAO andFDP and Hill activity were not affected by temperature pretreatment. 相似文献
9.
Time-courses of 14CO2-fixation and of enzyme activities involvedin photorespiration and photosynthesis were determined duringthe life span of cotyledons from sunflower seedlings (Helianthusannuus L.). Glycolate formation in vivo was estimated from theresults of combined labelling and inhibitor experiments. NADPH-glyceraldehyde-3-phosphatedehydrogenase, NADPH-glyoxylate reductase and chlorophyll werewell correlated with the time-course of 14CO2-fixation (photosynthesis).There was, however, a considerable discrepancy between the developmentalsequence of photosynthesis and that of both ribulose-l,5-bisphosphatecarboxylase and glycolate oxidase. Furthermore, time-coursesof glycolate oxidase activity in vitro and of glycolate formationin vivo differed significantly. Therefore, the use of glycolateoxidase as a marker for the activity of photorespiration ingreening sunflower cotyledons may be questionable. Results from14CO2-labelling experiments with cotyledons treated with theglycolate oxidase inhibitor 2-hydroxy butynoic acid suggestthat glycolate formation relative to CO2-fixation is reducedin senescent cotyledons. Key words: Development, glycolate oxidase, photorespiration, ribulose-l,5-bisphosphate carboxylase, oxygenase 相似文献
10.
TOBIN A.K.; SUMAR N.; PATEL M.; MOORE A. L.; STEWART G. R. 《Journal of experimental botany》1988,39(7):833-843
Tobin, A. K., Sumar, N., Patel, M., Moore, A. L. and Stewart,G. R. 1988. Development of photorespiration during chloroplastbiogenesis in wheat leaves.J. exp. Bot. 39: 833843. The rate of light-dependent ammonia accumulation in L-methioninesulphoximine (MSO: glutamine synthetase inhibitor)-treated wheat(Triticum aestivum L. cv. Maris Huntsman) primary leaf sectionsincreased with mesophyll cell maturity. Ammonia production inthe more mature sections (beyond 2.0 cm from the basal meristem)was inhibited by elevated CO2 concentrations and by incubationwith 10 mol m3 pyrid-2-yl hydroxymethane sulphonate (HPMS).In contrast, the low levels of ammonia which accumulated inthe immature sections (0 to 2.0 cm from the base) were unaffectedby such treatments. This indicates that the ammonia producedin mature wheat leaf sections is of photorespiratory originand that the capacity of this pathway increases with mesophyllcell and chloroplast development. Rates of CO2-dependent oxygenevolution by leaf sections (under saturating CO2) increasedin parallel with ammonia production. Levels of endogenous nitratewere relatively high and increased from 5.15 mol x 1013mesophyll cell1 in meristematic cells to 6.6 mol x 1012mesophyll cell1 in mature tissue. There was no significantchange in leaf nitrate level during 30 min light incubationof the wheat leaf sections, indicating that the majority ofthe nitrate was metabolically inactive and stored in the vacuole.Activities of key enzymes of photorespiration (glutamine synthetase,glycollate oxidase), nitrogen metabolism (nitrate reductase,glutamate dehydrogenase, glutamine synthetase) and mitochondrialrespiration (cytochrome oxidase), showed specific and distinctpatterns of development during leaf growth. Chloroplast glutaminesynthetase (GS2) and peroxisomal glycollate oxidase developedin apparent synchrony with the major increase in activity occurringin regions beyond4.0 cm from the leaf base, i.e. where photorespirationwas developing. Cytosolic glutamine synthetase (GS1) and nitratereductase (in vivo) activities were identical throughout leafgrowth, reaching maximum rates at 4.0 cm from the base and thenremaining constant. Activities of the mitochondrial enzymesglutamate dehydrogenase (GDH) and cytochrome oxidase were highin meristematic cells and increased in parallel, attaining amaximum towards the leaf tip. This indicated a respiratory,as opposed to a photorespiratory, role for GDH in wheat leafmetabolism. The evidence for controlled, co-ordinated synthesisof pathway enzymes at specific stages of organelle biogenesisis discussed. Key words: Photorespiration, organelle biogenesis 相似文献
11.
