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1.
Effects of Sodium on Photosynthesis in Panicum coloratum 总被引:2,自引:0,他引:2
Foliar application of NaCl to sodium-deficient Panicum coloratumstimulated photosynthesis, as did application via roots. Effectsof sodium on photosynthetic responses to internal concentrationsof CO2 under different light intensities and initial productsof 14CO2 fixation suggested that CO2 fixation and aminationof oxalacetate were limited by sodium deficiency.
2 Present address: Institute for Life Science Research, NihonNohyaku Co., Ltd., Kawachi-Nagano, Osaka, 586 Japan. 相似文献
2.
To study the wavelength-effect on photosynthetic carbon metabolism,14C-bicarbon-ate was added to Chlorella vulgaris 1 lh suspensionunder monochromatic blue (456 nm) and red (660 nm) light. Thelight intensities were so adjusted that the rates of 14CO2 fixationunder blue and red light were practically equal. Analysis of14C-fixation products revealed that the rates of 14CO2 incorporationinto sucrose and starch were greater under red light than underblue light, while blue light specifically enhanced 14CO2 incorporationinto alanine, aspartate, glutamate, glutamine, malate, citrate,lipid fraction and alcohol-water insoluble non-carbohydratefraction. Pretreatment of the algal cells in phosphate mediumin the dark, which was essential for the blue light enhancementof PEP carboxylase activity, was not necessary to induce theabove wavelength effects. Superimposition of monochromatic bluelight at low intensity (450 erg.cm2.sec1) on thered light at saturating intensity caused a significant decreasein the rate of 14CO2 incorporation into sucrose and increasein incorporation into alanine, lipid-fraction, aspartate andother related compounds, indicating that the path of carbonin photosynthesis is regulated by short wavelengdi light ofvery low intensity. Possible effects of wavelength regulationof photosynthetic carbon metabolism in algal cells are discussed.
1 Part of this investigation was reported at the XII InternationalBotanical Congress, Leningrad, 1975 and the Japan-US CooperativeScience Seminar "Biological Solar Energy Conversion", Miami,1976. Requests for reprints should be addressed to S. Miyachi,Radioisotope Centre, University of Tokyo, Bunkyo-ku, Tokyo 113,Japan.
4 Present address: Department of Chemistry, Faculty of PharmaceuticalSciences, Teikyo Univ., Sagamiko, Kanagawa, Japan. (Received August 6, 1977; ) 相似文献
3.
Effect of Salicylhydroxamic Acid on Respiration, Photosynthesis, and Peroxidase Activity in Various Plant Tissues 总被引:1,自引:0,他引:1
Earlier reports from our laboratory described salicylhydroxamicacid (SHAM) stimulation of O2 uptake by expanded soybean leavesor older green cotyledons. This stimulation could not be interpretedin terms of engagement or capacity of the cytochrome and alternativerespiratory pathways. In this report, we tested the possibilitythat a soluble peroxidase, which can be easily eluted from soybeanleaves and cotyledons, might be responsible for SHAM stimulationin whole tissue. The peroxidase catalyzes oxidation of NADHby O2, is strongly stimulated by SHAM and benzhydroxamic acid(BHAM) and inhibited by KCN, propyl gallate and gentisic acid.This peroxidase, however, does not seem to be responsible forSHAM-stimulated O2 uptake in whole, green tissue. In our earlier work reporting SHAM-stimulated respiration ingreen tissue, the samples had not been shielded from room light(1020 µmol photons m2.s1). In thisreport, we show that O2-uptake rates of controls measured indarkness were always greater than those measured in room light.SHAM stimulation was not observed in the dark or in tissue withoutchlorophyll. We also found that CO2 uptake of whole leafletsin saturating light was completely inhibited by SHAM fed throughthe transpiration stream. SHAM, therefore, is a potent inhibitorof photosynthesis. We conclude that the SHAM-stimulated respirationof green tissues we reported earlier likely was due to verylow rates of photosynthesis occurring under room light.