Quantitative and electrophoretic changes in o-diphenol oxidase(o-diphenol: O2 oxidoreductase, E.C. 1 10,3.1) were studiedduring the entire period of cotton (Gossypium arboreum L. cv.Sanjay) fibre development. A significant increase in o-diphenoloxidase activity was recorded during the fibre initiation phaseand it is suggested that a shift in redox balance towards oxidationmay play an important role in fibre initiation. Low o-diphenoloxidase activity during elongation and its high activity duringthe phase of secondary thickening, together with isoenzyme patterns,suggest an important role of this enzyme in cotton fibre development.The role of o-diphenol oxidase in relation to auxin turnoverand redox balance is discussed. Gossypium arboreum, cotton, fibre development, o-diphenol oxidase, redox balance, auxin turnover 相似文献
12.
Tezuka Takafumi; Tsuruhara Akiko; Suzuki Hajime; Takahashi Susumu Y. 《Plant & cell physiology》1997,38(2):107-112
An attempt was made to examine the possible connection betweenself-incompatibility in Lilium longiflorum and the stress responseusing pistils after self-incompatible pollination. The growthof pollen tubes in the pistil after self-incompatible pollinationwas promoted by treatment with germanium compounds [(GeCH2CH2COOH)2O3and GeO2], which are scavengers of active oxygen species, suchas O2 and H2O2. The promotion by germanium compoundsof the growth of pollen tubes after self-incompatible pollinationwas reflected by the detection of elevated levels of activityof superoxide-forming NADPH-dependent oxidase, xanthine oxidase,superoxide dismutase, catalase and ascorbate peroxidase, allof which are associated with stress responses, in pistils uponself-incompatible pollination as compared to the activitiesof these enzymes after cross-compatible pollination. A possibleconnection between self-incompatibility and stress in pistilsupon self-incompatible pollination is discussed on the basisof these results. (Received October 9, 1995; Accepted November 11, 1996) 相似文献
13.
Arum spadix mitochondria exhibited a rapid cyanide-resistantoxygen uptake when oxidizing malate, NADH2 or succinate, anda slower, cyanide-sensitive oxygen uptake when oxidizing ascorbate+tetramethylphenylenediamine(TMPD). Cytochrome oxidase does not therefore appear to functionas the terminal oxidase in the presence of cyanide, and therather low cytochrome c oxidase activity obtained using ascorbate+TMPDmay exclude it from possessing a major role even in the absenceof cyanide. ATP synthesis has been shown to accompany substrateoxidation. In the presence of antimycin A the P: O ratio accompanyingmalate oxidation was reduced by half, while phosphorylationaccompanying NADH2 or succinate oxidation was almost completelyabolished. It is proposed that electrons from exogenous NADH2enter the electron transport chain at a site after that whereendogenous NADH2 donates electrons and that electrons from exogenousNADH2 are not coupled to ATP synthesis at site 1. The cyanide-resistant,non-phosphorylating electron-transport pathway may functionin the absence of cyanide and account for the low efficiencyof energy conservation observed in this tissue. 相似文献
14.
Changes in nitrate reductase (NR) activity during growth andsenescence of attached oat leaves were studied, in order tounderstand the influence of certain regulatory mechanisms onthe in vivo activity at each stage of foliar development. Theenzyme activity was greatest in 7-day-old leaves. It decreasedin young, still-growing 11-day-old leaves, was stable with the15th day, and decreased again at the onset of leaf senescence.The first decrease in NR activity coincided with the beginningof leaf unfolding and with the increase in endogenous oxidations,and also with the maximal activity of neutral proteases. Thisdecrease was prevented when plants had been exposed to low O2pressure. High O2 pressure impaired the NR activity increaseoccurred from 5 to 7 days in the control (21% O2). Cysteineimproved NR activity at each stage of leaf development. Thesecond decrease in NR (during senescence) did not occur whenNADH was supplied to the assay medium (in vitro test). These results suggest that during growth, NR activity is regulatedby oxidation of SH groups and by the activity of neutral proteases.During senescence, reductant availability may also contributeto the regulation of NR. (Received February 24, 1987; Accepted August 10, 1987) 相似文献
15.