3Present address: SANDOZ Ltd., Agrobiological Research Station,4108 Witterswil, Switzerland
4Present address: WTC 1A3, Weyerhaeuser Co., Tacoma, WA 98477,U.S.A. (Received June 23, 1989; Accepted October 20, 1989) 相似文献
4.
The pattern for primary products of CO2-fixation and the chloroplaststructure of Amaranthus retrqflexus L., a species which incorporatescarbon dioxide into C4 dicarboxylic acids as the primary productof photosynthesis, were compared in various chlorophyll containingtissues,i.e., foliage leaves, stems, cotyledons and pale-greencallus induced from stem pith. Despite some morphological differencesin these assimilatory tissues, malate and aspartate were identifiedas the major compounds labelled during a 10 sec fixation of14CO2 in all tissues. Whereas, aspartate was the major componentin C4-dicarboxylic acids formed in foliage leaves, malate predominatedas the primary product in stems, cotyledons and the pale-greencallus. The percentage of 14C-radioactivity incorporated intoPGA and sugar-P esters increased and 14C-sucrose was detectedin the prolonged fixation of 14CO2 in the light, not only infoliage leaves, but also in stems and cotyledons.
1 This work was supported by a Grant for Scientific ResearchNo. 58813, from the Ministry of Education, Japan.
2 Present address: Institute of Applied Microbiology, Universityof Tokyo, Tokyo, Japan.
3 Present address: Department of Biochemistry, University ofGeorgia, Athens 30601. Georgia, U. S. A. (Received July 10, 1971; ) 相似文献
5.
Glycine as a substrate for photorespiration 总被引:1,自引:0,他引:1
Substrates for photorespiration were examined by feeding 14Clabeled compounds to tobacco and corn leaf segments and by measuring14CO2 evolution in light and darkness. CO2 release in the darkwas rapid, but in light CO2 release was slow due to refixationby photosynthesis. Carboxyl labeled glycine was more rapidlydecarboxylated than were glyoxylate, glycolate or serine. Hydroxypyridinemethanesulfonate, an inhibitor of glycolate oxidase, blocked CO2 releasefrom glycolate but not from glycine. Isonicotynyl hydrazideblocked CO2 release from both glycine and glycolate. DCMU blockedphotosynthetic refixation of the released CO2, consequentlythe rates of CO2 release in light and dark were about equal.It was concluded that CO2 release during photo-respiration camefrom the conversion of 2 molecules of glycine to one serineand one CO2. 14CO2 release from glycine-l-14C in the dark or with DCMU inlight can be used as an assay for photorespiration ability. CO2 release from glycine and glycolate by corn leaf segmentsin the dark proceeded at the rate of that in normal tobaccoleaf. This result, together with other work on O2 exchange andenzymatic analysis, indicates that corn and other plants docarry on photorespiration, but it is not manifested by CO2 releasein light. A yellow tobacco mutant, Consolation 402, had high rates ofphotorespiration by the 14CO2 assay, nearly half (or more) asmany peroxisomes as chloroplasts, and high rates of CO2 releasefrom glycine-l-14C or glycolate-l-14C. A common tobacco, BrightYellow, had lower rates of photorespiration, fewer visible peroxisomes,and slower decarboxylation of glycine and glycolate. The amount of 14CO2 release from glycine-l-14C or glycolate-l-14Cincreased only slightly when the temperature was raised from25 to 35°C.
1Parts of this work were abstracted at the Annual Meeting (April,1969) of Japanese Society of Plant Physiologists, Kanazawa
2Department of Biochemistry, Michigan State University, EastLansing, Michigan, U.S.A. (Received September 3, 1969; ) 相似文献
6.