Adhikary Siba Prasad; Murakami Akio; Ohki Kaori; Fujita Yoshihiko 《Plant & cell physiology》1990,31(4):527-532
Respiration of the cyanophyte Synechocystis PCC 6714 was studiedin relation to conditions for cell growth. Under our experimentalconditions, the KCN-sensitive O2-uptake observed with intactcells was found to be limited at the step catalyzed by the terminaloxidase in thylakoids, indicating that the activity of O2-uptakeby intact cells corresponds to that of the terminal oxidasein thylakoids. The activity was found to be variable dependingon the growth conditions; it was higher under conditions wherethe level of PS I, another terminal component of the thylakoidelectron transport system (ETS) was elevated, whereas it waslower under conditions where the level of PS I was reduced.Changes in the activity did not occur when protein synthesiswas suppressed by chloramphenicol. The results suggest that,similarly to the regulation of levels of PS I, the activityor the amount of terminal oxidase in thylakoids is regulatedin response to the redox steady-state of intermediate component(s)of ETS, in order to maintain a balance between the efflux ofelectrons from the ETS and the influx to the ETS.
1Present address: P.G. Department of Botany, Utkal University,Bhubaneswar-751004, Orissa, Keonjhar, India (Received September 27, 1989; Accepted March 22, 1990) 相似文献
16.
In roots of sweet potato (Ipomoea batatas Lam. cv. Kokei 14),the metabolic response to wounding was remarkable only in theproximal side. We assumed that the polarity resulted from apolar movement of indole-3-acetic acid (IAA) produced in thecut surface (8). As the metabolic response was slight in thedistal side, the effect of IAA and the other plant hormoneson the development of various enzyme activities was examinedin this side. Increases in activities of L-phenylalanine ammonia-lyase,acid invertase, NADPHa2 : cytochrome c oxidoreductase, peroxidase,cytochrome c : O2 oxidoreductase and o-diphenol oxidase, whichdeveloped in response to wounding, were stimulated by the treatmentwith IAA. Gibberellic acid had a stimulative effect on the developmentof only acid invertase activity. Abscisic acid and kinetin hadlittle effect. The results strongly support our hypothesis thatIAA plays an important role in the metabolic response to wounding. (Received September 29, 1979; ) 相似文献
17.
Turner, J. C. and Hall, N. P. 1988. Identification of geneticallyinduced lesions and sites of action of inhibitors affectingphotorespiration by simple tests on leaf discs.J. exp,Bot. 39: 345-351. Six photorespiratory mutants of barley deficient in catalaseand two mutants lacking phospho-glycollate phosphatase wereidentified by a novel screening method using leaf discs. Leaf discs were punched directly into an appropriate bufferedreagent in which the enzymes diffused from the cut edges ofthe discs causing a change in the colour reagents. The reactionswere observed from 15 min onwards depending on which enzymeactivity was being followed. Hundreds of plants can be screenedrapidly for major differences in enzyme activity. The methods depend on the formation of a red product in thereaction of hydrogen peroxide (H2O2) with 4-aminoantipyrenein the presence of peroxidase. To detect P-glycollatc phosphataseand glycollate oxidase, the product of the linked reactions,H2O2, was measured. For catalase, the disappearance of addedH2O2 is followed. By omitting peroxidase from the colour reagentmixture, peroxidase activity in leaf discs can be measured. The method was evaluated by applying it to existing enzyme deficientmutants of barley lacking P-glycollate phosphatase and catalase.Further mutant plants were detected by this method. The techniquecould also be used to screen for inhibitors of the glycollatepathway for use as herbicides. Key words: Phosphoglycollate phosphatase, glycollate oxidase, catalase, peroxidase, hydrogen peroxide 相似文献
18.