Changes in photosystem stoichiometry in response to shift ofenvironments for cell growth other than light regime were studiedwith the cyanophyte Synechocystis PCC 6714 in relation to thechange induced by light-quality shift. Following two environment-shiftswere examined: the shift of molecular form of inorganic carbonsource for photosynthesis from CO2 to HCO3 (CO2 stress)and the increase in salinity of the medium with NaCl (0.5 M)(Na+ stress). Both CO2 and Na+ stresses induced the increasein PSI abundance resulting in a higher PSI/PSII stoichiometry.CO2 stress was found to elevate simultaneously Cyt c oxidaseactivity (Vmax). The feature was the same as that caused bylight-quality shift from preferential excitation of PSI to PSII(light stress) though the enhancement by either stress was smallerthan that by light stress. Under our experimental conditions,PSI/PSII stoichiometry appeared to increase at a fairly constantrate to the basal level even when the basal level had been differentlydetermined by the light-quality. Enhancing rates for PSI/PSIIstoichiometry and for Cyt c oxidase activity were also similarto each other. Since the two stresses affect the thylakoid electrontransport similarly to the shift of light-quality, we interpretedour results as follows: three environmental stresses, CO2, Na+,and light stresses, cause changes in electron turnover capacityof PSI and Cyt c oxidase under a similar, probably a common,mechanism for monitoring redox state of thylakoid electron transportsystem.
1On leave from Department of Biology, College of Natural Science,Kyngpook National University, Taegu 702-701, Korea.
2Present address: Department of Marine Bioscience, Fukui Pre-fecturalUniversity, Obama, Fukui, 917 Japan. 相似文献
7.
The inhibitory effect of linolenate on intact spinach chloroplastsdepends on the level of the internal pool of metabolites. Chloroplastsfrom preilluminated leaves or chloroplasts artificially loadedwith 3-phosphoglyceric acid required higher concentrations oforthophosphate for maximal rates of CO2 dependent O2 evolutionthan untreated chloroplasts. The loaded chloroplasts were moresensitive to linolenate, and in the presence of linolenate theoptimal phosphate concentration was shifted toward lower values.We propose that the inhibition of photosynthesis by linolenateis due to inhibition of the "phosphate translocator".
1 Part of this work has been published in the Book of Abstracts,4th International Congress on Photosynthesis, Reading, U.K.,1977, p. 265266.
2 This work is part of a doctoral programme carried out by L.Mv6 Akamba in this laboratory.
3 To whom reprint requests should be adressed. (Received October 14, 1978; ) 相似文献
8.
Gu Tian-Qing; Iwama Yumi; Murakami Akio; Adhikary Siba Prasad; Fujita Yoshihiko 《Plant & cell physiology》1994,35(8):1135-1140
Changes in the activity of cytochrome c oxidase (EC 1.9.3.1
[EC]
,Cyt-oxidase) in response to growth conditions were studied withthe cyanophyte Synechocystis PCC 6714 in relation to changesin PSI abundance induced by light regime for photosynthesis.The activity was determined with the Vmax of mammalian cytochromec oxidation by isolated membranes. The activity of glucose-6-phosphate(G-6-P):NADP+ oxidoreductase (EC 1.1.1.49
[EC]
) was also determinedsupplementarily. Cyt-oxidase activity was enhanced by glucoseadded to the medium even when cell growth maintained mainlyby oxygenic photosynthesis. G-6-P:NADP+ oxidoreductase was alsoactivated by glucose. The enhanced level of Cyt-oxidase washigher under PSII light, which causes high PSI abundance, thanthat under PSI light, which causes low PSI abundance. The levelwas intermediate under hetetrotrophic conditions. Although theactivity level was low in cells grown under autotrophic conditions,the level was again lower in cells grown under PSI light thanunder PSII light. The change of Cyt-oxidase activity in responseto light regime occurred in the same direction as that for thevariation of PSI abundance. Results suggest that in SynechocystisPCC 6714, the capacity of electron turnover at the two terminalcomponents of thylakoid electron transport system, Cyt-oxidaseand PSI, changes in parallel with each other in response tothe state of thylakoid electron transport system.
1Present address: Institute of Botany, Academia Sinica, Beijing100044, China
2Present address: Department of Botany, Utkal University, Bhubaneswar,India 751004 相似文献
9.
When Chlorella vulgaris 11h, Chlorella vulgaris C-l, Chlamydomonasreinhardtii, Chlamydomonas moewusii, Scenedesmus obliquus, orDunaliella tertiolecta were illuminated in with 0.5 mM NaHCO3,the pH of the medium increased in a few minutes from 6 to about9 or 10. The alkalization, which was accompanied by O2 evolution,was dependent on light, external dissolved inorganic carbon(DIC) as HCO-3, and algae grown or adapted to a low, air-levelCO2 in order to develop a DIC concentrating mechanism. Therewas little pH increase by algae without a DIC concentratingprocess from growth on 3% CO2 in air. Photosynthetic O2 evolutionwithout alkalization occurred using either internal DIC or externalCO2 at acidic pH. The PH increase stopped between pH 9 to 10,but the alkalization would restart upon re-acidification betweenpH 6 and 8. Alkalization was suppressed by the carbonic anhydraseinhibitors, acetazolamide, ethoxyzolamide or carbon oxysulfide.The pH increase appeared to be the consequence of the externalconversion of HCO3 into CO2 plus OH during photosynthesisby cells with a high affinity for CO2 uptake. Cells grown onhigh CO2 to suppress the DIC pump, when given low levels ofHCO3 in the light, acidified the medium from pH 10 to7. Air adapted Scenedesmus cells with a HCO3 pump, aswell as a CO2 pump, alkalized the medium very rapidly in thelight to a pH of over 10, as well as slower in the dark or inthe light with DCMU or without external DIC and O2 evolution.Alkalization of the medium during photosynthetic DIC uptakeby algae has been considered to be part of the global carboncycle for converting H2CO3 to HCO3 and for the formationof carbonate salts by calcareous algae from the alkaline conversionof bicarbonate to carbonate. These processes seem to be a consequenceof the algal CO2 concentrating process.
1Present address: Department of Biology, Faculty of Science,Niigata University, Niigata, 950-21 Japan. 相似文献
10.
The regulation of photosynthesis in wheat leaves under varyingO2, CO2, and light was studied by analyzing certain metabolitepools and enzyme activities. Under high light when the rateof photosynthesis was limited by low intercellular levels ofCO2 (C1) there was a high level of ribulose-1,5-bisphosphate(RuBP) (about 100 nmols per mg chlorophyll). As C, increased,there was a parallel decrease in the ratios of RuBP/3-phosphoglycerate(PGA) (from 0.18 to 0.08 under 21% O2) and triose-phosphate/PGA(from 0.16 to 0.07 under 21% O2). The results suggest carboxylationis limited at low Ci, and that there is high carboxylation andlimited assimilatory power at high Ci. As photosynthesis increasedwith increasing Jight intensity under atmospheric levels ofCO2 the ratios of RuBP/PGA and triosephosphate/PGA remainednearly constant (near 0.12 to 0.13) suggesting there may bea coordinate regulation by light of the different phases ofthe cycle. There was increasing activation of ribulose 1,5-bisphosphatecarboxylase oxygenase (Rubisco) and fructose 1,6-bisphosphatase(FBPase) with increasing light intensity. The ways in whichthe light activation of the enzymes Rubisco and FBPase may regulatecarbon metabolism in the cycle are discussed.
1 Current address: Biological Sciences Center, Desert ResearchInstitute, PO Box 60220, Reno, Nevada 89506, U.S.A. (Received March 24, 1987; Accepted June 23, 1987) 相似文献
11.
Green Light Drives CO2 Fixation Deep within Leaves 总被引:5,自引:0,他引:5
Maximal l4CO2-fixation in spinach occurs in the middle of thepalisade mesophyll [Nishio et al. (1993) Plant Cell 5: 953],however, ninety percent of the blue and red light is attenuatedin the upper twenty percent of a spinach leaf [Cui et al. (1991)Plant Cell Environ. 14: 493]. In this report, we showed thatgreen light drives 14CO2-fixation deep within spinach leavescompared to red and blue light. Blue light caused fixation mainlyin the palisade mesophyll of the leaf, whereas red light drovefixation slightly deeper into the leaf than did blue light.14CO2-fixation measured under green light resulted in less fixationin the upper epidermal layer (guard cells) and upper most palisademesophyll compared to red and blue light, but led to more fixationdeeper in the leaf than that caused by either red or blue light.Saturating white, red, or green light resulted in similar maximal14CO2-fixation rates, whereas under the highest irradiance ofblue light given, carbon fixation was not saturated, but itasymptotically approached the maximal 14CO2-fixation rates attainedunder the other types of light. The importance of green lightin photosynthesis is discussed.