Kosugi Yusuke; Oyamada Naoko; Satoh Shigeru; Yoshioka Toshihito; Onodera Ei-ichi; Yamada Yuko 《Plant & cell physiology》1997,38(3):312-318
We partially purified 1-aminocyclopropane-l-carboxy-late (ACC)oxidase from senescing petals of carnation {Dianthus caryophyllusL. cv. Nora) flowers and investigated its general characteristics,and, in particular, the inhibition of its activity by ACC analogs.The enzyme had an optimum pH at 7-7.5 and required Fe2+, ascorbateand NaHCO3 for its maximal activity. The Km for ACC was calculatedas 111-125 µM in the presence of NaHCO3. Its Mr was estimatedto be 35 and 36 kDa by gel-filtration chromatography on HPLCand SDS-PAGE, respectively, indicating that the enzyme existsin a monomeric form. These properties were in agreement withthose reported previously with ACC oxidases from different planttissues including senescing carnation petals. Among six ACCanalogs tested, l-aminocyclobutane-l-carboxylate (ACBC) inhibitedmost severely the activity of ACC oxidase from carnation petals.ACBC acted as a competitive inhibitor with the Ki of 20-31 µM.The comparison between the Km for ACC and the Ki for ACBC indicatedthat ACBC had an affinity which was ca. 5-fold higher than thatof ACC. Whereas ACC inactivated carnation ACC oxidase in a time-dependentmanner during incubation, ACBC did not cause the inactiva-tionof the enzyme. Preliminary experiments showed that ACBC andits N-substituted derivatives delayed the onset of senescencein cut carnation flowers. (Received August 19, 1996; Accepted November 26, 1996) 相似文献
19.
The effect of exposure to elevated CO2 on the processes of leafcell production and leaf cell expansion was studied using primaryleaves of Phaseolus vulgaris L. Cell division and expansionwere separated temporally by exposing seedlings to dim red lightfor 10 d (when leaf cell division was completed) followed byexposure to bright white light for 14 d (when leaf growth wasentirely dependent on cell expansion). When plants were exposedto elevated CO2 during the phase of cell expansion, epidermalcell size and leaf area development were stimulated. Three piecesof evidence suggest that this occurred as a result of increasedcell wall loosening and extensibility, (i) cell wall extensibility(WEx, measured as tensiometric extension using an Instron) wassignificantly increased, (ii) cell wall yield turgor (V, MPa)was reduced and (iii) xyloglucan endotransglycosylase (XET)enzyme activity was significantly increased. When plants wereexposed to elevated CO2 during the phase of cell division, thenumber of epidermal cells was increased whilst final cell sizewas significantly reduced and this was associated with reducedfinal leaf area, WEx and XET activity. When plants were exposedto elevated CO2 during both phases of cell division and expansion,leaf area development was not affected. For this treatment,however, the number of epidermal cells was increased, but cellexpansion was inhibited, despite exposure to elevated CO2 duringthe expansion phase. Assessments were also made of the spatialpatterns of WEx across the expanding leaf lamina and the datasuggest that exposure to elevated CO2 during the phase of leafexpansion may lead to enhanced extensibility particularly atbasal leaf margins which may result in altered leaf shape. The data show that both cell production and expansion were stimulatedby elevated CO2, but that leaf growth was only enhanced by exposureto elevated CO2 in the cell expansion phase of leaf development.Increased leaf cell expansion is, therefore, an important mechanismfor enhanced leaf growth in elevated CO2, whilst the importanceof increased leaf cell production in elevated CO2 remains tobe elucidated. Key words: Phaseolus vulgaris L., dwarf beans, elevated CO2, biophysics of cell expansion, xyloglucan endotransglycosylase, XET, water relations 相似文献
20.
Differential screening, aimed at the isolation of cDNA clonesof mRNAs whose accumulation is influenced by GA3, resulted inthe isolation of a cDNA clone of an mRNA whose level was decreasedby GA3 in segments of epicotyls of Vigna angularis. The putativeprotein encoded by this cDNA resembled the 1-aminocyclopropane-l-carbox-ylateoxidases (ACC oxidases) identified in other plant species (about80% homology at the amino acid level). Thus, the correspondinggene was designated AB-ACO1 (azuki bean ACC oxidase). GA3 alsodecreased the activity of ACC oxidase in azuki bean epicotyls,but it did not decrease the rate of ethylene evolution. In fact,GA3 increased the rate of ethylene evolution and the level ofACC. Thus, GA3 seemed to increase the production of ethyleneby promoting the synthesis of ACC. (Received January 10, 1997; Accepted July 31, 1997) 相似文献