1Supported in part by grants from Competitive Research GrantsOffice, U.S. Department of Agriculture (Nos. 91-37100-6672 and93-37100-8855). 相似文献
12.
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
13.
A diurnal rhythm was found in the Hill reaction in cell-freeextracts of the green alga Bryopsis maxima. The rate of photoreductionof 2,6-dichloroindophenol showed a rhythm synchronized withthat of photosynthetic O2 evolution. A diurnal rhythm was alsoobserved in the rate of O2 evolution accompanying the reductionof P-benzoquinone with phase and frequency similar to thoseof the rhythm of photosynthesis. These results indicate thata regulation mechanism underlying the photosynthesis rhythmexists in the photosynthetic electron transport chain in chloroplasts.
1 Present address: Mitsubishi Yuka Laboratory of Medical Science,Narimasu, Itabashi, Tokyo 175, Japan. (Received January 6, 1979; ) 相似文献
14.
Kikuyama Munehiro; Hayama Tomio; Fujii Sumiko; Tazawa Masashi 《Plant & cell physiology》1979,20(6):993-1002
The effect of the intracellular concentration of ATP ([ATP]1)on the light-induced potential change (LPC) in tonoplast-freeChara cells was studied. The LPC was hardly affected by loweringthe [ATP]1 by about 1/10 or by raising it to about 10 timesthe normal cytoplasmic concentration (0.51.3 mM). Theinsensitivity of LPC to [ATP]1 excludes the possibility thatan increase in [ATP]1 due to photosynthesis may induce the LPC.However, extreme lowering of the [ATP]1 to about 12 µMcompletely inhibited LPC, although photosynthetic O2 evolutionwas not significantly inhibited. This fact supports the hypothesisthat light stimulates the putative H+pump fueled by ATP. Theuncoupling agents DNP and CCCP greatly depolarized the membrane,and inhibited LPC strongly, but they did not decrease [ATP]1.Photosynthetic O2 evolution was inhibited to some extent by2 µM CCCP and strongly inhibited by 0.1 mM DNP. Sincethe membrane resistance increased significantly, these chemicalsare believed to act on the membrane as an inhibitor of the electrogenicH+ pump not as an H+conductor. Introduction of 1 mM ATP intocells treated with uncouplers, to a large extent restored theirability to produce LPC although the membrane potential in darknesswas maintained at a low level.
1Present address: Niigata College of Pharmacy, 5829 Kamishinei-cho,Niigata 950-21, Japan.
2Present address: Department of Agricultural Chemistry, Collegeof Agriculture, Kyoto University, Kyoto 606, Japan.
3Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan. (Received March 9, 1979; ) 相似文献
15.
1. The effects of "carbonyl" reagents on the photosyntheticin-corporation of 14CO2 into the assimilation products of tobaccoand spinach leaves were studied. The presence of "carbonyl"reagents causes an increase in the ratio of 14CO2 incorporatedin glycine and a decrease in serine. The incorporation of 14Cfrom glycolate-1-14C and glycolaldehyde-2-14C into glycine andserine was also affected by "carbonyl" reagents, as in the caseof 14CO2-experiment. 2. The feeding experiments of glycine-1-14C and serine-1-14Cin the presence and in the absence of "carbonyl" reagents revealedthat these reagents inhibit the conversion of glycine to serine. 3. The results obtained above, together with the effects ofthiols on 14CO2 incorporation presented in this paper, supportthe assumption that glycine and serine are formed via glycolateand glyoxylate during photosynthesis in green plants. 4. Comparison of 14C incorporation in malate from 14CO2, glycolate-1-14C,glycine-1-14C and serine-1-14C in the presence and in the absenceof "carbonyl" reagents suggested the occurrence of the pathwayof the malate formation via glycolate and glyoxylate, not passingthrough glycine and serine, during photosynthesis.
1 A part of this paper was presented at the Symposium on "Nitrogenand Plant" by the Japanese Society of Plant Physiologists, inOctober, 1963
2 Present address: Radiation Center of Osaka Prefecture, Sakai,Osaka 相似文献
16.
A novel photorespiratory mutant of Arabidopsis thaliana, designatedgld2, was isolated based on a growth requirement for abnormallyhigh levels of atmospheric CO2. Photosynthetic CO2 fixationwas inhibited in the mutant following illumination in air butnot in atmosphere containing 2% O2. Photosynthetic assimilationof 14CO2 in an atmosphere containing 50% O2 resulted in accumulationof 48% of the soluble label in glycine in the mutant comparedto 9% in the wild type. The rate of glycine decarboxylationby isolated mitochondria from the mutant was reduced to 6% ofthe wild type rate. In genetic crosses, the mutant complementedtwo previously described photorespiratory mutants of A. thalianathat accumulate glycine during photosynthesis in air due todefects in glycine decarboxylase (glyD, now designated gld1)and serine transhydroxymethylase (stm). Because glycine decarboxylaseis a complex of four enzymes, these results are consistent witha mutation in a glycine decarboxylase subunit other than thataffected in the gld1 mutant. The two gld loci were mapped tochromosomes 2 and 5, respectively.
3Present address: Department of Crop and Soil Sciences, MichiganState University, East Lansing, MI 48824, U.S.A.
4Present address: Department of Applied Bioscience, Facultyof Agriculture, Hokkaido University, Kita-Ku, Sapporo, 060 Japan
5Present address: Department of Biology, Carnegie Institutionof Washington, 290 Panama Street, Standford, CA 94305, U.S.A. 相似文献
17.
Shoots of intact peanut and sunflower seedlings evolved CO2in the light which was enriched more than 10 per mille in 13Ccompared with simultaneous CO2 evolution from the roots. Carbondioxide collected from tobacco leaves in the light was 10 permille enriched in 13C compared with that collected in the dark.Anaerobic conditions inhibited photorespiration but did notchange isotopic ratios of dark respiration.
1 Department of Biology, Fresno State College, Fresno, California93710, U. S. A.
2 Deceased. (Received February 29, 1972; ) 相似文献
18.
Carbonic anhydrase (CA, EC. 4.2.1.1
[EC]
) activity in air-grown Characorallina was detected mainly in the intracellular fraction,most of which composed of chloroplasts and cytoplasmic gel,and not on the cell surface. Only minor levels of CA activity,on the basis of equivalent volumes, were detected in the cellsap and the cytoplasmic sol. The maximum rate of photosynthetic O2 evolution by air-grownChara corallina at pH 6.0 was twice that at pH 7.6, while theapparent Km for external inorganic carbon (Ci) at pH 7.6 wasabout three times that at pH 6.0. However, the apparent Km(CO2)was about three times larger at pH 6.0 than at pH 7.6. The Km(Ci)-valueat pH 7.6 increased severalfold in the presence of acetazolamide(AZA), an inhibitor of CA, but no inhibition was observed atpH 6.0. The pH-dependence may be due to differences in the permeabilityof AZA at the given pH values. Fixation of 14CO2 at 20 µMand of H14CO3 at 200 µM over the course of 5 swas very similar at pH 7.4. Addition of CA significantly suppressedthe photosynthetic 14CO2-fixation but it stimulated the H14CO3-fixation.This result indicates that free CO2 is an active species ofCi that is incorporated into the cell during photosynthesis. These results together suggest the following: (1) Free CO2 isutilized for photosynthesis, (2) CA is mainly located insidethe cell and functions to increase the affinity for CO2 in photosynthesisby facilitating the supply of CO2 from the plasmalemma to thesite of CO2-fixation.
3Present address: Biological Laboratory, The University of theAir, Wakaba 2-11, Chiba, 260 Japan. (Received December 9, 1988; Accepted March 22, 1989) 相似文献
19.
Characterisation of Non-Uniform Photosynthesis Induced by Abscisic Acid in Leaves Having Different Mesophyll Anatomies 总被引:29,自引:0,他引:29
Terashima Ichiro; Wong Suan-Chin; Osmond C. Barry; Farquhar Graham D. 《Plant & cell physiology》1988,29(3):385-394
The effects of abscisic acid (ABA) on photosynthesis in leavesof Helianthus annuus L. were compared with those in leaves ofVicia faba L. After the ABA treatment, the response of photosyntheticCO2 assimilation rate, A, to calculated intercellular partialpressure of CO2, Pi, (A(pi) relationship) was markedly depressedin H. annuus. A less marked depression was also observed inV.faba. However, when the abaxial epidermes were removed fromthese leaves, neither the maximum rate nor the CO2 responseof photosynthetic oxygen evolution was affected by the applicationof ABA. Starch-iodine tests revealed that photosynthesis was not uniformover the leaves of H. annuus treated with ABA. The starch contentwas diffferent in each bundle sheath extension compartment (thesmallest subdivision of mesophyll by veins with bundle sheathextensions, having an area of ca. 0.25 mm2 and ca. 50 stomata).In some compartments, no starch was detected. The distributionof open stomata, examined using the silicone rubber impressiontechniques, was similar to the pattern of starch accumulation.In V.faba leaves, which lack bundle sheath extensions, distributionof starch was more homogeneous. These results indicate that the apparent non-stomatal inhibitionof photosynthesis by ABA deduced from the depression of A(pi)relationship is an artifact which can be attributed to the non-uniformdistribution of transpiration and photosynthesis over the leaf.Intercellular gaseous environment in the ABA-treated leavesis discussed in relation to mesophyll anatomy.
1 Present address: Department of Botany, Duke University, Durham,NC 27706, U.S.A. (Received September 30, 1987; Accepted January 13, 1988) 相似文献
20.
Permeability coefficients (PS values) for CO2 of the plasmamembrane (PM) of the unicellular green algae Eremosphaera viridis,Dunaliella parva, and Dunaliella acidophila, and of mesophyllprotoplasts isolated from Valerianella locusta were determinedfrom 14CO2 uptake experiments using the rapid separation ofcells by the silicone oil layer centrifugation technique. Theexperimental PS values were compared with calculated numbersobtained by interpolation of Collander plots, which are basedon lipid solubility and molecular size, for D. parva cells,mesophyll protoplasts isolated from Spinacia oleracea, mesophyllcells and guard cells of Valerianella, and guard cell protoplastsisolated from Vicia faba. The conductivity of algal plasma membranes for CO2 varies between0.1 and 9 ? 106 m s1, whereas for the plasmalemmaof cells and protoplasts isolated from leaves of higher plantsvalues between 0.3 and 11 ? 106 m s1 were measured.By assuming that these measurements are representative for plantsand algae in general, it is concluded that the CO2 conductivityof algal PM is of the same order of magnitude as that of thehigher plant cell PM. Ps values of plasma membranes for CO2are lower than those for SO2, but are in the same order of magnitudeas those measured for H2O. On the basis of these results itis concluded that theoretical values of about 3000 ? 106m s1 believed to be representative for higher plant cells(Nobel, 1983) and which are frequently used for computer-basedmodels of photosynthesis, lack experimental confirmation andrepresent considerable overestimations. However, with severalsystems, including higher plant cells, the conductance of thePM for CO2 was significantly higher in light than in darkness.This suggests that in light, additional mechanisms for CO2 uptakesuch as facilitated diffusion or active uptake may operate inparallel with diffusional uptake. Key words: Conductivity, CO2, permeability coefficient, photosynthesis, plasmalemma 相似文献